DIES AND WONT START WHEN WARM

1997 GMC Truck

Tiny

97z71

May, 21, 2010 AT 9:38 AM

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

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11 Answers

Tiny

97z71

May, 21, 2010 AT 6:37 PM

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)

Tiny

97z71

May, 23, 2010 AT 3:47 PM

I thought I donated 5 dollars for a guranteed answer?

Tiny

mmprince4000

May, 26, 2010 AT 8:43 AM

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?

Tiny

mmprince4000

May, 26, 2010 AT 9:02 AM

P0341 diagnosis:


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

Tiny

97z71

May, 26, 2010 AT 9:31 AM

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

mmprince4000

May, 27, 2010 AT 8:28 AM

Just remembered, they will have to program new VIN into PCM, TechII can do that.

Tiny

97z71

June, 14, 2010 AT 7:18 AM

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

mmprince4000

June, 15, 2010 AT 9:25 AM

PCM must be reflashed with correct VIN. A TechII can do this.

Security system could also be problem.

Tiny

97z71

June, 15, 2010 AT 9:43 AM

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

mmprince4000

June, 16, 2010 AT 7:13 AM

Have the CPS data read in live data mode, if within specs, then PCM, if not then CPS or wiring to it.

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