low and unstable idle - Engine Troubleshooting


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low and unstable idle

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rlee81indy
New User

Feb 20, 2008, 8:01 PM

Post #1 of 3 (1491 views)

low and unstable idle	Sign In

I have a 1993 ford f150 4x4 with a 302 engine. Its got 145,288 miles. When running it idles low and unstable ie: high and low idle. The unstable idle is nearly constant meaning you can almost time the high and low. This is when the truck is in park or neutral. Once I put it into gear sometimes it stalls. When the truck is cold I have to keep my foot on the gas to keep it at 1000 rpms until it warms up enough to drive it, then I sometimes have to put it in neutral and keep my foot on the gas when I stop at lights.

Also, in a possible unrelated issue, when driving it looses power like its not getting fuel for a few seconds. By gently pressing the gas pedal, I can get it going again. I replaced the feul filter but this did not fix the problem.

I just bought this truck the other day so I dont have much of a history on it. If you need more description just ask. I was hoping to figure this out without taking it to the shop. Thank in advance for any advise.

Tom Greenleaf
Ultimate Carjunky / Moderator
Tom Greenleaf profile image

Feb 21, 2008, 3:48 AM

Post #2 of 3 (1478 views)

Re: low and unstable idle	Sign In

Check for vacuum leaks. There are elbows, PCV down in back, brake booster - check them all out. If this still uses a "soup" can for a vacuum reservoir make sure it is hooked up and not rusted out - you can fix those if rusted and when those are bad you notice the air ducts default to defrost all the time with loads on engine.

Idle speed motor could be slow but check for vac leaks first,

T

rlee81indy
New User

Feb 21, 2008, 6:27 AM

Post #3 of 3 (1475 views)

Re: low and unstable idle	Sign In

thanks for the advise. Ill try exploring that today.

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