2001 exp eb 5.4 l bad cop??

[jaytuck]

Have 2001 Exp (5.4L) with 165K. Have following symptoms:

1. Hard starts only when engine cold - starts OK when engine warm.
2. Idles at normal RPM in park (700-800 RPM) but idles rough.
3. Seems to shift OK up to O/D but not smooth
4. Rough idle (in drive) at a stop.
5. Lack of power - acceleration not smooth

Symptoms seem indicative of bad COP. Had steady check engine lite which would intermittently blink when accelerating. As of today, have not been able to pull codes as they were cleared due to dead battery and havent been able to get OBD to re-establish fault codes.

One other symptom - with engine idling, there is a loud "buzzing" noise which seems to be coming from either cylinder 1 or 2 (passenger side counting back from front of engine). Never known failed or failing coils to buzz - could it be injector going bad?

Drove vehicle some more this evening to try to get CEL to come back on and hopefully retrieve fault codes. So far, unsuccesful to get CEL to come back on even though running poorly.

Thanks in advance for any thoughts/advice!!

 

[jaytuck]

Determined the cause of the buzzing noise - it was PVC. Replaced with new one.

As far as rough idle, etc., bought a new COP and cycled thru all cylinders. Also checked spark plugs. All pluhs OK and none of the COP's were bad.

Truck still running bad - been driving around trying to get CEL to come back on but no luck (go figure). Just to confirm - tried to pull codes again with my scanner but none there.

 

[markNtennessee]

I have been chasing a rough idle and lack of power for over a year now, and just recently got a CEL and found the problem. its was a vacuum leak at my intake manifold. but i was having just about the same problems that you are experiencing.

Also might want to check your PCV hose to if it has any holes in it before you start tearing into replacing the intake gasket.

 

[cbiii]

I have a similar situation. 99 EB 5.4 that has always had a miss and poor gas mileage. I swapped plugs initially and after seeing 11.8 mpg i decided to do COPs. After that it ran a bit better initially(~13.4mpg) and then dropped back to 11.8 and eventually developed a sputter. I swapped fuel filter last night and took it out for appx 25 miles. It ran great (minus a slight hesitation which I assume is my trans) and was seeing ~14.6-15mpg. I parked it overnight and went to leave today and I had terrible hesitation, no accceleration and im seeing ~10.7mpg. When i floor it, it just stumbles and never really picks up.

Granted these numbers are all from the overhead, but it still shows somethings definately wrong.