tonyc

Hi,

After this service have noticed a slight lag in the throttle around 2000 rpm. Not every time but occasionally.

The revs don't drop but the for a second or two there is no acceleration.

Any ideas.

Tony

Babalouie

I seem to recall that this improved when I cleaned the ISV.

It usually happened after a spell of coasting off the throttle, and when you squeeze the pedal again there's nuthin for about a heartbeat, right?

tonyc

Yes that's it. What the ISV?

Rocket Rob

ISV = Idle Stabilization Valve. Its in the top center of this photo.

power_up

Any chance is the dead spot of air flow meter?

Geoffrey

It happens to me on my car when going down a long incline with very, very light throttle. At the bottom when I need to push the throttle down more to maintain speed, the engine is dead for 2-3 seconds then returns. I believe this is related to the injectors shutting off on overrun. It may also be related to a dead spot on the AFM, however, several 964s I've driven have done the same thing in the same place on the same road.

crg53

I had the same problem with my car, coasting down hill then back on the throttle and no response for a few seconds. I changed the idle/wot micro switches because of a unrelated issue, and since then the hesitation has gone away.
May just be a coincident, but what that says to me is the idle microswitch was sticking on occasion.

dkcaims

After converting back to a N/A intake after selling the supercharger, that's the only nagging issue I have left.
I'll try cleaning the micro switches and perhaps adjusting them or the throttle cable since it's new and I'm not 100% certain it's adjusted properly.

Thought I was the only one !

Shamus964

Same thing here - my research has led me to believe it's AFM related, haven't pulled it apart and cleaned/adjusted it yet though.

crg53

I did the AFM, took it all apart and cleaned it, made no difference what so ever, also did the ISV, same thing, no difference, but as I said earlier, when I changed out the idle/wot micro switches, problem gone.

tbennett017

Phew... every time it happens to me my heart skips a beat too... but then a bit more throttle and we're all good-to-go... Glad to hear it's 'universal'

Babalouie

Idle microswitch sticking, huh? Well that does make a lot of sense. I wonder if giving it a squirt of switch cleaner lube might help

StanUK951

The more I think about it the more I want Motec. These Motronic (my iPad just corrected that to Moronic, is that ironic?!) systems just feel old hat now with their stuttering stalling power delivery... It is much better with a regular system adaption but my BMW 330d is so smooth and linear.... Not a great comparison and a bit harsh to compare a diesel to an air cooled flat six but...

Babalouie

The whole setup with microswitches was already pretty old fashioned in 1990

FeralComprehension

Hey, at least it was EFI. Waaaay more advanced than CIS!