1987 Grand Am LE

TBDK

MEMBER
1987 PONTIAC GRAND AM

I have a 1987 Pontiac Grand Am LE. Mileage: about 15000. Motor is a V6 3.0 bored out.40 over. I bought this car from family cause the V6 in a 87 is pretty rare. It ran fine until recently. When I'm driving it feels like it's losing power. After a mile or 2 you can feel it get more power without your foot moving on the gas pedal. Car was just tuned up. New plugs, Coil pack, wires, the who shabang. Has compression and fuel pump works fine. Checked the fire and it's a good spark. Check engine light is on and car backfires. Drinks more gas than a vega. I used about 1/4 tank going 15 miles. I have been told to check for a MAP sensor fault or a Throttle
Position sensor failing. I don't know how to check the light cause the local stores can't diagnose a car so old. What are your opinions? Thanks

1 Reply

TBDK

MEMBER
24 POSTS

Turns out I was wrong on both counts. I bought the Haynes manual and read through it thoroghly. Upon reaching the sensors section I found out it's not the MAP or Throttle Position Sensor. The 1987 doesn't even have a MAP sensor. It was the crankshaft position sensor. I replaced and car runs great. No more backfire and fuel economy has returned to normal. That just proves you gotta check, even things you wouldn't think to, in order to fix.