Well if it's not one thing it's another, I just cant seem to get ahead anymore. Well my 96 Sport with a Jeep 2.5 has a really messed up issue and it's really making me scratch my head. Well about a week ago she started farting in the morning, well the issue just kept getting worse and worse, it threw a code out P0171 saying the "Fuel System is to lean", well the most common problem I have found during my reading is the Front 02 Sensor is shot. Well changed that still no help, I know the map sensor could be shot, fuel injector could be shot, or a fuel injector. When I first start it in the morning she will idle fine for a minute (lately not even that long) then the issues start, it sounds likes she choking to death, she will fart, burb, engine will go down to 400-500rpm instead of 1000 where she normally sits, this goes on for another 10-20 min. After that she will run fine for a while then it will happen every once in a while as I'm driving. It don't seem as if the injectors are screwed, plugs looked fine, cap and rotor are new, coil is new, I'm just really scratching my head on this one. Well here is a little more information for you about it, motor has 10,000 mile (freshly rebuilt), no cat, Flowmaster 40, cold air intake, and no CEL light for the cat lol. Hopefully one of you guys can come up with an answer.

 

It could be anything. Check the fuel pressure, maybe a bad pump or clogged filter.

 

Changed the pump last August when it went. The pump and filter are all one piece.

 

there should be another filter somewhere between the tank and the engine it looks like a silver canister alittle smaller then a soda can

 

96 does not have the post pump filter. I still say check your PSI.

 

In order to get to the filter, I have to drop the tank so that's why I said it's in the tank. The Fuel pressure is at 50psi when the key was turned, took over 30 min for it to even slightly drop when the key got turned off. So the pressure is good, it seems like when the weather is cold it acts up more so when the weather is nice, I'm beginning to think it's the Air Intake Temperature Sensor or the MAP sensor. It's really strange, when I hooked up a scan tool to check everything and use the sensor visuals on the scanner, the map sensor gave off some really strange reading, or at least threw the reader. With the key turned engine not running it didn't change at all, unplugged still gave a reading, engine running barely moved on the scan tool. So I think that might be the issue, but before I change it I wanna have the mechanic I know look at it, I try not to use a mechanic unless I can't do the job or unless it's a real brain teaser.

 

You can test the map w a digi multimeter and see what happens.

 

If your PSI is at 50, it may be to high. For a V8 it is 30-35 PSI after the regulator. I don't know what the 4cly should be rated but I doubt it is suppose to be 50. And you should test it while the engine is running.

 

Well, after some testing yesterday, the MAP sensor was putting out the right voltage, but something was wrong internally. It was the only thing that was reading wrong popped in a new sensor and BAM she runs like a champ again. I hope I never have to replace it again tho, took 10 parts stores to get the right one. Kept pissing me off the ones all the parts stores had were all backwards.