TBI question

[cardinal fang]

My 55 has a 1992 Chevy 350 TBI engine. After switching the fuel pump to a stronger motel, I have had no problems with it all. But a few weeks ago, the battery ran down real low. Now the engine light comes on every time I drive it. But, it does not register a code. When I start it and drive, it runs great, but the light comes on. I have the TBI software that runs on my laptop. I hooked it up to the computer, the light comes on, but it shows no error codes. When the light comes on, I can feel a little change how the engine runs, but nothing major. It just bugs me that the light comes on every time after about 10 minutes of driving.
Come next year, after I get the Vortec done in the 40, I am going to replace the TBI for a 5.7 Vortec.

 

[PabloCruise]

Did you try disconnecting the battery for a few minutes?

 

[cardinal fang]

Thanks for the reply.

Yep, tried that a few times. If I could get a code out of it, I would be able to fix it. Even with my laptop monitoring the engine running, the software does not show any codes. I will play around with it some more and see what I can find. I still drive it just about every day with no real issues. Just that light on all the time.

 

[YotaJosh]

What software are you using to check the codes? WinALDL?

Probably the O2 sensor is bad. When your truck gets to the proper operating temperature to start closed loop fueling, the ECM starts polling the O2 sensor, but can't get a proper signal, so it throws a code and turns on the light.

I have this exact problem with my TBI system right now. I haven't had the time to go get a new O2 sensor. I killed it by trying to tune the ECM, and O2 sensors don't work well once you've sooted them up.

 

[Trollhole]

How about running winaldl and logging a few minutes of data and posting it up. You can cause the TBI to go into limp mode at low voltage.

Make sure the computer is seeing a good strong voltage.

 

[cardinal fang]

Yes, it is WinALDL. I did log data for severl minutes. I will get it out of the laptop tomorrow. Thanks for ideas.

 

[nat]

What pressure is your pump operating at? TBI doesn't like too high a pressure.

 

[cardinal fang]

I finally got the computer to spit out an error code. = 24
"Speed sensor circut malfunction". Hmm, My speed sensor is from JTR. I would say 3 years ago. Cost about $100 IIRC. Now, at least I know the problem.