1985 Help
10-11-2013, 10:13 AM
#1
Cruising
Thread Starter
1985 Help
I am new to this site and hope i am doing this right.
I live in Comfort Texas and several months ago purchased a 1985 from a guy who bought it from a guy who had done a lot of work on the car then just gave up. The car sat in a barn for several years when i purchased. We don't know exactly what was done to the car but a lot of new parts including crane cam, Hedman headers and Elderbrock High Flo injection. Suspension is all new or rebuilt. We are currently putting the pieces back together but have no clue on where to go for wiring/ECM help. Also the engine has 292 angled plug heads and trying to determine what sending units go where has been difficult if not impossible. On each head there can be 3 sensors/sending units, We know the engine was at least partially rebuilt but not being able to find the builder, don't have a clue.
We did find a local Corvette guy who helped with some of the wiring but still a lot to do.
Can someone tell me where i might find some answers to the following:
1) What ecm should i get for the car. Currently stock and we know has to be changed. I have spent hours on the internet trying to get answers and just get more confused.
2) What are the sending units/sensors that go in the heads.
3) Will i need new wiring harness for the engine?
Have worked on/rebuilt many cars when young but really at a loss on this one as you most certainly can tell. Very close to giving up and going back to the 50's for one of those carberated, even a dummy can do it, models........
Any help will be greatly appreciated.
CK
I live in Comfort Texas and several months ago purchased a 1985 from a guy who bought it from a guy who had done a lot of work on the car then just gave up. The car sat in a barn for several years when i purchased. We don't know exactly what was done to the car but a lot of new parts including crane cam, Hedman headers and Elderbrock High Flo injection. Suspension is all new or rebuilt. We are currently putting the pieces back together but have no clue on where to go for wiring/ECM help. Also the engine has 292 angled plug heads and trying to determine what sending units go where has been difficult if not impossible. On each head there can be 3 sensors/sending units, We know the engine was at least partially rebuilt but not being able to find the builder, don't have a clue.
We did find a local Corvette guy who helped with some of the wiring but still a lot to do.
Can someone tell me where i might find some answers to the following:
1) What ecm should i get for the car. Currently stock and we know has to be changed. I have spent hours on the internet trying to get answers and just get more confused.
2) What are the sending units/sensors that go in the heads.
3) Will i need new wiring harness for the engine?
Have worked on/rebuilt many cars when young but really at a loss on this one as you most certainly can tell. Very close to giving up and going back to the 50's for one of those carberated, even a dummy can do it, models........
Any help will be greatly appreciated.
CK
10-11-2013, 10:35 AM
#2
Melting Slicks
As a fellow 85 owner, I'd like to say welcome to the Forum.
I will try my best to answer your questions.
1) What ecm should i get for the car. Currently stock and we know has to be changed. I have spent hours on the internet trying to get answers and just get more confused. - as far as I remember, the 85 has a stand alone ECM and uses a MAF Burn Off module whereas later years have a relay. If the car still has the original wiring, you will need to get an 85 ECM (#1226870 or #88999128; this also is the same unit used in the 3rd gen F-body GM cars with TPI).
2) What are the sending units/sensors that go in the heads. - typically, the sending unit on the right side head for the 85 controls the auxillary cooling fan (that's the fan on the front of the radiator if its so equipped, the main fan is controlled by the ECM); the sender in the left head is the temperature gauge I believe
3) Will i need new wiring harness for the engine? - if the wiring harness currently in the car is shot, then go for a new one with the matching ECM; I believe Painless might sell complete wiring harnesses for your C4, but I'm not 100% sure, you probably could source a used one from one of the many recyclers
I hope that helps
I will try my best to answer your questions.
1) What ecm should i get for the car. Currently stock and we know has to be changed. I have spent hours on the internet trying to get answers and just get more confused. - as far as I remember, the 85 has a stand alone ECM and uses a MAF Burn Off module whereas later years have a relay. If the car still has the original wiring, you will need to get an 85 ECM (#1226870 or #88999128; this also is the same unit used in the 3rd gen F-body GM cars with TPI).
2) What are the sending units/sensors that go in the heads. - typically, the sending unit on the right side head for the 85 controls the auxillary cooling fan (that's the fan on the front of the radiator if its so equipped, the main fan is controlled by the ECM); the sender in the left head is the temperature gauge I believe
3) Will i need new wiring harness for the engine? - if the wiring harness currently in the car is shot, then go for a new one with the matching ECM; I believe Painless might sell complete wiring harnesses for your C4, but I'm not 100% sure, you probably could source a used one from one of the many recyclers
I hope that helps
Last edited by ejscarfo; 10-11-2013 at 10:50 AM.
10-12-2013, 02:07 AM
#4
Melting Slicks
well ck67 if you have bought an '85 you will be needing a hand ! 
i had a set of those angle plug (double hump) fuellies on my old speedway engine, the theory was that the angle plugs fired at just the right angle on high domed, high compression engines, but didnt really make much difference on flat top pistons.
Do you know what the specs on the crane cam are ? if its not too radical you can get away with the stock chip in the computer as the maf setups are a bit more forgiving (does it still have the maf ?),
if you need some engine bay pics showing sensor locations let me know and i will post some for you
i had a set of those angle plug (double hump) fuellies on my old speedway engine, the theory was that the angle plugs fired at just the right angle on high domed, high compression engines, but didnt really make much difference on flat top pistons.
Do you know what the specs on the crane cam are ? if its not too radical you can get away with the stock chip in the computer as the maf setups are a bit more forgiving (does it still have the maf ?),
if you need some engine bay pics showing sensor locations let me know and i will post some for you
10-12-2013, 03:58 AM
#5
If so you would be well advised to modify that
see
http://www.eecis.udel.edu/~davis/z28/ecm_swap/
and install the much better and well supported '165 ECM from a '86 -'89 car that you can easily get a modified tune for to suit your engine mods and also does away with the one year only burn off module
Nobody supports the one year only ECM in your car
If you have no harness then you could get a 86 -89 Vette harness to suit the above ECM and it would be PnP as a stock setup