The original Renix injectors made by Siemens-Deka were only “one holers”. That means the fuel was discharged through only one hole.
Not the most efficient design by today’s standards. Modern injectors have at least 4 spray holes for better fuel atomization.
Another issue is the original injectors were prone to leaking fuel at a seam and spraying gas all over hot manifolds. Not good!!
A nice upgrade is to use Volvo injectors. The use of these injectors was pioneered by Programbo from Cherokee Forum when he suggested them to DFlintstone there. Flintstone was the guinea pig and reported excellent results. I have experienced the same results as have many others. The 746s, as they’re called, have the 4 hole design and the complete Bosch part number is 0 280 155 746.
These injectors can be purchased refurbished for not much money and are a direct bolt-in.
WARNING: AVOID THE CHICOM KNOCKOFF INJECTORS!!!
BUY ORIGINAL BOSCH/VOLVO REFURBISHED INJECTORS HERE IN THE USA.
You will experience smoother idle and better throttle response. Perhaps some MPG improvement also.
186 thoughts on “Best injectors for Renix”
Not to mention a slight boost in mpg. Injectors plus the ’89 or 90 ECU in an ’87 Renix Cherokee equals one smooth running vehicle.
So does an 88 or later TCU.
What mileage have you gotten on a highway trip with those mods?
Just got back from a 300 mile trip and averaged 20.6 mpg. Went through a quart of oil though haha.
Flintstone Here. I thought I picked more MPG “mucking around”. Yarden logs and getten wood on the trailer might have gone from 10 something to closer to 16. That might be a stretch. Hwy MPG went up, but less than two Mpg. Tough to isolate the two and other things changed as well. I’m pretty sure the swap pays back In $, (at some point), and the smoothness and snappy throttle response is welcome as well ! Testominails here> http://www.cherokeeforum.com/f2/1990-renix-volvo-bosch-19-280-155-746-injector-swap-163105/
With a little tail wind on the Hwy, I logged 24 MPG once, in my 90 with over 280K, and packen over 500 Lbs. of tools and stuff.
I ‘m pretty careful, I keep good logs…
Thanks for the mention. Actually I stumbled upon the 746’s based on someone suggesting the Volvo 702’s as an alternative to the Neon 703’s for mid-90’s XJs. This was based on a mis-print on the Bosch data sheet which shows the 702s and 703s being identical. In reality the 702 is just another version of the 746. That being said I first learned about injectors from Rainman who posts regularly on an Aussie XJ forum.
Well, thanks for your contribution. I’ve used other 4 hole Bosch injectors before. Traded them out for the 746s, and there is a noticeable difference.
703 will work in my 1990 xj though right
Not really. 746s are the proven best.
Negative on the 703. I tried them in my 89 with the snap on scanner hooked up and it went into closed loop for a minute. Then slowly the fuel trim went down to 0 from 128 and default to open loop.
Thing is, it ran great and couldnt tell it was in openloop save for the scan tool. I was due for a smog check that week so I’m glad I bought the snap on when I did.
Changed back to stockers and new 02 sensor passed smog. Now I have the yellow 746 and have passed smog withthem
Do you still have 746’s available?
I don’t sell them but they can be had on ebay.
I got a set of 746 today.
Was noticing the 4 tiny pin point size spray holes on the bosch, looking at the factory 1 hole 90 renix injectors it seams like the 1 hole would put out at least 25% more volume than the 746.
Also what is with the small plastic hat or cap on the end of the bosch 746.
any input appreciated.
Put em in!!!
How much money
I have an ’87 with 89 computers. tried the 703’s and they were too much so went to the 746’s. It runs great; starts, idles, pulls better but the MPG seems to have gone down the tube. I am not sure where to start checking. I did not remember the procedure for resetting the computer. Any help is welcome because my hopes were up and are now are rather deflated.
“Seems to have gone down” isn’t a scientific conclusion.
You need to do the calculations based on miles traveled divided by gallons used based on a full tank.
Drive it for a while. You’re not getting heavy on the skinny pedal now that it’s more responsive, are you?
Thanks for the quick response.
You are right. I should have been more explicit. I will do those things. It is typically driven to town, 50 miles each way, about every three weeks or so. The last trip the gauge went from just over 3/4 to just under 1/4, but sill not very scientific.
Tips 33 – 35 and 38 – 39 seem to be dead links on the index page.
That’s because I haven’t done those write-ups yet.
First off, thanks for all the tips. My coworker and I both own MJ’s and we refer to your word as gospel.
