LT4Camaro

Ive had this car for 16 years so I'm not new to it but this kind of has me stumped . The car was my daily driver i drove it ALOT and the last time i changed the optispark was 8 years ago, and never had a problem with it. The car hasnt needed anything in 8 years really except the starter went but i got pretty sick and the car sat for about 2 years, i would still go take for a little spin every couple months, it always fired right up on half a turn even when it was buried over the roof in snow... now the nice weather is here and i'm feeling better than i have in years so i go to take my car for a spin and its just dead no spark . the last time it started was a month ago no problem..... ive done all of the tests to the coil and module and at the opti harness and everything is pointing to the optical sensor not picking up the cam/crank signal, everything checks out fine except the 1-4v AC signal i am not getting when the engine cranks. So no spark even coming out of coil. i already tried a spare coil AND icm and its not that... I just find it very hard to believe the optispark would just fail sitting for a month am i missing something? i just cleaned my garage and am getting ready to start pulling this thing apart but if theres something else i might be missing that i should check please lmk!
these optis are so sketchy i just only trust brand new GM ones, which i cant even seem to find now anyone think its worth a shot to just replace the optical sensor inside? the car ran perfectly fine before ....
Thanks

Injuneer

Have you scanned it for codes? Failure of the optical cam position sensor will set one or two codes. What year is the ECM/PCM?

LT4Camaro

the problem is i dont have an OBDI Scanner, its a 95 PCM
i do have the cord for the laptop to tune it but i cannot find the old scanner software i used to use i think it was called scanmaster? is there any software i can use just to scan for codes with OBDI cable? i actually bought the data logging software many many years ago but god knows where it is now and i cant find it online.

Ryan

timnfxr

https://www.camaroz28.com/forums/com...95-lt1-874306/

shoebox

Make sure some critter has not been chewing on your opti harness.

LT4Camaro

thank you so much for the link to the software! I scanned the car and there are no codes but the battery was dead so how long would I have to keep cranking it over for
before it would set a code? I already checked the wiring on the opti harness it looks perfect and tested at the opti end for the right voltages and everything seems to be okay there just wondering if it was the optical sensor and my battery was dead clearing the codes how long would it take to set?

LT4Camaro

i had some more time to mess with it today and hooked up the datalogger, i cranked it over a whole bunch but theres no code for the optical sensor no codes at all and the RPM on the datalogger just shows 45 all the time even when cranking shouldnt it say 0?
i know the datalogger is working right you can see when its cranking from the MAP signal but the rpm just stays the same 45. will the optical sensor set a code if the engine isnt already running?

GaryDoug

If the scan app shows 45, it means it sees NO rpm from the engine. The thing it reads for rpm is the Opti low resolution pulse output. If there is no low res pulse, the pcm will not know the engine is turning and will not set any codes. The Opti or it's cable is likely the problem. Normal cranking rpm is about 200 and that should be read as such in the scan app.

LT4Camaro

I tested everything all the wiring was fine it had to be the Opti I pulled it apart today and the sensor was rusted so I'm just going to order a remanufactured GM one and hope for the best