I agree. However, Tom asked why the IAC counts are 0 when there is air going through the IAC passage. IF there is air going through, a thumb there will tell if it is really going through or not. Further, if the count is 0 and the engine still runs with the thumb blocking the hole, well, the air has to come from somewhere and if the blades are closed, there is only one explanation. There is a leak somewhere either in the gaskets or the hoses or the joints of the hoses. Without the IAC opening, and if the blades are somewhat closed, I doubt there is enough air going past the blades to actually keep the engine running without a leak somewhere. Ask me how I know.

 

Yes, I just wanted to make sure the OP knew that.

 

Just an update... I believe I have a suspect IAC. The problem has been hit or miss. Given the results of the scan and the fact that I found a bad injector on the right side (one read 5 Ohms as opposed to 12.8 on rest) I'm going to do several things. I'm going to replace plugs/wires. I've also ordered 8 new fuel injectors. And an intake gasket kit due to oil leaking on the front china wall. Thanks for the help so far. I'll update in a few weeks once I complete the work. Any tips are appreciated. I feel confident doing the work. Will snap photos. Till then. Cheers.

 

Update; I installed new injectors, plugs and wires. The plugs and wires were as much fun as advertised... I also readjusted the ASR per the FSM. I went out for a drive and took this scan:

As for the original issue of the idle being high at intermittent times it still exists. I do know when the idle is high the air is passing through the IAC passage despite a count of 0. I may just go ahead and replace the IAC ( again ) and check the wiring. It occurred very seldom so I'll get back to it when it bugs me again. If you fellas have any suggestions on a replacement IAC let me know. The first one I put it was an AC Delco from the dealer... Thanks guys.

 

Unless I am missing something, it says your TPS is 0.86V which means you are depressing the pedal some? At which time, your IAC count is 90. So what is your count when it is at stable operating temp with everything else off but the motor? Should be around 20-30

 

Started scan before I left for short ride, IAC counts at 21 normal warm idle 650. When I returned and parked, the idle was still normal 575 or so. IAC counts at 0. Didn't have any problems on 10 minute drive. Its a strange one. May also try a different scan program next time to compare.

 

If the IAC is 0, where is the motor getting all that extra air? Perhaps a leaky hose or manifold gasket?

 

Interesting development tonight... I got a new pigtail connector for my IAC since the clip was broken on the original. I wired in the a new connector in anticipation of a new IAC valve arriving tomorrow. Just to make sure a bad replacement part isn't causing my grief. I disconnected the purge solenoid lines to do the wiring and noticed a bunch of small black "pebbles" in the line coming from the line that comes from below the firewall. So.... I knocked as much as I could out of the line and then blew into the top of the solenoid to clear the build up I could see in the connector on the bottom. Air passed through.

So as I was finishing I was thinking about this. The valve was open. I didn't know what the solenoid did until I got out the FSM. If I understand it correctly the valve should be closed and is opened as needed.

So my thinking is this. Could the purge solenoid being stuck open and partially blocked with the black media, (charcoal? not sure what it is) be part of my Idle issue? And is this an obvious sign that I should replace the purge solenoid? HELP!! Would this even cause a high idle, or cause poor idle. Any help would be awesome!!! Thanks as always. The car really runs good 90% of the time. I just want to get this figured out.

 

Hood up as usual...




This is the solenoid that had the contamination

 

Could I ask where you purchased the cable from? Are you using Windows 10 by chance or? I'm also new to using a scan program, hoping that a scan will point me in the right direction with small gremlins in my 93.
Thanks for posting your info hope you find your issue!

 

[QUOTE=jph46;1592163507]Could I ask where you purchased the cable from? Are you using Windows 10 by chance or? I'm also new to using a scan program, hoping that a scan will point me in the right direction with small gremlins in my 93.
Thanks for posting your info hope you find your I


I got the Cable from http://obd2allinone.com/diagnosticsoftware.asp They have 12 pin ALDL Cables for OBD1 and they sent a Disc with some scan programs as well. I downloaded Datamaster which is working fine. and Yes I'm using Windows 10. The connection constantly recycles... that is to say that its connected for a few seconds, disconnects and reconnects quickly over and over Instead of one smooth connection. Not sure if that problem is on my end or the car??

