EJ25 SOHC Air Idle Control Valve.

stubbie · Force Sensitive Joined: 30 Aug 2009 Posts: 14

My AICV seems to be playing up and seems to be slow to operate. My ECU is showing two fault codes one for the Vehicle speed sensor and one for the AICV.
The symptoms im getting are -
1) That the engine will occasionally continue to rev for a period after I have taken my foot off the accelerator to change gear.
2) The engine will occasionally stall when I take my foot off the accelerator / when I have stopped, normally when engine is warm.
3) The engine overrevs on starting (most recent problem)
4) On one occasion the engine sounded like it was only running on 3 cylinders when idling, but this seems to have sorted itself out and has not happened since.

On the basis of the above I have ordered a second hand unit from the states (part number A33661R02) after my local subaru dealer quoted £419.56 for a replacement!!

I have removed the existing AICV to give it a clean, but everything looked to be fine. I have reset the ECU overnight by disconnecting the battery but on start up the AICV fault along with vehicle speed sensor fault code reappears.

The AICV appears to be a simple solenoid that is driven in or out to stem air flow, but I have read that these are factory set, is this true??? what does the ECU measure to determine ACV position?

Are there any other problems that could be causing the above faults.

Where can I locate a factory manual that covers the 1999 EJ25 sohc engine?

PS: Are these RJES sumps ever going to arrive??

rjes · Posted: Sun Oct 25, 2009 6:09 pm Post subject:

The IACV can only affect all the cylinders. If it's been running on three, it will be caused by something else.
The valve does work magnetically, so it has that in common with a solenoid. However, I wouldn't describe them as 'simple'. They actually have more in common with a moving coil meter than a solenoid. There are two coils. One opens the valve and the other closes it. Both coils are fed a PWM signals with inverse duty cycles simultaneously, and the balance of the two signal's duty cycles determines how open or closed the valve is. They are very prone to dirt contamination because of the small operating forces and tight tolerances.
After resetting the ECU, the vehicle speed sensor error message is very unlikely yo come back immediately. If you mean it came back before you'd even driven it, I suspect it never actually went away. Did you check that there were no codes after reconnecting the battery?

Many of the other symptoms you mention could easily be caused by a lack of a vehicle speed sensor on an ecu that needs one particulary '2' and maybe '1'. Some more info about your conversion world be useful please, especially did I do the wiring harness work for it, whether or not it has a vehicle speed sensor, and what part number your ECU is (the long number starting with 226). There is at least one EJ20 ECU which gives false IACV error codes if there is no speed sensor, yet idles perfectly.

The 1990 - 1999 IACV's were supplied preset. If you lose the actuator position on one, trial and error is the only way to find it again. It's not uncommon for people who don't understand fuel injection systems to fiddle with them in an (incorrect) attempt to alter the idle speed, but you can usually see where they have been set by the unexposed brass under the screws being cleaner than the rest of the slots. You can't get it wrong if you scribe a line between the actuator and body before you undo the screws though.

Buy a manual on CD off eBay. Exactly what models are covered, and what market / spec models are covered can be hit and miss - its not uncommon to find the CD does not cover exactly what models you wanted, but they are only a few quid. If it's mechanical info you are after, getting an exact match manual may not be too critical, but if you're after wiring diagrams, some of them are incredibly hard to get.

Yes, my cast sumps are going to arrive.
_________________
Regards,

Richard,

R J Engineered Solutions
Quality Subaru Powered VW Components
www.rjes.com

stubbie · Force Sensitive Joined: 30 Aug 2009 Posts: 14

Thanks Richard,
I realise now that its a bit more than an open / closed solenoid valve. I will get all the details you have asked for regarding ECU serial numbers. The conversion was done by Syncroengineering (Pete) using parts supplied by yourself. The wiring loom however was made up by a friend of Petes (Andy?). Pete fitted a vehicle speed sensor supplied by yourself, I can see it plugged in at the back of the speedo housing and will send you a photo. What I dont know is where it connects into the ECU.

I have now fitted the IACV supplied from America and touch wood everything seems to be running a whole lot better with no over revving when changing gear or on start up. I will be resetting the ECU overnight to see if the fault code disappears.

