I have a 2002 Supercrew - 4.6L V8 - about 98500 miles
Here's my problem:
When I start the engine, it won't idle in park...it just dies. When I start it and give it gas (up to about 2K RPM) and hold it for about 30 sec I hear a faint 'pop' sound and then it idles just fine. Also, if I start it up, give it gas (again to about 2K RPM), and put it in gear it seems to run OK.

I think it is a dirty IAC that needs to be cleaned, but when I unplug my MAF sensor and plug it back in, it seems to idle OK in park...for one cold start then back to the old problem.

I'm also thinking about cleaning my MAF sensor just to be sure.

Any help or insight would be greatly appreciated.

 

clean the MAF sensor for sure, and if that doesnt work definitely try the IAC, just spray some carb cleaner in there, shake it up, and blow it out, or let it dry.
good luck!

 

Clean them both for good measure. Sounds like IAC issue. Once it will idle it is fine for the rest of the day?

When you have the IAC off and clean it, make sure the plunger works freely. Give it a quick blast with wd-40 after cleaning and before reinstalling. Be careful with that MAF, and use a cleaner that doesn't leave behind any residue. Try to stay away from crc products, as they are known to leave behind residue, which makes cleaning it pointless. While your in there, check any or all of the pcv system, along with the other vacuum system hoses for any cracks, soft spots or signs of rot. Especially in the back of the intake plenum at the 90 degree elbow.

 

Update:
Only had time to clean the IAC last night, but gave it a good dose of carb cleaner and WD40 on the plunger assembly. Worked the plunger after and it seemed to move freely. Haynes says: "The IAC valve itself is an electrical component and must not be soaked in any liquid cleaner, as damage may result." How much carb cleaner is too much?

Checked the resistance on the IAC before cleaning, and everything was OK except the resistance from a terminal to the IAC body wasn't reading (maybe an internal ground?).

Didn't get a chance to clean the MAF, but that is on the list to do tonight. Update to follow.

To answer your question Toyz, 'no'. If I shut the engine off, the whole thing starts over again (stall if not given gas). Is the IAC plunger supposed to be fully seated when it is removed?

 

Toyz, can you recommend another brand of cleaner?

 

I would use the CRC. I have used it many times and never a problem.

They have one specific for MAF but I use this one. I suspect they are the same thing, just different lable.

 

I've used them as well with no issues. But have heard they leave behind residue, on the contrary have also heard they don't. Their website data sheet sais it leaves behind no residue, it seems to have a high alcohol content.

 

Try tapping on the EGR sensor. You probably have carbon buildup under the EGR and/or EGR port. I'd say if you have access to a scanner and pull the codes you'll see P0401. You'll need to clean the port and under the EGR with carb cleaner.

 

I actually pulled the EGR valve off not too long ago and cleaned it (for another problem that ended up being my DPFE sensor).

 

How did the gasket hold up when you did so, they normally fall apart.

 

The egr sensor, valve as you call it, ain't the problem bro. You've got carbon build up in the egr port. You'll need to "ream" it out. Did you clean the holes under the egr valve/sensor? It doesn't take but a flake of carbon in the port to cause the problem you're having.

 

Update:
Cleaned the PCV valve and MAF sensor. Still have the problem. PCV hoses looked OK, but I will need to pull the throttle body to get to the 90 elbow at the intake. The part inside the PCV rattled pretty good, so I think it's OK. AZ and Advance didn't carry the PCV, so I didn't have anything to compare it to.

The 'pop' sound I mentioned earlier when holding the RPM around 1500 after a cold start is now followed by a hissing sound for a second, then it idles OK in park. Anyone ever seen this problem with a faulty EGR vacuum regulator? Any other ideas?

jward: I pulled the valve (with the silver flying saucer on top) and cleaned it...but that's not to say that's not the problem. I just find it hard to believe that it would ONLY create problems after a cold start and ONLY in park. It's one more thing I can try...

 

CRC makes this for cleaning MAF