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

JEREMY ZORLANDER

MEMBER
1994 CHEVROLET SUBURBAN
5.7L
V8
4WD
AUTOMATIC
240,000 MILES

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.

1 Reply

KASEKENNY

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The 37 code is for a brake switch stuck on, and unless your brake lights are on all the time then this code is no longer active and can be ignored for now.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

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