Why do my RPM's drop?

[nene]

I am continuing to wonder why my RPM's drop all of a sudden (to idle at 800 and does not die) when clutching, whether the car is cold or hot, though they drop faster when cold. Normally, any car that I have driven (stick-shift), the RPM's drop slowly between shifts when cold or hot.

BTW, I have looked at all vacuum hoses that are around the engine, which appear to be in good shape, unless I am missing other areas that have vacuum lines. Would vacuum leaks be the culprit, or a mixture adjustment issue?

86 Carrera BTW...

Thanx,

Serge

[Tippy]

Short stroke motor with low rotating mass.

Other cars use the EFI to slowly rev down to keep RPM's up for smoother clutch re-engagement.

Not sure what car you have? Can't see sigs on iPhone.

[nene]

Tippy, it's an 86 Carrera so Motronic FI.

[Tippy]

Yep, Motronic was very basic EMS back then.

I love engines that rev to idle quick vs the older American iron carrying a heavy flywheel that takes seconds to get back to idle.

[JAR0023]

Search "idle bounce" here and you should find some quality reading.

From memory on the motronic cars the computer is supposed to catch the falling revs around 11-1200 rpm and help it fall softly the rest of the way to 800. Again from memory one of the culprits of an idle that falls like a rock all the way to 800 can be an aging ICV. As it ages it it reacts slower and can't catch the falling idle and you can end up with idle bounce where idle will fall all the way down below 800 and bounce back up. -J

ETA - Let me back up, before you start throwing parts at it on my accord the engine ought to drop quickly to 800 rpm if you disengage the clutch with the throttle closed. But you should see a little slow down just over 1000 rpms and it shouldn't fall below 800 rpm.

[DRACO A5OG]

Practice Rev Matching your clutch will thank you

[nene]

I have done more research on this issue and did not find anything related. Anyone else have any ideas?

Serge

[Eli W]

My car does this as well, I get around it by keeping my foot on the gas when shifting which goes a long way to helping revmatch.

[fintstone]

The idle on My '89 with a 3.2 does not drop any faster than expected.