Hi guys, bought my s2k like 2 months ago. it's year 2000 and has around 9xxx miles on it. Now it has about 11000 miles on it. The idle problem doesn't happen a lot but when it happens, let's say i'm approaching the stop light.. if I don't downshift and just shift the neutral and let the rpm drop, it will drop too low and the engine shakes, then rpm goes back up. it happens sometimes when I 'm backing up my car too.
I have already replaced new spark plugs, cleaned idle air control valve, throttle body, reset ECU, ....

Anything else will cause this problem? by the way, the car is bone stock.

Pls help.

Thanks

 

Moved to UTH

 

sounds normal to me all the cars i have ever owned have done this from time to time.

 

The car's fine (at least it sounds that way from your description, but without driving it myself I couldn't say for sure). When it's happening when you're backing up, it sounds to me like you're just bogging the car. Put your foot into the throttle a little more and slip the clutch.

 

Isn't this a MAP sensor issue?

 

Try the MAP sensor "whack". It's the thing on top of the throttle body with the wiring harness going to it. Unplug it, give it a few good thumps with the rubber handle of a screwdriver and plug it back.
It may also be the idle air control mechanism or it may just need a few more episodes before it learns to hold the idle up in those circumstances.

 

I vote for xviper's second suggestion. Has the weather changed near you recently? I typically see this on a warm day after a cool spell (never gets COLD here). The ECU has to re-"learn" the proper timing to catch the idle smoothly in the new temp/humidity conditions.

 

You can read out the data from the ECU using Davis' CarChip -- the EX model logs a bunch of parameters you can then download to your PC and plot. Oxy sensor and fuel trim are among them.

Barry
DARK PREDATOR

 

You can do the same with any decent scanner.

 

Absolutely so. What I like about the CarChip is that it's a logger that lives on the OBD II connector and isn't much bigger than the connector, so it's convenient to leave in the car while you drive. Because idle events are often dynamic as the car warms up, a scanner or logger that sits in the shop probably isn't usable, and not everyone will want to have a scanner in the passenger seat.

Barry
DARK PREDATOR