Hey everybody, I swapped out my engine from my 96 and put in a 95 lt1. I have my 96 pcm and wiring harness connected to the 95 engine. I know the 95 is the obd1 engine and the 96 is obdII, I am getting signal to all my injectors with key turned on but I am getting no pulse during turn over to get engine to run. If I put fuel into the intake it will start long enough to burn off the fuel in the intake. Can anyone help me troubleshoot this to get it running and on the road? Weather is too nice for it to be in the garage. Any help is appreciated.

 

EDIT: Just realized that I misread your message. I thought you put in 96 engine/ECM in a 95 car. Just figured out you put a 95 engine in a 96 car. heh..


I'm no expert, but it could be VATS. http://shbox.com/1/pass_key.html

I don't know if the 95 cars had a BCM. Did you swap the BCM and interior wiring harness from the 96 into your car along with the engine wiring harness? I'm thinking that the 96 computer is looking for a signal from the 96 BCM that the correct key pellet is being used in the ignition. If that signal isn't present then it will refuse to ground the injectors.

If that is the problem then you have lots of options. I think you can reprogram the BCM to your 95 key pellet with a Tech 2. If you have LT1 Edit or the Jet Tuner you can flash VATS out of the ECM. There are also some aftermarket solutions that you can wire into the 96 harness to emulate the signal it wants to see from the BCM. Another option is to find the resistor value the BCM wants to see, bypass the wiring in the ignition, and wire the correct resistor in. I'm not sure if the ignition key cylinders swap, but if you have the 96 car key and cylinder you might could use those in the 95. It gets a little murky because it depends on which pieces of the cars were swapped along with the engine, harness, and ECM.

Since the car turns over with the ignition key, it sounds like the starter defeat is happy with your current key, or the relay has been bypassed. I'm sure someone more familiar with the individual cars will chime in with better details.

Good luck!

Chad

 

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Which opti are you using? The pulse comes from the optical sensor.

http://shbox.com/1/4th_gen_tech2.html#opti_test

 

I've got the stock 95 on it.

 

Is it a vented opti? I don't know if the opti harnesses are the same so that may be a stupid question? If it's somehow an OBDI-non-vented opti it will not communicate with a '96 PCM. That's at least to my knowledge which can be janky at times.

 

95s are vented.

 

Pretty sure that link provides a way to see if a pulse is being generated from the opti.

 

So the 95 would work the same as the 96?

 

ok, so I disconnected the wires going into the icm and I had 3 volts on B, I have a good ground on C, and A and D I have 12v. I unplugged the connector on the other side of the opti and have no reading at all. So I'm assuming that it may be bad. Do you know if the 96 is interchangeable with the 95?

 

Are you checking the PCM side or opti side of that connector? You should be checking towards the PCM.

I don't see why a 95 opti would be different than a 96.

 

Ok, so I just got home from tearing into it. Turns out I think the 96 is a vented opti and the 95 isnt. I read elsewhere that you can swap the cam and housing from the 96 to make it work, anybody know if that's true? Because I was thinking maybe the opti was bad and losing signal internally somewhere and was just gonna switch them but doesn't look like they're interchangeable. I first checked the connector on the ignition control module under the coil and got all the right readings and then unplugged the connector on the opposite side (pcm side) and got nothing, on any of em A,B,C, or D. Which one do you mean by the pcm side? The connector up near the fuel rail?

 

Must be an older opti. I've had a couple 95s and they are/were both vented.

And yes, the opti connector near the fuel rail/on the intake. Unplug it and probe towards the PCM. What I'm asking you to do is to probe the BLACK (not GREY) side of this connector:




If you're getting 12v/5v/5v/ground on the black side of the connector but not at the grey side of the connector, then the connector is your problem. I've had to replace that connector a few times but only had to replace an optispark once.