My Renix STUMBLE,BACKFIRE fix

Well after month's of battling with my cherokee on the issue of stumbling,backfiring,poor idle,bucking etc etc... I HAVE FOUND A FIX!!! not sure if this will help you guys but i figured i would post it just in case..

I went through pretty much every sensor,checked and replaced a few but there was one sensor i overlooked. The INTAKE AIR TEMP SENSOR!! One stupid little sensor and that was my problem.. i unplugged it and the truck ran like new again. Never would have thought that this sensor would cause these problems but it did.

The inspection for this sensor is to run the vehicle up to operating temperature, turn off vehicle and check resistence across the sensor, should be around 185ohms @ 100c or 212f, my sensor was around 1400ohms, which is very high.. The vehicle will run without the sensor but is cheap enough to buy so i'm gonna replace it.

Hopefully this can be of help to some of you guys out there experiencing similar issues.

Happy trails, 88rubixj

Is this the sensor mounted on the intake? Not on the throttle body....

yes sir, sure is.

Ok, cool. Is it something that can be cleaned, etc? I never took that one out yet, never thought to

I had to replace mine last year. At the time it was causing both idle speed (high idle) problems and first morning cold engine starting problems.

its a fairly cheap sensor i would just get a new one, don't bother cleaning

I'm not having any problems anyway...

Sorry for dragging a post back from the dead, this is my exact issue, where would the sensor be located?

It's on the intake manifold, behind throttle body. It has 2 wires coming out of it.

I think I'm going to try to pull that thing out as an experiment.

good catch on the air temp sensor. My MJ ran like crap in open loop mode and then after it went into closed loop, it had an extremely irritating and constant miss between 1800 and 2000 rpm. I had tested or changed all the usual suspects with no luck. After i saw your post, i disconnected my air temp sensor and voila........she runs like a new one...

tugalo said:

good catch on the air temp sensor. My MJ ran like crap in open loop mode and then after it went into closed loop, it had an extremely irritating and constant miss between 1800 and 2000 rpm. I had tested or changed all the usual suspects with no luck. After i saw your post, i disconnected my air temp sensor and voila........she runs like a new one...

Click to expand...

While I diagnosed a bad Air temp sensor and replaced it I never tried running with out. Interesting that you say it ran great with it disconnected.

I do know that the O2 sensor and CTS sensor can be disconnected to test for bad sensors thus forcing the engine into a rich burn, open loop mode. I guess the TPS, CPS and MAP sensors are the only real hard core must have sensors to run and drive in open loop, or limp home mode.

After I posted that message, I got to thinking about it...just before i disconnected the air temp sensor, I fabbed and connected a really heavy ground wire to the block/chassis.
I did notice that the MJ was trying to load up a little after driving it awhile with the sensor disconnected, so I removed the air temp sensor and it was gunked up. I cleaned it with carb cleaner and gently torched it to watch the resistance change....it was working fine altho the resistance was a little high.
Bottom line is....I now believe that it was the improved ground that solved my major problem altho the air temp sensor may have been a contributor.
I suspect that driving around with the sensor dis-connected would eventually cause you to run pretty rich and raise cain with your mileage.