A more worrying problem however is that when I was parking the van this evening the oil pressure light started flashing, as soon as I revved the engine the light went out. The oil level is fine as I topped it up before taking it for a test drive. Which I suppose brings me to my biggest worry, and that is I seem to be losing oil, about 0.5 litres every 125 miles.. The exhaust gasses look fine, no blue or black smoke, no oil spots on paper held over the tail pipes, I'm not leaking anything on the drive way, bit of a worry this isn't it? Engine was supplied by Grade A.

ElusiveStranger · Posted: Sat Oct 31, 2009 12:50 am Post subject:

stubbie · Force Sensitive Joined: 30 Aug 2009 Posts: 14

I will call Grade A on Monday, but i'm not going to hold out much hope. My dealings so far have been less than ideal. I paid top price for this engine and when I asked them for the results of the compression test they said they didn't know. During the installation Syncro Pete found a few things wrong that indicated the engine had done a lot more miles than the 56000 that Grade A claimed. Pete tod me that he had a lot of trouble getting Grade A to sell the parts at a reasonable price even though I had paid top dollar for the engine..... should have sent the engine back then and should have Got Pete to do a compression test. All this said and done the engine does sound nice and quite and goes like stink but that might just be the RJES exhaust covering over the sound of an engine on it's last legs. I'm going to take it to an MOT center and get the gases checked.
It's such a shame because I finally have an Engine that to all intents and purposes is the right engine for the van.

stubbie · Force Sensitive Joined: 30 Aug 2009 Posts: 14

Oil pressure could be a sensor, a blocked filter, or oil pump failing couldn't it. But then take into account oil loss and it's pointing at something much bigger... just getting a bit desperate here. But you would too if you had just spent over £4000:00 on an engine conversion that is looking doomed.

stubbie · Force Sensitive Joined: 30 Aug 2009 Posts: 14

All four cylinders compression checked at 12.8 barg. Image of plugs to follow but essentially they were all dry and all were a light light brownish red colour. ECU reset overnight and all faults cleared. Have spoken with Richard and will be fitting a new vehicle speed sensor.

stubbie · Force Sensitive Joined: 30 Aug 2009 Posts: 14

New VSS fitted and still doing the overreving thing, if anything slightly worse with the new one. I have left battery disconnected overnight to check whether I get VSS fail fault with new unit.
The engine I have is now confirmed as a year 2000 AT, presumably AT is Automatic ?
Would the ECU in an Auto behave differently, i.e an automatic does tend to hold revs when changing gear? trouble is sometimes it all seems to work perfectly so that tends to rule that theory out.
Tomorrow I will be mostly checking VSS voltages all the way to the ECU.
Got a damned good factory manual of ebay for £3:95 covering my engine.

stubbie · Force Sensitive Joined: 30 Aug 2009 Posts: 14

stubbie · Force Sensitive Joined: 30 Aug 2009 Posts: 14

stubbie · Force Sensitive Joined: 30 Aug 2009 Posts: 14

Reset ECU overnight and have taken new VSS for a drive, the over revving symptoms are still there, however when I checked the ecu afterwards the fault light was clear, no VSS fault and no IACV fault... so what is the cause of the over revving?

rjes · Posted: Fri Nov 20, 2009 3:36 pm Post subject:

The oil pressure figures all look OK to me. I can't remember the compression test target, but usually you're looking for variance between the cylinders more than that actual figures 12 bar is in the right region for an engoine with an 11ish compression ratio. It sounds like all yours are the same, which is definitely a good sign.

If your ECU has an NPS terminal (some but not all auto ECU's have them), it may need earthing, or if it's already earthed, try disconnecting it. If it's an ECU which is used in both auto's and manuals, your ECU may have the terminal but the harness may not in an auto, and the ECU may need configuring for use in a manual by modifying the harness. I didn't do the conversion work on your harness, so I'm guessing what may or may not have been done. All I know is how I would have done it.
_________________
Regards,

Richard,

R J Engineered Solutions
Quality Subaru Powered VW Components
www.rjes.com