My idle drops right after starting the engine on my 300. It does this immediately for 1 second....then it jumps back up to a higher rpm....then rests at 1200 rpm. Even when driving....and hitting the pedal fast in 5th gear....feels like it wants to stall...but never does.

Any reason why? Is throttle body sticking?

Started doing this after installing aftermarket header and mid pipe...and Blitz exhaust.

Thank for any help.

Pete

 

Try cleaning the throttle body.
Check to see if MAF sensor is plugged in completely and all hoses are on correctly.
Have you tried resetting the ECU?

I did notice the same problem on my Acura when I installed a whole bunch of mods to let the exhaust flow freely. My car ran leaner after the header/straight pipe/exhaust/no catalytic converter. Maybe not enough back pressure and it's causing the ECU to overcompensate.

 

Ricky,

Thanks for chiming in on my situation. Yah...throttle body was cleaned last month....SRT filter...cleaned too...I did not over re-charge.....MAF Sensor...cleaned.....hoses...all secured and tight.....ECU has been reset twice (overnight).

I did notice the MAF Sensor plug does NOT "click" in cuz the SRT mount prevents plug from completely plugged in. Its about 1 mm from clicking on tight. Maybe I should remove my MAF Sensor from the SRT pipe...and grind the mount area down with my dremel.

Hope thats the reason for it. Maybe its the dang ethanol in the gasoline.

Pete

 

Interesting, Pete. I posted the same issue a few months ago. Did you use the search feature????

Anyway, my car behaved exactly like yours. It would fire up at around 2,000 rpm, and then immediately drop like a stone to about 300-400 rpm, and then jump back up to around 900 rpm where it would sit until it got completely warmed up, and then would idle around 600. I went ahead and cleaned the throttle body and noticed an immediate change. On the very first start after cleaning my TB, the car still fired up around 2000 rpm, but then dropped slowly down to 1,100 rpm where it sat until the car warmed up. Once warm, the car now idles at around 750.

I just reread your original post, though, and I see that you already cleaned your TB. So I guess nevermind. Sorry I couldn't be of more help.

e

 

Yo E...

Thanks. Throttle body is clean...but may not be lubricated. Gonna check into that. Maybe spark plugs needs replacing?

Pete

 

What kinda gas are you using. I have been hearing that the Tesoro brand is putting too much ethanol in and that quite a few cars have had idling problems with the gas. you may wanna try using Shell or Chevron as I understand they put in Ethanol but not in such large amounts.

Yeah and get the MAF secure. or get rid of the SRT pipe

 

Does Tesoro supply Costco? If so...then its time to go w/ Chevron + techron.

Why get rid of SRT pipe? What other option do I have?

Pete

 

If it is an SRT intake perhaps the map needs more fuel. It sounds like the car is running lean and not able to idle correctly. This is either there is a leak somewhere post MAF or the ECU fuel parameters are off. I know my RMM intake does this also if I set the SAFC settings to zero because the inner diameter of the MAF housing is wrongly sized and bigger thus rescaling the intake and causing a lean condition.

 

OK...idle fixed....hangs around 600 rpm at idle after warmed up. No drop in needle after startup. NO feeling of stalling at turns.

What I did was....

- Re-cleaned with Mass Air Flow sensor cleaner
- Re-cleaned with Air Intake Cleaner (Throttle Body Cleaner) w/ Teflon lub
- Cleaned outside wires and links with Carbuerator Cleaner.
- Added Fuel Injection Cleaner to gasoline

Pete

 

Pete,

What cleaners did you use?
I am having some idle issues of my own and wanted to try cleaning things up like you did.

Thanks,

Randy