00Nassau

We are working on my daughter's 95 LT1 with 130,000 miles. It was running rough with some backfire and engine vibration. A couple of months ago we had to replace water pump, so I assumed it was probably the optispark. We changed out the opti-spark, plugs, wires, coil and ignition controller. The car now sounds good at idle and does not backfire, but when you put it under load it vibrates and does not have the normal amount of power.

Any suggestions on where to start looking for the problem?

Thanks,
Allen

DRAKEFAMILY2

Are you sure you didn't cross a couple of plug wires.

ittlfly

Any codes?

00Nassau

I checked the passenger side spark plug wires and they are correct. My old eyes cannot see well enough to be sure on the driver's side.

I pulled the codes and got C12 and H65. I used to have a list codes and what they meant, but I can't locate it right now. I will keep looking.

00Nassau

I just found that:

65 Oxygen Sensor Circuit (Rich Exhaust)

The car did smell like it was running rich this morning, and it normally runs very clean. The wife even commented on smelling gas.

Any suggestions on where to start looking for the problem?

Thanks,
Allen

00Nassau

I just did a search on H65 and found it is actually an ASR code. When we first started the car there was a wire disconnected on the ASR and we got a warning light on the dash. Plugged the wire back in and that code has gone away.

MikeC4

just to be sure your O2 sensor is bad, disconnect the negative battery terminal for at least 10 seconds to clear all sotred error codes. Then run the car a day or so and see if the code re-appears. Keep in mind that the O2 sensor may be OK, and another condition is causing the rich mixture in the exhaust. If the car idles fine but lacks power during normal acceleration, you may have clogged cat(s). Also, when you re-installed the coil wire, did you make sure you connected nice and tight?

but your comments below sure sound like restricted cats....
"sounds good at idle and does not backfire, but when you put it under load it vibrates and does not have the normal amount of power"


just my $0.02.......

Texas CE

The Crank Position Sensor may be the culprit for all of the above problems. They cost $45-50, are held on with 1 bolt and can be changed in 15 minutes with no other disassembly.

kkonen

When my opti went bad, it completely fouled my spark plugs and o2 sensors. You said you changed plugs. My guess is you need to change o2 also. At the very least I would pull them out and see what they look like. If they are covered in soot, they are probably fouled. I would also pull your plugs out and see if they are black also. If so, they need to be cleaned.