Hi all, for a couple of months now ive had an issue where if my jeep sits over night, while on the way to work when i come to a stop light and the rpms drop and it will die. The engine will start right back up with no problem, It also seems to do it when i make quick stops. It seems like once the engine is at operating temp it will not do it anymore. I read here on the forum somewhere that it was more than likely my IAC Valve which i replaced lastnight. This morning when i was on my way to work within the first 10 minutes of my 20 mile drive it died at the first stop light and again started right back up and was fine. On my lunch break i went out and started it up and the rpms wanted to stay around 1700 until i put it into drive and the rpms returned to normal. I then put it back in park and the rpms went back to 1700 +/-. This afternoon when i got off work it started up and seem to do ok. I contacted my local dodge dealership and explained that i had changed the IAC Valve and was still having the issue, They suggested the crank sensor and the crank shaft position sensor be changed. Ive gotten accurate and knowledgable advice from here in the past and im hoping someone here can make some suggestions. I also want to add that even when the engine stalls and dies, it never trips the check engine light
I would try what the dealership suggests first, they tend to know common issues.
While it's not likely the cause of your problem, if you have a leaking brake booster that could also cause the issue. I had it happen on my 4.2 yj; because it leaked there was atmospheric pressure in the booster, and every time I hit the brakes it forced that air into the intake, leaning out the fuel mixture, to the point that it would stall if i held it long enough. The only way the mechanic diagnosed it was pumping smoke through the entire vacuum system, so I would try replacing the sensors first.
For my 04 V8 Laredo....the TPS going bad caused the torque converter to unlock while driving. Where you see the 200-300rpm surge at times. When it got even worse it would unlock the TC and jump down into third. Only when trans started shifting did I get the TPS performance code. Of coarse that was on a February trip to Erie pa.
For Grammys 04 Limited her bad TPS shown up as funky start ups cold. Tagging the starter would send the RPM' to 1700-2000. Then it drop to 1000, then to 1500-1700 then to 1000 and hunt like that for 20 to 30 seconds. It also shifted odd in traffic when is drive it to work. (32 mile commute ).
Neither one of them I could ever associate the stalling at a intersection with the bad TPS. Just a good cleaning of the TB and the IAC bypass passage.
Both idle down to 500rpm real smooth. No problems.
Hi guys and thanks for all the replies. Been working like crazy and haven't had time to get online but since posting this thread here is where im at with it.A few days ago I did end up replacing the Idle Control Valve and cleaning the throttle body and the cavity the IAC fits into before installing the new one. when i initially installed it and started the engine i really didn't notice much of a difference. I drove the jeep for about 23 miles and it still would do the same thing. Its never threw any codes and the check engine light has never come on so i didn't have to reset anything. The other morning, on top of the stalling at stop lights issue i started also having a minor issue where it would idle up and wont to move forward while at stop lights right after it would initially almost stall. Then after that it would do fine and act normal the rest of the day. I ended up buying a new throttle position sensor but followed the testing procedure mentioned on page 6-13 of my Haynes manual (Book number: 50025 '93-'04) and had the 5.0 volts at the connector. connected the harness back on the TPS and back probed the connector as indicated in the manual and my closed voltage was within range however fully open only read 3.8 volts, not the 4.5 stated it should have in the manual. I installed the new TPS and decided i would perform the same test on the new one however i got the same exact voltage readings on both the old and new sensor. I drove it to my moms house which is 23 miles on the interstate but the issues were still present afterwards however after that initial drive i had no more issues that day until thats afternoon when the engine would jump from aprox. 600 to 1500 and back to 600 repeatedly which was kinda funny because someone who pulled up beside me at the store and ask what kind of cam i had in that thing lol. when i pulled out of the parking lot i got on the throttle a bit it was almost like i had dropped a cylinder and the the engine had this machine gun miss to it untili would back off the throttle. I was able to drive home i just couldn't accelerate very quickly. Once i got home and turned off the engine i connected my scan tool and checked to see if it had thrown any codes although the check engine light never came on and it hadnt. started the engine and it ran fine and did for a day. This morning i went out and started it to head to work and the rpms shot up to 1500 and stayed there until i eventually threw it in drive however the check engine light came on. When i got to work i connected my scan tool and got a P0204 "Injector Circuit Open-Cylinder 4". I reset the code and drove around the block and i set the light off again and everytime i would slow down it would stall and die. Checked the code and got a P0123 "Throttle/Pedal position sensor A ciruit high input: code. i tried clearing it but it would throw the code as sonn as i started the engine. I tried clearing it several times but had the same result with it staying on. When i was leaving for lunch with the light still on the jeep ran fine and the idle was fine. When i started it up this afternoon the idle was a little weird for a few seconds but it started to run and act fine. I got a new TPS sensor (Thank god for a friend at the parts store) and replaced the already new one but still cannot get the light to clear however at the time i parked it a little while ago it was running fine. while i was changing the TPS tonight i happen to notice a connector (grey in cloro i think) that is plug into something that is going straight down into the top of the engine right beneath the IACV and TPS i noticed that what ever that connector is connected to feels loose almost loke its fitting into a rubber gromet? At this point i dont want to throw anymore parts on to this thing until something starts making sense. I had planned to replace the crank and crank shaft sensor but im not sure what to do at this point. Me and a friend from work when over the engine with carb cleaner and 2 sets of ears trying to find vacume line issues but couldnt. I work as a small engine tech so i would like to think we would have had a good chance of finding vacuum issues if they were present. One thing i forgot to mention. i noticed this morning when i went to use my cruise control that when i pressed the on button "Cruise" is no longer lighting up on the instrument panel and cruise isnt working. I know its not a vacume line issue as i replaced those under the batter a month ago... Any further suggestions would be awesome. And thanks again for all of your replies. I really love this Jeep and im in this for the long haul but i sure would like to fix this issue myself before i have to bow down to my local Dodge dealership in defeat at 85.00 an hour..
Also want to add that i also replaced the new IACV with another new one this afternoon just in case the 1st was bad but it made no change. Someone said something about unscrewing it to adjust it however i did not do that because i was under the impression it self adjusted after i drove for a while
I had a similar issue with my Cherokee. It turned out a bunch of wires in the rear end got rotted to ****.A combination of a short when I hit the breaks and a very poor battery resulted in my engine not getting the right voltage and stalling out. Just an idea, hope it helps man
My wj was doing the exact same thing I finally took it to the dealership after the car woukd then not start at all they replaced the cam and crank position sensors along with the oil pump drive under the cam sensor 4.0 Il6 and I went up next day the car started and ran like a champ but at that point bank was closed so had to wait untill next day to actually pick it up went back the next day back to no start at all and im still havent got it figured out the dealership has had it over a month and I finally took it out yesterday trying to figure it out myself again