Over the last few months, I've had a few instances of very sluggish response when trying to accelerate from stop in 1st. It generally only happened once or twice on the trips it would happen, and would always go away after a second or two.

The other day, when leaving work, I tried to start up my car, and was met with the engine cranking, but no ignition. After a few tries, the car started, but something seemed a bit off. I managed to make it around the block and down the street a bit before the car died on me. It will sometimes start, but only idles at a little over 200rpm, and will immediately die as soon as I touch the gas, or try to move it at all.

I am thinking it is the AFM. If that is the case, and I am not able to clean up the contacts enough to get it working again properly, can anyone confirm that part 0280202064 works for the 84 models? My part number is 0280202028, but I am not able to find that one available anywhere in the US.

Thanks.

 

At idle the engine does not make use of the AFM signal so a poor idle would not be a result of a faulty AFM (unless the AFM flapper door were actually stuck closed).

Try this...on the top left corner of your throttle body is a little stud with a 7 or 8mm nut on it, loosen the nut and then turn the screw to the right as if you were tightening it, this will open the throttle body a little bit (this is the throttle stop screw). What this will do is take the throttle position switch off of its idle contact (you should hear a light "click" when the contact disengages). Try starting the car with the screw set just past the "click" point. Does it start up ok?

With the throttle position switch disabled (the DME thinks it's at part throttle if not at idle or WOT) the DME then starts paying attention to the AFM output signal. If engine runs ok (maybe high idle speed since the throttle is cracked open) then the AFM is likely not the culprit and the throttle position switch may be faulty or require adjustment.

If you do end up needing an AFM, for your car the AFM from any 1982-1985 944 (built up through February 1985) will work directly. I should have one or two spare functional units if you want to purchase one.

 

Before you do all of that, I'd search for the vacuum leak it sounds like you have...

 

Van - always start with the hard stuff, it builds character!
I've not encountered a vacuum leak severe enough to stall the engine that would ever let it really "catch" in the first place. As in...if a leak is large enough the engine won't ever start/idle in the first place.

Small leaks the engine should catch and run, perhaps erratically, but don't think they would get suddenly more severe to the point of stalling out?

Could be wrong of course.

 

V2 are you sure that the AFM isn't referenced at idle? It seems like some sort of air density figure would need to be incorporated at least for RPM lookup. Which the AFM has the temp sensor for. Ultimately the TPS could also be the issue and the DME is looking at the wrong map altogether during idle.

 

I have, on turbo cars, when you blow off one of the boots rubber connectors to the intercooler...

I'm wondering if there's a tear or break in the j-boot or something that is "mostly closed", but when you open the throttle body, the air pressure difference makes the opening larger and the engine stalls.

 

It's got its own separate fuel and spark mapping based on rpm and coolant temperature.

You can start and idle the car just fine with the AFM completely unplugged/uninstalled...

J boot should always be about atmospheric since pre-throttle, no?

 

My car will definitely not idle with the AFM unplugged. It will catch while starting and immediately die...maybe it's different for late models?

 

my first thought given that issue is to check the fuel pressure .