Getting hosed? Fuel problems? EGR? (long)

[keevel]

Greetings: '96 5.7L with hesitation problems. First week or so - no SES light- only hesitation problems (give it gas and the engine bogs down like it isn't getting fuel), a mechanic I trust could find no indication of the problem via diagnostic computer - tested fuel pressure, replaced several components with known OK parts - all with no effect. He recommended I take the vehicle to the dealer and added that he has never had a Chevy he couldn't find the problem on and to have the dealer call and he'd tell them what he had already checked. The dealer couldn't have cared less about anything the mechanic checked and promptly said the fuel pump and possibly the sending unit needed to be replaced. I asked if they were sure, since the mechanic checked that out as OK. I paid for the diagnostics and the plan was then to have my mechanic do the repair. About this time, the transmission decided not to have a functional reverse (8 months into a 12 month warrantied tranny rebuild) so I take the truck to get the tranny fixed and then when it's time to dyno and road test the truck, they notice the problem and by now they are getting a SES light and the code shows EGR valve malfunction. hmmmm. So I'm a bit confused by all this and wonder where the problem might actually be. Any clues?
Many TIA. -keevel

[Jeremy-WI]

If the code was a P1406, the EGR might just need cleaning

[pdalton]

Originally Posted by keevel

Greetings: '96 5.7L with hesitation problems. First week or so - no SES light- only hesitation problems (give it gas and the engine bogs down like it isn't getting fuel)

I have a 97 Sub that was experiencing this same problem. I checked out all I could, including installing a new fuel filter. No success.

So I took it to the dealer, asuming they would be able to read the computer and get right to it.

Dealer said computer reported bad fuel pump, so I let them replace it.
The problem re-appeared shortly after driving out, so I went back.

The Dealer re-diagnosed & said the replacement fuel pump was bad, so they installed another N/C.

Left dealership again, same problem persisted.

Returned to Dealer for 3d time and talked to Service Manager. He supervised another "full" check and said that they could get no more specific than that, if it wasn't the fuel pump (which their diagnosis still claimed), then the problem could be due to failure of one of 3 parts: Mass Airflow Sensor; Throttle Position Sensor; or Intake Air Control Valve. He said that it would be very expensive for them to just replace each of these until they discovered which was faulty.

So, I drove to the (independent) parts house and bought all three parts, came back home, and installed them myself one at a time (in increasing order of cost), running the Sub for a while after each (my hope being that I might find the problem early and then return any more expensive and unnecessary part(s)).

Of course, and as a corollary to how Murphy's Law works, the bad part was the last and most expensive: the Mass Airflow Sensor. After replacing it, my Sub ran great. That was 2 months ago and it still runs great.

I don't know if this is YOUR problem, but maybe something in here will help. All 3 were easy to replace and -- actually -- the MAF was the easiest of the 3.

- Paul