IAC ...error code 24, help

Stinky · Post by **Stinky** » Mon May 15, 2006 12:00 am

Hi, this is my first post. I have a 91 Legacy EJ22 in a VW Vangon. It's a great engine, and I would be driving it everyday, but the emissions referee here in Cali won't pass me with my one error code....code 24 (actual smog numbers are great). I have read many post about the IAC here, and have Vikash's scan tool on my laptop (thanks Vikash!)

What's strange is that the IAC adjust the idle well to about 700 rpms after warming up. The duty cycle goes from 45% cold to 20% when warm(using BC-BF scan tool). I have cleaned it with brake cleaner (can't find seafoam here).
The Clymers 'checks' all checkout correctly. I have tried another IAC with a different part Number that I already had, but same code. ( mine is AA032...tried the AA033). I should also be getting the 51 & 33 (neutral switch & VSS) as I don't have those, but they haven't shown up. Subaru/Vanagon people I know on the web dont have a VSS and have no issues like mine.
My engine seams to miss once warm now using the "proper" IAC AA032 ran better before with the wrong one.No vacuum leaks that I can find with Starter fluid.
I would love to buy a new IAC, but they are not cheap. Not even sure it would go away with a brand new one.

Thanks!

Post by **Legacy777** » Mon May 15, 2006 4:06 am

You seem to be having minor temp issues. You might want to replace the coolant temp sensor.

Also, I'm quite surprised you're not having more issues without the VSS. My car did really funky things without a reading.

What happens if you reset the ECU? Does the code come back right away?

vrg3 · Post by **vrg3** » Mon May 15, 2006 3:30 pm

What is a Clymers 'check?'

What ECU are you using?

Stinky · Post by **Stinky** » Mon May 15, 2006 8:27 pm

I have a brand new Temp Sensor installed. And my laptop shows a good temp. I know those little temp sensors can really swing the performance, that's why I got a new one.

I'm currently designing a simple circuit with a 4 pronged metal plate that I will attach to the VW speedo cable behind tha dash. It will ground the pin 4 times per revolution using a proximity sensor and the spoked plate. But the computer (should) think the vehicle is simply not moving. I have heard of people having a problem slowing down from highway speeds and the engine starts dying with no VSS. But my problem is at idle with a freshly reset ECU code.

After reset, the computer just does it's double flash in 'read-mode', indicating no error. Once I rev it for a while or drive it around the block, it gives me the "24" IAC error code only. I expect code 33 and 51 too, but none. The emissions Referree will let me go with 33, 51 because they are not emissions related. Not sure why they aren't showing up. Maybe it somewhere in my 70 wire splice job

The Clymers (oops, sorry, Haynes) checks I was talking about are 12 VDC on pin 2 and the resistances between (1,2) (2,3) being 9 Ohms. After warm, I remove the IAC to see the Shutter has closed, I'm not sure if they mean the plastic looking knife edge or the metal parts behind it when looking in from the manifold side. But the plastic never moved and I can't really tell if the metal did or not, air still passes thru the valve after warm. The BC/BF scan tool tells me the IAC duty cycle is adjusting to what I would think is proper and the engine idles well.

By the way, Desipe all this, the van has great power with the Subaru in. It looks like it was supposta go there, beautiful engine.

Thanks!

Stinky · Post by **Stinky** » Tue May 16, 2006 2:12 am

I guess the more direct questions is what is the Part number of the IAC I should use with a (22611 AA 383 F) '91 Auto ECU.

I have a 22650 AA 032
and a 22650 AA 033

The computer complains about either one. Is my problem a matter of finding a matched set? My setup is a frankenstein, so I'm not sure if they are off the same car...They should have been , but who know now.

Post by **Legacy777** » Tue May 16, 2006 3:50 am

You should have 22650AA032 from the parts book I have.

However 22650AA033 superceeds 22650AA032, and should work fine.

If you get the same code with both IAC's, I would suspect you have an issue with your wiring.

vrg3 · Post by **vrg3** » Tue May 16, 2006 3:28 pm

Hm, yeah, those IAC valves should work with that ECU... What model did your wiring harness come from?

