George993

Hi Guys

1996 993 C4 with about 115k miles, California, all stock except K&N filter and a custom free flow exhaust dies when coming to a stop unless I keep the revs up pressing the accelerator with right foot heal. Without it will hunt up and down and stall/die. Runs and idles very well otherwise.

First I expected the usual (had that problem years ago) and cleaned the Bosch idle regulator. It helped a bit but not much, so I replaced the regulator with a new one. No improvement :-(

Any ideas of what the typical other causes could be on this model?

thanks a lot!

George

JM993

I'd recommend checking for a vacuum leak next.

Cheers,
Joe

CalvinC4S

Did you recently replace a dead battery or disconnect it?
Then on first start tap the throttle?

Let the ECU learn at idle for 15 minutes or so.

96 cars do this, when the batteries go dead.

deep_purple

Pesky problem this.

Long shot, but these threads may help:
https://rennlist.com/forums/964-foru...-downhill.html

https://rennlist.com/forums/964-foru...tion-long.html

George993

Thanks JM993, CalvinC4S and deep_purple, I'll check it all but Calvin's clearly first - not only I've disconnected the battery, but recently I'm doing it after *every* drive with a disconnect switch since I don't drive the 993 often and otherwise the battery goes dead after a while. Let's keep the fingers crossed that's it and a trickle charger or driving more often it's all what's needed after the ECU learning :-).

CalvinC4S

Your ECU is being wiped every time, that's your problem.

Nollie

This wasn't a big deal for me until I switched to a light weight flywheel. But now after disconnecting the battery I plan on the first few outings to include stalls at stops so I take the back way to where I'm going

CalvinC4S

It shouldn't be a big problem if you allow the car to run it's idle adapt stage on first start up. I don't recall the amount of time it takes off the top of my head, but relies it is important not to touch the throttle at all.

The car will be a dead stick the moment the clutch is disengaged. The only way to keep it running under this condition is by keeping the RPM up and softly bringing it to idle. Once at idle it will be hunting from 600rpm to about 1800.

I have reason to believe this condition happens when the ECU sets the closed throttle at a incorrect value during the idle adapt stage due to the foot bumping the throttle peddle on initial start up.

Due to the adaptive design of the 96-98 ECU, I recommend using a battery maintainer over a quick disconnect system.

e9stibi

I hear you. You just need to run "adoption sequence" and you will be good. I posted it a while ago and was impressed that I just needed one attempt.

element

mine was doing that.. DME relay - good thing to try and if it doesnt fix a good thing to keep in the car $30

phil.

George993

Problem fixed :-) 15 minutes idle after connecting battery it's all what was needed - beats spending $280 on a new idle regulator which makes no difference. You guys are great!