 

There's a fairly easy check of the purge solenoid in the FSM, chart C-3, page 6E-C3-6. ( I think the 92-93 systems are close).
The charcoal might be a failure of the canister, not sure how to check it?

 

As others have asked, did you lube and reset the Throttle Cable? I just had this exact same problem on my 96, and after throwing a ton of parts at it, the issue was resetting and retorque of the throttle/cruise cable. The cable was keeping the butterflys open just a smidge.

 

I did reset the ASR per the FSM. I believe it is torqued properly. I didn't lube it however in the past I've had the idle high while parked and the throttle blade stop was against the set screw.

After discovering the bad Evap canister, I ordered a new canister, Evap purge solenoid, Pcv check valve and an EGR valve. Probably overkill but if I still have the random surge after that... I may seek professional help, for the car too

The FSM has been regular reading for me lately. It's been a great learning process. Would be nice to clear this small issue up and maybe focus on more fun tinkering. Thanks guys

 

Try it again, but lube it this time. That is an important step. Good luck.

 

Well. I replaced the PCV valve, old one was filthy but seemed fine. I also replaced the EGR Valve, which I also knew was likely a wasted effort. I did replace the Evap purge solenoid as the old one was stuck open likely contaminated with the charcoal pellets from the failed EVAP Canister. I was able to access the canister rather easily by removing the Right Rear wheel well plastic and the car raised. This is different from the FSM but better I think. All said and done the car still has the exact same issue. I'm gave one more check for Vac leaks with smoke. No problems found. When it occurred today, I parked the car and the idle was at 2000 rpm. I shut the car off. When I returned in about ten minutes the car ran to 1100 and quickly fell to about 600. Ran just fine. I'm Having the ASR on or off makes no difference. It comes and goes usually after being at cruising speed. It will be idling hard at a stop, If I wait an extra few seconds at the stop it corrects itself, then may not return... I'm going to be looking into getting the ECM refurbished. If I'm way off on this please let me know but everything I've tried hasn't altered the behavior at all. And if anyone has had luck with a service that rebuilds ECMs please let me know!! Thanks everyone. I appreciate everyone's input and advice.

 

[QUOTE=AJT84;1592244076]Well. I replaced the PCV valve, old one was filthy but seemed fine. I also replaced the EGR Valve, which I also knew was likely a wasted effort. I did replace the Evap purge solenoid as the old one was stuck open likely contaminated with the charcoal pellets from the failed EVAP Canister. I was able to access the canister rather easily by removing the Right Rear wheel well plastic and the car raised. This is different from the FSM but better I think. All said and done the car still has the exact same issue. I'm gave one more check for Vac leaks with smoke. No problems found. When it occurred today, I parked the car and the idle was at 2000 rpm. I shut the car off. When I returned in about ten minutes the car ran to 1100 and quickly fell to about 600. Ran just fine. I'm Having the ASR on or off makes no difference. It comes and goes usually after being at cruising speed. It will be idling hard at a stop, If I wait an extra few seconds at the stop it corrects itself, then may not return... I'm going to be looking into getting the ECM refurbished. If I'm way off on this please let me know but everything I've tried hasn't altered the behavior at all. And if anyone has had luck with a service that rebuilds ECMs please let me know!! Thanks everyone. I appreciate everyone's input and advice.[/QUOTE

I am not sure if yours does the same, but even though I just came to a full stop, my mph still is dropping from 4-5 mph down to 0. its usually takes a couples seconds for it to hit 0, then my idle drops down. Wasn't sure if you noticed if yours was doing that also.

 

Mine does that as well and I'm having intermittent idle problems.

Can I download that datamaster program anywhere for less than $100?

 

I downloaded Datamaster free... limited to 20 scans before having to register.

 

Shipped out my ECM to SIA Electronics. Over the phone the guy I spoke to said IAC control problems were very common. It will be at least a week by the time they go through it and get it back. Once it returns and I try it I will update.