Help

I have a 1974 450SEL with electronic fuel injection. Car starts fine, runs at 2000 rpm, blip throttle revs drop but dont settle to steady idle. Engine revs up to 2500rpm then cuts, drops to 500rpm and catches and revs to 2500 rpm again. If I blip the throttle again the engine will rev to about 3000rpm and stay there. Have I lost a temperature sensor? Is the cold start valve stuck on? How do these things measure air flow? The Haynes manual is as much use as a chocolate fireguard. Any ideas of what to check first would be gratefully received. Any ideas of where I can get an engine manual with ignition info would be a bonus. Thanks .

Colin Whyte

Try eBay Motors for the factory manual. There were several used copies up the other day for the M117 engine. I bought one Saturday for $53.00. Bidding is fierce on these.

Keyword search M117, Mercedes Manual, your car model etc.

Good luck

STS

Check the base idle adjustment. If it is set too high it will go up and down because it can't find itself. The base idle adjustment is the flathead screw right beside the warmup idle control.

Check the archives here for Djet & Jetronic issues (EFI is also a good keyword).

I have assembled a 1meg zip file that explains lots of good stuff.
Email me (cth@mbz.org) and I will reply with the file.

-CTH

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