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I’ll throw in my vote again for a bad cam sensor in the dizzy. I may be way off since I’m by no means a renix guru. But most efi systems pulse the injectors based on the cam signal. It may be though as @scaleless mentioned that it can batch fire to at least get it running without a solid cam signal. But for many engines (especially those using only Alpha n), a bad cam signal will cause a no start

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11 hours ago, gvthnks said:

Just went through something similar with an 87 that had sat for 11 years.  Be sure your injector wires are hooked up to the correct injectors.  On mine there was enough room for there to be confusion. 


If it'll run on starting fluid, it's a fuel issue.  On mine, I ended up with the head off and engine out to replace all the freeze plugs and lifters but the injectors were so fouled with gunk on the bottom where the fuel was supposed to come out, that even if they were firing correctly, it wouldn't have been good. 

 

Like others have stated, check that map hose not just where it plugs into the map sensor, but also where it plugs into the throttle body.  Mine was sucking air there too causing issues.  Check all the other vacuum ports too and make sure the EGR valve isn't stuck open.  Crack the throttle just a hint when you're cranking.  I've seen the idle air control valve so badly dirty that it wasn't letting anything through and the engine can't run without air.  Cracking the throttle will bypass the IAC and allow enough air in to let it start and run.  Clean the IAC and throttle body when you can.  Nothing will work correctly if the TB unit is very dirty.  As a matter of course, I clean the IAC and throttle body on every one of these engines I work on, cause they're all dirty.  Then you've alleviated that as a possible issue and I guarantee you it needs it anyway. 

Mine would run on 4 cylinders when I first started trying to get it going, but I had to crack the throttle some to get it to crank.  That told me the IAC was dirty or non-functional.  Easy fix. 

 

Lastly, don't fret.  If it ran before, it'll run again.  Go over Cruiser54's list and read through all the comments on his page.  There's more knowledge there that's renix specific than anywhere else I've found.  I've had probably 15 of these 6 cylinders over the years but avoided the renix versions.  After reading some theory about how it works and the common failure issues, it isn't so bad.    The info here has helped me tremendously getting mine resurrected.  It's not on the road yet, but we're getting close. 

All wiring to the injectors is correct, we found a wiring diagram and checked, we are only getting .25 volts to the fuel injectors once the engine is started and running off of brake clean. Any thoughts on what this might be? We also took the ecu out and uncovered it. It looks brand new, no corrosion 

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On 6/27/2021 at 2:22 PM, JMO413 said:

This is the first place to start. IMHO

So we only have .25 volts going to the injectors when it’s running off of brake clean. We check the inside of the ecu and everything looks very clean, no corrosion! Any more direction? This is where we’ve narrowed it down to

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Using a voltmeter or 12vdc testlight (preferred) check for B+ on the following pins (use battery negative terminal for ground):
D1_5:  B+ (Hot at all times)
D2_4:  B+ (Hot during KEY ON/CRANKING).
D1_6:  KEY ON (B+ (Hot for 2-3 seconds)) or CRANKING (B+ (Hot during CRANK)).
 

D1_D2.jpg.6a80c3f7836373dcaeefc968569a8d65.jpg

 

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14 hours ago, scaleless said:

A cheap meter won't accurately read such short pulses even on AC.  I would ignore it. 

Agreed.  Use a test light, and if it's pulsing, the voltage is most likely fine.  Now whether the injector is bad or not and not pulsing like it should is another matter.  The possibility of all of them going bad at the same time is remote however so I'd look for another culprit. 

 

Spray starting fluid down the intake hose while trying to crank it.  If the problem is fuel related, it'll pop, cough and start for a second or three.  If not, there are other issues.  Have you taken the injectors out of the intake to inspect them visually? 

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1 hour ago, gvthnks said:

Agreed.  Use a test light, and if it's pulsing, the voltage is most likely fine.  Now whether the injector is bad or not and not pulsing like it should is another matter.  The possibility of all of them going bad at the same time is remote however so I'd look for another culprit. 