I just installed the 746’s in my 92′ Comanche Elim. Reason being, the Renix and HO both come with the same stock fuel injectors, so I figured why not try it out. The install went fine, and when it’s running it feels smoother and there is less noise coming from the engine. Power feels the same. Haven’t tested for mpg.
Only one issue: When I crank the motor is needs help turning over with a little tap on the gas pedal. I haven’t heard of anyone else having to do this. if I don’t tap the pedal, half the time it will start. I’m gonna recheck all my vacuums and such, but what’s your opinion on why this is happening? Maybe the 4-port injectors aren’t properly cleaned? Or the HO needs more juice? I’m not sure.
I would double check things around the installation process. Vacuum lines and such.
I’ve never used 746s in the later application, but I certainly see your logic.
Great work in developing these helpful, correct, and welcome Renix Jeep upgrades, Cruiser54. The tips on sensor tests and ground improvements worked quite well for me. Installing the dual-diaphragm brake booster upgrade has paid back in performance and safety. But my vote for “best tip” has to be: 4-port fuel injectors!
For 86-90 Renix Jeeps you nixed the 703 fuel injectors and confirmed 746 injectors: I heartily agree. My ’89 Wagoneer had developed one leaky injector, so I hunted a full replacement set. Another website had rec’d 703’s (nowhere stating the properly applicable year Jeeps), but with them my engine ran black-smoke rich and its ECU refused to learn to adjust for them. I resold the 703s on eBay, and then luckily found your website.
I followed your recommendation to install 746 injectors. Mamma mia! Now the Wagoneer idles and runs more smoothly than I’ve ever experienced. In a week or so I’ll have two 150-mile highway trips for MPG data to post here, too. Thanks!
Keep us in the loop. I’m pleased to hear of your successes. Enjoy your Renix Jeep!!!
January 30, 2018: in 400 miles of mixed speed-and-terrain highway travel, mostly 65 MPH, it averaged a familiar 20 MPG. So no MPG increase, but heck, the nice idle, smoother power curve, and quieter engine with the 746 injectors makes it a winner.
Thanks for the update. Very typical result.
Hi. Firstoffall sorry for bad english. I did the injector upgrade to my -88 4.0 renix, i buyed the 746 injectors, and installed them. But there is some issues, iddle is 1000rmp on D when car is stop, and car shakes litlebitt. On driving it feels like some power is missing. I just cleaned the throttlebody and adjusted tps. With the original injectors it worked fine, and there was huge different after adjusting tps and cleaned throttlebody. Could it be like too low fuelpressure, or what could it be? Thaks beforehand!
Did your injectors come with new o-rings? I would suspect you have a leaky one or two. easy to check. With the engine running, spray some carb cleaner around each injector. If there’s a vacuum leak there, you will notice an immediate change in engine rPM.
Yes they came with new o-rings. I l try that carb cleaner tomorrow, and report back, if there was some leaks. Thanks for the tip!
Did you use any oil on the o-rings before installation?
Yes, i used some basic vaselin to help them go on place.
Please inspect the hose/tube from your throttle body to the MAP sensor on the firewall. It may have been damaged during the injector installation.
Ok, i think i do “tip31” just to be sure in this case. Thanks for the advices!
You’re very welcome.
Hi again. So, i did test with startpilot spray to injectors, no leaks. And that mapsensor tube, is ok also. I measured fuelpressure, and it was 2bar when idlle, if reved it dropped to 1-1,5bar and raised to 2bar when idle. I tryed to raise pressure to 3bar, but no change. Feels still heavy to drive, like power is missing. And i just changed fuelfilter, so thats new.
can you translate the fuel pressure figures from bar to PSI?
I throw video to youtube about mesuring, the red scale of the meter is psi. https://youtu.be/AjDTnNFh6M8
I throw video of measurig to youtube https://youtu.be/AjDTnNFh6M8
The red rcale is psi
A bit late but i just found your wonderful website (’87 XJ with 305K – I’ve done only the last 3-4K). 1 Bar = 14.7PSI , so he is saying that he essentially has 30PSI at idle and 15-22 when revved.
Either the fuel pump is weak, or the internal hose from the pump to tank outlet is deteriorated from using ethanol fuels.
I was just wondering when we might get ur updated post on how to reduce cabin noise
Woulda been a long time ago if Mopar hadn’t discontinued the windblocker parts.
In the meantime, make sure the weatherstrips on the A pillar are sealed from top to bottom. The gaps between those plastic rivets creates wind noise.
