HELP save this car from being burnt!:golf iv engine management light problems

[robbob123]

Hi
i have a golf iv 2.0l 8v Gti on a 51 plate(engine code AJZ) and the bl@@dy thing has been driving me crazy with various warning light troubles over last 18 months. It started when the engine management light came on and i took it to a VW specialist who did various jobs(charging me each time) and then declared the cat was sh*gged and a new one would be £530! I thought this a bit steep and scoured/replaced the cat myself and a a shareware copy of VAG COM. All was ok for several months then the light came back after changing several parts and a few months i took it to another garage who again diagnosed a faulty cat and replaced it again.
Six months later and the bloody light is back again!

To date I have replaced 2x cats, the engine temp sender, had the throttle bodies cleaned out, used fuel system cleaner,had 2x sets new spark plugs, new HT leads, new coil pack, both o2 sensors, new air filter, new brake light switch and replaced the MAF sensor.

Am at wits end now and am reluctant to spend more money on the car at the dealers. Am sure this is an AIR/FUELLING issue because of below:

When i fitt he new MAF the enginge light staysout but the EPC light comes on intermittantly when accelerating hard and the acceleration is not smooth. A Vag Com scan reveals this code:

17549-Load calculation error, implausible value. P1141-35-10 intermittant

when i refit the origional MAF the EPC light stays out, the car accelerates better out after a few miles the engine management light comes. Vag Com reveals this code:

17573- long term fuel trim additive air bank 1. Range 1. System
too rich p1165-35-00__

i cannot believe that the cat is knackered again as have had 2 in about 12k miles .but do i have a 2x faulty MAF? Can anyone help before i scrap/or burn this otherwise good car?

[kenney]

AJZ ????????? are you sure? Have you used a genuine VAG MAF sensor?,have you checked for unmetered air,there is the possibility the manifold pressure sensor is faulty

[ImCammers]

AJZ ????????? are you sure? Have you used a genuine VAG MAF sensor?,have you checked for unmetered air,there is the possibility the manifold pressure sensor is faulty

Thinks its a simple typing error, the engine code is AZJ ?

[robbob123]

Hi all thanks 4 your replies

Yea sorry engine code is AZJ.

Have tried running car without MAF(disconnected) on tickover n seems to run ok except EPC light on always.

New MAF sensor is a genuine BOSCH one(as the origional) with exactly same item no except for the last letter which is A on new one and D on the old one.

Have run measuring block 1 on VAG COM n 02 sensor runs at -25% on tickover(760 rpm) which suggests too much air in system methinks. This figure reduces to bout -5% if u rev engine up.

Have looked for air leaks in system n sprayed WD40 around the air intake pipe listenin for a change in engine revs or pitch no all seems fine with no nocticable leaks

Wots the manifold pressure sensor, wots it do n where is it?

Ta 4 your thoughts

[robbob123]

ps

thinkin about it engine mangement light only ever seems to come on when throttling back? ie decelerating with foot off throttle.

I was wondering if the man crasher has got any thoughts?
Ta