Didn’t pass MOT/TÜV…Spanish ITV

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balto8
Knows an Aerodeck isn't a 480
Posts: 221
Joined: Tue Jul 22, 2014 3:02 pm

Didn’t pass MOT/TÜV…Spanish ITV

Post by balto8 » Wed Oct 10, 2018 4:00 pm

Short version. Did not pass Spanish MOT duo to high CO2 emissions. My non catalyzed 1991 turbo should be around 3.5, it is at 4.2. Along with some other lesser faults.

Lately I’ve fiddling around with my ever faulty idle. It used to be around 1000 rpm when cold, but then around 1200-1300 as the engine warmed up.
I tried following the steps in the idle adjusting guide.

viewtopic.php?t=19073

Have cleaned throrougly the throttle body with carb cleaner. Replaced the gasket. Put some gasket sealant.
Throtle position sensor is perfectly asjusted. I can hear the click with the minimum displacement of the buttlerfly.
Then I did the adjusting of the idle speed: while earthing that loose cable around the oil dipstick I turned the nut at the front of the throttle body several turns down until idle speed came down to 800 +/-, the I “unearthed” the cable and revs went up to 1000. It was fine I thought. Untill MOT day came.
I believe that turning that bolt down has altered the proportion of the mixture while idling, that’s why I got higher emissions, that’s also why the revs went down. So I’m not so sure about this idle restore guide no more.
Next thing I’ve replaced the idle valve for a new one: as engine was still cold revs stood around 1600, whe warm it went up to 2200 and jumping up and down.
Replaced that idle valve for the old one afer clenaning it up with carb cleaner: it behaves exactly the same.

So I am thinking about a false temp sensor ( have already ordered and new sensor ). Am I headed in the right direction?
Now I don’t know wich was the original position of the throttle body adjustment bolt? Any ideas?

Thanks guys
1991 480 Black Turbo
2012 Seat Exeo ST
2013 VW Polo TSI DSG

Ortovox77
480 Newbie
Posts: 42
Joined: Fri Sep 14, 2018 10:50 pm

Re: Didn’t pass MOT/TÜV…Spanish ITV

Post by Ortovox77 » Sun Oct 14, 2018 10:24 pm

I will try to help even if I don't have any experience with the non catalytic turbo.

I don't think the idle adjustment has to do with the emission problem.
Atleast in Sweden the emission is measured att 2000rpm. My guess is that you have som leakage somewere that sucks in air so it does not pass through the airmass meter. That will mess up the air to fuel ratio and can have other strange affects.

I had problem with my turbo many years ago and found that one of the metalpipes going into the intake was loose.

Regards Jonas
------------------------------------------------
Volvo 480 Turbo 1994
Volvo 480 ES/GT 1995
Volvo 480 Turbo 1988
Volvo 480 Turbo 1990 (will be scrapped)
BMW Z4 coupe (ESS supercharged)
Saab 9-5 2006
Rotax DD2 Gokart
------------------------------------------------

balto8
Knows an Aerodeck isn't a 480
Posts: 221
Joined: Tue Jul 22, 2014 3:02 pm

Re: Didn’t pass MOT/TÜV…Spanish ITV

Post by balto8 » Mon Oct 15, 2018 1:16 pm

Thanks for the interest.
I will check for every hose and tube integrity asap. I have have ordered a coolant temp sensor and have new spark plugs ready to go in. But I need to try one thing at a time and see how does it affect the issue.
Will report soon what the coolant sensor change does.
1991 480 Black Turbo
2012 Seat Exeo ST
2013 VW Polo TSI DSG

Robou
Knows an Aerodeck isn't a 480
Posts: 255
Joined: Sun Jul 08, 2007 11:34 pm

Re: Didn’t pass MOT/TÜV…Spanish ITV

Post by Robou » Tue Oct 16, 2018 6:34 am

The guidelines in the topic you refer to aren't correct, my contribution was limited to a problem with the two cylindrical connectors.
The right sequence (I copy/paste most text):

The throttle cable should have some play.
Start the engine.
-Switch off the airconditioning and wait until the thermostat is fully open and the cooling fan has switched itself off.
Stop engine.
-Move the idle speed regulating valve to the basic setting by earthing the cable* in the test point near the crankcase ventilation.
-Slacken the lock nut (the chrome one on top of the TB(throtle body))
-Back off the adjusting screw until the throttle valve is fully closed.
-Tighten the adjusting screw until it contacts the link rod, then tighten it a further quarterturn.
Start the engine again and adjust further until the idle speed is about 700 rpm.
-Hold the adjusting screw in the correct position and tighten the lock nut.
Stop engine.
-Check: the click should be heard with the slightest angular displacement of the valve spindle.
(Because the position of the throttle valve has changed.)
If not adjust the throttle valve switch.
-Slacken the two bolts.
-Turn the throttle valve switch first clockwise (looking from bottom!!) and then slowly counterclockwise (!!) until a click is heard.
-Fasten the throttle valve switch in this position (the clicking noise is caused by a microswitch).
Start the engine again, disconnect the cable and the idle speed should be correct.

