ISV/IAC valve

[ABV-VR6 12]

Cleaning up some parts while still waiting for my engine to be ready... While checking my IAC today I figured I should check the specs and not just clean it... Bentley says it should be between 10 and 20 Ohms. I have two, the one that came on my low miles car sits at 7.7 and the other one is 9.6 so I'm kind of surprised? Has anyone ever checked that out? Sucks because it's NLA, what to do now even if I clean it it's not going to help the situation. 

[ABV-VR6 12]

Okay I've spent several hours looking into this and I'll share my results. I think I found the holy grail replacement! Readily available Bosch OE on eBay. I dug up an 11 years old thread on Corrado Club Canada, originally the thread was created because the part was expensive and the guy was looking for a match but now 11 years later we are looking for an OE part because it's NLA... So apparently the Jetta/Vento OBD1 1995 2.0L shared the same IAC. Same two prongs plug, size etc... I zoomed in on the picture, part number for Bosch is 0 280 140 551 and VAG is 037 906 457 E

http://www.corradoclub.ca/forum/viewtopic.php?t=14284&highlight=idle+valve

I'm going to order one, cheers! 

[oneohtwo 8]

Ah, this is potentially a great find. How did you get on? I know my ISV has been sticking a bit, Stealth freed it up and cleaned it with some carb cleaner, but it's still not 100%. Do occasionally stall when pulling to  a stop, so assume that's the ISV sticking

[fla 9]

3 hours ago, oneohtwo said:

Ah, this is potentially a great find. How did you get on? I know my ISV has been sticking a bit, Stealth freed it up and cleaned it with some carb cleaner, but it's still not 100%. Do occasionally stall when pulling to  a stop, so assume that's the ISV sticking

that can also be the dashpot not catching the throttle quickly enough when you take your foot off the gas.  Might be worth checking the damper and winding it up a turn or two

 

[oneohtwo 8]

Interesting, I remember seeing some guidance in the Bentley on this, so will double check what the tolerance should be. Would that just have the effect of causing the throttle to snap shut suddenly, rather than a slowly close? 

[fla 9]

Its basically a damper that as you rightly say controls the closure of the tb. Sometimes this completely fails and you get the snapping shut action. Sometimes it can be assisted by adjusting the dashpot upwards

[ABV-VR6 12]

On 3/19/2022 at 7:33 AM, oneohtwo said:

Ah, this is potentially a great find. How did you get on? I know my ISV has been sticking a bit, Stealth freed it up and cleaned it with some carb cleaner, but it's still not 100%. Do occasionally stall when pulling to  a stop, so assume that's the ISV sticking

Well that's what I was thinking too, I though I found the holy grail but no interests lol

So I ordered one, it's exactly the same 100%. I'll say get them while they're still a few NOS left on ebay. Not expensive either, paid about the equivalent of £90 shipped. 

Here's where it goes deeper in the rabbit hole. I have 3 IAC here, one that I know for sure worked flawlessly. So the reason for me to look into that was that in the Bentley it says that it should have between 10 and 20 Ohms. Mine had 8.6 I think so it made me question it... I looked into the other one of unknown condition and very similar results... Ordered NOS one, shows up, guess what, same! So now I have 3 IAC with all similar values. 

Perplexed by this I went on the Canadian FB group. About 5 guys tested theirs and they all had similar results, none of them had values between 10 and 20 Ohms like described in the Bentley. I'd like to point out that one of them was a brand new Corrado specific Bosch and also scored 8 point something... 

The conclusion is there's an error in the Bentley which apparently according to a VW tech happens more than we think. Just look at the variations between the Bentley MK3 or Passat B3 and Corrado for the same thing... 

That's where it's at! Unfortunately my engine is not installed yet so I can't test it. But according to the old thread I found on CCC, the guy who first did this a long time ago it worked flawlessly. 

[oneohtwo 8]

Hmm, I think I'll pick one up. Any obvious differences between the new and old? They look pretty well identical as far as I can see. If the electrical values are the same across all three, I can't see why it wouldn't work properly.

[ABV-VR6 12]

As you can see on the pictures mate, 100% de same. Same size, same plug etc... You have the part number on the picture. Get it while you can ill say! 

