start up hesitation 2006 S60 2.5 T FWD 140k Miles

adrian22 · Post by **adrian22** » 22 May 2022, 16:47

random symptom: starting from parking the idle hesitate, run erratic and drops to the point of stalling--looks like the engine is coughing-It gets better if I accelerate but not moving from parking-There is no check engine light and no engine codes
I replaced spark pugs and coils-air filter --no fix
I always use premium gas and synthetic oil

I suspect is MAF or fuel filter?

ignatz · Post by **ignatz** » 23 May 2022, 03:49

Or possibly the fuel system is loosing pressure, or bleeding back somewhere. A strong dose of Chevron Techron "could" clean something in the fuel system that's sticking. Sometimes it takes days for that stuff to work. At least the Techron will be working to fix your car, while you try to figure out the problem.
Sad part is, this stuff was $5 last year at WalMart, now its $10.

adrian22 · Post by **adrian22** » 23 May 2022, 06:34

what about a sticking throttle body door?

Post by **vtl** » 23 May 2022, 09:17

Read the fuel trims (STFT, LTFT) and report back.

adrian22 · Post by **adrian22** » 23 May 2022, 11:46

now I got code P0170, P0087

What is (STFT, LTFT)? fuel pressure?

Post by **vtl** » 23 May 2022, 20:01

adrian22 wrote: ↑23 May 2022, 11:46 now I got code P0170, P0087

What is (STFT, LTFT)? fuel pressure?

No, fuel adaptation. Engine computer constantly monitors oxygen sensor sitting right behind exhaust manifold and adjust air-fuel mixture accordingly.

https://trade.mechanic.com.au/news/unde ... uel-trims1

Now you need to trace your fuel delivery. These generic codes don't tell everything, with DiCE+VIDA you can diagnose it more precisely. It will even show your fuel pump's duty cycle, which may tell you whether the pump is dead or the problem is somewhere else.