Remove interior trim panels from rear passenger seating area to the tail gate exposing the interior metal of rear quarter panels.
Completely clean all interior surfaces of both quarter panels. Check drain plugs. Correct/ address any rust. Line interior side of both quarter panels with squares of ultra dense home carpet padding. Use 3M 777 spray adhesive to secure it. DO NOT COVER DRAIN PLUGS. Next cover all (nonvisible) sides of the interior trim panels with the padding, the same way. It will make them heavier. Re-install all trim panels. Enjoy! Noise level drops dramatically.
A few guys I know used “stall mats” from Tractor Supply (comes in 1/2 inch to 1 1/2 inches thick). Made a template with cardboard and then cut mats with Sawzall, Install from as high up (as possible) the cabin side of the firewall all the way to the back seating area (or whole interior if you like). Be sure to check under carpet for rust and address it. Ultra dense rubber stall matt reduces noise/ vibration without adding a lot of weight (40-45lbs max.)
As I’m moving my project along on the MJ the next thing on my list is a complete tune-up to include plugs, wires, distributor cap/button and injector replacement. Sounds like everyone is pleased and had good results with the Boschs. I’ve looked on EBay and there are quite a few people selling them, any recommendations on seller(s) would be appreciated if you have one.
There are Jeep community members supplying injectors.
jhc7399 on Cherokee Forum and Neil at http://www.meanlemons.com.
Found them over at the Cherokee forum. I’ll be ordering shortly.
Great. always best to support the community!!
Completed the 746 swap today, much better idle and appears to have a little more pep but the verdict is still out. Other than some missing parts on the fuel rail that the PO failed to mention to me I’m satisfied and consider it money well spent.
It’s a nice upgrade. Where did you get the injectors?
Over off the Cherokee forum, jhc7399, you mentioned his name on some earlier correspondence. Fast shipping and smooth transaction.
So get a load of this, the PO evidently swapped out one of the injectors, one of them was basically new, during the installation I found one of the bracket bolts missing that holds the rail in place and the retaining clip that holds the gas line in place on the fuel railing missing. The gas line tubing was just shoved up into it, I’m surprised the pressure in the fuel rail didn’t blow it out. Dodged a bullet on that one, had to order one and won’t be driving it until that is definitely fixed.
Just installed these and it’s like I have a new Comanche. Working my way thought all of these and loving the difference it makes. Cruiser you are awesome from a current Mopar service manager. Thank you for this sure it is amazing.
Gotta love POs…………
Was looking through the comments and didn’t see it asked, but am I guessing correctly that this wouldn’t work for us 2.5 TBI folks? If not, are there any options for injector upgrade/refresh? Thanks.
You are correct.
Have you refreshed the firewall to head ground yet?
Yes, I’ve completed tips 1-3, installed a new 02 sensor, upgraded to an aluminum value cover, and replaced the battery cables with a MeanLemons kit.
scrape the firewall mounting point to bare metal?
Yes, to bare metal.
I just ordered bosch equivalent #0280155703 injectors after doing some research that was the part# I came up with. Did I understand the previous comments that thats not right or just that theres better ones such as the 746s, because on ebay part #0280155703 is the most common for a 1990 4.0 cherokee. Frustrated and now confused, and I swear, you can engage the fuel pump and just watch a stream of fuel come out so just about anything is better than that. I didn’t come across mention of volvo 746s, neon and ford but not volvo and cherokeeforum is one of the spots I checked before I ordered. Good job on the site,good real world information
You might have gotten some bad ones. Return them and get some 746s.
To clarify my post from 9,7,18: I just ordered part# 0280155703 injectors on 9,7,18 because that was the part# I came up with, so is that right and will they work? The ones currently installed (probaly original) are the ones that are leaking. Side question, how do I disconnect the fuel pressure regulator from the hard fuel line? Push the two sides of the plastic connector and pull? I just want to make sure I’m doing it right so I don’t break anything.
The injectors in the provided link shows them as 830’s. In the description it said they were the 7.46’s
Give them a call and verify what they are offering.
Any advice on how to locate injector connectors that are compatible with the bosch 749 injectors and the 1990 renix?
I meant the 746
746 injectors plug right into the stock connectors.
I need to replace my connectors because the wire coating are cracked and hard. So I need one that fit the 746 injectors. And thanks for the replies.
My research shows aftermarket injector connectors with pig tails come with 2 white wires.
The factory 90 xj connector wires are black and green.
Does it matter which way the connector is wired in?
thanks in advance
Correct on the fuel pressure regulator.
