OldCelica

Hey all,

I have been having some issues getting my 91 5.0 TBI to pass DEQ. All of the sensors test fine and my scan tool shows that the relation between the integrator and O2 reading is what would be expected with it running rich. I have ruled out the ignition system, and all of my sensors test out fine and give accurate readings on my scanner.

I have the issue narrowed down to either the ECM is fried, or I have a fuel pressure problem. I am waiting to get a T adapter to test the fuel pressure. It is in the mail and should get here tomorrow. In the meantime I decided to pull my computer out to see if it was scorched or corroded inside. Once I had it apart, I noticed that the prevous owner had swapped the stock PROM out for a JET CARB EO#D-234-4 chip.

I am fairly certain at this point that my issue is with excessive fuel pressure or injectors since it has passed DEQ with this chip 2 times that I know of. But I have a few questions about this chip:

1. What is the difference between this chip and the stock one? I know that most off the shelf chips just advance the timing and dump more fuel at WOT. Is this just one of those "snake oil" chips, or is there actually some benefit over the stock programming?

2. Is this a chip that I can get my feet wet with chip burning. I have been wanting to get into that for a few years now and why not start now

3. Does anyone know a place to get a stock chip for my car? I would really like to try a stock one to see if there is any difference in the way it runs. The car has always fallen flat at WOT since I bought it. If I back off the gas just a little from WOT, it picks up just a bit. I am blaming this "performance" chip at this point.

Thank you!

Tuned Performance

iTrader: (92)

are you running a 1228746 ecm ? many of the older tbi stock chips are still available from acdelco. You can just go to the junk yard and pick up a few robinson nugget eprom holders and burn a 2732 eprom. alot of the bcc $61 are available on diy-efi. you should also post this in the correct forum. If you let me know your rear end ratio and transmission type I will tell you the correct bcc. If its the original ecm it will have it listed bye the service number three too foul letters.

Tuned Performance

iTrader: (92)

ftp://ftp.diy-efi.org/pub/gmecm/bin_lib/1228746/

the axks could be used although it is for a automatic.

OldCelica

Thanks for the reply!

That is the ecm I have. The fore letter code is AXKU. I have no idea what my tranny and rear ratio are. Tranny is a 5-speed manual. I think everything is stock, but my speedo doesn't read accurate and I have stock size wheels/tires. So maybe one or the other has been changed and the speedo wasn't re-calibrated. 25MPH is actually about 28ish on the speedo.

Tuned Performance

iTrader: (92)

AXKU released 1989 gm part number 16161117 ecm 1228746 FB L03 5.0 M39 borg warner 5 speed MAN GU4 308 rear

if some has changed the 308 gears it would throw off the spedometer reading or if the transmission was changed and wrong spedo gears were installed.

Tuned Performance

iTrader: (92)

http://www.oewarehouse.com acdelco 16161117 shows still available