There is no way to adjust the idle speed by any other means, it is all coded in the Jetronic depending on temperature and AC, provided the basic settings as above are correct. So never ever touch the adjusting screw again for the years coming.
The variations in idle speed are mostly caused by a dirty idle speed valve or bad electrical connections of said valve or the MAF.
The mixture at low revs and low load are set by the CO-pot situated on the MAF.
Turning the nut at the front of the throttle body can only have undesirable effects, as a matter of fact I don't even know where it is meant for.
Too old to bother
480 Turbo midst '91

balto8
Knows an Aerodeck isn't a 480
Posts: 221
Joined: Tue Jul 22, 2014 3:02 pm

Re: Didn’t pass MOT/TÜV…Spanish ITV

Post by balto8 » Tue Oct 16, 2018 9:21 pm

Well thanks for clearing things up. Now I've touched that golden bolt on the front of the throttle body, thank God I should have another complete throtle body to check for the original "adjustment" of that screw. Don't touch it ever. Anyway I think what it does. The throttle body has this "alternative" air passage other than the opening of the throttle valve itself. It's a small passage, as said, and it's opening is controlled by the adjustment of this golden screw at the front of the throttle body. So having it loosen will allow more air in while idling, and tightening it will do the opposite thing. That's why I think that tightening the damm screw reduced the amount of air at idle therefore enriching mixture. But again that's only a complete ignorant on basic mechanics opinion.

I've been recommended both to look at a faulty Maf and for air leaks at the hose following the maf.
Will do as soon as my working hours allow me to.

Could you guys repeat me what resistance should I have at the maf pins?
1991 480 Black Turbo
2012 Seat Exeo ST
2013 VW Polo TSI DSG

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jamescarruthers
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Re: Didn’t pass MOT/TÜV…Spanish ITV

Post by jamescarruthers » Wed Oct 17, 2018 8:05 am

I think the whole point of adjustable screws on the throttle and adjustable potentiometer on the MAF are so that *your* car can be set up correctly. It is fine tuning for each engine-- if not they'd have just built them with a fixed throttle air orifice and a fixed resistor in the MAF.

Copying MAF values and throttle screw settings from another car will get you close but it won't be perfect. ‎ I think you'd be better to eliminate all air leaks then follow Robou's advice to return your car to normal, rather than change the throttle body.

It sounds like the MAF CO potentiometer is what adjusts the CO mixture, which is what you failed your MOT on. Surely, this is simple to adjust during the test (after fixing the throttlebody settings) when the exhaust gasses are being analysed. On my B18E (non-turbo) I adjusted the CO potentiometer to the correct value during the test-- it can only be fine tuned while analysing the exhaust gas output, anything else is just guess work.
1987 Volvo 480 ES, 507274, 217 - Red (Ness)
2001 Volvo C70 2.4T convertible (Olivolvo)
2008 Mini Cooper convertible (Mau)

Previous 480's:
J123 CFU -- ES
J449 MNL -- ES auto
D864 CPV -- ES
L691 JFC -- Turbo
F70 MNR -- ES
H858 FGV -- Turbo auto
E981 KHM -- ES (509849)

balto8
Knows an Aerodeck isn't a 480
Posts: 221
Joined: Tue Jul 22, 2014 3:02 pm

Re: Didn’t pass MOT/TÜV…Spanish ITV

Post by balto8 » Wed Oct 17, 2018 11:44 am

So changed the temp sensor. Nothing at all happened. Still the same. Excuse my ignorance, is it normal that unplugging the MAF connector drops the revs down? Am I looking at a faulty or already manipulated MAF? I can see the plastic covering the regulation screw is gone.
Anyone with a working MAF for a phase I turbo?

https://drive.google.com/file/d/19N9rVE ... p=drivesdk
1991 480 Black Turbo
2012 Seat Exeo ST
2013 VW Polo TSI DSG

Robou
Knows an Aerodeck isn't a 480
Posts: 255
Joined: Sun Jul 08, 2007 11:34 pm

Re: Didn’t pass MOT/TÜV…Spanish ITV

Post by Robou » Thu Oct 18, 2018 10:48 am

@balto8
The resistance between pins 2 and 6 on the MAF from where to begin adjusting is ±320Ω. If a mod is involved I advise ±520Ω.
Remember the set value, during a MOT it may be necessary to change it.
Removing the MAF connector will have strange effects. Revving up quickly will cause a well-adjusted engine to die.
Too old to bother
480 Turbo midst '91

balto8
Knows an Aerodeck isn't a 480
Posts: 221
Joined: Tue Jul 22, 2014 3:02 pm

Re: Didn’t pass MOT/TÜV…Spanish ITV

Post by balto8 » Sat Oct 20, 2018 6:17 pm

Found it ! Has to be that....

