Mechanics

STALLING

1997 Pontiac Grand Prix

Engine Mechanical problem
1997 Pontiac Grand Prix 6 cyl Front Wheel Drive Automatic 97,000 miles

I have a 1997 Pontiac Grand Prix, that stalls out while driving. It does not matter if you are driving at highway speed or residential neighborhood speed, it will stall. Serveral things have been replaced that has been known to cause this problem, but still no fix.

The car first showed a hard code for the mass air flow sensor.(Only code that has ever shown up). When removing the old mass air flow sensor, it practically fell out, broken at the soder joints. Cool, Fixed? No.

Checked fuel pressure, even when stalls, no drop in fuel pressure.

Swapped out ECM, no fix.

Was advised by mechanic to replace Cam sensor, and crank sensor, replaced. Still not fixed.

Checked ground on transmission, ok.

Car also had blower fan, headlight, rear defroster issue. If you turned up (past 1st notch) the blower fan, the headlights would cut out and rear defroster would not work. Found by replacing ingnition switch, solved this problem, still stalls.

Tried replacing ignition module. Still stalls.

Removed idle air contol valve, cleaned, replaced. No fix.

Finally take it to pontiac dealer for diagnosis,
Was told needed fuel pump, they got to drop pressure. Replaced fuel pump assembly (in tank) drove for 2 days, fine, stated stalling again.

So I am looking at this point were to go from here. Any ideas would be greatly appreciated. I am left scratching my head at this point.

Thanks
Scott
Avatar
Satmiller
June 13, 2008.



Is this super charged? Does it start right back up? Does it stall while on the throttle or when slowing?

Tiny
Mastertechtim
Jun 15, 2008.
No, the car is not super charged. It will stall on the throttle or when slowing, no consistantancy.

As far as starting back up, sometimes it starts right away, other times it takes a hour to re-start. Again no consistancy.

It does not matter if your on a short hop to the store 2-3 mile away (on and off the throttle) or on a longer trip of 50 miles, (consistant on throttle) it will stall at any condition.

Thanks for your help.I'm stumped!

Scott

Tiny
Satmiller
Jun 16, 2008.
When it takes an hour to restart you need to find out if you have spark. Do this by removing a wire at the plug and place it near ground and crank engine and tell me if you have spark or not. If you do have spark try spraying starter fluid into intake and see if it will start on that. Get back to me. Also double check the crank sensor to make sure its not rubbing on harmonic balancer

Tiny
Mastertechtim
Jun 16, 2008.
Okay, Yes there is spark and it is getting fuel. When the car is sprayed with starting fluid it backfires through the intake and/or the exhaust.

When the car shuts off and you try to start it without starting fluid, it blows alot of back smoke out of tail pipe. Also while cranking, it backfires through the intake and/or exhaust.

No noticable rub for the crank sensor.

Thanks

Tiny
Satmiller
Jun 24, 2008.
Black smoke indicates raw fuel. Double check all cylinders for spark. You could have a bad coil causing 2 cylinders to drop out. Also check the fuel pressure regulator vacuum hose for raw fuel, if there is then replace it

Tiny
Mastertechtim
Jun 25, 2008.
Tim. Thanks for this updated info, I will check this out next.

I appreciate your time and knowledge.I am a diesel mechanic by trade, been doing it about 20+ years. Thought I would use this forum for a fresh set of eyes, friends of mine in the field (car mechanics) have had another idea. Broken solder joints in the ECM, heard of that one?

Thanks again, I will let you know how it goes!
Scott

Tiny
Satmiller
Jun 26, 2008.
Have you take a look to the main fuse box usually the connections for the fuel fuse is burned making the engine to stall as you describe.

Tiny
Victormonterroso
Aug 15, 2012.