[mabolzich]

I have a 1986 Corvette that runs very well. It keeps throwing out these error codes in different combinations after about 15 or 20 minutes of driving.
:z1-2:25 MAT sensor High temperature fault (EFI/TPI/SFI)
32 EGR circuit fault (EFI/TBI)
36 MAF/MAP sensor too high
41 Electronic Spark Timing
42 Electronic Spark Timing monitor error

I can't help thinking that there is one cause for these codes. The grounds seem good, the EGR is new, I've checked everything I can think of. I'm hoping for some real knowledge from folks who know.:z1-2:
Thanks, Dan

 

[lostvette]

Try Disconnecting the Battery for a few minutes.

 

[mabolzich]

Thanks. Been there-done that.

 

[vettex2]

do you have a factory manual ?
it shows what to do and in what order to trouble shoot it
if you don't let me know and I'll try to scan it and email the pages you need
I have an 86 as well......

 

[vetteoz]

25 MAT sensor High temperature fault

Possibly a bad MAT sensor ( shorted to ground ) or the tan wire to ground somewhere

32 EGR circuit fault

The computer is not seeing the EGR valve operating when it commands it.
Typically a fault with the EGR temp switch or it's wiring ; check the wire is still attached to the switch , commonly breaks off
http://www.chevythunder.com/egr_code_32.htm

36 MAF/MAP sensor high

http://www.chevythunder.com/maf_code_36.htm

42 Electronic Spark Timing

http://www.chevythunder.com/est_code_42.htm

 

[vettex2]

that's almost as good as the manual , maybe better in some ways :thumbsup:

 

[mabolzich]

Finally, somewhere to start. Yes, I have a manual, but sometimes advise from smart people puts me on the right course. Thanks so far!

 

[vettex2]

I always just go by the factory manual first and then try to figure out the shortcuts second.
The C4 one is only one book
the C5 is THREE books