allevolution

2000 Jeep Cherokee 175,000 miles.
Just finished installing a 1998 AW4 and NP231 that was known to be good.
Used Merc/Dex Trans fluid because Dex 3 was not available.

Ok so heres all the info I can gather and the story:
Car ran great for about an hour.
Even idled like a champ for about half of that time.
On a short drive the car started to "buck"
Bucking to me is an intermittent loss of power while accelerating.
If I keep my foot completely steady on the throttle, the car will cut in and out of power. Like I am playing with the pedal.
It mostly only happens under load, if I shift it to neutral and rev it most likely will respond instantly like normal.

On the ride home the car struggled to idle, idle was low and even while driving at speed the car would loose power and nearly stalled a few times. Its almost like it was struggling to run. It does smell strongly like fuel, So my first idea was an O2 sensor?
But so on, the car would not have any power unless I floored the gas pedal and then let off. And even with that method, the car was on and off with the power at anything else less than 100% throttle.
It scared me at first because I had originally thought it was a transmission issue, But I am pretty sure I can rule that one out.

Today the car can barely idle, actually almost stalled a few times at idle.
I can smell alot of fuel. Fuel pressure holds steady at 50 psi at key on and while idling. Occasionally at idle it sounds like one
(maybe two?) cylinder is missing. I would say it could be a spark issue. But then again all the ignition parts are new quality dealer parts (and this car has been looked over well over in the ignition department.) Previously had an issue with the CamPS signal wire in the PCM plug but that was all fixed up.

On really cold starts and occasionally warm starts, it will literally sound like I have a huge cam in it. Camming is the best way I can describe this problem idle.
I would say the "camming" idle is the closest to the normal idle I can get the car to do now. So why would the engine be imitating a huge cam would be a good question? I should mention this idle would occasionally come around previously, long before the huge drive ability issues I am having now.
And I can admit the car acted similar to the way it is now IF the "camming" idle would occur on that cold/warm start up.
I would previously resolve this "camming" idle by turning the car off, and then start it again and the car idled perfect and drove great.
I really think this "camming" idle could point to the issue now that I think of it.

I tried to disconnect the TPS after the motor was warmed up. The motor ran exactly the same as with it connected.
IAC would be my next idea, but it doesnt make sense to me on how that would affect engine above idle?
I dont want to bias everyone's answers on my issue, But I really want to point to the O2 sensor. I did spill a little amount of trans fluid on the sensor while removing the trans, but majority of it seemed like it hit the O2 wiring (on the sensor itself) and didnt seem to pool in the connector of the sensor. I had it hanging upside down to prevent any fluid from sitting in it. And I remember connecting it and inspecting the plug to make sure no fluid was in there.
Dont know about the cars history, but I would bet its original 175K sensor.

It would seem like from my short period of driving it that, The issue is from 0RPM- 1750RPM. If I can get it near 2000RPM it would seem like I am fine in that gear until the next gear.

Any input would be greatly appreciated. This is my 3rd Jeep and I would hate to leave the Jeep game with my tail between my legs!

allevolution

I should add, NSS is missing and has been for a while. It broke a while back and I didnt see the importance of replacing what seemed to be only for the reverse lights/which gear would allow starter to power on.

allevolution

One more thing, I know reading the codes is #1 to solving this.
I am awaiting my friend with a scanner, I will report back with the codes as soon as he comes around.

allevolution

Alrighty 8 codes great just what I wanted to see.. I put them into lists depending on how I see them

Codes imo that could help resolve the solution are:
P0118- coolant temp (could this really cause an issue? Heard of it before but never thought this could cause any real issue)

P0132- front O2 reading to high voltage

Pending: P0141- O2 Sensor Heater Circuit Malfunction (Bank 1, Sensor 2)
(I am guessing this is the rear sensor? but not sure)


Codes imho that I dont see as a threat:
P0443- evap (oh great just what I need on top of the original issue)
P0123- TPS voltage to high (disconnected for test)
P0122- TPS voltage to low (disconnected for test)
P1899- NSS? Hard to find this code
P0138- rear O2 (wiring is tangled, sensor was caught in driveshaft not an issue)

allevolution

After a quick google search I am thinking its the
P0118- coolant temp

"A coolant sensor that always reads hot may cause cold driveability problems such as stalling, hesitation and rough idle."
That would sum up my issues to the exact point. Minus the fuel smell occasionally.

