I have a 95 Yj 4.0 automatic that just turned 201k. it wouldn't start last week, needed a new fuel pump because it would not even prime so i cut a trap door to get to the tank so i didn't have to drop it. i replaced it and it still wouldn't start but i could hear the pump priming now so i checked for codes and nothing just a 12 and 55, so i did some research and found out that i had a bad crankshaft position sensor. replaced and it starts right up, YIPPIE! after letting it idle in my driveway for 10 minutes it idles like crap. then after about a minute of idling like crap it goes away and it idles great without any sign of sputtering or loss of power.
before i did the fuel pump i replaced plugs, wires, and distributer cap because winter is coming.
now every time i start my jeep i have to let it idle in the driveway for 10 minutes so i do not have the sputtering issue on the road and have a loss of power, but like i said it goes away and drives great after the initial 10 minutes. so yesterday i took off the throttle body and cleaned it. while i had it off i read somewhere on this forum that it may be a bad/dirty IAC so i just bought a new one since she just turned 201k. i also read somewhere on this forum that it may be a bad TPS sensor so i just bought a new one and put that one on. i kept the battery disconnected for about 10minutes then started it up hoping that the sensors were my problem. sure enough 10 minutes later it sputters and has a loss of power...grrr. i check the codes again and it says that TPS is too high or too low. did i really just put in a new part and get a code that says the new part is defective? so i disconnect the battery again, clean the old TPS and put it back in. now i checked the codes again and it is the same code coming back...TPS is too high or too low.
so all in all i have a new code saying a new part and the old part are defective, and still have a sputtering issue pretty much exactly at 10 minutes from a cold start up. i do not have the sputtering problem the rest of the day just in the morning when it starts cold. i am assuming this problem will continue to get worse the colder it gets...suburbs of Chicago get freezing in the next couple of months.
so all i can think of is a bad O2 sensor but wouldn't that come up when i check the codes? the reason for the thought of the O2 sensor is due to maybe a closed/open loop problem. I have not checked the fuel pressure in the line but i dont think it is that because it has gas getting to the fuel injectors when it starts up and after the sputtering.
any tips/ideas would be greatly appreciated.
After replacing the sensors mentioned, you should have taken the + battery cable off of your battery and grounded the end of it out for 30 seconds or so. That dumps the learned memory in your ECU. Hook the + battery cable back up, fire it up and take it for a ride when the engine is cold.
DO NOT sit there at idle. The ECU needs to relearn and only does that when you go from cold to hot engine driving.
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definitely a temperature related sensor issue. Depending on how stock your engine is it could be coolant temp, Incoming air, EGR, or cold start enrichment(choke). If you can get a decent ODBII reader you should be able to track what sensors you have and what is actually happening before during and after the stumble. That will tell you the problem.
how about the bluetooth ODBII readers from amazon? Id love to download an app and have my codes show up on my phone. anyone have any good experiences with them?
yes i cleaned the hole that the IAC goes into before i placed the new one in.
i also put shell v-power in my tank in hopes of cleaning it out and it seems that the sputtering is less frequent but it is still there. maybe bad gas as well? idk just trying to think of everything...