Ok ever since ive bout my car its been nothing but a love/hate relationship. I am getting 10 Miles Per Gallon... Yes a 305 TBI SBC is getting 10 miles per gallon... problem is im 17 and i cant afford gas with that gas mileage... Well ive tried everything to get my gas mileage decent: tune up,o2 sensor changed,thermostat changed, coolant temp sensor changed, timing adjustment, Seafoam treatment... To me it seams like its getting nothing but worse. as far as idle goes however it had NEVER stalled on me.

The car car with a little generic "gorrila chipz" chip however it was removed i believe its an aftermarket POS that goes to the ecm

My theory is the previous owner installed this and fried the ECM

-The car gets bad gas mileage
-small misfire
-some surging
-the fan does not turn on by itself and will overheat if i dont turn on the AC
-there is a code 54

My dad says seeing all of these together and doing what we have done it is probably the ECM.

These issues are not affordable to me and it is making me give up on the car overall.. think im gonna get like a 4th gen with a 3.4 or 3.8 if i cant solve this problem.

So do you have any ideas if this is ECM related or not?
Or should i just buy a different car

 

Code 54 is a fuel pump voltage issue which could cause bad milage. A clogged cat will do the same.

Open the ECM and see that you have the proper chip in there. That could casue bad fuel milage.

Paying someone to use a scantool could find the problem. All these ideas are cheaper than buying a new car...

EDIT: Nah I changed my mind. You should get a new car and sell me that old, good for nothing POS that's nothing but trouble. Where you located?

 

how do i know what the proper chip is and if it is not the proper chip how do i get one?

what is the number on the ecm for a 1991 firebird tbi 305?

my dad says a clogged cat would hurt the top end where as this is hurting all over

EDIT: Do 305s and 350s have the same ECM w/ a different prom?