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More Renix problems and questions

Gunter

NAXJA Forum User
Location
Aurora, Colorado
1989 mj
280,000 miles
running issues--
stutters at constant speed. runs good above and below the part where you hold throttle at a constant speed( like 55mph for example)

what I have done--
Cruiser54's ground and terminal cleanup ideas.i gained a lot of functionality back but not quite there yet.
new plugs, cap and rotor. and wires. new battery and alternator.
swapped radiator and got new(er) style overflow tank setup.
changed CPS on bellhousing
swapped out both sensors on throttle body , no change for the better or worse. it runs the same plugged in for both and unplugged for both.
cam sensor in distributor--swapped a used one in and no change from either sensor.


current problems--
ignition switch I ll fix this weekend
brake light switch/fuse keep popping and brake lights work and don't work etc.
will clean up trailer wiring as a preventative measure.
driveability is there, LOTS of power but it is idling high(this used to be very intermittent, now all the time)
and from time to time the stuttering while holding steady speed.
each time I change or repair something I gain ground but still cant hold steady speed and it kills my fuel economy.

thanks to everyone who posts
about getting my truck running smoother.

G :eeks1:
 
I had an O2 sensor issue that would give me a stutter or bucking right around 2200 RPM on a warm motor, seemed to be only with a constant throttle. I could accelerate through it or decelerate under it and it would run fine. I also couldn't rev anywhere near redline, it would crap out well below redline under load.

I replaced the O2 sensor and did some harness repairs at the same time, so I'm not really sure which was the problem, maybe both.

The O2 harness was cooking in the front of the exhaust manifold where the O2 sensor, knock sensor and engine temperature sensor harness runs up the front. I only figured it out after disconnecting the sensors at the bottom of the harness and pulling the harness up. The burnt part of the harness was pretty much invisible from the top. I did figure out I had an issue by ohm testing the O2 heater circuit. I had ohms with the O2 sensor connector disconnected. It was a partial meltdown, the circuit still had resistance but was partially shorting out.

High idle is most often a vacuum leak. I plug off every vacuum opening in the intake except the fuel regulator and see if the idle falls. Then I plug them up one at a time to see which raises my idle. The vacuum line running under the battery box is prone to getting eaten up, my guess is from spewed battery acid. The vacuum canister behind the front passengers side bumper is prone to breaking off the mounting tabs and then kind of rolls around inside the bumper, the vacuum lines pop off. Tighten down the TB, the gasket shrinks. Re torque the intake/exhaust bolts, they come loose. Sometimes the end studs on the intake/exhaust manifold will snap off if you look at them wrong. I usually leave the end studs alone when re-torquing.

A stuck open IAC or a misadjusted TPS can also cause high idle issues. If the TPS gets wet it is prone to idle the motor up, way high.
 
I had an O2 sensor issue that would give me a stutter or bucking right around 2200 RPM on a warm motor, seemed to be only with a constant throttle. I could accelerate through it or decelerate under it and it would run fine. I also couldn't rev anywhere near redline, it would crap out well below redline under load.

I replaced the O2 sensor and did some harness repairs at the same time, so I'm not really sure which was the problem, maybe both.

The O2 harness was cooking in the front of the exhaust manifold where the O2 sensor, knock sensor and engine temperature sensor harness runs up the front. I only figured it out after disconnecting the sensors at the bottom of the harness and pulling the harness up. The burnt part of the harness was pretty much invisible from the top. I did figure out I had an issue by ohm testing the O2 heater circuit. I had ohms with the O2 sensor connector disconnected. It was a partial meltdown, the circuit still had resistance but was partially shorting out.

High idle is most often a vacuum leak. I plug off every vacuum opening in the intake except the fuel regulator and see if the idle falls. Then I plug them up one at a time to see which raises my idle. The vacuum line running under the battery box is prone to getting eaten up, my guess is from spewed battery acid. The vacuum canister behind the front passengers side bumper is prone to breaking off the mounting tabs and then kind of rolls around inside the bumper, the vacuum lines pop off. Tighten down the TB, the gasket shrinks. Re torque the intake/exhaust bolts, they come loose. Sometimes the end studs on the intake/exhaust manifold will snap off if you look at them wrong. I usually leave the end studs alone when re-torquing.

A stuck open IAC or a misadjusted TPS can also cause high idle issues. If the TPS gets wet it is prone to idle the motor up, way high.

I have a photo of the proper routing of that harness, but I can't post photos. Crud.
 
I have a photo of the proper routing of that harness, but I can't post photos. Crud.

I found out today I can't post photos here, maybe admin is trying to save data storage or maybe Photobucket has changed their format again and I'm screwing it up?

I researched the legality of re-posting, excerpts, diagrams and schematics. And the gist of it was, it is OK for discussion purposes, but not OK for resale.

Now I understand your PM, thank you for the info. Routing that harness is a pain, it took multiple tries to figure out a way to avoid the exhaust manifold, not run out of cable and then not being able to reach where it needed to reach.
 
I found out today I can't post photos here, maybe admin is trying to save data storage or maybe Photobucket has changed their format again and I'm screwing it up?

I researched the legality of re-posting, excerpts, diagrams and schematics. And the gist of it was, it is OK for discussion purposes, but not OK for resale.

Now I understand your PM, thank you for the info. Routing that harness is a pain, it took multiple tries to figure out a way to avoid the exhaust manifold, not run out of cable and then not being able to reach where it needed to reach.

I've got a ton of great photos, mostly mine, but I wish I could share them on NAXJA.
 
I've got a ton of great photos, mostly mine, but I wish I could share them on NAXJA.

you should be able to post photos just fine, you just can't attach them to the post (attachments are uploaded directly to the forum, that is not allowed). they need to be uploaded to an image host like photobucket, imageshack, etc.
 
photobucket makes it very easy, you just upload the pics, click the one in your library you want to share, and it gives you a list of links to copy and paste into your post. for this forum you want the link with the
 
I think I ll head to boneyard and cut off a harness and see what the inside looks like with the grounds on the fuel rail side. I might have to try some brain salad surgery on it sometime. I ll get pics of it too and store them on my cloud space .


Have you ever indexed the distributor?

Connector refreshing throughout the engine bay?

Sensor ground test?

Replaced the Oxygen sensor?
 
I think I ll head to boneyard and cut off a harness and see what the inside looks like with the grounds on the fuel rail side. I might have to try some brain salad surgery on it sometime. I ll get pics of it too and store them on my cloud space .

Funny you should bring that up. I have a bad back, tracing wires through the engine bay is back breaking. I Pulled the complete harness out of a Renix at the junk yard. Now I open my binder with all my wiring diagrams, unroll my harness on the ground, figure out where point A and point B is on the harness on the ground and then go find it in the XJ. Sounds like the hard way, but believe me it is the easy way, especially if it your first time through that specific pathway. I have most all of the harnesses rolled up in five plastic buckets. While your at the junkyard, pull a large box full of those plastic tubing cable protectors with the slit in the side, all sizes and lengths off of any car handy. As long as your tracing wires in the engine bay or under the dash, you might as well up armor anything that may rub or chaff in the future. I also buy cable ties by the hundreds.
 
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