Sticky RPM

[dpointt]

Hi,

Not too sure how to search for this one problem that is persisting...

First of all, my ride just had a top overhaul, changed the fuel filter and timing belt within the last 6 months

But here's the issue even after this overhaul done:

when cold start, with air con compressor turn off; my rpm shows a 750 rpm
even idling for 1 or 2 minutes later, I do get a sticky rpm

here's the scenario, at 750rpm, it idles quite steadily...
when I step on the gas, it will naturally goes up to 3000 or 4000 rpm (no prblem here) but when I release it, the rpm will drop to below 750 rpm, approx abt 600rpm then rise to abt 950rpm before stablizing at 750rpm again... not sure wat's its called, sticky rpm??

Its gets pretty pretty low that it seems like the engine will just died w the red lights blink once or twice

is this common for old cars? cos its sometime behaves quite normal without any problem (but its not often though) even after driving for a few miles, still have same symptom

its less obvious with aircon turned ON but still get;s the same feeling and rpm is at 900...
cos when changing the gears, I get lags with my manual transmission due to this problem!??

Pls advise!

[jlevie]

That could be a sticky ICV, pehaps aggravated by small intake leaks.

[AndrewBird]

I would look for vacuum leaks. Pull the accordion looking intake boot off and look at that. It often cracks between the folds and is hard to see unless taken off to look at.

[dpointt]

hi guys, thanks for response...

I had gotten tt replaced too even before the overhaul done
FRL or ICV problem??? but so far car starts easily in the morning and no idling problem, or perhaps a little with no biggy issue encountered on it

Other sticky suggestions?

[dpointt]

gotten a rather new AFM yesterday
had it replaced and not no more 'stickiness' from the engine and rpm on the odometer

purrs like a kitten now!! heh...