Will not go over 45 MPH, flooring it makes it worse

1994 CHEVROLET SUBURBAN

240,000 MILES • 5.7L • V8 • 4WD • AUTOMATIC

JEREMY ZORLANDER

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So, I have the SUV listed above that i can't figure out. It won't go above about 45 MPH unless you're on a downhill, and flooring it makes it worse, you have to have the throttle just right to get it to get that fast. I've checked codes and got a 22 and a 37.
Replaced the TPS sensor on the carburetor and the TCC Brake switch as well, it starts a bit better now (had a bit of a rough start but the TPS sensor fixed that).

Going to pull the governor tomorrow and check that, other than that i have no idea where to go with this.

Dec 10, 2021 at 1:53 PM

KASEKENNY

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18,907 POSTS

If you have two codes, then we need to chase those down. 22 is what I would start with.

I am attaching the testing below as this will cause the PCM to not apply the torque converter which will cause poor acceleration.

While this could be a fuel issue or plugged exhaust and it is worth checking using these guides, it is more likely related to the DTCs unless the check engine light was on prior to this issue starting. If this issue started when the check engine light came on, then I would start with this testing.

https://www.2carpros.com/articles/how-to-test-a-catalytic-converter

https://www.2carpros.com/articles/how-to-check-fuel-system-pressure-and-regulator

The 37 code is for a brake switch stuck on, and unless your brake lights are on all the time then this code is no longer active and can be ignored for now.

Please run through this testing attached and let me know what you find. Thanks.

Images (Click to enlarge)

Dec 11, 2021 at 11:17 AM