Ok so for the past while my 95 Z28 has been sputtering out, with random RPM drops and such while cruising, not under acceleration, and throwing a check engine till it clears up. Been using a Snap On Modis code reader, and nothings there when I check it. The other day it just wouldn't start. I replaced the module and coil, and was cranking it while reading voltages and such, and found out if I crank it for about 15-20 seconds, it'll start up finally, but a check engine light will be on and still nothing on the code reader. It'll start everytime after cranking it long enough. So before I go drop $400 or so on an opti, does that sound like the problem?

Thanks.

 

Is the MAF sensor giving a good reading? Pull yhe opti harness extension and check the pins and connections. What codes is it throwing?

 

Long shot and maybe completely wrong, but maybe check fuel pressure as you start the car and clean your fuel filter. Some of the symptoms you have might be explained by that. Maybe you have a lack of fuel pressure for the first 15 seconds for some reason. So yeah, maybe check that out and see what it is doing.

Also, do you have spark on your cylinders? I might check that out, too. If you have spark in all your cylinders, it's prolly time to look at fuel/air problems. And yes, codes would be invaluable at this point. Just trying to save you some money before you spend $400 on an Opti.

 

Are you setting the Snap-On scanner to OBD-I? Are you using the correct connector for the OBD-I pinout on your 16-pin OBD-II "style" ALDL connector?

 

shbox has a great guide to doing it here:

http://shbox.com/1/xraycable.jpg

 

Ok got a hold of the code reader again, started her up and got these

16- DIS fault line open or short
&
31- Cam sensor

So yeah, guess that would be the damn opti wouldn't it?

 

DTC 16 is loss of low resolution signal from the cam position sensor in the Opti. But it isn't unusual to see that code as a stored code. The fact it won't start would indicate its probably an active code, because the PCM shuts down the fuel system when it sets. Clear it (pull "PCM BAT" fuse in the underhood box for 30 seconds), and see how fast it comes back. The loss of signal can result from either the optical sensor in the Opti, or the wire that runs from the Opti to the PCM.

I don't think you really mean DTC 31. That is not a valid code for your 95. I suspect it is DTC 32, for loss of high resolution signal from the optical cam position sensor in the Opti. It is looking like the Opti.... but check the harness connectors first, as suggested in the first response above.

 

Ah.....the wonders a few codes can do. You know, I think you're right Injuneer, about the reputation of the opti being worse than it deserves. I think the reason that it's so bad is because sooner or later, it's going to need to be replaced, and that's where we get all these posts with people changing them out.

 

Thank you very much for the help guys.