951 Idle issues?

[Fast Freddy 944]

I know this question has been asked before, but while I was driving the engine ran great, then I later hit a stop light and it started running badly, I went in to a store for a bit, went out to start my ride, and it cranked over but no start, I tried again with some throttle added to get it to crank, and it fired right up, only thing I did to the car was an after market airfilter kit, with a new gasket, I checked my coil, and sparky wires, and all vaccum lines, I might add that this issue appears after a long day of driving,? something is getting hot? any ideas would be appreciated! thanx fast freddy!

[thekidd]

When she didn't start when warm, did you notice if the tach bounced? Reference sensors can go bad just like that (the 2 times it happened to me was coming out of a store after she was fully warm. started find when starting cold).

[Fast Freddy 944]

Originally Posted by thekidd

When she didn't start when warm, did you notice if the tach bounced? Reference sensors can go bad just like that (the 2 times it happened to me was coming out of a store after she was fully warm. started find when starting cold).

I think the tach stayed steady, I may have to repeat the process tomorrow, and see if it comes up again, now a tach bounce is it pronounced? or is it a small needle movement? and could my issues be dme related? I just went out a few minutes and it started and idled just fine, mabe its occouring when its warm?

[mytrplseven]

When you initially engage the starter and before the engine starts, you should see the tach needle bounce 1/16 to 1/8 inch. It's easier to diagnose this if you pull the coil lead from the center of the distributor so the engine doesn't start. Then you can watch for the needle to move. I'd suggest you do this right after you shut the engine down while it's at it's normal operating temp so you'll have the proper conditions where the failure occurs.

[Fast Freddy 944]

Originally Posted by mytrplseven

When you initially engage the starter and before the engine starts, you should see the tach needle bounce 1/16 to 1/8 inch. It's easier to diagnose this if you pull the coil lead from the center of the distributor so the engine doesn't start. Then you can watch for the needle to move. I'd suggest you do this right after you shut the engine down while it's at it's normal operating temp so you'll have the proper conditions where the failure occurs.

So like, if I do this procedure, how or what will it be telling me? What part should be replaced during said tach boune?

[Fast Freddy 944]

I checked and rechecked all the vacuum lines, and I checked the coil and cleaned the corroded wires, bingo idle issue solved! I took it out for a spin, and my boost gauge actually worked, thanks for your imput!