Accelerates to much by its self

DIBARRA

MEMBER
1987 NISSAN TRUCK
2.4L
4 CYL
2WD
MANUAL
225,000 MILES

My truck has been accelerating by itself way to high. I've down the idle and nothin. Also the tune up has been done too.

Thursday, May 28th, 2015 AT 8:05 PM

3 Replies

CARADIODOC

MECHANIC
33,873 POSTS

High idle speed is usually caused by a vacuum leak. Start by checking for a broken or disconnected vacuum hose. You can also pinch them off at various places to see if one brings the engine speed down. Intake manifold gaskets can leak too but that's less common. Spray some water over the top of the engine while it's running and still cold to see if it gets sucked in somewhere.

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Thursday, May 28th, 2015 AT 8:18 PM

DIBARRA

MEMBER
2 POSTS

Hello thank you for answering my question. I checked that and nothin is disconnected or anything. When I did the last smog they disconnected the temp. Sensor. And it fix itself it stay how it was suppose to. Now it won't and everything is connected. It's been having this problem for a time already. We went and got another throttle body and put it on the truck and it still does the same thing. Hope you can help.

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Thursday, May 28th, 2015 AT 8:33 PM

CARADIODOC

MECHANIC
33,873 POSTS

The only way a throttle body assembly can cause a high idle is if air is sneaking in past the bushings for the throttle blade shaft. You can find that by squirting a little water on them, then watching to see if it gets sucked in.

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Thursday, May 28th, 2015 AT 10:21 PM