mk3 golf gti 30% power loss need help 2nd time trying!! long thread but all info

[dragongreengolfgti]

Right to start then ! im looking for a positive answer now im trying this again as no one replied last time only want a serious answer if you think what could be up with my car please! i know its a long first question and i am quite new to vw but i know my stuff about cars im just stumped oh and ive searched google etc already ive read probably every forum going and still no joy !

i have a 96 n reg golf gti 2.0 ltr 8v engine its a (agg code) Im from uk btw lol anyway its not quite right its lacking about 30% power in my opinion if i put my foot down it dont wanna know makes loads of noise just no go !

bit about what ive changed and done !

1. ive checked the timing all spot on including dissie timing. with new distributor, cap and arm .
2. changed all usual suspect relays, fuel ecu etc
3. brand new crank position sensor
4. not new but two different coolant temp sensors water temp gage seems to work fine dosnt over heat never goes over half way maybe has sticky open thermostat though ?
5. new vacum hose from servo to inlet has improved idle which is spot on with occasional over rev normally on start up!
6. new metal water hose around bottom of engine also flushed out and checked other pipes for tears and gaps all look fine!
7. new intake breather pipe to air box which i have tried standard air box with new filter in also it had a piper cross air filter kit on there which is now off!
8. i have tried 3 different MAF sensors and 2 different air temp sensors
9. new spark plugs, leads are fine sprayed them no arching or rips
10. new coil pack i know is fine
11. different purge unit and pipes to charcoal chamber
12. cleaned throttle body etc
13. just done oil and filter change this week with new set of plugs also
14. new fuel filter
15. not new but different lambda sensor (o2 sensor)

things you need to know .

i have a de cat pipe on there which is connected to a stanless steel system and magnex back box which is old. i know there is a exhaust leak on the join from down pipe to cat will sort that out! but that alone shouldnt affect the performance loads would it?

i have read about sluggish performance while accelerating on this website and 8 times out of ten its the o2 sensor but i have replaced that recently it was second hand but good i believe! now my question is can it still be that if theres no engine management light on ever! i havnt had chance for a vag test so i dont know if any codes are present.
also sometimes my car stays running after i have removed the key not often at all could have been me though as i removed a none standard immobiliser from the system and may have disturbed a a wire somewhere hasnt done it for over 2 months now though after messing with wires !

oh yeah its using loads of fuel maybe averaging 25mpg on good run 28mpg! it was worse than this at 14mpg before i replaced the coolant temp switch ! however recently i have seen the gauge at 41mpg since last posted this add so its running spot on but laggin power on load still grrr!

i dont know where to go from here i will try a new knock sensor soon only thing i can think of after looking at other people's probs on here. Any help though would be good i just want it as fast as it was when i bought it instead of crap fords overtaking me lol
also i need a new clutch pedals right at top and when cold kinda grinds a little into second only and hard to select first at junctions apart from that drives fine ! maybe another thing is when i acellerate say in first a short distance at about 2k rpm then let off the acellerator it pops and bangs like back firing but maybe its just the de cat pipe ? also when i put ignition on to start car should the engine management light come on aswell as mine dosnt perhaps theres old codes to be removed with vag com? hope this is enough info and i get a good answer and have a look at my pics i put on today in photo album cheers for looking

[VR6_Wherry]

Try replacing the Leads (I know you checked them already)

Have you linked it up to a VAGCOM yet??

You mention the clutch, does it need to be replaced? is it slipping?

[dragongreengolfgti]

Hi mate ive replaced the clutch now already thats not a problem at all now all brand new with clutch cable i could try some more leads i guess dont cost loads of money just seems to bad to be leads ! and yeah just literally got my vagcom through the post today off of ebay came up with 2 codes which are :-

00523 and 00532 now i know what they mean from the book but how to cure is something else

00532- now i understand this one means :-

00532- Supply Voltage B+
00532 -Supply Voltage B+: Signal too Low. However this could just be an old code because i had the battery disconnected a few weeks back ! the one that is bugging me is

00523- meaning :-
00523 IAT Sensor - Temp High - Circuit Low - G42 A
00523 IAT Sensor - Temp Low - Circuit High - G42 A

what ive read about this on forums so far is that its the temp sensor in the air flow not the (MAF) but im unsure i have about 4 of these and i cant see them all being faulty. anyway ive cleared the code and will post if it comes back tomorrow has anyone actually fixed this code and how did you do it?
im starting to get really cheesed off with this car now its about as slow as 1.2 nova 
cheers for quick reply mate

[VR6_Wherry]

I'd suggest clearing the codes and going for a short journey and then try again 

[VR6_Wherry]

From what i've been reading, it seems that Error Code 000523 is the reason on it's poor performance..

Found this, don't know if it's any help?

00523 Intake air temperature sender G42

Two versions

1) Short to earth

This fault message is stored if the voltage of the signal from the intake air temperature sender is less than 0.4 V.

a) G42- defective
b) Short to earth in wiring

2) Open circuit/short to positive

This fault message is stored if the voltage of the signal from the intake air temperature sender is greater than 4.7 V.

a) G42- defective
b) Open circuit or short to positive in wiring

[dragongreengolfgti]

now this is abit more than i have found you have good resources cheers wherry im gunna have a look at the wiring now and see if theres any split wires anywhere in that loom cheers for the up sight i will go for a little burn aswell see if the code does come back nice one 

[dragongreengolfgti]

well i have checked the wires on the temp sensor and they were split at the connector so i have wired a new plug onto it the codes havnt come back since so all running sweet however my cars still sh!te and very slow and under powered so ive bought a new engine and will be dropping that in soon hopefully would be nice to find out the problem still! knowing my luck it wont solve the problem and the new engine will probs run the same lol cheers though

[Woppit]

2 things, your oil breather into ya manifold/inlet pipe, check that, ive been having no end of crap with my 1.4 which turned out to be a bunged up/split pipe. failing that, yes that exhaust leak can cause that much power loss for sure, i had a blowing exhaust before CAT and it went absolutly nowhere, train of thought here, when i got my golf it had an *expensive* exhaust on it and it was gutless, went back to a standard set up and goes like stink now. try that.also advance the timing on the dizzy a bit ... muck about with it.. just remember where it was set. good luck!

[dragongreengolfgti]

alright mate ive replaced my oil breather pipes with new items even gone to the extremes of replaceing the rocker cover complete with the disc chamber on top changed charcoal canister purge valve and vacum lines so i know thats all good.
It could well be the exhaust on the gti 2.0ltr they got a weird down pipe which flexes not sure if its the same sort of thing on the 1.4 you got but i think theres a split in it somewhere possibly!  it is rather noisey however ive tried replacing it and cant get the bas!ard thing out anyway i tried only way i can see how, is taking the hole subframe apart or maybe the exhaust mani and inlet off 

Im not sure though and as all the bolts are corroded its gunna be a weekend job and i just dont have time atm to p!ss ass about with it so il drive it how it is for now through the winter probs and attack it in the spring when weathers warmer again lol i mean the car ticks over spot on perfect in fact fires up fine heats up normal stays dead on 90c due to fact i put new thermo in last wed lol it even runs nice up untill you try to pull off after about 2500-3k rpm basically if i put my foot down it dont wanna know but if i do it gently and smooth it will pull all day long im still stumped so im gunna try the exhaust possibly if we get anymore nice weather but if not thats it game over till next year !