Stinky · Post by **Stinky** » Tue May 16, 2006 6:13 pm

My wiring harness was from the same car as the computer (91 EJ22), I never met the car, kind of a long story. I'm not sure you want to know, but to give you an idea, I have a JDM Short block, U.S. ECU and all sensors, intake, and my wiring harness from the orginal car is pretty much just the plugs...I rewired everything in-between. You're very smart to pick up on the wiring problem...I'm sure I have one. I'll have to look more closely tonight, because I can't think where the 3rd wire from the IAC is going. The Black and White wire go into D1 & D2 of the ECU...is the other wire ground? (sorry, I'm thinking out loud). I do get 12 VDC on pin 2, so something is wired right. I'm going to really check my grounds to that IAC.
Anyone know what pin is what on the IAC (1,2,3) and what D1 and D2 on the ECU are?

Thanks for the Part info!

Post by **Legacy777** » Tue May 16, 2006 6:17 pm

Pin 2 of the IAC connector is 12v switched. It supplies power to the solenoids on the IAC valve.

The ECU sinks the voltage at specifically timed intervals to get the properly duty % of the IAC valve.

vrg3 · Post by **vrg3** » Tue May 16, 2006 6:23 pm

91 EJ22 automatic non-turbo, then?

The middle wire is supposed to go to ignition-switched +12v and the other two go to the ECU's pins. The ECU completes the ground when it wants to actuate one of the solenoids.

The wiring diagrams in the manual scans that Josh has posted are applicable to 90-91 automatic non-turbos.

Stinky · Post by **Stinky** » Tue May 16, 2006 8:19 pm

Yes, it a 91 NA Auto...but I have B48(pin D20) unconnected to change it to Manual..like my van.

Thanks..I'll check tonight, but I think I have everything wired correctly. And I seams to 'work'....just the CEL giving #24.

vrg3 · Post by **vrg3** » Tue May 16, 2006 9:23 pm

Out of curiosity, what happens if you hook the Transmission ID back up?

The reason I ask is that 1991 non-turbo automatics use a different type of IAC valve than 1991 non-turbo manuals.

Stinky · Post by **Stinky** » Tue May 16, 2006 9:33 pm

I like where you are going with this....
Man, I may have to leave work early now!

Post by **Legacy777** » Tue May 16, 2006 11:30 pm

It shouldn't matter what you do with the Trans ID pin.

The IAC valve is spec'd to the type of ECU you have. JECS ECU runs 3-pin IAC valve.

When I did my AWD & MT swap, I used my 90 AT ECU, pinned the trans ID for MT, and didn't have to do squat to the IAC valve.

Stinky · Post by **Stinky** » Wed May 17, 2006 4:57 am

Vikash and Josh...I'd really like to thank you 2 for helping me! I grounded the transmission ID pin and the computer stopped flashing the IAC error code at me. It baffled me for weeks.

Everthing else fell into place because now I have errors #33, 51, 52...why would I be happy about those, you ask? Because The California Emission Referee allows me to have 33,51, 52 ONLY. Before it was JUST #24, yet I expected 33,52,52 (VSS, Neutral Switch, Parking Switch).

Intrestingly enough..while doing my 'midnight run' (no legal tags), I was suffering from the engine dying when slowing from crusing speed. This didn't happen when I had the Tranny ID pin to Manual. I will get rid on that with my rigged up VSS.
Also, as I'm sure you guys know, the engine doesn't drop the rpms as fast during shifts. It kinda works out beause it takes me a while to find the gears in this VW. It shifts like and Army Deuce-and-a-Half.

Thanks again, I can focus my attention on my speed sensor, tuning, and finding good surf with it.

-Andy

Post by **Legacy777** » Wed May 17, 2006 6:19 pm

That's interesting to hear that solved the problem. I wouldn't have suspected it would have done anything. I ran mine that way....must be a difference in the ECU's.

