E437 DMX 90q emissions fail. Help please - Page 2

quattromnc · 20-09-17, 07:36 PM

By adjusting the butterfly you're just adjusting the resting position of the butterfly valve, it's rare this needs adjusting, maybe the odd fine tuning.

What you need to work with is the mixture screw on the metering head (mentioned in point 1), this adjusts the fuel to air mixture at all engine revs, you need to get the car hooked up to an exhaust gas analyser and adjust it until it runs within acceptable limits, only then do you set your idle. This isn't something you can really guess, so to do this properly you need an analyser, especially if you're new to this.

sinbin5t · 20-09-17, 07:46 PM

Quote:

Originally Posted by quattromnc

By adjusting the butterfly you're just adjusting the resting position of the butterfly valve, it's rare this needs adjusting, maybe the odd fine tuning.

What you need to work with is the mixture screw on the metering head (mentioned in point 1), this adjusts the fuel to air mixture at all engine revs, you need to get the car hooked up to an exhaust gas analyser and adjust it until it runs within acceptable limits, only then do you set your idle. This isn't something you can really guess, so to do this properly you need an analyser, especially if you're new to this.

Sorry to butt in, is this what i need to do after putting a new fuel metering head on my 200 5T ? i have a running too rich problem too.

steveb · 20-09-17, 07:54 PM

you may have already thought of this but, where it had the hole in the servo had the mixture been adjusted to compensate ? ie richer as it would have been running weak with the servo leaking.

quattromnc · 20-09-17, 07:55 PM

Quote:

Originally Posted by sinbin5t

Sorry to butt in, is this what i need to do after putting a new fuel metering head on my 200 5T ? i have a running too rich problem too.

Almost certainly yes, the adjustment is completely individual to the specific engine at that point in time. So even if a metering unit is runs perfectly on one car, it will need adjustment when fitted to another, all sorts will affect it, specific air flow, compression, exhaust flow, everything you can think of. If it was brand new it won't be set up at all, just built and sent out, it will definitely need to be set up.

sinbin5t · 20-09-17, 08:06 PM

Quote:

Originally Posted by quattromnc

Almost certainly yes, the adjustment is completely individual to the specific engine at that point in time. So even if a metering unit is runs perfectly on one car, it will need adjustment when fitted to another, all sorts will affect it, specific air flow, compression, exhaust flow, everything you can think of. If it was brand new it won't be set up at all, just built and sent out, it will definitely need to be set up.

Yes it was brand new, now i have a clue to the over fueling problem i have.
Many thanks for taking time to reply.

iconauto · 20-09-17, 08:28 PM

Hadn't thought of that.Thanks. Is the adjuster down a small diameter tube inbetween the fuel lines and the igloo?

quattromnc · 20-09-17, 08:44 PM

No Problem, always happy to help.

Correct, IIRC it's a 3mm very long allen key you need, this is a pretty sensitive piece of kit so be very careful not to press down on it too hard. Adjust slowly a half turn at a time, and count your turns in case you need to reverse it. As you're adjusting you need to let the engine settle for a couple of minutes before you take a reliable new reading.

Something like the gunson's EGA would work for the home mechanic, not as accurate as a full size system but it will get you very close.

http://www.gunson.co.uk/product/G4125

Kenquattro · 26-09-17, 07:59 AM

Any updates on this, Matt? I noticed it passed it's MOT yesterday with no advisories.

iconauto · 26-09-17, 11:24 AM

Went to Ilkley over the weekend to pick up a Gunsons gastester professional. Set the CO on sunday using it and its running sweet as a nut now. Took it in for the retest Monday afternoon and it passed with flying colours!
Re-taxed now so back on the road.
Thanks for all the advice/help.

John. · 26-09-17, 11:29 AM

Quote:

Originally Posted by iconauto

Took it in for the retest Monday afternoon and it passed with flying colours!

Why not really celebrate by posting some pics of it here !!?

20-09-17, 07:54 PM	#13
steveb Senior Member Classic Audi Club Member Join Date: Jul 2008 Location: West Berkshire Posts: 1,155	you may have already thought of this but, where it had the hole in the servo had the mixture been adjusted to compensate ? ie richer as it would have been running weak with the servo leaking. __________________ [FONT] '76 Leyland Princess 2200 HLS '79 Scirocco storm '84 WR '89 coupe quattro '01 A2 1.4 TDI SE '14 A3 1.4 TFSI COD [/color][/size][/font]

20-09-17, 07:36 PM	#11
quattromnc Grown up member Join Date: Mar 2011 Location: Newton Mearns, Glasgow Posts: 177	By adjusting the butterfly you're just adjusting the resting position of the butterfly valve, it's rare this needs adjusting, maybe the odd fine tuning. What you need to work with is the mixture screw on the metering head (mentioned in point 1), this adjusts the fuel to air mixture at all engine revs, you need to get the car hooked up to an exhaust gas analyser and adjust it until it runs within acceptable limits, only then do you set your idle. This isn't something you can really guess, so to do this properly you need an analyser, especially if you're new to this.

20-09-17, 08:28 PM	#16
iconauto Grown up member Classic Audi Club Member Join Date: Oct 2011 Posts: 63	Hadn't thought of that.Thanks. Is the adjuster down a small diameter tube inbetween the fuel lines and the igloo?

20-09-17, 08:44 PM	#17
quattromnc Grown up member Join Date: Mar 2011 Location: Newton Mearns, Glasgow Posts: 177	No Problem, always happy to help. Correct, IIRC it's a 3mm very long allen key you need, this is a pretty sensitive piece of kit so be very careful not to press down on it too hard. Adjust slowly a half turn at a time, and count your turns in case you need to reverse it. As you're adjusting you need to let the engine settle for a couple of minutes before you take a reliable new reading. Something like the gunson's EGA would work for the home mechanic, not as accurate as a full size system but it will get you very close. http://www.gunson.co.uk/product/G4125

26-09-17, 07:59 AM	#18
Kenquattro 4 ring whore! Classic Audi Club Member Join Date: Nov 2007 Posts: 6,267	Any updates on this, Matt? I noticed it passed it's MOT yesterday with no advisories.

26-09-17, 11:24 AM	#19
iconauto Grown up member Classic Audi Club Member Join Date: Oct 2011 Posts: 63	Went to Ilkley over the weekend to pick up a Gunsons gastester professional. Set the CO on sunday using it and its running sweet as a nut now. Took it in for the retest Monday afternoon and it passed with flying colours! Re-taxed now so back on the road. Thanks for all the advice/help.