I just purchased an 85 Z28 which originally had the 305 in it. The previous owner put a built 89 350 in the Z28. Bored, mild cam, ignition system, etc, as well as a different rear end. My question is, the car runs great but I think shes running rich. Does the stock PROM suffice or should I look at a replacement concidering the new engine isnt exactly stock.... If I should look at a replacement can someone point me in the right direction...

 

If the '89 engine has the correct 350 injectors then it will because computer thinks it still has smaller 305 injectors.
Need 350 prom and knock sensor

If you think your mods require a custom tune then there are plenty of mail order places that can do one and also do mods like delete EGR / AIR and change fan operating temps , etc

 

How do I find out if the car has the proper PROM already installed?

 

Take the inspection cover off the computer and read the 4 letter code written on the silver label inside the blue cover of the memcal ( Chip ). Then post it up here
See
http://tpiparts.net/inc/sdetail/19022

 

The main ECM number is 7-7165 and the code inside of the blue chip is APYU 3516. Previous owner claims that he added a Hypertech chip. Where would this chip be if he actually did replace it.

 

4?

 

APYU is a '89 350 w/auto chip

Hypertech chip replaces original in the ECM
http://www.performancepartswholesale...B3YXJyYW50eS4=

 

Ok so my ECM is correct... where should I look now for the running rich issue... Just put a Cat on here or is it something else.


Would the Hypertech be good enough for the modifications on this drivetrain....... or going to somewhere.. say Thunder Racing for a custom tune/programming.

 

Could be rich because of the wrong thermo and fans as well. Remember it's also a different engine perhaps the ecm could be wrong for the engine. It's best to custom tune it(if you dont know how you can bring it someone) Most of the time its an ecm error. But, it could be something else.

 

He has a '165 ECM (86 -89 TPI) on a '89 TPI engine with a '89 chip

 

Oh,didn't read that. Then it's clearly something else.

 

Do you know the specs for the cam?

It might not be a computer friendly cam.

Check your vacuum at idle, if its below 15 inches it could have too much overlap for the ECM.

 

I have no clue what cam the PO put in the car... no way to find out without tearin er down...lol

 

are there any check engine codes?
how old is the o2 sensor?

 

O2 sensor looks quite old, I will change it when I get paid. I need to change the check engine light bulb, as it is not illuminating. Can't very well pull codes with a burned out light...lol.....I think I will change em all while I have the cluster out.

 

A thought
Some aftermarket chips attach to the side of the original chip using a adapter and can't be seen through the inspection hole.
Take ECM out , open it up ( 4 x 7mm nuts on sides ) and see if there is a 2nd chip attached

 

I pulled the whole ECM from the car, and removed the PROM, stock chip installed, PO claimed that he had put a chip in it.... BS...lol

I really dont see the need to go for a custom tune for the mods that have been done to the car... I was thinking about just ordering a performance chip from one of the companies.... So many choices, lol, hard to tell whats the best bang for the buck.

 

anyone by chance have a picture of the inside of the ECM, my dici cam is down, but therea a white wire running from the center of the ecm back to a spot beside where the vehicle harness plugs in. about 4 inches long.... just seems out of place....

 

I just installed a chip in mine and it had the same white wire inside. Must be normal.