Mechanics

DIES AND WONT START WHEN WARM

1997 GMC Truck

Engine Mechanical problem
1997 GMC Truck V8 Four Wheel Drive Automatic

I just put a new 5.7 engine in my truck.
It runs great when cool but as it gets warm will start a slight sputter and die when approaching stop lights, signs, etc.
When it does this it is throwing a check engine light that is never on when it is cool and running good. It will start back but you have to hold it to the floor and it will sound like you pulled off a few plug wires(pop, pop, pop pop) and sometimes will smooth out but not always. When it cools back down it starts and runs fine again.
I have replaced the spider injection, crank position sensor, and plugs.
Can a CONTROL MODULE cause this?
I cant get it anywhere to check the codes for awhile but my father in law owns a salvage yard where getting parts to swap are fairly easy.
Thought there might be a couple " common" causes. Thanks, Rod Hipsher
Avatar
97z71
May 21, 2010.




I just ran the codes with a scanner and get the following

p0339 Camshaft position sensor A circuit intermittent (did not show until it started to run bad and die)
p0341 CPS A circuit range performance (bank 1 or single sensor)
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Tiny
97z71
May 21, 2010.
I thought I donated 5 dollars for a guranteed answer?

Tiny
97z71
May 23, 2010.
Sorry for the delay.

Best approach is to scan CPS in live data mode with scanner, look for erratic output.

If crankshaft sensor has been replaced, then replace the camshaft sensor.

Was previous engine a 5.7?

Mmprince4000
May 26, 2010.
P0341 diagnosis:


http://www.2carpros.com/forum/automotive_pictures/108325_p0341_1.jpg


Mmprince4000
May 26, 2010.
Yes I replaced Crank and Cam sensors. Previous motor was 5.7 350 same.
It is only happening when warm, runs like a top for about three miles?
It is at a garage now being hooked to a tech II
Thanks

Tiny
97z71
May 26, 2010.
Just remembered, they will have to program new VIN into PCM, TechII can do that.

Mmprince4000
May 27, 2010.
Well it has been to 2 shops and noone can figure this thing out?
Are you saying that buy entering new vin into scanner. To refash computer?
This thing runs great and if you wipe the code it will not throw it again until it has idled for about 10 minutes then it is like you pulled 4 plug wires off, starts, missin, backfireing through exaust. And throws the check engine light.
Do these computers need flashed for a new(rebuilt) block?

Tiny
97z71
Jun 14, 2010.
PCM must be reflashed with correct VIN. A TechII can do this.

Security system could also be problem.

Mmprince4000
Jun 15, 2010.
The vin from engine or from the truck itself?
It has been hooked to a tech2 where they entered the vin under windshield.
This thing has us baffled. Changed all the sensors. And its is still throwing that cps (cam position sensor) code but not until it runs for a while.I can drive it 3 miles and it runs like a top. Checked fuel pressure it is in like the 65 + pound range. Changed computers, changed distributor (runs fine in my 97 suburban).
I am so lost on whats causing this, this truck ran great before removing the engine it just had a bad lower end knock.

Tiny
97z71
Jun 15, 2010.
Have the CPS data read in live data mode, if within specs, then PCM, if not then CPS or wiring to it.

Mmprince4000
Jun 16, 2010.

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