Rough idle on cold starts.

[koda2000]

When I first cold-start the engine on my 2001 Explorer 4.0 SOHC V6 it runs/idles super rough for a few seconds then it smoothes out and the idle goes up to around 1,300 RPM for a second before returning to a more normal 800 RPM or so. Once all this happens it runs great and on warm restarts it starts normally. I scanned for codes and there are none. Someone suggested if might be the EGR valve. I checked the EGR valve with a vacumn pump and it at least holds vacumn. Plugs, wires, dist cap, air filter and PCV are new. Any ideas?

 

[koda2000]

FYI: I've also done the following. Replaced the fuel filter, cleaned the MAF sensor and throttle body checked the OHMs resistance on the IAC (w/in range). After reading other posts I tried waiting for the fuel pump to pressurize before starting (5 secs), swapping all the relays around and I removed and cleaned the IAC (it was pretty sooty).

After cleaning the IAC the engine seemed to start easily and idle much more smoothly, but i'll have to wait until tomorrow morning to really know if it corrected the cold-start problem. I'm hopeful. I also turnned up the idle to about 850-900 RPM as it was settling down a little low at about 650-700.

 

[BrooklynBay]

Welcome to this forum! I've moved your thread into the stock 95-01 section. Check the vacuum line going to the DPFE sensor, and to the vacuum reserve canister. Check the intake manifold gaskets with intake cleaner to see if the idle changes.

 

[92muddyXJ]

It's been my experience that if it's the IAC, when you clean it, it will run better but only for a short amount of time like maybe a day. I had a Jeep that had this problem and it was disgusting, I cleaned it and it helped but only for a short time. The part is over $100 though I know that because I need one too.