rpm drop very slowly when shifting.
 

My car is a 88' 944S(16v). My rpm will not drop like normal when shifting after the engine gets warmed up. I've replaced the distributor cap and rotor, checked the throttle cable and found no problem. Yet the problem continus after I start the car and city drive it for about 15 minute. It takes almost 3 second for the rpm to drop from 3500(where I normal shift) to 2500. ALthough everything appear to be normal when I first start the car in the morning.

I am guess it might be the bad AFM.

Any suggestion? Also, if it is the AFM problem, can I adjust it somehow instead of replacing it? Thanks in advance for any help..

I doubt it's the AFM, I would guess it is the Throttle switch, failing to detect a fully-closed throttle, which normally shuts off the gas until the rpm hits around 1600 or so ... the haynes manual has the procedure for removing the throttle body and inspecting the switch (unless the later models are radically different).

That would be where I would start.

E

I agree with Ehab. I also think it is the throttle switch. You should hear a faint click just as the throttle closes.

hrottle switch... or also the throttle cable or throttle body itself could be sticking. i once had a sticky throttle cable in the 924... the RPMs would stay up just like what is happening to your car now.

good luck!

obin

Another vote for throttle switch!
Should hear a slight click when you open it and then again when you close it (the throttle..operate it by hand from the engine bay).

If thats not it, idle stabilizer is the next possibility. I know when my car's would stick...idle would be 1500rpm and it would take forever for the revs to drop down.

good luck!

--adrial

Great thanks for the help, guys...I will check it out this weekend.

I have the same problem on my '87 944S. Except mine only 'hangs' for about a second before coming down. Let me know if you find anything, and I'll do the same.