Sure hope those two quick connects can be reused ’cause I can’t find them anywhere, even tried the dealership and what size are they 3-8 or 5-16? The injectors are #710s (ford I beleive) not #703s, that was confusion on my part. Sorry about that. Thanks for the input, it’s appreciated.
I was just wondering which injectors are the stock ones for the xj 88,cause mine’s have two classes of them, have four 53030262 and 2 4554130,and let me tell you this thing consumes big fuel and puke to much black smoke, so tired about it!
i’m aware of the 703’s ,746’s,but i can’t get those inyectors where ‘im living
recently i tried the Ford injectors F1ZE-A2B that i have as a spare but they won’t work
so any tip would be appreciated
I honestly don’t know off hand. Perhaps someone can chime in with the numbers off the stock injectors they removed when upgrading. All mine are long gone.
I recently changed mine out to the 746s and kept one of them. It’s in my shop someiwhere and I’ll see if I can find it and get a part# for you. I have an 88 MJ but I would think they are the same.
Just wondering, you mentioned that you couldn’t get the 746s, I ordered my online and had them shipped to me???
Couldn’t find the injector, thought I had saved one of them but evidently didn’t.
I wonder why he can’t get injectors. Any way we could help?
Well I replaced the injectors with the Volvo one’s. It does have quicker throttle response and seems to be smoother running down the road. But now at idle it sounds like it has a miss, only at idle though. It almost sounds like its cammed, kind of a lope. Any thoughts?
I bet you disturbed the line from throttle body to MAP sensor.
I did the injector swap and everything is running great with the exception of the fuel rail O-rings. Many years ago I lost (stepped on) the spacer that fits on the fuel rail just before the O-Ring. I double stacked the O-ring and everything was fine. when I did this install the double stacking wouldn’t work so I added another to make it seal. Does anyone know the OEM part number or where I can find this spacer. I do not trust the triple stacked O-rings and I would like to fix it the right way.
Thanks in advance.
The injector connectors for the 746 and stock injectors are the same and are readily available.
Randy, it doesn’t matter which wires go where on one injector.
Can anyone chim in on what is the small plastic hat or cap on the end of the injectors?
Does it get install with the injector?
Yep. Lube up the o-rings with oil and install them in the rail first.
Make sure you don’t bust the throttle body to MAP line in the process.
I replaced my injectors with 746.
I then tested the original 90 renix injectors using a 9v battery… but no clicking sound coming from them.
Do the factory injectors need tested using a 12v battery?
5 volts should fire them. Maybe they are being fired but are crudded up a bit.
Is there an upgrade or improvements from using a ecu from 90-92 XJ on a 87 Xj?
89 and 90 yes. Later than that are incompatible.
Hey I just want to know is the 746 injectors the only I should on my 87 jeep comanche or is it another compatible type
The 746s work the best. There are some others that will “work”, but I’ve replaced tose with 746s and there is an improvement.
Do you have any suggestions for the throttle body fuel injector? Would like to upgrade it if I could.
The volvo or bosch 746 injectors flow 20.2 and the factory 1990 4.0 injectors flow rate is 18.6.
The 746 injectors will cauae a rich condition and throw off your fuel trims..
Hmmm. I wonder why they work so well in actual real world experiences then.
My advice to you is to not use them then. Ignore the hundreds of success stories across the different Jeep forums and stick to your profound research results.
So I guess that you have a fuel trim study on them. Would like to see it then.
Just don’t use them if you’re not convinced by empirical evidence.
I don’t have a horse in this race and I provide this website at my own expense. My time is better spent helping others who are friendly and not contrarians. Please don’t come back here anymore. I’ve had enough of your crap..
You might want to double check the fuel pressure on a 1990 4.0l cherokee before you start spouting the figures. In reality, the flow rate is just a bit over 19.3 lb per hour in my experience. Enough to help, not enough to harm.
My teen sons and I just bought a 89 Cherokee to have fun, learn some basic auto mechanics and have more fun. Is changing the original injectors (225k miles) with 746’s a good basic job to try for us?
I would think so. I don’t know your skill level though. LOL. Cherokee forum has some write-ups. check them out.
Have you guys completed Tips 1,3,4, and 5 yet?
We have not completed those tips yet, but sounds like some good weekend projects. Probably got to find the OxGard and other supplies first. We’ll take on these tasks before the injectors. Also, vehicle seems to run rough when gas is less than 1/4 tank and turning corners.
Good plan. Hang loose on the injectors for now. Complete the Tips we discussed first.
