Low engine power

1994 CHEVROLET SUBURBAN

239,000 MILES • 5.7L • V8 • 4WD • AUTOMATIC

FLATHERS707

MEMBER
2 POSTS

My SUV seems to have moments where it stalls or if I don’t give enough gas it will shut off on me at times. I have a 6 inch lift kit on it and 35 inch tires and I have a lack of power in the engine. I thought it may be because of that but do to the stalling of the engine and severe lack of power going up hills I believe there’s something else wrong. It has a new engine in it and new transmission but still is not providing the power I had hoped for. I can get decent power in the low gears but once I start to drive above 25 acceleration is a joke and makes it hard to get up to 70. Going faster than 70 is a prayer. That can make it tough out here on the California freeways. Just replaced fuel pump and filter. Every once in a while the engine will make a pop noise while trying to accelerate.

Aug 11, 2021 at 2:40 PM

SQM

✓Experienced Mechanic
6,383 POSTS

Hello,

Does the vehicle have rough idle or low idle?
You could have a faulty idle air control valve. Over time the IAC valve can get dirty and get clogged, which can impact your idling.
You might be able to clean it out and improve the idle quality. The IAC is located on the side of the throttle body (see diagram below).
It will also be a good idea to clean out the throttle body while you are at it (if it appears dirty).

https://www.2carpros.com/articles/how-a-idle-air-control-valve-works
https://www.2carpros.com/articles/idle-air-control-valve-service

Did you experience the same lack of power before the lift kit and large tires?
Or did you purchase it this way?

Large tires add mass to the rotation of the drive shaft, which makes the engine work harder as it has more weight to rotate. It impacts more so than if you had a small trailer that you were towing.
Depending on the lift setup it can make the vehicle difficult to stop when you are driving at highway speed.

https://www.2carpros.com/articles/engine-has-low-power-output
https://www.2carpros.com/articles/symptoms-of-low-engine-power

Please me know of any questions.

Thank you.

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Aug 11, 2021 at 3:40 PM

FLATHERS707

MEMBER
2 POSTS

Thanks for the ideas! The idle is pretty smooth and doesn’t seem low enough to notice by ear. I don’t have a tachometer to see if it falls within specs but seems okay. I will look into the IAC as it seems pretty quick cheap and easy.

There was a lack of power somewhat present before the lift kit but I think it is just magnified now. It has a very slow acceleration and power throughout the gears after take off from a stop. If I am already driving and need to punch it to merge or pass someone, good luck to me cause ain’t happening. Haha.

Aug 12, 2021 at 2:50 AM

SQM

✓Experienced Mechanic
6,383 POSTS

You're welcome.

Also it might be a good idea to do a basic tune up, if you have not done one in a while. It can restore some performance.

Here is basic guide of what to do:

https://www.2carpros.com/articles/how-to-tune-up-a-car-engine

Also with bigger tires sometimes the transmission will have little more struggle to shift as there is higher load on a given speed.
The symptom you are explaining is not unique to your vehicle. I have seen similar issues with other Chevy trucks of the mid to late 90s.

Let me know how it all turns out.

Aug 12, 2021 at 2:57 AM