Hey guys,

I am experiencing roughness when under light and part throttle acceleration. It is most noticeable when going uphill and feels like my car almost stumbles when accelerating lightly. However, when I accelerate anything more than half to full throttle acceleration is smooth and strong with no roughness or stumbling.

My car has 65k miles. Any thoughts what the problem is?

Thanks

 

you might try cleaning your throttle body and then disconnecting your battery to reset you ecu.
does it seam to be your engine or transmission?,happen every time.
any more information my help.

 

No check engine light? Throttle body and dirty maf are good places to start looking.

 

I've reset the ECU with no luck. It definitely is the engine that is running rough, not the transmission.

I notice it primarily when the car is in higher gears at low engine speeds under load. Easiest to notice when going up a grade putting a load on the engine. never notice it going downhill.

No check engine light ever. I will do a search on cleaning MAF and throttle body.

Thanks fellas!

 

first thing i would do go to walmart buy the chevron fuel system cleaner, not the fuel injection one, then on empty tank or 3.4 empty pour bottle in , fill with shell premium gas and respond to me in couple days saying problem solved, all kidding aside 40% of time this will work with a clogged injector

 

Did the following and still have the low rpm stumbling:

1. Used several bottles of fuel injector cleaner at the last couple of fuel ups
2. Cleaned the MAF w/ CRC MAF cleaner
3. Cleaned the throttle body w/ CRC throttle body cleaner
4. Disconnected battery to reset ECU

Any other ideas to eliminate the stumbling? As mentioned previously, I notice it mostly when in top gear around 45mph under part throttle going up a grade.

Thanks

 

MAF could actually be shot. Maybe get the FI's professionally cleaned?

 

Could be a bad TPS (which is not good cause i think its integral part with TB assy) or a slow responding 02 sensor. Hopefully its not a VVTi solenoids or anything. Id plug it into a obdII scanner and see the readings while you drive to see whats happening. Id point to the MAF as well, and when cleaning them make sure you are cleaning all the way inside the tube because the element is actually way towards the back hard to spray spot. Make also certain there is no debris or dirt on the element. A single tiny piece of dirt can cause all sorts of false readings.

 

As far as fuel system cleaners go, from past experiences with virtually all major cleaners on the market only 2 left me rather impressed that it actually does something. the BG44K and the Redline SI1 Fuel System cleaner.