won't idle at cold start

[gainer]

99 explorer won't idle at cold start..but idles after warms up..coolant sensor, iat sensor, fuel pressure regulator, or tps ????? any ideas

[brian m thomas]

I have a 2000 Explorerer and it's exhibiting the same problem. The idle is low and stalls at every stop .If I apply a little bit of gas then it won't stall. Did you have any luck with yours? I'm going to try and clean out the carb first before checking the iat or tpsm as I know the coolant sensor is functioning.

Good Luck
-Brian Thomas

[JAN02]

My 96 Explorer has started doing the same thing. Wont idle at a cold start but will after it warms up. If you turn on the AC it idles better. Did you find any solutions to the problem? I'm still trying to figure it out.

[brian m thomas]

Originally Posted by JAN02

My 96 Explorer has started doing the same thing. Wont idle at a cold start but will after it warms up. If you turn on the AC it idles better. Did you find any solutions to the problem? I'm still trying to figure it out.

I drove my '00 Explorer around for 1 hour this morning and didn't experience any idle stalls or problems. I'm guessing that moisture might have gotten into the gas tank, resulting in the low idle.

I put in a bottle of Valvoline carb cleaner anyway, just to see what happens next.

[Visioner28]

Originally Posted by brian m thomas

I drove my '00 Explorer around for 1 hour this morning and didn't experience any idle stalls or problems. I'm guessing that moisture might have gotten into the gas tank, resulting in the low idle.

I put in a bottle of Valvoline carb cleaner anyway, just to see what happens next.

Hello, I own a 99 Explorer and I'm experiencing the same problems with idling early in the morning. At startup, the engine jumps to 3-3500 rpms and then falls sharply just above stalling causing the red battery light to flicker on and off. The vehicle idles rough then jumps back up to just under 3000 rpms to repeat until it levels off at around 1000 rpms. I don't know what would be the most probable cause or where to start. I'd appreciate it.

[brian m thomas]

Originally Posted by Visioner28

Hello, I own a 99 Explorer and I'm experiencing the same problems with idling early in the morning. At startup, the engine jumps to 3-3500 rpms and then falls sharply just above stalling causing the red battery light to flicker on and off. The vehicle idles rough then jumps back up to just under 3000 rpms to repeat until it levels off at around 1000 rpms. I don't know what would be the most probable cause or where to start. I'd appreciate it.

Hi,
Sounds like it could be the carb. Have you had it checked out? If the carb is ruled out then possibly the Intake Air Temperature Sensor. Find a mechanic that you trust if the problem continues. good luck.

[Doug.Geary]

My 2000 Explorer developed the same problem over the winter. On really cold days (-30c) it would take about 10 minutes of keeping pressure on the gas pedal before it had warmed up enough to idle by itself. Most days it just takes a few minutes, and when the temparature is above freezing, there is no problem.

I recently had the truck into the garage for regular service, and I'm told it is a manifold intake gasket that has developed a leak and is drawing in air. They say that once the truck warms up, the gasket expands and seals the leak. They didn't fix it that day, as they had to find/order the part and work up an estimate.

Interestingly, while cleaning up my office, I found a bulletin from Ford from 2001 that extends the warranty on 2 parts to 6 yrs/120,000 km... and one of those parts is the lower intake manifold gasket! (the other is the camshaft chain tensioner). This bulletin applies to 1997-2000 Explorers and 2001 Explorer Sport/Sport-Trac's with 4.0L SOHC engines. It's from Ford Canada, so if you guys are in the US, check with your dealer to see if there's a similar update.

This was an incredibly timely find... as I don't really clean my office that often, my truck is at 114,000 km, and I was about to pay to have this fixed. The quote came in at $500 Canadian. Looks like this will be covered under warranty though!

By the way, the RPM surging/dropping described above by visioner28 is pretty much what I am experiencing when the temps are below freezing... although mine will usually stall out.