It wouldn’t hurt to have the kids peruse some of the other Tips also.
Good hands on stuff. I admire your efforts to educate and spend time with them.
1987 Cherokee 4.0 with the Renix FI system. I’m swapping out the fuel injectors with 746s I got the injectors seated properly but when I tighten the fuel rail bolts to the manifold cover the injectors pull out slightly.
I’ve tried tightening the bolts in various sequences and progressively without any love. Does anyone have any advice?
Do they leak? If not, you should be just fine. Kind of a “wobbly” setup. A bit unnerving.
This is a case where I should have double checked first. They sent the wrong injectors.
Best to get refurbished 746s from someone on a Jeep forum.
I’ve been looking at these on eBay. Some sets of 6 as low as $35. That scares me because I’m thinking Chinese knockoff. Any legit dealers with good pricing?
If you come across an ad for injectors that says something like Bosch “type” injectors then they are junk Chinese knockoffs
You want injectors refurbished in the USA. The Chicom injectors should be avoided like the plague. Pun intended.
USA all the way!
Wanted to let you know that after completing several other tips, I finally got to check this one off the list. I wasn’t expecting a big difference, but I hopped in – after making sure we were leak free – normal throttle, and flung half the rocks outta my driveway. Hoping this helps with my horrendous gas mileage (broken manifold bolts not helping). Awesome work here!
Gotta love it!!
I need to reiterate something here.
Always get refurbished injectors done in this country.
The Chicom stuff is absolute junk.
It should help. If that original hose/pipe was leaking vacuum, your MAP sensor was telling the ECU to richen the fuel mixture. Enjoy!!
The 746 conversion for my 1988 Xj is almost complete. I am concerned about the “penetration depth” if the injector in both the rail and the intake port. I have never seen pictures of an installation to notice these details.
For the rail – There are two scored lines below the upper o-ring. Which of these should we place the injector clip in?
For the intake – How much of a gap between the yellow injector body and the intake?
I attach the injectors to the rail with the clips. Then, with the o-rings lubricated with engine oil, carefully line the injectors to the intake manifold and then push/hit the rail with my hands until all the injectors are seated and the rail can be fastened with the bolts.
I waited to see how the injectors settled as a result of the pressure from both o-rings before attaching the clips. This resulted in using the lower of the two grooves on the injector for the clip. Strictly, speaking, this is a partial groove because it is not continuous around the perimeter.
The other comment I should add is that the fuel supply line places a sufficient, yet small, pressure on the rail such that it biases injector #1 to be withdrawn from the intake slightly more than the remaining injectors (i.e., sight down the injector/intake line to check for this potential misalignment). I loosened the fuel rail bolts the following morning and applied pressure with my hand near the front of the rail and then tightened all rail mounting bolts. This improved how my injectors were seated at the intake. I never experienced leaks at any location throughout this process.
I purchased my 746’s from Motor Man in MI. Great source for refurbished injectors!
Installed 746’s today, they seem to seat right in and no leaks at the injectors. But, I have major fuel leak where fuel line meets the fuel rail with a quick connect piece. Ideas why there is a leak there and how to fix? Also, I am getting a lot more black smoke at the tailpipe after the F.I. Swap.
First off, fix the fuel leak. Here’s what you need:
Quick disconnect part numbers
The Napa part numbers for just o-rings *is:
Napa 730-5018 3/8 Viton individual o-rings
Napa 730-5017 5/16 Viton individual o-rings
*Remember to re-use your old spacer between the 2 new o-rings!!
Napa CRB 212305 fuel line repair kit 5/16
Dorman 800-750 trans line repair kit 3/8
Mopar repair kits:
83502745 fuel line repair kit 5/16
83504447 fuel line/Trans line repair kit 3/8
As for the black smoke, verify that the MAP sensor hose to the throttle body has NO LEAKS. This is easily disturbed when doing the injector install.
I agree with with everything cruiser54 stated. It is common for the o-ring or polymer washers to fall away from the fuel rail fitting when the supply line is separated from the rail when these sealing components are retained by the fitting at the rail.
I have the parts he suggests for the MAP/throttle body vacuum line upgrade and will be performing this task today. I noticed more black buildup on my tailpipe yesterday while preparing regions of my undercarriage for POR15. This told me I have a leak associated with this vacuum line.
Correct as usual. The vacuum hose from the MAP disconnected from throttle body. I had to make an adapter to reinstall. I will look into O-rings next. The leak is at the end of the fuel rail under the MAP sensor, I think that is the “return” side. Would that be 3/8 or 5/16?
