Low Idle Cold Start on Occasion

[sierraoneill]

I've got a 99 Explorer with the 4 liter SOHC. On occasion (doesn't have to be in the winter, just the first start of the day) it will idle incredibly rough and low. After a few seconds it will balance out and be normal. Another way to remedy this is to quickly turn the key off (so the engine runs poorly for less than a second) and then re-start and it runs perfectly. Another way to avoid the issue (but not always) is to turn the key to on, wait a few seconds till you hear the fuel pump shut off, and then crank it over. Doesn't always happen, and sometimes it will even run perfect first thing in the morning (even if its 20 degrees outside). No CEL present.

gas mileage is normal and it always starts up instantly (the engine turns over and starts instantly even when it goes into low idle condition for a few seconds)... b

Any Ideas??

Thanks

 

[Mbrooks420]

It could be your Idle Air Control Valve, or IAC. It's a pretty commonly replaced part. Very simple to replace. Some of them can be taken apart and cleaned, some are sealed units. Does the vehicle ever stall? Whenever the one on my previous Explorer needed cleaned it would stall occasionally when idling.

 

[tchalm]

I've got the same problem with my 98 4L SOHC. I just start it up and keep tapping the gas while it gets going. But I like the idea of checking the IAC.

Thanks!
TC

 

[tchalm]

Yes! Cleaning the IAC solved the problem I had with rough idle on cold start. Now she purrs like a kitten - well, maybe not quite.