Quick question

hi all, I have a 95 z28, and a few days ago a heater hose blew up:confused: and soaked the opti with coolant. now it has a rough idle, it runs fine other than that. is there a way I can confirm its my opti with freescan? its not throwing any codes. TIA

No... there is nothing in the PCM that detects problems on the high voltage side of the Opti. Have you pulled all the plug wires and the coil wire, dried them off, and checked the terminals on the Opti for corrosion and coolant? Also check the Opti harness connector for coolant or corrosion. Make sure there is no coolant on the coil and IC Module.

No... there is nothing in the PCM that detects problems on the high voltage side of the Opti. Have you pulled all the plug wires and the coil wire, dried them off, and checked the terminals on the Opti for corrosion and coolant? Also check the Opti harness connector for coolant or corrosion. Make sure there is no coolant on the coil and IC Module.

great advise! today is my day off so, I'm sure I can do that in no time. one question though, If there was something wrong with the opti connections,terminals, or the opti itself, would it just affect idle?

and I scanned it with freescan yesterday and I saw that the knock count was like 4030 within 2 minutes of driving, is this normal?

The Opti is used to set the ignition timing and injector timing. If the optical signal is screwed up, its going to have the potential make it run poorly anywhere in the RPM/load range. On the high voltage side, the higher the load on the engine, the more likely the voltage is going to break down, or find some path to follow other than through the spark plugs.

Knock count is a "cumulative" field. It appears the PCM is constantly looking at the engine operating data, and identifying conditions which might produce detonation (knock). When it sees those conditions, it increments the knock count field proportional to the severity of the conditions. It is completely possible for the knock count field to increment upwards without causing knock retard. At least not until the PCM has experienced the knock sensor picking up detonation.

It is very normal for the knock count to increase a bit on startup. You don't need to worry about it, unless you are also seeing knock retard. The field might have been at say 2,000 after the last shutoff, and then incremented upi another 2000 counts on startup. It will just keep increasing the number until it gets up ~65,000 or so, then reset to "0" and start over again. The magnitude of the number is not important, its whether it is increasing, how much its increasing, and under what conditions.

The Opti is used to set the ignition timing and injector timing. If the optical signal is screwed up, its going to have the potential make it run poorly anywhere in the RPM/load range. On the high voltage side, the higher the load on the engine, the more likely the voltage is going to break down, or find some path to follow other than through the spark plugs.

Knock count is a "cumulative" field. It appears the PCM is constantly looking at the engine operating data, and identifying conditions which might produce detonation (knock). When it sees those conditions, it increments the knock count field proportional to the severity of the conditions. It is completely possible for the knock count field to increment upwards without causing knock retard. At least not until the PCM has experienced the knock sensor picking up detonation.

It is very normal for the knock count to increase a bit on startup. You don't need to worry about it, unless you are also seeing knock retard. The field might have been at say 2,000 after the last shutoff, and then incremented upi another 2000 counts on startup. It will just keep increasing the number until it gets up ~65,000 or so, then reset to "0" and start over again. The magnitude of the number is not important, its whether it is increasing, how much its increasing, and under what conditions.


so if any of that was hapenning with the opti there would be a misfire,leading to a dtc correct?

also, the idle seems to calm down when it goes into closed loop?

sorry, I'm new to this kind of stuff.