TBIM

[Jeff_in_Atl]

GM replaced the harness along with the OPTI 2/25/03.

I found the vacuum lines to the OPTI were not connected. According to Rob's (shoebox) picture http://csce.uark.edu/~jgbertr/rb/opt...um_harness.jpg The line to the manifold was not connected at the manifold. The one to the elbow was not connected to the elbow. I also noticed there was a port out of the back of the air pipe between the filter and the MAF sensor that wasn't connected to anything. I think it was connected before they did they did the air pump recall. I don't see a hose that is laying around that it should be connected too.

I guess I'm going to have to start working on this thing if I want the work done right.

[Injuneer]

Couple comments on earlier posts....

There is no crank position sensor on a 95. That was only added in 96, and is only used for misfire detection. The Opti low res pulse is, in effect, the crank and cam position sensor.

DTC 36 is the loss of high resolution pulse from the Opti, not related at all to the MAP sensor.

There is a 5/8" port on the air intake duct between the air filter and the MAF sensor. That is the air supply for the AIR pump. It should not be open. If the AIR pump is still functional, there should be a hose from the port to the AIR pump. If for some reason the AIR pump is disabled, that hole in the air duct should be capped with a 5/8" vacuum cap. I will let dirty air bypass the filter, but won't cause the problems you are having.

Everything it pointing to the ignition system. Erratic behaviour is often from a poor ground, a wiring harness problem, or a high voltage wire running too close to the Opti harness. I was looking at some early wiring diagrams for a 92 Corvette LT1, and that year the Opti harness had a grounded shield around it... but for some reason it was deleted in later years, and never included in the F-Body.

[Jeff_in_Atl]

Update.

Dealer called. Said the connector on both the OPTI and the harness were corroded real bad. They are replacing both under warrantee. I told him to use dielectric grease this time so it won't happen again. He said OK. Hopefully I will get it back today.

[Jeff_in_Atl]

Car is back home and running fine. GM warranted everything. New OPTI, OPTI harness, water pump gaskets, and all labor. I asked the service writer what I owed and he held out his hand for a handshake. Not a cent except 2 tow bills which I have insurance for. FYI OPTI has a 1 year warrantee. Coil, Module, harness has a lifetime warrantee.