rads2

When i let go of the throttle the rpms drop to 300-500rpm for a second and then bounce back to normal. Today for the firs time the car stalled. At first it only happend when the engine was cold, but now it really doesn't matter if it's cold or warm. I didn't try to fix this yet, so if you have any idea what's wrong fire away .

Thanks
Rad

Chris_924s

<Make sure the AFM is pluigged in>

bearone

fw wilk's site has a fix for that.

87951

Jeremy

I believe FR Wilk's site refers to the early 944 "shudder" fix. I experienced this terribly on my 83 944. Any chance you have an upgraded throttle response cam (circle), rather than the OEM (lady finger design)? If so, make sure the accelerator cable is somewhat taut - mine had loosened and the RPMs came back correctly with a little twist of the locking nut -

Jeremy

Serge944

It is not the AFM. The car will die immediately it is unplugged. Also, the shudder is only supposed to be present on the early cars.

It is likely that some of your ignition components have seen better days.

Danno

Yeah, the shudder was only on the earlier cars and had to do with a fuel-shutoff that didn't come back on soon enough.

The problem that Rad has is due to air-flow volumes. When he lets off the throttle, the plate closes and cuts off the air. The idle-stabilizer takes a fraction of a second to open up and supplement the air-volume that's getting past the throttle-plate to stay at correct idle speed. This time-delay is what cuases the drop to lower-than-idle speed.

How is idle-speed adjusted on the 944S? There isn't an idle-adjuster air-bypass screw on the throttle-body like the earlier cars right? What about the stop-screw? Is it letting the throttle close too much?

944CS

what rpm does your car normally idle at?

gtroth

Mine does that sometimes when cold. Sticky idle stabilization valve, I think. Could also be TPS, especially if yours is doing it when warm. Make sure you hear the click when you pull the cable slightly, then also check the switch signals at the DME connector. Vacuum lines might also be a place to look.

I'll be changing out my TPS and ISV this summer since you have to remove the intake manifold to do either one on the S. And while I'm at it, vac lines, injector seals, IM gasket, and whatever else I can find since I don't want ot take the manifold off again for a while.

rads2

Normal rpms are about 900-950.
I belive that you can't adjust the idle on S or S2 models, they are using a system called adaptive idle speed volumetric efficiency regulation.

I'll check the TPS and ISV this weekend and see if i can find something there.
Anything else that i should take a look at?

Rad

944cruiser

I had a similar problem with my 88' 944S - the engine would stumble badly when coming to a stop (no throtle response at all for 2 - 10 seconds), and sometimes stall (most embarasing at stop lights). I checked the TPS, AFM, and ISV but all were functioning correctly. In my case it turned out that the speed/ref sensor was adjusted too low (there were scrape marks on the bottom) I put in a new one (the S has only 1) and re-adjusted the height and it has not stalled since - over 1 yr. now.

Dan

rads2

Thanks Dan, I didn't think of that. I'll check that too.

unsigned

What about those of us with an N/A? On cold mornings it idles at about 500 until warm. Sometimes its a bit low when warm, like 800ish. I replaced the vaccum lines and the switch that clicks is good. FPR too.