Removing 1.4 petrol (AUA) intake manifold (+ System Too Lean troubleshooting)

jannes

jannes

Member
Anyone know of a guide or have any tips on how to remove the intake manifold on the 1.4 petrol?

I had a quick peek and it seems straight-forward apart from the fact that's it's in the tight space but of course a few words of advice from someone who has completed this would be great.
 
easy. where are you?

you'll need a big pair of pliers for the clip at the back, the rest is simple. or at least it should be.... what exactly are you trying to do?

- Bret
 
the pdf below is a comprehensive AUA reference- although for the Fabia version of the AUA. Main difference as far as I could tell would be the ventilation intake on the A2 occupying some space above the throttle body and intake side of the AUA (but having done the TB on mine you can work around it - there are also instructions for removing this to get more hand-room on A2oc)

I can't see a bit on the intake though - maybe I'm looking in the wrong place.

http://archief.audi-a2.nl/uploads/editor/pv/ka13bxycpvcx.pdf
 
Thanks for the pointers gentlemen as well for the reference, seems still very useful although I couldn't find a section on intake removal/installation either, how odd. It's definitely better than nothing in any case. As for why, I'm combating the infamous "System too Lean" fuel trim error code and I thought I'd inspect the intake manifold next along with all the pipes. I also have a couple of spare VAG intake manifolds so I'll take a look whether I can transplant any of those for better throttle response.
 
did you check the lambda sensors? They can be broken enough to cause the error but still allow you to pass katsastus.

- Bret
 
Nicely played Bret, how did you do that? Indeed, the car passed katsastus (for you other gents, it's the Finnish term for MOT) a while ago with no issues. I noticed the front sensor has been changed recently but it's an aftermarket piece and I read somewhere that they might not work properly, any truth in this? I'm yet to check it with VCDS, though. I cleaned the throttle body yesterday and although it was filled with crust, no improvement. Also found one leak but it was in a pipe that goes in before the tb so I presume it doesn't count. Thats said, idle is slightly fluctuating which seems to point into an air leak.

I also read that the brake booster vacuum hose is prone to deteriorating, where is this?
 
mi0ne sticks at 4V :) If I delete the errors and use the car regularly, I see minimal problems. I'd also run some injector cleaner through (Liquimoly from Motonet seems to work well for me), and I always use 98...
Hunting idle is a common thing and I have it myself. I understood the problematic lambda to be the front one, too, and it's €125 or so to replace. If you read German, try searching a2-freun.de for "magergrenze" - there's a couple of threads which explain issues found (with an immediate one being the connection between EGR and block). I'd run it warm, drop VCDS on it and try recalibrating the throttle body next.
I've also seen a mild issue at the bottom of the air filter where it wasn't screwed back together cleanly after a change.

I'm away the next two weekends but after that probably have some time if you want another pair of eyeballs :)

- Bret
 
Have the same issue with my AUA so very interesting read;

Status myself;
1) lamba incl wiring has been checked
2) check for hose leak with startgas pending (have you checked your hose behind the fuelrack coming from the oil separator to the TB; that is worn on mine)
3) oil refil cap is tired
4) check/replace oil separator/EGR valve
 
Good tips, thanks.

I didn't have much time today (all work no play) but I did reset the throttle body adaptation, no change however and CEL came back shortly. Only later I read on that German forum that Bret linked that you can also reset the values first (VCDS: Adaptation => Channel 0 => Apply / Save) which I didn't do, so I will have to try again. Also checked and cleaned the EGR valve, didn't actually see much crust build-up in it so I doubt it's the culprit. I guess I need to use that old jump start gas trick too, thanks for the reminder. Also need to run through the VCDS tests when I have time.

I doubt the oil separator is going to be a suspect since it goes in before the throttle body? It was loose on mine but putting a clamp on the end made no change.
 
There's no MAF on AUA, only MAP. That's what leads me to believe anything before the throttle body can be disregarded.
 
You are right.

How did your TB looked like; mine is greasy/oily on the outside?

Any easy way to disable/close the EGR? I will check if unplugging the wiring will activate the EML in dash.

266C303A-F7F8-4A08-980F-03DEA60E2389.png
 
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Looking towards the engine, the MAP sensor is located on the left hand side of the intake manifold (take out the intake pipe first).

If your tb is oily on the outside it's probably coming from the breather pipe that connects to the separator nearby. Mine was the same due to the pipe being loose but clamping it didn't fix the lean mixture issue. The tb looked pretty sad inside too with a lot of oily dirt and grime, but cleaned up pretty nicely with carb cleaner.

To close the EGR you could fabricate a blind flange and replace the gasket with it. I thought about doing that but I figured the EGR does work since otherwise there would be a specific error code for it so I decided to leave it be at least for the time being. Not sure if unplugging will bring out the choplifter light in the dash but I would assume so.
 
Thanks for advise. See that you replied the same moment I edited hehe; I located the MAP by looking under the bonnet.

Would like to close the EGR as it just make harm anyway. Pretty sure blind plate also may be purchased.

Did you only clean the TB or also the intake the TB bolts on to and where the EGR pipe enters?
 
I noticed; your tb looks about the same as mine was but inside it will look even worse I bet. For some reason there's quite a bit oil coming from the crankcase ventilation pipe but I'm not sure whether that's a sign of an issue or just by design.

I cleaned the intake only to the extent I could without removing it, so not much. Basically after cleaning the tb I put it back on but left the intake plumbing off, started the car, sprayed as much carb cleaner down the tb as I could without the car stalling and then gave it some revs. Repeated this for a couple of times. For proper cleaning you would sadly need to take the manifold out but I haven't gotten around to doing that yet.
 
I think I found the culprit. Using VCDS to log EGR it seems like there's no pressure difference between the intake manifold and EGR, which to my understanding sounds like the EGR valve is open at all times. Going to order a new one, not sure yet whether I will test with a blanking plate in the meantime.
 
Very interesting. Talked with Audi dealership and they also mentioned EGR is typically to mess up.

Did you log during driving? At idle/standstill I would assume the EGR is open at all times.


Luckily it seems like the EGR is cheap and also very accessible.
 
Actually, the EGR should be closed during idle, it will otherwise cause rough idling and/or lean mixture. Something that's puzzling me is that there were no fault codes directly related to the EGR, one would assume that there would be a fault code for excessive flow in the event that the valve got stuck open. I guess I'll find out when the new one arrives. I ordered a genuine Pierburg one for £78 so it's not too bad and like you mentioned, it's not difficult to replace at all, it's not even necessary to detach the pipe from the tb flange.
 
Some of my findings for future generations...

On 1.4 petrol, blocking the EGR will light up CEL due to insufficient EGR flow.

Furthermore, if you live in cold or moderate climate it's not a good idea to block the EGR since the car will reach normal operating temperature significantly slower.
 
Did the new EGR remove the lean fuel trim error?

Would think the petrol engine would heat up relatively quick even with EGR blocked
 
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