my Renix issues...

Ok i bought my 90 renix a few weeks back. first it was a high idle issue. adjusted the tps into spec. well the best i could since its an auto and i cannot match the two values using cruisers info. ones off either way. well i bought a new one same thing. took it back and tried another. same issue. while i was in that area i seen my throttle blade stop was bent back. no more high idle!! but now i have a new issue. When i start it up runs great no idle issues and drives great untill it warms up. then it starts to idle low and you touch the gas it dies. but only in gear. Once it dies i can restart it and runs fine for 5 mins then acts like it loads up and dies.. im about to part ways with it. can anyone help??

try cleaning your idle air controller and throttle body. it might be so gunked up that it needed the extra air from the main throttle to run. also the IAC might be sticking.

I own 2 Renix era jeeps so I feel your pain but you just need to have patience with them. My guesses would be to look at the Idle air control valve- take it out and clean it or maybe heat soak on the fuel rail causing vapor lock?? when it dies again after getting warm use your keys to open that valve on the fuel rail and see if you hear air escaping out before the fuel finally comes out? My brother has been experiencing a similar issue with his 96 XJ getting hot and dying and then starting again after a few minutes of cooling off, we just wrapped the fuel rail with exhaust wrap to see if that keeps the heat out. We did this last night and he's out wheeling the Rubicon today so we'll see if it fixed the issue when he gets back.

I have cleaned the tb and iac. i will check for heat soak which ive delt with on my old 2000 xj. this just kinda confuses me since it only does it in gear. could there be a bad head gasket? its never overheated on me since ive owned it tho.

Adjust the throttle stop? Every RENIX I have owned has had someone monkey with that screw to fix other issues. You should idle around 600-650 in gear and don't trust the factory tach. Re-adjust the TPS after you get this set.

Anyone with a link to properly adjust that?

One thing you can do is to ohm test the TPS ground. Typically the ECU half of the TPS can achieve a "0" ohms, less than point five (0.50) is marginally acceptable. You can jump the ECU half of the TPS straight to battery ground for a test.

The TCU half of the TPS typically has a little resistance inside the TCU that you may never get to "0" ohms.

There is a built in adjustable bypass for the throttle plate. The adjuster is covered with a lead slug. Most times it comes from the factory fully closed, but some have it opened a little. If it is adjusted slightly open from the factory, clean out the passageway. Trying to adjust the idle from this bypass is futile, the IAC will just re-adjust again and you are back where you started.

I typically end up with 0.6 volts on the ECU side of the TPS and 3.8 volts on the TCU side of the TPS. If yours is way out try splitting the difference and see what happens.

Vacuum leaks can also mess with your idle, enough of a vacuum leak and it will eventually idle high, but a small leak and the motor management may try to compensate and sometimes over compensates and lowers the idle. I usually start out checking for vacuum leaks when troubleshooting idle issues and re torque the intake/exhaust manifold.

The throttle plate should be adjusted until it just barely clears the TB neck. My guess is so it doesn't (over a period of years) wear a groove into the TB neck. I typically adjust the throttle plate so I can slip a small piece of paper through the gap.

Also check the valve cover CCV vent tube coming from the rear of the valve cover. That engineered leak is part of your idle.

If all else fails you may have to use that throttle plate adjuster, clearance about the thickness of a Nickle is a good place to start.

I eventually got mine to idle right, it took me around 2 years and I finally found the solution by accident. The catch is I repaired numerous cable faults at the same time and I am unsure which one was actually causing my issues.

Side note, it took me awhile to figure out my harness had the ECU half of my TPS wired to ground through my TCU and the TCU half of my TPS wired into the ECU ground circuit. Somebody got their wires crossed. Made in Mexico by the lowest bidder.

Well i just changed my oil... Seems my fuel is seeping past my rings? You can see the gas sitting on top of the oil. id say its water but it sure smells like pure gas. any ideas?

Check your map sensor and the vacumn line going to it from the throttle body.

High idle on a Renix is usually caused by a vacuum leak. How do your heater controls work. Do you have defroster all the time? If so you need to check the hard vacuum line under the battery.

comatose760 said:

Well i just changed my oil... Seems my fuel is seeping past my rings? You can see the gas sitting on top of the oil. id say its water but it sure smells like pure gas. any ideas?

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that's a lot of gas!! I'd pull the injectors and see which one(s) is leaking. Just lay the rail and injectors on a piece of paper and cycle the key a couple times-- the leaker(s) will be obvious.

Well i pulled the rail and didnt find any leakers.?.?. tho as i was told to check i can smell gas in the vacuum line going to the fuel press reg. could that mean a bad reg?

regulator diaphragm shouldn't let any gas past-- if there's gas in the vacuum line, the regulator is bad.

comatose760 said:

Well i pulled the rail and didnt find any leakers.?.?. tho as i was told to check i can smell gas in the vacuum line going to the fuel press reg. could that mean a bad reg?

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Bingo! and will cause high/low idle issues!

Well i will get a new one and swap it in and let you guys know if it helps. Also has anyone relocated the ecu to the glove box? any issues that could arise from doing so? it was done by the PO and i was just curious if that could be affecting anything aswell. thanks for the help!!

comatose760 said:

Well i will get a new one and swap it in and let you guys know if it helps. Also has anyone relocated the ecu to the glove box? any issues that could arise from doing so? it was done by the PO and i was just curious if that could be affecting anything aswell. thanks for the help!!

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Are you sure its the ECU and not the TCU? The TCU would be easy to put in the GB but the ECU would be a wiring nightmare. Lots of things could go wrong there.

If i knew how to post pics i would post them of the ecu in the glove box. Im thinking of relocating it back to the factory spot. i guess ill just need to check the harness for any cut hidden or taped plugs that may have been disconnected.

comatose760 said:

Anyone with a link to properly adjust that?

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Cruiser’s Renix Throttle Body Butterfly Adjustment

Okay. Let's start from scratch. First off, that's not an idle adjustment screw. It's a throttle butterfly stop screw. It's purpose is to allow the butterfly to be as close to completely closed as it can be without binding or wearing into the throttle body. It was never intended to be adjusted in the field. But, Uncle Bob didn’t know that, did he?

Engine off. Back off the butterfly stop screw with a 3/32” allen wrench until the butterfly is completely closed. Now. turn the screw in until the FAINTEST movement of the butterfly opening is detected. This can be done more easily with the throttle body removed. If you remove the throttle body, be sure to replace the gasket underneath it after thoroughly cleaning the old one off.

Revised 07/07/2012

For a complete set of write-ups regarding your renix, click on the link below.

http://www.cherokeeforum.com/f51/cruiser54s-mostly-renix-tips-153657/

Ok so i installed the new fpr and no change.. at times its now missing on a cylinder or 2. so i come home from work tonight and get out my chilton man. to test everything. i start with my injectors. books say the should be 3-6 ohms replace if outside that range. hmm ok mine test at 14.5 14.5 16.5 16.3 16.7 and 16.5. wtf how is it running? how is this possible? is this book wrong? please help me.