1997 sohc v6 p0171 p0174 p0301 p0304

[sohcmike]

Guys,
I spent last night reading through all the posts regarding these codes. My Explorer runs fantastic after it runs for a couple minutes. At startup when its cold, it runs horribly and as soon as it warms up for a couple minutes its awesome. I've read all the recommended fixes and i'm going to start out by replacing the fuel and air filters and cleaning the MAF sensor and checking the pcv hose. I regularly get 18-20mpg and the only problem is at initial COLD startup. This things runs great other than that. No hesitation, no nothing. Just at cold start.
At this point, does anyone recommend anything thats easily checked. I was told to replace the IAC motor which i did and there was no change.
Thanks, Mike

 

[xcraveddreamsx]

Change the upper and lower intake gaskets

 

[chapsdeva]

+1 on the Intake Gaskets!!!

 

[sohcmike]

Here's what i've found and fixed so far. Thursday I found a vacuum hose that was rubbed in two under the windshield washer bottle. Its gray and goes to something under the alternator. I fixed that. Today I cleaned the MAF, replaced the airfilter, replaced the fuel filter(it was fine), checked and cleaned the PCV valve(it wasn't stuck) and while i was looking around i found an upper intake manifold screw that was backed almost all the way out. There was probably 3/4 of it out of the manifold. Tomorrow morning is the test! We'll see what happens.

 

[sohcmike]

No change in cold starting after the work i did yesterday. I filled up this morning, 19MPG on the last tank.

 

[janolsson]

As said above upper and lower intake gaskets. They may be on there way out and with heat expanding enough to seal when warm. Not too bad a job with a long shaft T30 torx bit, various wobblers or uj's and extensions ( the back most bolt is a pig to get to)
Just make sure you connect everything back up on reassembly, oh and be careful with the clips for the hoses that go onto the underside of the upper intake.

 

[bobflood]

You might also check the engine temp sensor used by the PCM (not the one the guage uses). If computer doesn't know engine is cold, it doesn't set up properly for a cold start.

 

[sohcmike]

Where is that sensor?

 

[sohcmike]

I replaced the upper and lower intake gaskets today. Lets see how it starts in the AM.

 

[sohcmike]

Runs smooth as silk again! Thanks for all your help guys!