Our Community is 705,000 Strong. Join Us.


Bad acceleration at first then clears up


Dash Jones
08-10-2010, 12:28 PM
Looked over the forums for an answer to my specific problem, but I didn't find one. The S-10 will start fine, it will accelerate fine up to 10 MPH. At 10 MPH it feels sluggish, as if it refuses to get enough fuel, and the engine becomes abnormally loud. This ONLY lasts for the first minute or two OR once I get above around 20 MPH. If I let it idle for a minute, it also works fine and has no problems.

I recently changed the oil, transmission fluid, transmission filter, serpentine belt, changed out the coolant fluid and made sure the sensors were clean, but I'm still having this problem. BEFORE I changed the transmission fluid I had the same problem, but it occurred around 20 MPH and cleared up around 30 MPH. It didn't have any other problems with it typically, though it occurred MORE often on rainy or cloudy days. Prior to me doing this with the transmission fluid change, it occasionally wouldn't happen at all.

I thought it could be a transmission fluid thing which is why I changed the fluid and filter, but apparantly I've made it worse.

As I said, it only lasts for a minute or two, or until it accelerates enough. I'm about to put some stuff to clean up the fuel injectors, but I'm not certain that will do the trick either. I think it could be some water in the fuel? But my last guess on transmission fluid was apparantly really far off.

Any ideas on what could be causing this?

PS: I should add it's a 4.5 V6 if that adds anything that may be specific to this model.

old_master
08-11-2010, 08:20 PM
4.3L V6
What year is the vehicle?
Did you use Dexron V fluid or DexronIII?
Have you checked fuel pressure and leakdown?
Is the SES light on?
Have you checked for/retrieved any DTC's from memory?

Dash Jones
08-12-2010, 02:45 PM
4.3L V6
What year is the vehicle?
Did you use Dexron V fluid or DexronIII?
Have you checked fuel pressure and leakdown?
Is the SES light on?
Have you checked for/retrieved any DTC's from memory?

It's a 1999

I used Dex-cool and there doesn't appear to be a leak in the fuel lines. There is no SES light on, didn't check DTC's however.

old_master
08-12-2010, 04:33 PM
Could be low fuel pressure, if it is low, the SES light might not come on. Get your hands on a fuel pressure tester, some auto parts stores rent them and Harbor Freight sells them for under $20.

Key on, engine off, fuel pump running, fuel pressure should be 60psi to 66psi and must remain above 55psi for 3 to 5 minutes after the fuel pump shuts off.

Dash Jones
08-15-2010, 09:16 PM
thanks, I'll check out the fuel pressure.

Add your comment to this topic!