Hello guys/girls, I know this is a this is mostly a camaro forum, but when i google all my searching leads me to you guys. So I'm a new member here and i hope maybe someone here could maybe help me with my 305 tbi problems. So you know a bit about me I'm a LVL 2 auto tech here in canada, but now moved on to a diffrent trade working on Locomotives, as a HDM, anyways I have a 1991 chevy Caprice classic with a 305 TBI, and have an OTC scaner with access to OnDemand 5, my problem is when the car is running and cold it has great throttle response and power, but when it starts to warm up the power starts to drop and the car becomes SLUGGISH, I have checked for codes, and looked at my DATA STREAM, the only thing that looks odd is my MAT is showing 200 degrees celcius, i changed the sensor with a new one, same reading, i checked the harness from ECM back to the MAT and its all good, is this my problem? or is the 200 degrees celcius just somthing the OTC scaner is seeing as default?

 

well i picked up a new ECM and now my reading are ok car runs good, but i think the ecm was pull from a 93 caprice cop car, with a 350 will this make a diffrence on my car? like a sayed the car is running great. will post ecm service and prom tomorrow maybe somone could help.

 

so did you not have any dtc's?

 

with the old ECM no, and with the new ECM nothing also,

 

you will need to swap eproms. prom is specific for engine size. maybe you already have.

 

I tried swapping my prom, but got bad running engine and a dtc with code saying wrong eprom, so whent bad to the original from NEW ecm and it runs good?

 

In backwards? The original eprom should not cause an issue. Is the new ECU same as the old on the ECU#? 1228746.

 

Eprom will only fit one way.

New ecm: 16136965 AYKA, car has good power/running well
Old ecm: 1227747 ADTT, no power.

I know the service numbers are wrong so the new ecm is no good now?

Looking at the 1227747 abd googling a bit seems like the ecm was pulled from a truck did these come in the cprice?

 

1991 Chev uses a 16136965. LO3 and LO5. 7747 is a truck ECU. I cant find anything on AKYA. 6965 used in 4.3, 305, 350. AKYA could be any of the three. Plus the california specific .bin. I searched her on this site. nothing.


I found this:
The '7747 was only used in trucks, not going to find a Caprice BIN for it. Here is the AYKC BIN. It was used in at least the '92 Caprice/Roadmaster wagons. MaskID of $62. Interestingly enough was used in both the 16136965 and 16135320 ECMs. Must have been a change in the ROM code.
It is for the 5.7l engine. I thought I had more BINs for the wagons.