danja2
NAXJA Forum User
- Location
- New Britain, CT
So Ive been having a high idle problem ever since a little incident that I had. Have a 2000 cherokee with 106k on it, put a used motor in it from a 96 with 113k because the original was bad. Everything was going great when i started the new engine up the first time until the system got super pressurized and the lower radiator hose blew off because I forgot to tighten the clamp. I couldnt get to turn the engine off until after about 3 or 4 seconds of it exploding. Antifreeze went everywhere, and it looked like an erupting volcano:doh:
So after that, I refilled it up with antifreeze, rinsed the front of the engine and body with water to get all the antrifreeze off. Ever since then, my idle has been very high. From a cold start, it would start idling at around 2500, then drop to somewhere near 1750 to 1500, then slowly go back up to 2000 rpm and stay steady. I have gotten a few codes, all random. I clear them, and it does the same thing and eventually comes back up. I have gotten an idle system malfuntion code, a tps code, and a iat sensor code. Also got an O2 sensor in there somehow once.
So I changed the iat with another one that i had, same thing happened. Replaced the tps sensor with a brand new one, same thing. Also replaced the idle control sensor with one from a junkyard and still does it. I cleaned out the throttle body because it was dirty as hell, but still the same.
Once in a while, when I would cold start it, It would idle normally and it would be fine. But mostly, it happens all the time. When I drive it, the idle doesn't cool down because the car just wants to move and i have to hold the brake pretty hard.
I know this is a long post (sorry), but It all needs to come out because it is quite complicated. I doubt there are any vacuum leaks because it was idling find when the engine was first put in, and i turned the new engine off and on 4 or 5 times before the radiator hose blew, so I know that I wasn't just "lucky" with the first start of the new motor.
I was wondering if anyone had this happen to them. I read that simply resetting the computer by leaving the battery disconnected form at least 8 hours might fix it due to the computer reading voltage wrong for some reason ( like a surge). Also was wondering if maybe it can be the ecm (damage to it due to antifreeze splashing everywhere). I disconnected the battery not long ago, but was wondering if there might be anything else that I am missing. I tried to research, but couldnt find much about this particular problem!
So after that, I refilled it up with antifreeze, rinsed the front of the engine and body with water to get all the antrifreeze off. Ever since then, my idle has been very high. From a cold start, it would start idling at around 2500, then drop to somewhere near 1750 to 1500, then slowly go back up to 2000 rpm and stay steady. I have gotten a few codes, all random. I clear them, and it does the same thing and eventually comes back up. I have gotten an idle system malfuntion code, a tps code, and a iat sensor code. Also got an O2 sensor in there somehow once.
So I changed the iat with another one that i had, same thing happened. Replaced the tps sensor with a brand new one, same thing. Also replaced the idle control sensor with one from a junkyard and still does it. I cleaned out the throttle body because it was dirty as hell, but still the same.
Once in a while, when I would cold start it, It would idle normally and it would be fine. But mostly, it happens all the time. When I drive it, the idle doesn't cool down because the car just wants to move and i have to hold the brake pretty hard.
I know this is a long post (sorry), but It all needs to come out because it is quite complicated. I doubt there are any vacuum leaks because it was idling find when the engine was first put in, and i turned the new engine off and on 4 or 5 times before the radiator hose blew, so I know that I wasn't just "lucky" with the first start of the new motor.
I was wondering if anyone had this happen to them. I read that simply resetting the computer by leaving the battery disconnected form at least 8 hours might fix it due to the computer reading voltage wrong for some reason ( like a surge). Also was wondering if maybe it can be the ecm (damage to it due to antifreeze splashing everywhere). I disconnected the battery not long ago, but was wondering if there might be anything else that I am missing. I tried to research, but couldnt find much about this particular problem!
