1999 Pontiac Grand Prix Won't idle

1999 PONTIAC GRAND PRIX
180,000 MILES • 3.8L • V6 • FWD • AUTOMATIC
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ERICKARSNER
  • MEMBER
  • 1 POST
My sons car recently died and won't start. We had a diagnostic run on the engine and shop reported 3 bad injectors and fuel in the oil. I replaced all 6 injectors and changed the oil. Now the car will start but won't idle, I fact when it does start it runs extremely rough like not all cylinders are firing, but when we rev it to 4500 rpm the engine smooths out.

Is this a cam sensor problem or is there another issue possible?
Dec 7, 2013 at 4:42 AM
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FREEMBA
  • ✓Experienced Mechanic
  • 1,152 POSTS
Start the engine and get it to the lowest rpm where it will stay running. Then disconnect the injectors, one-at-a-time to see which cylinders are working. (Example: unplug #1, the engine should run worse. If not, that cylinder isn't working. Reconnect that injector and repeat the process on each of the remaining cylinders)

Once the non-contributing cylinder(s) is found test the spark plug and wires by swapping one from a non working cylinder to a working cylinder.
If the non-working cyl. now works then the spark plug wire is the problem (or spark plug, which ever one you swapped on that cylinder)
This will take some time (because you'll switch one wire and perform the test from above, then one spark plug, etc)

Let me know the results of these tests. I'll be glad to offer more assistance, if needed.
Dec 7, 2013 at 5:35 AM
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