Bog off the line

[dburgjohn]

My 92 LT1 has a bog if I hit it from stop or very low speed. Once the RPMs get up, its fine. Not a miss, just a bog down. Does not seem to affect it at higher speed / RPM. 70k miles, all stock.

 

[John Robinson]

Test this

Run a diagnostic test on the TPS (throttle position sensor)

 

[dburgjohn]

Run a diagnostic test on the TPS (throttle position sensor)

Love to, anyone tell me how?

 

[John Robinson]

For a 93

Throttle Position Sensor

The scan tool displays throttle position in volts. The voltage should display between .23 - .59, with throttle closed and ignition “ON,” or at idle. Voltage should increase at a steady rate as throttle is moved toward Wide Open Throttle (WOT) about 4.6 volts.

The ECM has the ability to Auto-Zero the TP sensor voltage if it is between .23 and .59 volt. This means that any closed throttle voltage between .23 and .59 volt will be determined by the ECM to be 0% throttle angle, and should display 0% when the throttle is closed. A failure in the TP sensor circuit should (MY OPINION MAY NOT )set a DTC 21 or 23.

Copied from the service manual for a 93 model

The TPS acts like the Accelerator pump that a Carb had. But with the ecm controlling fuel flow it tells the computer what the throttle position is and the computer then tells the injectors how much fuel is needed for that throttle opening. In the old days bogging off the line usually was a lean condition caused by a faulty accelerator pump. We are all sitting out here with our Shelock Holmes hat and pipe waiting for the answear to this mystery

 

[dburgjohn]

Thanks! I have a Autoxray 5000 scan tool. TPS voltage reads 0.66 at idle and 4.05 at WOT. The scan tool did show me a code 32 (EGR). Could this EGR code be part of the bog problem?

 

[John Robinson]

I don't know

Thanks! I have a Autoxray 5000 scan tool. TPS voltage reads 0.66 at idle and 4.05 at WOT. The scan tool did show me a code 32 (EGR). Could this EGR code be part of the bog problem?

I had an EGR problem with my Berreta a few years ago. It started when I had gone the first 50 miles on my vacation. I drove the car 1200 miles and then had a GM dealer look at it. He said it was a loose wire and fixed it. Just after I left the dealer it coded again. I drove the rest of my vacation with the EGR code. I did not notice any loss of performance just a reduction of gas milage by about 2 miles per gallon. Thats all I know abut that.:W

 

[dburgjohn]

not yet

Checked out the EGR system, it is working. Fuel presure good (40lb). Put meter on injectors, they showed good. This car seems like it is leaning out on launch. Anybody else had/fixed anything like this/

 

[mdsbch]

My 85 coupe used to bog down after a while of driving and I would have to pull over shut it down and wait a few minutes then restart. It had a vaccuum leak and fuel problems which caused the catalitic converter to fry (which I think was causing the bogging down). I put a straight pipe on until I got all my fuel issues cleared up. During the time I had the straight pipe on I would get intermittent code 32 (EGR). Once I put a new catalitic converter on everything cleared up (no more code 32's) and it has been running great ever since (about a year now). Hope this helps.

 

[dburgjohn]

My 85 coupe used to bog ...vaccuum leak...During the time I had the straight pipe on I would get intermittent code 32 (EGR).

Vac leak and turn off the ASR (thought it was off) and bog is gone. I think a previous owner hollowed the cats out, they ring if you hit them. Maybe that was the source of the code 32.

Any way to tell besides cutting them open or off?

 

[mdsbch]

I don't know if there is any way to tell for sure without taking them off. I guess, like you said if they sound hollow when you tap them, it might be a good indicator.