[oneohtwo 8]

Found one straight away on ebay for a good price, so snapped it up only for it actually to be out of stock! Typical. Only other source I can find is about £200 which is a bit steep seeing as you managed to find it for £90, but might still be worth it.

[ABV-VR6 12]

Ya unfortunately I see that my seller is now out... He had 3 when I bought it, someone else is reading my post 😉. 

I'll say £200 is still better than NLA... I found this one for £115 https://www.ebay.ca/itm/Volkswagen-Idle-Air-Control-Valve-BOSCH-0280140551-NEW-OEM-VW-/132560378126?mkcid=16&mkevt=1&_trksid=p2349624.m46890.l6249&mkrid=711-127632-2357-0

BTW I bought another one different brand from Germany, got also 8.2 Ohms so they all have this and not between 10 and 20 like Bentley says... 

[oneohtwo 8]

Yeah, I think that's the one I found also! £165 including shipping and taxes, so not that bad. We'll see if it helps out. Need to see about adjusting the dashpot as well.

 

[ABV-VR6 12]

That's not has good deal I got but pretty good I'll say for an NLA part. Keep me posted with your progress! Cheers 

[oneohtwo 8]

It's arrived from the US! Hopefully will get a chance to fit it this weekend.

Not expecting it to make any huge difference, as the stalling issue is pretty infrequent, but we'll see! Will be nice to know it is a brand new part as well.

[1xshaunx1 27]

Ooo that’s shiny

[Keyo 47]

An essential spare for sure.  One good thing about a VSR is you dont need the isv damper which is also a very hard obsolete part to now obtain- whilst on  the theme throttle body dash pot is also very hard to source, so all these parts one should keep for spares if a long term owner. 

Edited April 12, 2022 by Keyo

[oneohtwo 8]

Yes indeed. We're not all lucky enough to have a VSR though! How does the VSR get around the problem - I assume it uses the same throttle body?

Anyway, fitted the part today, all works fine with a nice strong idle. Can't say if it is any better than before for certain but it felt like it settled down to the correct idle instantly rather than hunting around for a bit. Should be more reliable anyway! Really good find this, thanks fella. 

For confirmation, the two parts side by side:

[fendervg 33]

VSR doesn’t need an ISV as they are rarely standing still long enough to idle!

In fairness I don’t really know - maybe if you use the motorised OBD2 throttle body from the Golf? Although the VSR was originally designed for OBD1 engines.

[Keyo 47]

It’s an isv dampener They don’t use guys the black box that are known to Grenade . 

The isv plugs straight into I grommet into the manifold  The grommet can be found on a mk3 abf . 

Edited April 15, 2022 by Keyo

[ABV-VR6 12]

23 hours ago, oneohtwo said:

Yes indeed. We're not all lucky enough to have a VSR though! How does the VSR get around the problem - I assume it uses the same throttle body?

Anyway, fitted the part today, all works fine with a nice strong idle. Can't say if it is any better than before for certain but it felt like it settled down to the correct idle instantly rather than hunting around for a bit. Should be more reliable anyway! Really good find this, thanks fella. 

For confirmation, the two parts side by side:

I'm glad to see that I've been able to help someone else with this find and happy to see that it made things smoother. Cheers! 

[ABV-VR6 12]

Nice pics Keyo as well, good to see close up pictures of how it's rigged up. Still dreaming of owning one, one day... 

[fendervg 33]

You and me and the rest of the VR6 world - still dreaming…

[ABV-VR6 12]

5 minutes ago, fendervg said:

You and me and the rest of the VR6 world - still dreaming…

Ha haa 🤣😁 yes I'm sure I'm not the only one dreaming! 

[Keyo 47]

It’s nice you both  appreciate a vsr many don’t and not even know what it is and even notice it in bay at a show . 

[ABV-VR6 12]

4 minutes ago, Keyo said:

It’s nice you both  appreciate a vsr many don’t and not even know what it is and even notice it in bay at a show . 

If I see a popped bonnet open and there's a VSR, that's all I see mate 🤣😁. Good for you that you found one! When I posted in the "want to buy" section I got like 3 scam messages lol