Hi, I have an '89 300CE wth 70K miles that continues to challenge the dealer and I with a hot start problem -- excessive cranking and rough running for several minutes . Cold starts and hot starts within about 5 min of shut-off are both OK. No other drivability problems, other than occasionally when idling at operating temp, hot start rough -run symptom reappears on acceleration.
The original suspicion was fuel pressure leakdown, but it doesn't seem to be that.
Any suggestions appreciated. Here's the facts:
- maintains fuel system pressure at 2.9 bar for 60 min, according to dealer
- recent new parts: OVP relay, fuel pump relay, fuel pressure accumulator, EHA, fuel pump check valves, distributor cap, rotor, and spark plugs. (The EHA, distrib cap, rotor and plugs were replaced for other reasons; the others, my failed attempts at solving suspected fuel delivery problem.)
- air flow sensor plate zero position OK in fuel distributor
- coolant temp sensor for EFI measures OK at 20C but has about twice the resistance (~ 434 ohm) at 85-90C compared to spec. Is this enough to be the culprit?
thanks in advance...DAN