Computer swap, high timing problems..

[Turbo__Tim]

I'm posting for Herb Fishman. He has swapped a '87 ecm in to replace his '85 ecm so he can run the newer chips. After much discussion, we conclude that he has high timming, causing severe knock at 6psi. This happened right when the swap was completed. All the usual things have been checked plugs, wires, pvc, different chips, calpacks, even a translator+ (not sure how far he went with that) High octane fuel works great...

Could the crank sensor, that is a different part number for the hot aired need to be changed to match the '87 ecm.

Also which cal pack goes into the new ecm? not sure what he did there....

Anyway I believe he is going to swap everything back, to the '85 set-up to get a starting point, and be sure this is not something mechanical.

He has turbo Link files, should be available tomorrow. Thanks for any help..

 

[cool 84]

The 84 crank sensor will work fine with the 87 ECM. The only difference is the early one has a foot long wire coming out that plugs into the wiring harness and the later one just has a plug on it. Other than that they are identical.

Have you checked the #s on the computer to make sure it's the right one and not a batch fire one?

If the timing is truly off, the only other thing I can think of is if the reluctor wheel on the crank pulley somehow moved out of position.

Is the alternator putting out a full 13+ volts? Mine would knock at low boost when it was still as high as 12.5V.

Is the turbo leaking oil into the intake? From experience it can leak enough to cause bad detonation without smoking.

 

[TurboRegal84]

hey Guys...I have some new info with my problem.

I changed over to the 84 ECM, 84 MAF, and all that stuff..

And the car dosent knock at ALL!

I tried many times to get it to knock:

Off idle WOT blast

Spool and then wot blast

a WOT stomp from 30mph

On all attempts I saw ZERO knock...if i were to do these things with the 87 stuff in then I would have gotton insane REAL knock!

What could be causing this knock with the 87 Electronics?
I like having no knock, but I hate driving the car without my scanmaster hooked up (cant use it with the 84 elec)


please help!

 

[Turbo__Tim]

http://www.gnttype.org/techarea/ignition/module.html

Guys, here is the correct procedure for doing this swap. At least it is in our archives now.

 

[dave84gn]

Herb, I'm getting knock with the new computer too, anything over 10psi and especially at WOT (13-15psi) I get knock (like 10 degrees of retard).

The weird thing was everything was fine with the 87ECM and stock 87GN chip for the first week, then this seemed to come out of nowhere, but I *think* it's turbo related (maybe vacuum leak). My car's stored now so I can't do any more testing.

And I don't know if I was knocking with the 84ECM because I never had a working turbolink with that ECM.

Let us know if you get this thing solved.

Dave

 

[SLOW_85]

http://www.turbobuick.com/forums/showthread.php?s=&threadid=19414

 

[TurboRegal84]

Dave....I put the 84 MAF on my car with the 87 ECM and Chip....the car runs alot better, and I am getting 15-16psi with close to no knock....try your old MAF with the new ECM.....worked for me...so it might just work for you!

 

[dave84gn]

I haven't got the 87MAF yet Been using my 84 the whole time. From the looks of it, the MAF maxes out at 255 around 10psi of boost (seems too soon to me)... What are your MAF readings w/the 84 and w/the 87 MAFs?

Let me know if anything else pops up.

Dave

 

[TurboRegal84]

With the 84 MAF....Readings are around 245-250

With the 87 MAF....Readings are in the 216 range!