Measure the metal piece to know for sure. Then let me know.
We replaced the o-rings (5/16”) where the fuel rail meets the fuel line return (up near the firewall) and no more leaks. I also re-connected the MAP vacuum tube. The engine is now purring along with no leaks and far less black smoke. Thanks for the help.
Hey cruiser I’m giving up on making my Jeep Cherokee run correct and thinking about going with a carburetor do you have any suggestions
I sure don’t.
Maybe you could help me it’s a 89 Cherokee and it starts to hesitate after warming up like it’s changing the fuel mixture I’ve checked all the sensors that I know about TPS IAC map sensor coolant temperature sensor manifold air temperature maybe I’m missing one
And those sensors” common ground? Have you cinched up your intake manifold bolts?
hey thank you for the reply i will check them and im going to order some injectors
Be sure to avoid new chinese injectors.
I had the injectors installed. My 89 definitely runs better, went from 14.5mpg to 18mpg last trip (mostly highway) but idles noticeably higher. Also, a lot of black soot coming out of the tailpipe.
Any suggestions? Should I reset the computer?
I truly appreciate what you have done on this site for everyone.
Have a Happy Thanksgiving!
double check the tube from MAP to throttle body. Has to be perfect.
Will do! Thanks!
Any solid resource to find the 746 injectors? Or an alternative for the renix?
I got my new Bosch Injectors from an E-Bay vendor in Latvia! Brand new in the original boxes. Not cheap but I couldn’t see how the injector itself could possibly be “refurbished”. Anyway, it runs much better now and the idle speed has dropped down to about 300 rpm and is very smooth. Throttle response is much better as well. Thanks!
That’s great news!! Thanks for the update.
The only problem is that the car is running rich especially at full throttle. It leaves a cloud of black smoke and I can see soot on the tail pipe. Will it take a while for the ECU to adjust or do I have another problem? It’s a 1990 Wagoneer with 165K on it.
No need for the ECU to learn the injectors on a Renix.
What DOES frequently happen in the install process, is that the line from the throttle body to MAP sensor gets broken in some way or another.
Nailed it! The tubing was cracked right at the point it entered the throttle body. I like the idea of installing a 1/8 NPT fitting but I didn’t want to get into pulling the throttle body at this point. I just used a piece of 3/16 brake tubing inserted into the rubber plug. Thanks again!
That will work!!
Well, the motor was still running rich so I re-installed the stock injectors and it’s running normally again. I’m a retired engineer so just putting it in it’s Last Known Good Condition. I need to drive it so I don’t have time for troubleshooting right now. Meanwhile I will work on more of your suggestions.
I love that philosophy. Running pretty good now?
Where did you source your injectors?
Running great. I got my new Bosch Injectors from an E-Bay vendor in Latvia! Brand new in the original boxes.
I just went to get the car smogged today and it flunked for the NO emissions. At 15mph the NO was 2609ppm and at 25mph it was 2194ppm. Max at 15mph is 71ppm and at 25mph is 613ppm. I believe the car is running lean now and it runs a little rough right around idle to off idle. The Hydrocarbons were only 50ppm at 15mph and 39ppm at 25mph. Max at 15mph is 123ppm and at 25mph is 103ppm. I guess I will check out the EGR valve next. Any ideas?
Make sure your intake manifold bolts aren’t loose.
drive it with the EGR valve hose disconnected and hose plugged.
I found two places where the crappy black plastic tubing was broken for the vacuum supply to the solenoid valve. I tested the EGR and the EGR transducer – all good. I read on another forum that the ECU switches the 12 volt ground to the solenoid on and off. Is that correct? When I put my voltmeter in the connector to the solenoid I get a constant voltage when the engine is running and warmed up to operating temperature and when rpms are increased. I put a vacuum gauge in the outlet from the solenoid and it briefly allows vacuum to pass when energized after rpms increase and then the vacuum bleeds off even though it is still energized.
Installed a vacuum test gauge by running a line teed into the line to the EGR valve. Drove around the neighborhood and observed it running on the average between 5″ to 7″ of vacuum.
I don’t know of a spec for the vacuum just before the EGR. Your intake manifold vacuum ought to be 17 to 21 depending on a few factors.
