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oscillating RPMs

R

ricksgpgtcolleen

New member
Last night I removed my TB and cleaned that massive buildup of carbon. At the same time, I replaced the MAF. I was hoping that the surging/lugging and oscillating RPMs would be cured...only to be disappointed. What else should I be looking at? I'm also getting really horrible MPG to the tune of 12-17mpg.
 


no vacuum leak that I can detect. I did the "ether test" where you spray TB cleaner or such like around the vacuum lines and detect an audible surge. No such luck.

yes, the screen is still installed on the TB.
 
when I put the car back together, I confirmed good connections were made. I'm not convinced a dirty K&N would cause these symptoms, but the oil will be dry and ready today. Other than the cone, what else could I be missing?
 


Good news is that my MPGs seem to have improved drastically. I got back to 90mi on 1/4 tank consumed. I'll be sure to get a more-accurate MPG when I refuel. The car is still oscillating about 3-400 RPMs while at idle.
 
Replaced the IAC and that did nothing different. The old one was well-coated in carbon build-up, so it's not EXACTLY a waste of money. There's only one other sensor on the TB, so now to go and look that thing up.
 
Is your MAP sensor sealing? It was the source of my random rpm surges. Sometimes people either forget to replace the o-ring on the PCV valve located underneath it, or it can deteriorate. My actual MAP sensor gasket (the ribbed one) was dry rotted and torn, giving me a sporadic vacuum leak depending on the temps outside/in the engine bay.
 
I was kind of leaning towards MAP now...admittedly simply because that's the only thing left in the throttle body to replace and I'm busy throwing money at the problem. Thanks for your help, yall.
 


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