Thread: Poor Idle When Warm

Originally Posted by Bully

I have to ask

What do u mean by dry join?

A dirty connection?

Me = n00b

sorry , I have to ask

yes basically, plug is in firm but corrosion or other buildup stops the 2 surfaces from mating so i didnt remove the stepper but just unplugged blew plucs our then lubed reconnected and all is good now.

now i have to remoce the viscous cpl. as it is engaging all the time. but damn its on tight. have to get on the mill and make a tool to hold the pully so i can crack thread. and before anyone say's anything lefty tighty righty loosy. left hand thread.

again thanks for the help guys.

A routine check a few days ago showed the IAC was out of adjustment in it's length & had reduced from the recomd. 28mm max. setting by apx. 10mm. This was on a cold engine with the ignition off when I removed it.

Still idling ok & it was clean as when I cleaned it last time, but I wonder if this is part of the problem in that the pintle being on a thread, slowly reduces over time?
Theoretically, it should self adjust & the 28mm is the maximum, but why did it reduce? By that amount it should have been idling it's nuts off but it wasn't.

Funny things, Idle Air Control Valves.

Well mine's gone potty again so I'm back to square one. I'm tempted to lob the IAC altogether & set the idle manually. Has anybody ever done this with hotwire? will it run?
I'm going to also get one of those OBD scanners off ebay and see what I find.

Of course it will run. Just set the base idle to about 750RPM.
BUT you may stall with the aircon cutting in, on full lock etc etc.
AND you will have to hold your foot on the accelerator when cold starting to stop it stalling.
The IACV is very reliable. I cannot see the fuss. Theyare only about AFAIK( recall) $160 from UK and a new one will last for a long time.
Regards Philip A

I'm happy to toss $160 at it if it fixes it, but again until I have my scanner I'm chasing my tail I think. But then another issue it has is that the ECU/IAC is slow to react. I like a sharp throttle response & I don't like the way it idles up under load then when you let the clutch in the engine roars. Just my bent. But it may have been on the pi55 the whole time I've had it and I haven't driven a new one to know any different. Is this the way they all are?

I have an auto so the effect is different, but it is a characteristc that on first start up it should go to full open.
This tells the ECU what full open is.
Mine then drops over about 1 second to fast idle, as it is a "stepper" it only goes in stages. If I change to Neutral from drive it flares up to say 1000 for about 0.5 seconds.
When hot it starts fast then drops in 2 stages to hot idle.
The reaction should be pretty quick, and slow is a symptom of a dirty or dying stepper.
On aircon compressor start up mine compensates within a very short time.
These are a pretty old tech now and the GEMS and Thor have a stepless IACV which constantly strives for set revs and has a much bigger aperture.
The Thor Manifold does not have a bleed on the throttle blade , so it made it interesting setting the base idle with the little throttle stop.
Regards Philip A

Originally Posted by Bully

I hope with all of us , maybe just maybe we can fix it all together

Well I'll throw in the fact that when I removed and cleaned the Stepper Motor IAC with spray Carby/Throotle Body Cleaner and then took off to clean the PCV hoses with the same spray, I saw that the small hole/aperture/bleed was TOTALLY blocked with gunk [I accidently broke the plastic Tee - it had gone brittle and really fragilewith age and heat etc] I cleaned up the hoses and replaced the Flame Trap wire filter on front of RHS rocker cover and put a new filter on rear of LHS rocker cover. I got a replacement chromed brass Tee (with correct sized orifice) and my idle problems are now solved!

I've also just remembered that the IAC receives a signal from the "Speed Sensor" [mounted on the Transfer Case, near Brake Drum] as to whether vehicle is in motion or is stationary and this would also affect Idle Speed. A dirty sensor will give erratic signals and thus erratic idle.