So, i got my vette, and i have a few questions in order of importance.

1) The car is an 87 with a swapped in LT1, and it runs rich, and gets hideously poor gas mileage (4-5 mpg) and since the previous owner told me that he planned to slap on a supercharger on the car, he sent the ECU to be retuned for that. Obviously those plans didnt quite work out, so now i need to find a way to get back to the original Fuel map/tune.
How would i be able to do that?

2) Also, the car does NOT like city driving, gets warm after fifteen minutes of driving at 25-45, and once that happens, i lose power and the car runs like crap. Dont know if this is connected to the richness issue or not. Oh, and also, it seems to pull fastest if i give it like 1/4 throttle, and seems to bog out when i give it more.
Any ideas?

3) when the car was swapped, the iterior was also updated to a 92, except that the 87 wiring harness remains (i found a 92 harness for cheap) so the LCD screen doesnt work (tach, oil temp gauge and coolant temp gauges work but oil pressure doesnt.)
What would i need to make the LCD screen work?

I have a lot more questions, but ill wait until later to ask those..
Thanks ahead

 

Ouch!!
Pull the motor and try an L98.
First off I would get a factory 93 LT1 manuel and start their.
You are tring to run an ob2 type system with a computer that can't keep up.
You are looking at the LT1 that needs diff map and o2 sensors along with a less restrictive exaust system,and the list goes on.I would change to a carb and save yourself alot of problems.
Don't get me wrong it can be done but for the beginner it will take you tons of $$$$ and most likely years to get it right.If you want to do it I would go to the fast system type computer and Lt1 edit or equilavent ,that would be a start .

 

Sounds like a cobbled up mess. Hope you got it cheap!

 

I have a manual
I thought OBD2 was 96+, and the ECU is an LT1 ecu, and has all the sensors and even the EGR and emissions stuff, and a 3 inch exhaust to boot.

 

Sounds like the computer is responding as tho the supercharger was in place.

Might be a long shot, but try reprogramming the computer.

 

If you have the LT1 computer I am thinking OB1 at least,you can use Lt1 EDIT and change the info in the computer yourself.If the car is running rich and It sounds like it is ,that means the engine is lean.Check the o2 sensors,intake gasket and egr.You can get some carb spray and use it around the intake to check for leaks.You can always get a used computer from the junk yard and install it.Just so you know any wiring on an 86 is not the best.Your oil line wire needs a sensor where the oil filter is,the wire should be at the back of the motor.
My 94 you program the computer it does not use a chip.

 

You might try posting a location, and maybe there's someone nearby who can help you figure out the tune.

Or if the car has a swappable PROM (I don't know LT1's) perhaps someone nearby can lend you a stock PROM or ECM to see how it runs on the GM tune?

 

96 was first year for OBDII.

 

Thats pretty much exactly what i was saying. Is there anyone around Salem OR that can retune my ECU? or should i just buy a stock one from a nearby junkyard?

 

tjwong@qwest.net

He can straighten you out. Im guessing if the guy did some SC tune you may have an injctor which is WAY too big in there also.

Sounds lke the conversion is done just needs some details sorted out.