Glad you got it squared away though.

vrg3 · Post by **vrg3** » Tue May 23, 2006 1:52 pm

That's great, Andy. Good luck with the rest of the stuff. Several board members have found that without a VSS their cars behaved very weirdly, including symptoms like you describe. So, once you cobble together a VSS you might be okay. Then figure out a way to trick it into thinking there's a neutral/park switch (maybe just stick a couple of microswitches on the clutch pedal or something?) and you might get all the codes to go away!

Well, Josh, remember that a 90-91 NA manual ECU in automatic mode (or vice versa) is something that was never ever done from the factory. We have absolutely no idea what kind of code they might have put in there for that situation. Now we apparently have some evidence that even the JECS ECUs might know that in a manual car they have to deal with a Hitachi IAC valve.

Also remember the Hitachi ECUs in turbo models use JECS IAC valves.

Post by **Legacy777** » Tue May 23, 2006 6:14 pm

I guess I'm a little confused. I ran my 90 FWD JECS ECU in manual mode with all the AT sensors, and had no problems.

vrg3 · Post by **vrg3** » Tue May 23, 2006 6:22 pm

Maybe a JECS IAC valve is able to satisfy a Hitachi monitor but not vice versa. It seems plausible given how they're wired.

Stinky · Post by **Stinky** » Wed May 24, 2006 5:11 pm

Well, the code 24 showed back up after extended driving. I haven't had a chance to really trouble shoot it or make the VSS. So it's still an open issue. It only gives my 24, desipe the fact that it stored 33,51,52 before....?
I keep you posted after I make some progress.

Thanks

Stinky · Post by **Stinky** » Wed Jun 28, 2006 6:34 pm

Just to follow up and close this thread, I finally fixed it. It is a unique problem to my vanagon conversion, but you might appreciate this info.
\
I kept getting error code 24 (IAC). MT/AT grounding pin didn't matter. What fixed it was the Speed sensor (VSS). I hooked up a 5 bladed sheet metal 'fan' to my CV boot and an inductive npn proximity sensor to pin b11 on the ECU that grounds the pin 5 times per revolution. I checked the speed with a GPS and Vrg3's scan tool...almost a perfect match. More importantly, the computer no longer throw CEL #24.

Thanks for the help!
Andy

Post by **Legacy777** » Wed Jun 28, 2006 6:42 pm

Glad to hear things worked.....and as I mentioned, the ECU does some funky stuff without a VSS

vrg3 · Post by **vrg3** » Wed Jun 28, 2006 10:42 pm

Wow, that's weird that a missing VSS signal could make an IAC code happen, because the IAC code number is lower than the VSS code number.

5 pulses per wheel revolution is right for stock Subaru-sized tires, so I guess your Vanagon's tires are similar in diameter to ours?

Glad you got it figured out!

Stinky · Post by **Stinky** » Fri Jun 30, 2006 9:18 pm

[quote]"5 pulses per wheel revolution is right for stock Subaru-sized tires, so I guess your Vanagon's tires are similar in diameter to ours? " [/quote]

I think me overall diameter is about 25". But I thought the Subaru VSS was a 4 pulse per revolution, But I guess I was wrong. So we must have about the same diameter, i forget what mine really is, it's not here right now.

BTW [color=orange]I PASSED CALIFORNIA EMISSIONS & INSPECTION[/color]! no easy feat.

Josh, you were right :) , I just convinced myself they were unrealeated a long time ago...I'm slow to change. The ECU would only throw the code When decelerating from 45 mph or higher. I’m guessing the ECU thought I was sitting in the driveway, revving the engine, but got ‘out of range parameters’ for…I don’t know, stuff like load? Then couldn’t make the idle adjustments to it's satiwith the engine braking going on…total guess.

Thanks!

legacycentral bbs

A forum for 89-94 BC-BF(BJ) Legacy Owners and Fans

IAC ...error code 24, help

IAC ...error code 24, help

PROBLEM SOLVED! Auto Vs Manual...IAC cared

Fix it..for good!