AGU problems.

[Wye-Fi]

Hi Guys! Im new here and posted a problem im having in the new members section. it was suggested i pop it on here for a bit more forum traffic. any help with any of my issues would be greatly recieved. look forward to chatting to some fellow golfers..

So here is my problem;
 i have had a bit of rough idling lately on my 2000 mk4 AGU 1.8t GTi and slight loss in power/mpg. with thanks to many of you on here i traced the fault to the temp sensor using my newly aquirred scanner. went about replacing the sensor this morning and i has definitely made an improvement to the idle and bottom end power but it still seems to be hitting a flat spot mid rev range. SO BACK TO THE FORUM! after searching some more i have read that it could be a number of things causing it so i have checked the following:

-unplugged MAF, this made no difference to the driving of the car however it did cause the engine to nearly stall when plugged back in (im thinking this is prob normal??)

-checked all pipes and vacuum hoses, i came across a loud hissing coming from the front of the engine and noticed i had a split hose. see pic


Can anybody please tell me what this hose is called please and what it does?? ive fixed the split temporarily but want to get a new one soon. fixing this has improved the idling even more i would say but hasnt fixed that flat spot. SO MORE SEARCHING!!

-Plugs & Leads all seem fine and there doesnt seem to be any misfire

-Now the interesting bit for me, the N75 valve. should unplugging this affect how my engine runs? ive unplugged it whilst it was running and it didnt make any difference at all (Is this like the MAF and no change is good or is this a sign mines faulty??) Also upon inspection ive noticed that one of the wires on the n75 plug is damaged slightly right by the plug itself, it doesnt look broken though, any ideas on a good fix for this? new lead/plug maybe?


-Randoms- every now and then i notice a fast ticking noise coming from what i think is a vacuum pump tucked over near the washer/header tanks. IS THIS NORMAL?? im not so sure as i used to own an Audi with what i think is pretty much the same engine and that didnt make the noise when it was running fine but it did start making that ticking not long before it died??


And Lastly (phew) I have had a look but cant seem to find an image with what i want in it. at the rear of the engine bay is a small bunch of electrics. it isnt mounted properly to its bracket or there are parts missing to enable it to be mounted and its just held on with a cable tie. can anyone show me what it should look like when mounted properly plz?? (Also what is this)


If during my searching there is anything you think ive missed a quick nod would be most appreciated.
Thanks in advance guys and keep up the good work, look forward to getting my horses back under the bonnet.
Kind Regards, Chazz. (Wye-Fi)

Cheeeeeerrs!!

[daz veedub]

Thats a oil breather pipe which has spilt ive just removed all mine and fitted a oil catch can ill have a look tomorrow at the part no. Then u can contact vw and order part, that n75v is a boost solinoid if the wire is damaged u will need to get that sorted, the other part ur looking at is a charcoal canistor and is suposed to click can also be removed, look in the maintenance section for more info on that, p.s welcome aboard

[daz veedub]

And that part which is cable tied is the ignition amp which is normally mounted on the airbox but if induction filter fitted its put out the way mine is also tied on down that area as long as its secure there its fine : )

[dom]

I've edited your first post to include the information from your post in the new members section.

As Daz says, it looks like a breather hose, part numbers are here:



With regards to the MAF, if it is working correctly there should be a noticeable difference when it is unplugged. If there is no difference when it is unplugged then that suggests it is not working correctly.

I'd replace the N75 wiring, if the valve itself was faulty then boost should be spiky which would be noticeable on full throttle.

Also as Daz says ,the ticking is perfectly normal, it's the carbon canister and deals with fuel vapours. The ignition amp is fine as long as it's secure.

[Wye-Fi]

Thanks!
I'll look into it, feels like I've found faults in each area that could cause my problems. Hope it doesn't end up costing me a fortune.

[Wye-Fi]

It's a bit weird as around where I live in 1st/2nd it'll pull like mad up to say 2000rpm then hit an annoying flat spot. I'm gonna try disconnecting the maf again tomorrow and take it for a bit more of a drive. Will the ecu have to adjust to this before I notice a change of will it be instant? It literally made no difference earlier when I went round the block in it (1mile max)

[daz veedub]

Have you had it scanned for fault codes ?

[Wye-Fi]

Ive scanned it myself but only got 1 code:

Since replacing the sensor i've erased this code and now dont have any engine codes.
only code im getting elsewhere is for "Airbag B tensioner not active" and i think this may have been turned off using something like vagcom for a child seat. is that correct do you know?

[Wye-Fi]

just took the MAF off as it made no difference to the driving whether plugged in or not. The inside was filthy dirty with an oily residue? I fixed my mums ford puma splutter once by cleaning the MAF and so thought id give it a shot. (nothing to lose) Before i started i couldn't read any info on the sensor inside the unit as it was covered in this oily sh#t. also i presume what are sensors on the other side of the circuit board piece weren't visable either. look how dirty it was!!!

All this came from the inside. haven't started on the outside yet.
Hoping this will make a difference. The inside of the filter is spotless though. thinking this MAF maybe the original. would a genuine one be a bosch unit??
Also with regards to engine codes, i did get codes for the N75 and MAF after id unplugged them which makes me think that wire isn't broken on the N75 else id be getting that same code with it plugged it???

[Dalo Harkin]

The pipe you listed is part of the PCV system, rip it all out and fit a catch can.

Temp sender - get a new one

And in regards to the MAF its probably not a genuine one, I don't use genuine ones but you should really, the reason I don't use a genuine one is that VW states if the car is modified BHP wise then they wont offer the guarantee they normally offer!