Cruiser I have a question I have 89 renix I just dropped a engine in after a debacle with the one previously in it. Took it out for a test drive and belt came off. Well long story short it over heated a block from the house so I limped it home. Now when I try to start it it makes a knocking sound and doesn’t start. Oil on the dipstick Is safe it’s not milky and smells like fresh oil. Prior to me trying to start it the starter would just hum, so I tapped it I mean barely tapped it with a pair of channel locks. Swapped the battery and it does that now.
Was it knocking when you got home?
Take a look at the starter. Loose? Drive sticking out?
Ended up being loose flex plate bolts thank God lol but now it won’t start tested the CPS and it’s reading 0.00 volts ac swapped to a another one I had lying round still same thing no spark and 0.00 volts ac. I know with the newer ones (99 that I had) if the cps wasn’t good or the asd relay was bad or such your fuel pump wouldn’t come on, which this one does, so my question is am I on the right track or should I check something else out?
What a coincidence on the flexplate bolts!!
You’re on the right track. Ever done the CPS mod?
I did the high altitude mod I need to waller out the bolt hole on that one still. It just don’t make sense that the CPS would just quit. Unless cause when it got hot the expansion tank blew out the side and sprayed the inside with hot coolant, I know a cps is sensitive to heat (I think). But the one I replaced it with was brand new from last year that I had took off when I sold the tranny. I’ll try that though and let you know. Preciate it. One last question though. Before the expansion tank blew out, it would idle fine and if you went wot it’d sound like a race engine but soon as you took off it would stumble and fall on her face for a few seconds then take off like a stripped ape, I know the renix disregards the sensor inputs at wot, what would cause that you think. TPS is adjusted fine I thought maybe a bad ground on the map sensor. But unfortunately it’s a h.o. (highly overated) block and I just spliced the coolant temp sensor wires and ran them to the sensor in the thermostat housing it still has the sensor sending unit in the rear of the block, so I figured I might be able to get away with it. Unless the resistance is different for the two sensors on the housing and side of the block. But I’ll stick to one problem at a time I reckon. Lol once again preciate help.
Coolant Temp SENSOR is in the thermostat housing? That big sucker?
No it’s the h.o. temp sensor in the thermostat housing lol I was just wondering if the resistance would be different tween the renix one in the side of the block and the smaller one that the h.o. used in the thermostat housing lol
Ok so I’ll get the CPS figured out and then I’ll work from there lol
Unplug that HO sensor and see what happens.
Had to order the cps that one wasn’t no good it’ll be in tomorrow but I did find out the 92 and the 87-90 coolant temp sensors are the same size just different sensor resistance so I put the renix one in the thermostat housing. Waiting til I pick up the cps during lunch tomorrow to try it out. Cross ya fingers and hope for the best for me lol
we need to clarify some things.
The temp SENDER is for the dash gauge. It mounts at the driver’s side rear of the head on a Renix and early HOs.
The temp SENSOR for Renix mounts in the driver’s side lower part of the block. It tells the ECU the coolant temp.
Yeah I know sender is 3/8 wrench size back ofthe head. the sensor for the ECU in the water jacket on side of the block is 3/4 wrench same size as the sensor that’s in the thermostat housing on the block I have. The renix sensor should measure temperature for the ECU regardless of if it’s in the side of the block or the thermostat housing correct? Wish there was a way to post a pic of them side by side to show you what I’m talking about.
Yeah. Sorta. After the thermostat opens.
Well that was a bust still not getting any spark. Idk at this point, that’s 3 sensors now. I mean I pushed the sensor down as far as I could get it. Still nothing. Oh well back to the drawing board I reckon less you know some one interested in a renix. Lol
Do you have your meter set on AC millivolts when testing the CPS?
I will this time though I weren’t sure where it was on this little craftsman multimeter I got bit I got it figured
That will be what you need.
Ok quick question then bub I was going through my 90 xj fsm figured it would work for my 89 being it’s still a renix. But I digress, anyways I was going through the diagnostic chart for the ignition system and it said down near the end of stuff to check for to check for voltage at the icm at terminal 1 at A & B and that it should have 9.5 volts with engine cranking. My brother was curious on the output at the icm so he checked it real quick and it was only pushing 6.5 volts while cranking. I know I should only do one thing at a time while running down my no spark problem. But was just curious bout that.
both years are the same. as far as ICMs.
I do preciate the time you’ve taken to help me here. I do love this jeep but it’s like a love hate relationship I love the simplicity of it, but I hate it at the same time if that makes any sense lol
We’ll get it.
