Brentis

Finally tired of my idle bouncing all over the place with my AC on. Have a PFC and while all the AC speeds work, the idle bounces all over the place. It [pfc] has NEVER learned.

What is the fix??

Many thanks!

airborne

woah, coincidence.
my car was doing that so i asked steve kan to have a look at it while he was out here. he tried everything with the pfc and it was no good. then SlimJim (jim) from here came over and unplugged the solenoid behind the uim, white plug. that was it, stopped the bouncing. so possibly bad solenoid? slimjim said he's seen it recently.

BUT i left it unplugged for my drive home and now the car started with the bouncy idle whether the ac is on or not. if i leave it go for a while it settles at like 1100rpm.

slightly nervous because this is a symptom of low compression but since it does steady out i'm figuring thats not it, if compression is low its low all the time and wouldn't steady like that.

long story short, try unplugging that solenoid then if that works replace it.

Brentis

alright - I'll check it out. The interesting thing is it appears that it only happens when the compressor starts as if the A/C is just pushing cold air - it works fine, once the load of something (poss. compressor) kicks on, it starts having fits.

Also, my stock ECU didn't have this problem...

Let's keep this thread live. Thanks!

Brentis

alright - I'll check it out. The interesting thing is it appears that it only happens when the compressor starts as if the A/C is just pushing cold air - it works fine, once the load of something (poss. compressor) kicks on, it starts having fits.

Also, my stock ECU didn't have this problem...

Let's keep this thread live. !

cavellm

When it was installed, were any of the wires cut, or was it just a direct plug in?

Mine was installed w/o any cut or capped off wires, and I get perfect a/c on all 4 speeds with no idle problem. Just kicks up about 200 rpms when the compressor comes on, but then smooths out immediately.

rynberg

Really? No other problems from not cutting the wires?

I just installed my PFC last night (with the pins pulled, not the wires cut) and my A/C only works on 1 and 4. Idle is pretty good, but it's obviously still learning a bit. BTW, the fix for the A/C that Zerobanger posted in the ECU forum works. If I put the fan switch BETWEEN 1 and 2, I get fully function speed 2. Same thing for between 2 and 3. Very strange.

Brentis

my pfc was an SR motorsports one which apparently does the clipping for you.

I'm very interested in the fix. Black & Dallas mix only with properly operating A/C!

airborne

Hmmm...my pfc is from SR as well. i'm going to work on it tonite. hopefully i can get the AC/off idle to stabilize by adjusting the idle screw. if i can do that i'll get back after the AC issue, starting with that solenoid. can't remember what they called it, i'm an idiot. but sometimes it'll stabilize then if you tap the throttle it'll go all haywire again.

when steve was working on it he looked at the ign map and you could watch the car hunting, hitting different cells in a circular motion. woulda been funny if it wasn't my car

rynberg

You are referring to the ISC solenoid (idle speed control). I got my PFC from Rotary Extreme.

airborne

thanks for the edumacation rynberg. and yeah, thats very weird to get AC when you put it between the settings....

airborne

ok i seem to have fixed it though i haven't driven it yet.

first i fiddled with the throttle screw and the air adjustment screw. no dice. unplugged the IDS and fiddled with screws some more and got it idling steadily at about 1k, ac on/off. then i plugged the IDS back in, and tapped the gas and with AC off it was fine, AC on it was bouncing. basically it seems once you tap the gas (ACon) the idle drops so far it almost stalls (did once) then it catches itself but can't steady. adjusted the aas some more, way toward closed and set the idle on the pfc for 950 when the ac is on. it all seems to be working fine now. so keep trying with the throttle screw and the air adjustment screw and the idle setting on the pfc.

if it starts screwing up again i'll let ya know.


oh and my vacuum is -400mmHg (15.75 in) or higher at 750 rpms on a ported motor according to pfc.

Brentis

dense question.. which idle setting does one mess with. Any more details that can help pass through my vino induced density are appreciated!!

airborne

under settings->rev/idle the ac setting is the last one, the one above it is for other electrical load like headlights, the one above that is no load. right now mine are at 850/900/950.

damned if i know what the first three things are!

rynberg

The first three things are what rpm the fuel injectors kick back on when getting off the throttle. For example, if you are coming up to a light at 3k rpm and just let off the gas and push in the clutch, your injectors actually shut-off while the rpms drop. The PFC needs to turn them back on before you stall. You can adjust the rpm the injectors turn back on for the three operating conditions.

BTW, airborne: Driving around last night, playing with the PFC, I started getting that hunting idle BS at every stoplight. A bit embarrasing. This morning, with no electrical loads, perfect idle at every stoplight. Looks like I might have to do some adjusting myself -- or just give the PFC a bit more time to learn.

airborne

Go figure, it is embarassing isn't it? what ended up doing the trick was turning the AAS clockwise a whole lot.

thanks for the info on those other settings, maybe they were too low, or the ISC solenoid is getting old and slow itself causing the injectors to cut on too late.

it was a b*tch finding that AAS! just feeling around for it from the pic in the manual. then once the car gets hot feeling around is not a whole lot of fun...

Brentis

argh - sounds like a pita!

airborne

if you reach down under where the intake elbow connects to the throttle body its slightly closer to the firewall and the screw is recessed in a hole, i stuck my finger in there and guided the screwdriver in that way. i think you'd have to look from under the car to actually see it.

if i hadn't seen steve use a philips head screwdriver i wouldn't even have known what kind to use!

airborne

any luck brentis?
took mine out for a drive last nite and it started up again. then when i park i get a buzzing noise from -guess where? just behind the UIM which is where the ISC (or IACV-Idle Air Control Valve, manual lists this as SAE standard) is located. found a post elsewhere that quoted $400 for this part, is that right? couldn't find anything on it in either shop or electrical manual.

rynberg

Hey Guys, I have something new for you to try.

Go under Settings/rev-idle. Change the first three idle settings to 1300 (default is 1000,1100,1200 I believe) and see if that doesn't help.

airborne

i tried that. hell i tried setting the idle to 1300 but all that does is just raise the area where it hunts, at least it doesn't stall.
goin to kd rotary tomorrow and sent him a heads up i'd like to swap in a good ISC to see if thats it. found some other posts where people had the buzzing noise so though rare i guess they go bad...

airborne

so i'm looking thru the fuel and emissions section of the manual and here's everything the troubleshooting sections lists as possible culprits.

Idle Air Control Valve
Primary Injectors
Fuel Filter
Fuel Pump
Fuel Pressure Regulator
Igniter
Ignition Coil
Spark Plug
Ignition Timing
Charcoal Canister
Purge Control Solenoid
Purge Regulator Control Solenoid
Air Filter
Low compression
PCME
Heat Hazard Sensor
Knock sensor
Fuel Thermosensor
MAP sensor
P/S MAP sensor
AC Sensor

Thankfully if you're only experiencing it under idle the one consistent thing is the IACV, unless it really is $400 then i guess you're not so thankful...

adam c

iTrader: (2)

I have adjusted mine with a standard screwdriver. I didn't think it was a phillips. If you use a mirror, you can see the screw. My car is a 94 also. I don't have the car today, so I can't look.

Is it a std or phillips?

airborne

sure felt like it was working

(with the philips)

Brentis

Tried that as well - did teh same thing as with Airborne. I don't think the part is bad as when you put the stock ECU back, the problem disappears.....

airborne

i haven't tried putting the stock ecu back, could try that tonite. i'm gonna put a post up in the pfc forum...