Runs rough when cold

[edenman]

I have a 97 Explorer w/4.0 SOHC.

The check engine light is on and comes back on within a day if it is reset.
The truck runs really rough when it is first started. The colder it is, the worse it runs (almost stalls).
There is a loud clatter coming from within the engine when it is first started that goes away gradually within a minute, almost sounds like a bad exhaust leak.
When I diagnose the computer (Using a friend's Snap-On diagnostic equipment) and run the self-tests, I get no error codes except for the ones that are stored in memory. These errors tell me that both banks of the exhaust are running lean, according to the downstream O2 sensors.

I replaced both downstream O2 sensors, and this did not change anything.

Any comments or suggestions would be greatly appreciated!

Thanks, Erik

 

[TURDS]

I am pretty sure i know what the problem is. It is called a "cold start". Honestly i have no clue what it does, what it is or where it is. But anyways i got mine replaced because i too had that really crappy idle. It would go from 500 RPM to 2000 and then from 500 to 1900 and then 500 to 1800 until it stayed at about 1000RPM. It cost me 350 bucks, but i had some other stuff done to it (brakes) so i don't know how much it actually was. I am also getting about 2.5 more mpg as well. It seemed to effect the way it drives too, now it hauls.

Travis

 

[edenman]

Thanks, Travis. I'll check it out.

 

[Robert]

Originally posted by edenman
I have a 97 Explorer w/4.0 SOHC.

The check engine light is on and comes back on within a day if it is reset.
The truck runs really rough when it is first started. The colder it is, the worse it runs (almost stalls).
There is a loud clatter coming from within the engine when it is first started that goes away gradually within a minute, almost sounds like a bad exhaust leak.
When I diagnose the computer (Using a friend's Snap-On diagnostic equipment) and run the self-tests, I get no error codes except for the ones that are stored in memory. These errors tell me that both banks of the exhaust are running lean, according to the downstream O2 sensors.

I replaced both downstream O2 sensors, and this did not change anything.

Any comments or suggestions would be greatly appreciated!

Thanks, Erik

You have two independant problems. Fortunately for you Ford will repair both at no charge under the Owners Notification Program 00M12. See my post under the General board regarding 00M12. I posted the letters I received from Ford. The lean condidtion is caused by your lower intake manifold o-rings leaking. They are allowing un-metered air into the engine which causes a lean condition. The clattering noise is the camshaft tensioners. Don't spend a dime on it until you check with Ford first.