Hi guys, since this damn winter cold has hit (feels like it's been cold forever), my idle has been crappy. Basically there are 2 issues:

1) When cold the idle shoots up to about 1500rpm, which is normal. However, when the car's warmed up, the idle seems to hang up around 1200rpms when I downshift and cruise to a stop & slowly drops to about 750 (normal)
2) The idle at 750rpm is not that smooth, I see/feel it rise & fall ever so slightly. I'm puzzled since the car has always idled quite smoothly.

Stuff I did this weekend:

- Cleaned out TB/MAF/K&N-drop in filter. No improvement

-What I haven't done:

- scanned for codes (NO MIL light on)
- checked TPS (I think it can be taken apart (but not recommended)
- by exhaust is leaking at the b-pipe/muffler pipe flange
- I have NGK coppers in there..maybe about 30k kms on them, Should be changed I guess.

Any ideas?

 

how did you clean on the TB? You may want to remove both the TB and IAC Valve and clean them thoroughly. make sure you use new gaskets. when is the last time you changed plugs? last time you used a fuel system cleaner?

 

Coppers should be changed around 30k miles so that may be the problem. When was the last time you replaced the PCV? Its a small cheap part, might not hurt to replace it. How did you clean the TB and IACV? Don't take off the TB, just take a whole can of brake cleaner and spray a bunch into the TB with the engine off. It will be pretty rough on startup, once it gets going, go into the engine bay, and with the engine still running, pull the hose that connects the intake to the IACV off at the intake end and spray a bunch of brake cleaner into the IACV. Or just take off the IACV and spray it down while its off.

 

I used a toothbrush with the TB cleaner then wiped everything off with a rag. I cleaned the throttle plate (back/front/the edges) until it was quite clean. I had cleaned the IACV valve last year, maybe I'll do it again when it warms up.

Plugs ay need changing & I don't believe in any fuel system cleaner

 

Probably an air leak - take out the stuff you removed during the TB cleaning and then put them back on carefully

 

An update..I removed the TPS and shot some lube on the middle part that rotates, taking care not to get it inside. I put it back on exactly as before, but noticed the car was idling around 900rpm. I checked for codes, but I also wanted to do this to make sure I can hear the IACV clicking, which it did. No codes, so I adjusted the TPS all the way back...and checked the ohm readings. They were in spec (.36kohm throttle closed, 4.3kohm wot). I also did a half turn on the IACV screw, now my idle is 700rpm which is much better. It's still not rock-steady, so I think I'll have to yank the IACV again when the weather cooperates.
Damn old cars...after 479,000kms (288k miles), you'd think it would run as new