I have a 2000 Dakota with a 4.7 and the engine revs up to about 1800-2000 rpms when first started in the morning. Most of the time it will settle back to idle in about 2-3 seconds, other times the engine goes from the 1800-2000 rpms then drops to fluctuates between about 1100-1500 rpms for about 7-8 seconds then it will go down to idle. Has anyone had this problem? Any ideas for a fix? Thanks in advance.
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Any other opinions? I'd like to here from anyone else that may have a fix for this. With the engine rpms only sometimes fluxuating, I think this is not normal. Also the engine at start sometimes may only rev to 1500, not always to 1800-2000.
This is not the normal high-idle speed. Mine does it too. It revs unusually high. I have a '90 B150 van with a 239 v-6. This just began happening about 8-9 months ago. It never happened during the first 14 years.
It would happen at start-up and while going down the road. If I put it in neutral and revved it even higher or turned the key off (while still going down the road) it would settle back down. I thought it might be a vacuum leak but I couldn't find one. I got an idle speed solenoid from the junk yard, that made it different. It didn't rev up while out on the road anymore but still did upon start-up most of the time. So, I got the solenoid from the parts house ($65) and it still does the same thing, probably 8 out of 10 times I start it.
Any ideas? This has to be hard on the motor. If its cold and there is no oil in the top, it can't be good to step in and race the motor.
yea my 00 4.7 does samething but sometime when im siting at stop light the rpms drop to like 400 (way down) and go from 400-800 real fast and it feels like ur pumping the brakes becuase it kinda makes truck hop. but ive gotten use to it i guess. doesnt do it all the time. im thinkin it has to do with my amp for the sub becuase i never notcied till about 2yrs about when i installed the stuff.
Sorry to raise a nearly dead post, but it didn't seem like there was ever a solution. There was a TSB issued by chrysler for the 4.7 grand cherokees to solve the rough idle (low idle) described by a few of you. It is a PCM software update. As for the fluctuating revvs, it may be a gunked up IAC valve. This is the valve in the side of the throttle body that controls the air flow into the engine when the throttle plate is closed. I would remove the throttle body, take the IAC valve out and clean the buildup off of it with carb cleaner and a rag. Try to do this with the valve portion facing downward to avoid getting the cleaner in the electronic portion. Hope this helps if you still needed it.
This has to be hard on the motor. If its cold and there is no oil in the top, it can't be good to step in and race the motor.
2000 rpm is hardly racing a motor. At idle the oil pressure is (at least on my 86) a lot lower than at 2000 rpm, which to me sounds like the increased oil pressure would feed oil to the top end faster.