 

Spray starting fluid down the intake hose while trying to crank it.  If the problem is fuel related, it'll pop, cough and start for a second or three.  If not, there are other issues.  Have you taken the injectors out of the intake to inspect them visually? 

Everyone on this thread who submitted direction and help, I really appreciate and want you all to know that it paid off. We checked voltage coming out of the map sensor last night and noticed it was off, so we picked up a new one from the parts store and threw it on today. Low and behold, she fires right up and idles very well! I couldn’t have gotten here without you all. Thanks for the help! But this probably won’t be the last time I need advice on my Comanche, so keep your eyes open for another help message! Lol. 

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4 hours ago, JMO413 said:

Good to hear you got it fixed.

Couldn't have done it without you! But sadly, I have more bad news. For reasons that I probably don't have to explain, the transmission is cooked. We dropped it the check the slave cylinder and rowed through the gears and are missing at least half of them. Is there an expert you could possibly point me to on AX15 swaps? I want to know what all it would take to make the swap. I found an AX15 with a transfer case and both drive shaft included for a decent deal and was wondering what modifications needed to be made before I jump into this. Thanks again!

 

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5 hours ago, Jackh37097 said:

Couldn't have done it without you! But sadly, I have more bad news. For reasons that I probably don't have to explain, the transmission is cooked. We dropped it the check the slave cylinder and rowed through the gears and are missing at least half of them. Is there an expert you could possibly point me to on AX15 swaps? I want to know what all it would take to make the swap. I found an AX15 with a transfer case and both drive shaft included for a decent deal and was wondering what modifications needed to be made before I jump into this. Thanks again!

 


Many of us have done an ax15 swap. Perhaps post up a new thread to get more views and relevant help to the new issue. I’m sure many will chime in. 

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In addition to the AX15 and matching tcase, you will need the crossmember, and tcase shift linkage.  The BA10 crossmember doesn't fit.  The tcase shifter can be "modified" to fit.  

 

What year did the AX15 come from?  The input shaft tip changed sizes in 94+.  You may have to change the pilot bearing/bushing.  Pre 94 - 1/2" tip; Post 93 - 3/4" tip.

 

Does the AX15 have the internal or external slave cylinder bell housing?  The external is more desirable.

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2 hours ago, 87MJTIM said:

In addition to the AX15 and matching tcase, you will need the crossmember, and tcase shift linkage.  The BA10 crossmember doesn't fit.  The tcase shifter can be "modified" to fit.  

 

What year did the AX15 come from?  The input shaft tip changed sizes in 94+.  You may have to change the pilot bearing/bushing.  Pre 94 - 1/2" tip; Post 93 - 3/4" tip.

 

Does the AX15 have the internal or external slave cylinder bell housing?  The external is more desirable.

I’m looking at getting a ‘90 ax-15 Cherokee swap with Cherokee transfer case and driveshafts. Is there any modifications that need to be done to a kit like the one linked below? Will the driveshafts swap from a Cherokee to a Comanche or can I get by with the old driveshafts?


