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Truck revving at startup and strange idle problems
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Desol
Novice
Aug 8, 2023, 1:14 PM
Post #1 of 10
(1479 views)
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Truck revving at startup and strange idle problems
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Hey guys. First post. I took my truck into a mechanic a while ago to have the rad replaced. All went good, got the truck back drove it for a week, then noticed a small leak around the big hose at the top.I took the truck back in and the next day I got a call that they found the leak and that it was repaired. Cool. So got the truck back took it home and went to bed. Woke up next morning, started the truck andit began revving pretty high (2000rpm) suddenly. Normally it only revs up to 1500 and quickly starts to come down. It stayed at 2000 rpm for a while and then after about 40 seconds it dropped down to a 1000rpm.Started the truck again...same thing...this time it stayed at 2000 rpm for over a minute. I couldn't kick it down. Had to shut it off. I got it to start the next day ok. So I continued driving it for a couple days to see if it was ok but the problem reappeared. It was doing weird things when idling driving around. Either idling too high, then dropping. etc. I've had this truck (nissan) for ten years. It's always started, idled ran without any issues. I took the truck back to the shop. Later that day I got a call back that it was fixed, he found the problem. Got there and he told me it was the cruise control that was causing the problem, and that when he wiggled the cable the problem disappeared. I asked him how he thought it happened...he shrugged his shoulders and said it was 'murphy's law". I was like umm ok. He said it didn't have a replacement part so I could either drive it away with the cruise control cable unhooked or he could order a new part. Well, I needed the truck so he told me he would check into a replacement part. He called next day and said there was no part available. My cruise control was screwed. So...next day started the truck and it did the same thing....started revving too high. Obviously not the cruise control. So while it was revving I opened the hood and pressed up and down on the round actuator that the throttle cable connects to. The engine immediately came down. So I called back and left a message last friday in the morning. The girl answered and said he was out but that she would give him the message and he would call me back. Didn't call back. Long weekend went by. Still hasn't called back. I'm waiting till tomorrow to call him for the second time. What do you guys think about this situation? I'm thinking when I took the truck back in to get the rad leak fixed, they were playing with the throttle revving the engine in order to get the rad to leak (it only leaked after I was on the highway), and possibly damaged the butterfly valve. Do you guy have any other thoughts?
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Hammer Time
Ultimate Carjunky
/ Moderator
Aug 8, 2023, 2:11 PM
Post #2 of 10
(1468 views)
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Re: Truck revving at startup and strange idle problems
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First eliminate all vacuum or air leaks in the system (very important) . You may have a bad IAC ( idle air control) but try cleaning the throttle body first. Remove the intake snorkel, have someone hold the throttle wide open for you and scrub the back side of the throttle plate and surrounding bore with an old tooth brush and some carb cleaner. Be sure to spray some into the small holes next to the throttle plate. That should help stabilize the idle. If it still has a problem, replace the IAC. ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.
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Hammer Time
Ultimate Carjunky
/ Moderator
Aug 8, 2023, 3:45 PM
Post #4 of 10
(1448 views)
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Re: Truck revving at startup and strange idle problems
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Ok, then why are you posting on an auto repair forum if what you need is a lawyer? ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.
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Hammer Time
Ultimate Carjunky
/ Moderator
Aug 8, 2023, 4:43 PM
Post #6 of 10
(1439 views)
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Re: Truck revving at startup and strange idle problems
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So, it's the cruise control that you are concerned with? It does sound like too much of a coincidence. Maybe you should take it to another shop and get a second opinion and if they damaged something, the other shop will see it. ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.
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Hammer Time
Ultimate Carjunky
/ Moderator
Aug 8, 2023, 5:26 PM
Post #8 of 10
(1425 views)
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Re: Truck revving at startup and strange idle problems
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I don't know what you expect from us. It sounds like you are describing the throttle plate sticking. I have no idea what the reason is or what caused it without looking at the truck. NO, they didn't damage it by revving the engine. There would be no reason to do that and it wouldn't harm the throttle body anyway. I don't even see you posted what kind of truck it is or how many miles on it. Take it to another shop and get a second opinion. ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.
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Tom Greenleaf
Ultimate Carjunky
/ Moderator
Aug 10, 2023, 10:15 AM
Post #10 of 10
(1298 views)
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Re: Truck revving at startup and strange idle problems
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Just look at area to do what was done. Anything unplugged there with other end nearby? Just a thought, Tom
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