Wet Pontiac Grand Prix. HELP!

RICHSAXTON

MEMBER
PONTIAC GRAND PRIX

I have this 1998 GP that is driving me absolutly crazy! If there is moisture in the air, or it is raining. This car does not want to run. It runs very rough, rich it seems. It will idle irraticlly, stall, and the exaust pipe will turn red hot, as well as the catalytic convertor. When I put it on a diagnostic tool it said that the mass flow sensor was bad. I have taken it to many differant mechanics including GM. No one can seem to figure this out. I have replaced the sensors, catalytic converter, fuel filter, plugs, wires, and ect. When I replaced the o2 sensor the wires were burnt. The insulation on the wires had melted. I replaced them as well, but I then realized that the wires that connect to the o2 sensor might be melted as well so I checked them. Just as I thought they had been burnt. I DID MY BEST AT INDIVIDULLY TAPING EACH ONE, THEN TAPING THE BUNCH TOGETHER. The wires run up into the engine compartment, I taped them as far as I could. So I am wondering if maybe that might be the problem. If so do I have to purchase the complete engine harness? Does this sound like that might fix the problem? If so how would I go about doing this? Any help, or feedback would be greatly appreciated. Rich

2 Replies

MCFERRANCE

MEMBER
100 POSTS

If the wires were hot enough to melt the insulation, they have probably gained a lot of resistance to carrying any electrical signals. These can be tested with an ohm meter. If they look anything other than shiney copper, they probably have been damaged and need replaced.

Most likely the best bet would be to find a salvage yard and splice the harness. If the plug is ok at the O2 sensor, you may be able to splice it and replace the burnt wires as necessary.

However, this problem may only be a cause of the original problem, but you have to start somewhere.