I recently purchased a 1997 Wrangler SE. I noticed it running very rough and it seemed to lack power. It had been driven barely 1000 miles in the last 2 years and I figured some new fuel and a bit of running would help it clear up. Within a day the CEL came on. I took it to autozone and the code was Fuel System Lean. I didn't get the number at the time and the clerk cleared it to see if it came back. When driving away it came back on with 1 mile. I also noticed it was using quite a bit of gas. I figured it to around 9-10 mpg. I can also see black soot on the ground where I let it idle for a while. I did some research and figured it could be a bad O2 sensor. If the O2 sensor gave off a voltage stating lean but it wasn't, the fuel/air mixture would be adjusted and it would actually be running quite rich. That would cause the poor performance and the excessive fuel consumption. They are not that expensive so I replaced the upstream O2 sensor.
The idle and power did improve somewhat but is still far from expected. With my foot to the floor in 5th gear I cannot get over 60-65 on the interstate. I am also now getting an intermittent code p0132, which would suggest it is running rich. What I think was happening before was the O2 sensor was defective giving off a bad signal that caused the lean code but now it is still running too rich after the new sensor but it is giving the correct code. When I checked and got the p0132 code at autozone the clerk checked his computer and suggested a fuel pressure regulator. That is a bit beyond my abilities and is also a bit more expensive than I would like without being reasonably sure that is the problem.
What I am wondering is what are the likely causes of the current code and poor performance given the above circumstances. Should I let it run for a few more days, maybe another tank of gas? A blockage in the fuel return line could also cause this too, correct? Is there any other sensors or parts I should check first before giving it to a proper mechanic to check and possibly replace the fuel pressure regulator?
1000 in 2 years.. did you check air box/ filter to make sure no pest brought in a bunch of crap in ? spark plugs changed? easy stuff first. i would run some Techtron in to help clean your engine.
my 4 cylinder will go over 70 mph ONLY on flat road with no winds.....
Oh yeah, I should have posted a bit more about some of those things. The dealer I purchased it from is a friend and he bought it at an auction for me. We cannot find out who has been working on it but from visual inspection I can tell several things. The air box and everything else from the throttle body up is new as is the filter. The plugs and wires are new and most of the vacuum lines are new. It also looks like the MAP sensor is new but I can't tell for sure. The a/c is bypassed, we are waiting on a new compressor for that.
I have been riding it today (soft top down, I love this vehicle!) and have figured out a few things. It still doesn't idle correctly, sometimes dropping down to 400-500 rpm. When riding on roads other than the interstate the CEL goes off. After a few miles on the interstate it comes back on but goes off after a few miles of off the interstate running at around 45mph or less. One thing I am curious about that I noticed today, it seems to be geared differently than the 5 speed s10 I am used to. I go into 4th gear at around 40 instead of 5th gear at 40 on the s10. Does that sound correct? That may account for the apparent lack of power, I was gearing up to fast.
One other note, the tires that are on it are 31X10.5R15. I know that is quite a bit larger than the stock tire size, how much would this affect interstate driving? I am starting to think that I just need to get used to the vehicle gear ratios and find some smaller tires before worrying about fixing anything else. I put some Lucas Deep Clean in it today also and the more I ride the better it is feeling.
The only worry I have left is the idle speed plus the CEL and seeming lack of power at high speed. I'm going back out for the day, maybe after I run another tank of gas through everything will be good.
there is an iddle dpeed controler, my iddle is not reg (not as bsd as yours) and my mech told me i may need to replace it, but its not bad enough for now do illl leave it alone. i have a 98 4cyl with 31 on it (stick shift), ill check at what speed/rpm im switching gear when i leave work today.
That is about where I am shifting now. Took a bit to get used to that, on the s10 I shifted as soon as it got close to 3000 and now I am shifting at 3500 or so. I put about 150 miles on it in the past 2 days and it is running much better. Still doesn't idle good but I may wait a month or so and if it is still doing it I'll put the idle air control on it then. One thing I hadn't thought of until I was reading about it, if the speedometer wasn't adjusted for the tires I am running a bit faster than it shows. When it shows 60-65 on the interstate I may be doing 70+. I took it back on the interstate this evening and it is much easier to hold at 65 than the other day.
I have found another symptom of the fact that it wasn't ran much in the past few years, the fuel sending unit isn't accurate. The first fill up it registered around 3/4 of a tank and I have filled it back up twice and it gets a bit closer to full every time. Still not sure where the fuel mileage will settle to, right now I'm figuring around 13 or 14.
Thanks for your help, after your tips and advise I was patient enough to get used to the vehicle and let some things work out on their own.
yeah the mph are a little wrong with the 31. 65 indicated gave me 70 on the gps (phone gps, how accurate??) I fill her up when I'm arround 180 miles on the odometer and add about 12 gal. I always reset the odometer when I fill up the tank, I never trust the gauge (never did on any car or bikes I own/ed)
I've had the same problem with mine. Randomly, it will bog down and become a pain to get up to speed. when this happens, the CEL comes on, throwing the p0132 code (o2 sensor). After a bit, the jeep starts to run fine and the CEL eventually turns off. Ill post results when i pick a new sensor, hopefully within a week. If this doesnt resolve the problem, my next guess would be possibly a clog in the fuel line/pump? BTW Im running a 2.5 5 speed on 33's.
Good morning! Just found this thread and was hoping to get some closure, too.
First of all - Mine's a 97' TJ, 4-cyl, manual, 60k miles.
My MIL came on a few weeks ago with no apparent indications of anything wrong. After about a week it went back off, just to return a few days later. This continued for a bit until I returned from returning my daughter off at summer camp one morning. With my street parking spot in sight the engine started sputtering. Almost like I was out of fuel. I hit the clutch, and the engine was trying to idle but couldn't get above ~400 before dying. I pulled in front of the last car on the block, waited a few minutes, turned her over again, and got stable idling at around 900-1000 RPM. Revving the engine a bit in neutral or with the clutch engaged didn't seem to indicate any misfires or the like. But Once I put it in reverse to back into the parking spot it started sputtering a bit again. (BTW, my gas gauge showed slightly less than 1/4 tank. I did fill it up all the way just in case.)
I've had the stuttering happen one more time since then and have just been driving a lot more conservatively since then. The stuttering hasn't returned yet.
Now, last night I borrowed my friend's OBD II PocketScan, which displayed a DTC of P0132. I take it from others' experiences that this is not simply a matter of replacing the upstream O2 sensor then? If that code means high power to the sensor, then does that actually impact the performance of the sensor? And is it the actual sensor's fault it's getting too much voltage? (Poor, misunderstood sensor)
Like the OP, I also barely drive my TJ. It's a '97 with 60k on it. Most of the week it's parked with the exception of moving it from one side of the street to the other for street cleaning purposes.
I finally figured mine out and it is running much better. The lack of power kept getting worse and it starting hesitating quite bad until I happened upon a post on this forum. It seems that bosch o2 sensors don't play well with jeeps. The original problem mine had was a bad o2 sensor (it was a bosch) and I replaced it with another bosch. When I read the posts on this forum about bosch I went to the dealership and purchased a mopar sensor. It was $40 more ($99 vs $59) but immediately after installation everything improved. I am getting better mileage and more power, I can even run 70 on the interstate now. Not sure if this will help you any but if you decide to replace the o2 sensor make sure you get it from a dealership.