My 1988 740 4 cyl. Wagon w/ fuel inj. is surging at idle from 1000 to 2000 RPMs. It starts and idles fine but any slight pressure on the accelerator causes it to begin surging. Hard pressure cause a stall. It has no power and won't go above 20 mph. I've replaced the air filter and plugs and cleaned the Air Mass Meter wires and checked for vacuum leaks. I suspect a faulty Air Mass Meter, failing fuel pump, or bad fuel filter. I would appreciate any suggestions, similar experience, or proven solutions. Thanks.

 

Clean the idle control valve, under the intake manifold.

 

Tedv - Thanks for the feedback. I did clean the air idle controller. No change. I replaced it. No change. I read about the fuel pressure regulator and changed it. No difference - still surging up and back repeatedly at slight acceleration, then it cuts out and drops to 1000 RPMs. I began to suspect the fuel filter and changed it today. Still no change.

So now I'm thinking it might be the fuel pump or the fuel tank pump. After that (and about $400), I'm out of ideas.

Is it possible that I'm "barking up the wrong tree" and what I may have is a timing belt that has slipped? I think I'm hearing a slight "misfire" when it reaches 2500 RPMs before it cuts out.

This is my wife's car and she's loosing her patience - and her faith in my mechanical abilities . . . Help!

 

Try this:

http://www.brickboard.com/FAQ/700-90...tyThrottleBody

 

had the same problem in my 84 740, was the catalytic convector clogging, came apart inside had to replace it and the muffler , pieces made it into there also.