Hey everyone. I'm at my wits' end so I'd like to get some opinions. I have a solid check engine light and my Diacom wont link to the computer at all no matter what. Shorting out A and B and putting the ignition on doesnt do anything. No code 12 or anything else. EPROM is brand new in a brand new CALPAK. Changed out the ECM with an Autozone one, it does the same thing. What the hell could it be ?!?

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92 Z28 5.7
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Trick Flow 23° heads, Comp Cams XR270HR-10 cam, Accel intake base + ported TPI,
TES headers, Flowmaster catback, MSD ignition, #24 SVO injectors, 1LE aluminum driveshaft.

Click here to see pics of my car !

 

What were you doing, or when did this start?.

If just happened out of the blue, well

Check all fuses. Some may look just fine, but be open, while your doing this actually remove the fuse, so that if it's a poor connection the R+R cures it.

If it still acts dead, then remove the ecm connectors, and with an ohm meter make sure all the grounds are actually grounded.

Next, and this is a PITA< just go wire by wire looking for something that is grounded that shouldn't be.

Some parts houses have a break out box. Little bit bigger then an ecm, and it plugs in where the ecm used to, and it reads out any problems, as far as sensors or loads go..

 

It just happened after I replace the intake gaskets a couple days ago. Today I drove it, and it seems like it's not gettng any spark advance. The exhaust is very loud, just like it is when the timing is not advanced at all. Two days ago when it did link, I remember looking at the Diacom screen and where it says "Spark advance relative to TDC = 0" where usually you do see a number there. Now I did replace the ignition module in the distributor and the "set timing connector" is plugged in. I'm really starting to think it's a melted wire somewhere.

 

Melted or pinched. That is so easy to do.
Sounds like your in limp home mode, No advance ofther then in the module design really clinches it, least by your discription.
Hope it's an easy one to find

 

Well it was a number of things working against me and I worked on this car for 3 days off and on trying to track down the problem(s). It was three things. The ignition module was fryed. The socket that I soldered on the calpak unsoldered 3 pins, taking me ECM into limp home mode as soon as the key was turned (making it much harder to troubleshoot), and finally the tach connection from the coil was bad. I just fixed all these things 30 minutes ago and it purrs like a kitten again Thanx for all the suggestions Bruce

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92 Z28 5.7
------------------
Trick Flow 23° heads, Comp Cams XR270HR-10 cam, Accel intake base + ported TPI,
TES headers, Flowmaster catback, MSD ignition, #24 SVO injectors, 1LE aluminum driveshaft.

Click here to see pics of my car !