Hi Everyone! Great Forum Guys!
Firstly I would like to thank everyone who has already posted on this problem in the past, reading some of your posts has been a big help to find out where i'm going with this but just want to clarify a few things 1st as i'm trying to learn about the faults my car has instead of just replacing stuff!
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)