BIG tear at the joint of the hose coming from the MAF with the lower one going to the turbo.
Also checked MAF filaments: all in place. Also checked MAF resistance: was at 190. turned it up to 320 and it's ready to go in once I find a set of new hoses.
Has anyone tried this?
https://www.marktplaats.nl/a/auto-onder ... ousPage=lr

Image
1991 480 Black Turbo
2012 Seat Exeo ST
2013 VW Polo TSI DSG

balto8
Knows an Aerodeck isn't a 480
Posts: 221
Joined: Tue Jul 22, 2014 3:02 pm

Re: Didn’t pass MOT/TÜV…Spanish ITV

Post by balto8 » Sat Oct 20, 2018 6:19 pm

Image

Image
1991 480 Black Turbo
2012 Seat Exeo ST
2013 VW Polo TSI DSG

Ortovox77
480 Newbie
Posts: 42
Joined: Fri Sep 14, 2018 10:50 pm

Re: Didn’t pass MOT/TÜV…Spanish ITV

Post by Ortovox77 » Sun Oct 21, 2018 8:54 am

balto8 wrote:
Sat Oct 20, 2018 6:17 pm
Found it ! Has to be that....

BIG tear at the joint of the hose coming from the MAF with the lower one going to the turbo.
Also checked MAF filaments: all in place. Also checked MAF resistance: was at 190. turned it up to 320 and it's ready to go in once I find a set of new hoses.
Has anyone tried this?
https://www.marktplaats.nl/a/auto-onder ... ousPage=lr

Image
Yes that tear must be the problem, good that you found it before changing and testing more stuff.
Had similar problem with that hose on my old turbo and ended up runnning for years with duct tape :) since I could find a replacement hose.
I will look into that kit since I think I might need it on my latest 88 Turbo I bought.
------------------------------------------------
Volvo 480 Turbo 1994
Volvo 480 ES/GT 1995
Volvo 480 Turbo 1988
Volvo 480 Turbo 1990 (will be scrapped)
BMW Z4 coupe (ESS supercharged)
Saab 9-5 2006
Rotax DD2 Gokart
------------------------------------------------

Ortovox77
480 Newbie
Posts: 42
Joined: Fri Sep 14, 2018 10:50 pm

Re: Didn’t pass MOT/TÜV…Spanish ITV

Post by Ortovox77 » Sat Oct 27, 2018 3:45 pm

I looked at the turbo hose kit that you linked to and it looks good. If you buy it then it would be nice to hear what you think of it.
Here is a link ti the those that make
https://www.chargertech.nl/en/silicon-h ... hoses.html
------------------------------------------------
Volvo 480 Turbo 1994
Volvo 480 ES/GT 1995
Volvo 480 Turbo 1988
Volvo 480 Turbo 1990 (will be scrapped)
BMW Z4 coupe (ESS supercharged)
Saab 9-5 2006
Rotax DD2 Gokart
------------------------------------------------

balto8
Knows an Aerodeck isn't a 480
Posts: 221
Joined: Tue Jul 22, 2014 3:02 pm

Re: Didn’t pass MOT/TÜV…Spanish ITV

Post by balto8 » Sun Oct 28, 2018 7:10 pm

I have finally got hold of a original set of a later turbo being scrapped at the Netherlands. So I won't be trying that tempting silicone set. I mean, it was 205€ shipping included. I got an original set, a maf, and some other small hoses and sensors for 100 shipping included wich is more like regular prices.
Eager to have it here and mount them on the car and see if it all works out.
1991 480 Black Turbo
2012 Seat Exeo ST
2013 VW Polo TSI DSG

balto8
Knows an Aerodeck isn't a 480
Posts: 221
Joined: Tue Jul 22, 2014 3:02 pm

Re: Didn’t pass MOT/TÜV…Spanish ITV

Post by balto8 » Wed Nov 21, 2018 9:12 pm

After replacing the hoses following the MAF for a good set free of tears and leaks idle has come to something more like normal.....more like it used to be before. But still suffering from the same problem.
Idle is at 1000 rpm while cold but raises up to 1200-1300 as it warms up.

Things done this far.

Replaced the mentioned set of hoses.
New engine temp sensor
New set of spark plugs
Cleaned with carb clenaer both ICV and throttle housing.
Reset MAF resistance back to 320 ohms

When replaced the hoses and started the engine saw something the MOT guy had pointed while running the test. There's a leak at the exhaust downpipe first section, right before the first silencer.
Have already found and bought this section ( all the exhaust really) and I will be replacing it all asap. Do you guys think this leak in the exhaust system could cause the idle problems. If not where to look next.
Kind of desperate this far to have a smooth running idle.

Haven't taken it to any garage yet to check for CO emissions
1991 480 Black Turbo
2012 Seat Exeo ST
2013 VW Polo TSI DSG

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