Let me add to that, I have a 160 degree thermostat. Could that also trigger the P0118?


--Just went out and played around with the coolant temp sensor connector. It is broken but I managed to zip tie it around the thermostat housing pretty tight. (no room for movement)
It idled very well for a short time, But then as soon as I went to accelerate it had same "bucking" accelerating issue as I described in post #1

Muaddib420

Try getting a new temp sensor. They're cheap and you're throwing a code for it anyways.

allevolution

I was more thinking it was the connection that I just fixed because I didnt really have a chance to drive it around to see if the code would stay or not.

But going to the parts store now.. ah I miss having money in my savings account jeeps eating it all..

allevolution

Well I never got around to the store. The Jeep was bucking to bad I didnt want to continue on driving in traffic. Considering I could only floor it to move.

Just drove it back this morning for about 15 minutes I would have to floor it, driving highway speeds 40-60mph

But after that first 15 minutes it kind of smoothed out and almost was driving normal.
So what would be most likely to be affected by not being in use? My guess is the O2 sensor.
I also did notice downshifting from 2nd to 1st was really harsh. Everytime I came to a stop I could hear it downshifting shifting harshly. So that makes me wonder if the line that goes by the throttle cables could be kinked? I forget what its called but its for the valve in the trans that allows it to shift according to throttle position. OR is my transmission done?

allevolution

Let me add to that, I noticed spider webs in the downpipe of the exhaust (right before the first O2) and I wonder if some debris in the sensor tip could affect its operation?
And possibly be slowly burning off?
I would usually just throw money at parts by now, But being unemployed I have to be conservative with my money.

Backfiring and bogging, if it feels like giving me a hard time. I am thinking it could be running lean maybe?
High voltage code from #1 O2 would be a rich signal from the O2 sensor. So then the pcm would lean out the fuel mixture to reduce the sensor's reading.
So Im guessing this is what I need to keep an eye on?

Just doesnt make sense to me how its so temperamental and runs decent sometimes, but other times can barely idle?
Someone please point me in the right direction

allevolution

Bump?
Someone give me some input please
My only car, Im about to fail out of college and loose yet another job if I cant make it there..

allevolution

Bumpin again..

Im almost positive it is the TPS as it is really temperamental.
Even though I back probed the signal wire and was checking the voltage range.
It varied from:

0.475- 0.875V @ 0% throttle
to 4V @ 100% throttle
And yes the range appeared to be smooth with no dead spots.
The car continues to run rich and I can smell the excess fuel very much so.



I would suspect the IAC, BUT the issue seems to be more than the car at idle.
Again issue area with the bucking is 0rpm-1700rpm

allevolution

I also noticed I am now continually getting both these codes after I cleared them 2 times and cycled the key after clearing:
(even though TPS IS IN SPEC)
P0123- TPS voltage to high
P0122- TPS voltage to low

PCM is NEW also. So I highly doubt a PCM issue.


I hear the TPS has a DIRECT AFFECT on the transmission shifting also?
Mine trans was downshifting pretty harsh this morning @ 6am. So not sure if thats related at all.


Another hint I have been seeing is while sitting at idle,
The motor will nearly die after running for maybe 5-10minutes. Then it will spring back to life just as it is about to go dead.

allevolution

one more bump before I go to bed.. I have helped out at least 20 people on here today I would appreciate an opinion
not trying to sound frisky lol

DESERTXJ206

It sounds like it could be a few things. I'd start with coolant temp sensor. I know they will give issues if starting to go bad.

Not sure if the tps is adjustable but you may have to adjust it if necissary. As for the running rich, maf sensor or o2 would cause this.

cruiser54

Get a Mopar thermostat in there. 83501426AC.

Your TPS is most likely toast. Replace it now. They don't last forever.

Repair any bad wiring. O2 sensor wiring being tangled up should not be ignored IMHO.