https://www.ebay.com/itm/284286961907?_trkparms=aid%3D1110011%26algo%3DHOMESPLICE.DISCLISTINGS%26ao%3D1%26asc%3D20191002092920%26meid%3D4f0ab6e23ede4e088b59e254a2643c5c%26pid%3D101103%26rk%3D11%26rkt%3D12%26sd%3D184796932053%26itm%3D284286961907%26pmt%3D1%26noa%3D0%26pg%3D2332490%26algv%3Ddefault%26brand%3DJeep&_trksid=p2332490.c101103.m3021&amdata=cksum%3A2842869619074f0ab6e23ede4e088b59e254a2643c5c|enc%3AAQAGAAAB8JfWYvsr%2B6d3onOc1mKrK9T%2FMlmA3m3nXoQM8llyEhqiRCbqCmuCsUiJo%2BKqg6EGskzu7UEz7i5FSc20PNtlrEZWHRPyLU2ErW8l6ANE02M7q9imdplUo%2BYhtdK8y6Dev6YQTsSex7mJdE%2FaoqblcWXhOPE9CDq%2FhzP27NagyWWlOidY76kb9Db%2FkvvrTWwwjV2i6%2FP22fU4d8%2Br5agE%2BY08E4ymI2NC5tHIfZXMzz7YjAPuPtoUGAlTYepdT%2BSGwEGG%2F0vDbLN0JEYUsvtfJrnjDc4FudR%2BnVDALrmf4mH1vUQRmrQIKvRcg%2BieRdrTA%2FRTUjV4AuOK14UERun7QbIvftJN3lYEVTrCCSIx9XWrZoY3s8tWJPfZSTD9dHJZuMHpGYikjhPB3jcirw6lmozNLOqs%2B5fU4t9KUd1sJT4DJIAbu9VAMcHJvOfkLo1IzKocNF6z3%2F9DenZXYtZU0QoXiY9JRHQFvYIOWJg7EzlOeT1cQlvQyxlNrcsJp8JLaNNvK4A5%2FjJ145lIgx5SqCdiSd07eaeF%2BOQ54k%2FWlNYwdG3o%2FSPINcuw5hdrPNkKN0pOOXfQW7ir7F6JErckD%2B71w36hX588%2FBz21jCqplJgt9vRYR4psgn7Kopur04tNoOu%2BRP1c3iqB%2FAXMcuAArU%3D|ampid%3APL_CLK|clp%3A2332490#

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1 hour ago, Jackh37097 said:

I’m looking at getting a ‘90 ax-15 Cherokee swap with Cherokee transfer case and driveshafts. Is there any modifications that need to be done to a kit like the one linked below? Will the driveshafts swap from a Cherokee to a Comanche or can I get by with the old driveshafts?

 

You can keep your driveshafts.  The XJ rear DS will be too short.  The front is the same for both MJ and XJ.

 

The picture shows the bell housing has the external slave cylinder :L:.

 

The tcase shifter in the picture looks like a YJ not an XJ.  If the set up came off a YJ, the tcase is clocked differently to the trans.  If so, when you install the tcase it may strike the bottom of the floor.  

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24 minutes ago, 87MJTIM said:

You can keep your driveshafts.  The XJ rear DS will be too short.  The front is the same for both MJ and XJ.

 

The picture shows the bell housing has the external slave cylinder :L:.

 

The tcase shifter in the picture looks like a YJ not an XJ.  If the set up came off a YJ, the tcase is clocked differently to the trans.  If so, when you install the tcase it may strike the bottom of the floor.  

I’ll have to get in touch with the seller and see if they may have the wrong picture. They sell a yj swap and an xj swap, but I think they used the same pictures. Hopefully the pictures are wrong and the cherokee swap will actually have the correct transfer case! You’ve helped me so much just by confirming that I can use my old driveshafts! Lol. I couldn’t find a source anywhere that said whether they could be used or not!

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The tcase may hang too low or strike the bottom of the floor.  I cannot remember which way it clocks to the trans.  Either way, a YJ tcase clocks differently than an XJ tcase.  The difference is from the bolt holes at the rear of the transmission, not the bolt holes on the tcase.

 

Also, looking at the pictures of your MJ, the grill is upside down.

 

Complete your signature: MJ yr., engine, trans, any modification done by you or a PO.  Include your location: state (US) or province (CA).

 

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I’ve got another question for ya’. The AX-15 sounds great and is exactly what I want to do, but where exactly is a good place to get a used one from? I was wondering if there was a decent company that sourced old ax-15s and resold them or if you just have to get lucky at a junkyard? Thanks!

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Junk yard!

 

The AX15 is not difficult to work on.  Having a shop press (or friend with one) is good to have.  Otherwise, some basic tools are all you need: socket sets, snap ring plyers, rubber mallet, feeler gauges...

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