If a 1998 Bonneville will not start and you have replaced plugs wires and a mass airflow sensor but none of that helped and it backfires a lot what else can you try?

Answer 1

it might be the timing beltGas can go bad if it has sat in the tank long enough. Try adding fresh good quality gas in the tank and going for a long drive to work the old stuff out. You may want to add a good fuel system cleaner to the gas before you take that long drive too. Most bottles of fuel system cleaner will roughly treat about 14-20 gals of gas so you only need one. If you anticipate letting your car sit, add a fuel stabilizer to the gas to increase to its 'shelf life' in your tank.

Sounds like an ignition problem. The backfiring is probably from the plugs misfiring or you didn't get the plug wires back in the correct spots on the ignition block. Did you replace the coil/ignition block? check the wires that go to the block or take it off completely and take it to an auto parts store. they can test it for you and tell you if you need to replace it.

Wait a minute, I have the same problem and I changed the spark plug wires and the MAF sensor and the O2 sensors. I am now going to the crank sensor, then I am selling my car.

I had the same problem with my 98 Bonneville 3.8L I replaced pluggs, wires, and coil packs. It turned out to be bad fuel injectors at least 2, however I decided to do all 6. I found remanufactured ones on the internet at very good prices all 6 under $200.

Check water level if you are losing coolant it is most likely a bad intake gasket either upper, lower or maybe both.

I have a 1995 Bonneville and at one time it sounded like it was backfiring also, but found out later that it wasn't. The problem was actually in the transmission and it only sounded like it was backfiring. I ended up having to replace the transmission.