Ok I drilled the top hole out on the cps mounted it and tested it. It tested out at .35 volts so it’s good but still no spark. What setting would I put the multimeter at to test the voltage to the icm. My little brother ain’t here so it’s gonna be just me doing it with a jerry rig remote start. Plus if it’s tests good should I move on to the coil. We ohmed it the other day but I can’t quite remember the numbers. But I do have some spare H.O. coils lying round could I possibly wire the harness for the H.O. coils to some female spade connectors and connect em to the tabs the renix coil sits in if the renix coil is bad? Sorry for the long questions, I’m just ready to get this thing on the road.
12 volts DC.
The HO coils are not compatible.
I know it’s late well late here but just outta curiosity, you could check for continuity on a coil right? I was in the process of cussing her and getting ready to tear every bit of electronics from the fuse box on outta her. And I figured I have my multimeter right next to me I’ll just pull the coil real quick and test the continuity on it. Neg post and positive post it beeped but positive to the coil tower didn’t do nothing so idk figured I’d ask if you could test it like that cause if so I think I found my problem. (Fingers crossed) And once again preciate you taking the time to help.
I saved this long ago but have never used it.
Three wire connector:
A = +bat voltage (from latch relay)
B = Ground….
C = Tach
Two wire connector:
only wire hooked up = spark pulse from ECM (5v square wave)
So, as I figured above, the ICM is just another version of the Duraspark II ICM (or more accurately, ignition amplifier, since all it does is take a TTL pulse and amplify it into ignition coil drive).
This one just gets the pulse from the PCM instead of directly from a hall effect sensor in the dizzy….
So, I rechecked the ground wire to the ICM (unplugged the 3 wire connector, measured from the B pin in the connector to the – battery pole. 0.1 ohms. Then I rechecked the +voltage. Battery voltage present when key is on..
So, I hooked up my scope to the 5 volt pulse line (back probed, both plugs connected to ICM) and grounded its ground clip
The ECM provides a nice pretty pulse both when the engine will run (it was nice enough to run for 30 seconds while I did this test) and when it has no spark.
When the engine died, the pulses continued until the engine stopped spinning (as one would expect with the key in the on position).
At this point, it is my opinion that if I can send a pulse into the amplifier (ICM) and not get a spark out, then the amplifier (ICM) must be bad….
Ok cruiser you lost me on that last one. 1) I don’t have a scope to check with. What I did manage to do was check voltage at 5V pulse line with my multimeter (not sure if posed to but I used the lightest volt DC to test it.) It had 4.8 with ignition on,pulled the coil and checked positive side of it with starter engaged it was at 9.45 +/- .05 during cranking and still no spark. Top it all off I can’t find a ICM anywhere. Rock auto it’s out of stock I even tried the ma and pop parts store here they ordered it sat but called today and said the place they use doesn’t manufacture em anymore. I’d try oriellys but I’m sure since it’s a special call store to order deal I’ll be told they don’t know where to get one.
There’s only 4 junkyards in Oklahoma I know bout and outta them four there’s only one renix style Cherokee. And it’s been there for a min so idk if it would even have the ignition control module in it still.
If you’re on any of the Jeep forums, you can let them know you need one.
I might have one.
That would be awesome. I’ll check on the forums first. Preciate it Cruiser.
Elijah, did you locate a ICM?
Try Amazon APDTY 109296 or Crown 33002299.
I am fighting my own battle of a engine that stalls when it is good and warmed up, not had time to trouble shoot, but suspect it too needs a ICM but I have old spare.
Have you completed any of my Tips?
Yeah I ended up getting one off of a 1990 Volvo they used the renix hardware back then I reckon cause of Renault and such but now I’ve got another problem busted my main shaft off my t-case it’s a 93 aw4 with a np 231 like busted flush with the t-case and no one makes one any more can’t find one in years compatible except for one outta 231dhd but not sure of the year of the truck so I don’t know if it’ll work no Cherokee in the local pull a part I don’t even know if one outta grand would work cause of them being hooked to a chrysler tranny in the range of years I need
Not yet, they are on the to-do list. In my case, the engine just sputters and dies after it has been running and driving for ~20-30 minutes. I suspect it is the ICM or coil finally getting hot enough to quit, but I want to do more troubleshooting (and checking all those splices) and checking the fuel system before changing it out. My rig is a Renix 4.0 from a Cherokee installed in a ’80 CJ5, with a ’95 head/intake/throttle body.
What about injectors for a 1986 2.5L?
Sorry, I have no recommendations on that.
I’m thinking about just installing one of the Volvo injectors now that I have the Renix Diagnostic display. Then I can check the injector pulse vs the other ones.
That might be interesting.