Another Idle Problem

[acuzerfdw]

My problem is a little different than what others have recently posted here. i tried to find one that was simular to mine, but could not find one.

I have a '97 4.0 OHV 2WD Explorer Sport. When the engine is cold and I turn it on, it tends to have a pretty rough idle. If I rev it to about 1500 RPM the idle gets worse. Once the engine is warmed up or hot enough, it smooths out. not a perfect smooth, but close to it. I already changed the IAC and that didn't help any. Anyone have any idea what could be causing this? Thanks in advance.

 

[bam_bam1ca]

Intake air temperature sensor IAT or PCM temperature sensor?? Those would be the first two that I would start with. Are you getting a CEL or code?

 

[acuzerfdw]

I'm not getting either. Where would I be getting a code at? Thanks for the quick response!

 

[jk051]

I had almost the exact same problem...turned out to be a cracked head on cylinder 3. When i first got the problem i changed the plugs and that fixed it for a week or so then it steadily got worse until the plug in cylinder 3 got fouled and it started running like complete crap all the time.

Hopefully your problem will turn out slightly less expensive....

 

[acuzerfdw]

OUCH!! That's a scary thought! I hope I just have a bad IAT sensor. It started happening when i changed my air intake to a K&N cold air system. I re-sprayed my filter with oil and maybe some got on the sensor. I'll check it tomorrow and get back to you guys.

 

[jk051]

Hmm...well the fact that you just oiled your filter leads me to think its your MAF sensor. Clean that in addition to the IAT and see what happens. Maybe you'll be lucky!

 

[Turdle]

intake manifold gasket--

 

[Tbars4]

the," i just oiled my filter", information would have helped you a lot faster...

 

[PRS]

This stuff works pretty good, I also cleaned the throttle body and that helped the idle a whole lot. http://www.explorerforum.com/forums/showthread.php?t=184766

Good Luck

 

[acuzerfdw]

Sorry for not supplying all the info, but I figured since I had already cleaned those areas it wasn't necessary to mention. So here's what I've done so far. I cleaned out the MAF and the throttle body as well. I replaced the IAC. The only thing left to check/clean/replace is the IAT sensor. I'll check it today and see what happens. Can that be cleaned or does it have to be replaced?

 

[dogfriend]

intake manifold gasket--

This gets my vote.

 

[bam_bam1ca]

The air filter oil is also known to wreak havoc on O2 sensors. Now that you mentioned the oil I definately suspect fouling of the MAF or the IAT.

 

[aldive]

The air filter oil is also known to wreak havoc on O2 sensors. Now that you mentioned the oil I definately suspect fouling of the MAF or the IAT.

Have you monitored the function of the O2 sensors?