The 98 TJ started coughing and sputtering but got me home. Checking the codes I found P0138, P0132, and P0107. So it's flagging both o2 sensors and the MAP sensor. Can anyone think of what's in common to all three of these to throw those codes? It doesn't seem likely all 3 went bad at once.

Does it?

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Matt Townsend
Sebastopol CA

02 Red Libby w/Frankenlift, Full armor incl AllJ stuff, 245 MTRs on Cragars, ARB locker, custom rack, K&N FIPK, 8000lb winch, RE rear LCAs, Optima Yellow Top, RL Rear Bumper, Custom Front Bumper
98 TJ w/5.5" RE Long arm lift, ARB front/rear, 35x12.5, Borla, Warn winch, Teralow, etc., etc..

Not likely Matt........I would think that the 02's are just smellin what the map sensor,or it's circut are causing,generaly rich or lean conditions.May want to take a look at vacum supply to map sensor,not sure if they are hose supplied vacum,or if the map is mounted directly to intake,but if the map is getting it's share of vacum,then you might just blame the sensor it'self.I could print up a diagnostic flow chart if you want to spend the time to run through it.We have "Alldata"where I work and it is a great benifit when you have to be right.Hope this helps.

Ron

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Ron
03 Red Libberty Sport
3.7 V6 Auto 4x4
Lifted
Cooper Discover ATRs 265/75/16
American Racing 16x8 Polished Baja Wheels
Moog Lower Ball Joints
Member#051397 L.O.S.T. Midwest

^^, that makes sense.

The map sensor makes it lean or Rich which makes the 02 sensors unhappy..

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Now there is a dang nice offer and a great resource. Maybe it would help me figure out what is wrong w/ my KJ that is throwing the loose gas cap code (can't remember it OTTOMH right now) and isn't being fixed by tightening the cap or replacing it. I suspect a bad hose somewhere.

Sounds like it is time to take it out into a pasture and feed it some lead Matt.

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That's not entirely true,the MAP sensor is short for "Manifold Absolute Presure",that sensor just measures the barometric pressure of the intake,it adjusts for elevation,hot,and cold climates.Basically "changing the jets" for the carb guys,yes it does adjust how rich/lean the engine is but to a point.The o2 sensors are the main things to make a engine run rich/lean.They detect o2 in the exhaust and produce a electric current depending on the amount of o2.The o2 sensors will not start working until they reach about 650 degrees,so when you first start your engine and till the o2's start working you are running on a set program that is in the PCM,if a o2 sensor goes out(upstream one's,before a cat) will keep you in open loop,causing the engine to be running on it's cold start setting all the time(bad MPG and performance),not really hurting the engine,just running rich.

Code P0107=MAP sensor voltage low,P0132=1/1 o2 sensor heater circuit voltage high,and P0138=2/2 o2 sensor heater circuit voltage high.Seems like you got some electrical gremlins,or you just got unlucky with both o2 sensors going out at the same time.Burned wires to the o2's?Cheap gas could cause early o2 sensor failure and alot of short trips that doesn't allow the engine to warm up.Also there was a rather large batch of Bosch o2's that where bad.LiLredLibby was correct about the MAP,check the vacum lines on that,then try replacing the sensor if all the lines and connections are good.

Hey JJ check the evap canister hoses under the rear of the KJ,the ones to and from the evap canister right in front of the gas tank.I had the same thing been happing to me,P0442 or P0456? I replaced the gas cap,still no help,only did it on cool mornings also.Found one of my evap canister hoses had a crack in it,got some 3/8" hose and replaced the 6" piece that was cracked,no more codes for about 2 weeks so far.

I'm going to go through all this info in the morning. It'd already screwed up my plans to do Deer Creek this weekend. Dang.

So, all this being said, the TJ does run but sputters and backfires. Is that just the computer laying in its default modes?

Well if it is running like it used to before the PCM threw the codes when first started(cold) then yes it's in open loop,if not then you probally have a good vaccum leak somewhere(MAP sensor?).With o2's being out it will just run like it does as when first started cold all the time even when fully warmed up(running rich).

This all happens after the first 10 minutes. Cold running and starting is good. And most of the time it runs good. I'd almost think it was running out of gas if it wasn't for the backfires.

Your running lean then,check all the vaccum lines.My guess would be around the MAP sensor area.

Ok. I replaced the MAP Sensor and have had no problems after 100 miles of driving.

Thanks for all the help.

Ready for the Rubicon in a couple of weeks.

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Matt Townsend
Sebastopol CA

02 Red Libby w/Frankenlift, Full armor incl AllJ stuff, 245 MTRs on Cragars, ARB locker, custom rack, K&N FIPK, 8000lb winch, RE rear LCAs, Optima Yellow Top, RL Rear Bumper, Custom Front Bumper
98 TJ w/5.5" RE Long arm lift, ARB front/rear, 35x12.5, Borla, Warn winch, Teralow, etc., etc..

That is good news.....don't forget the pics.

Ron

_________________
Ron
03 Red Libberty Sport
3.7 V6 Auto 4x4
Lifted
Cooper Discover ATRs 265/75/16
American Racing 16x8 Polished Baja Wheels
Moog Lower Ball Joints
Member#051397 L.O.S.T. Midwest