Mk4 over fuelling backfiring choking itself please help

[Norfolknudger]

Hi all I bought my t reg 1999 golf early last year and have run around in it happily until recently she's been modified air intake decat remapped to 212bhp when I first had her she had a small occasional back fire  but recently it's started to over fuel with plenty of backfiring and she also seems to be choking  under throttling and missing I've changed the airflow meter the lamba sensor as its been decated it only has 1 and I've changed spark plugs but still no joy so I changed the ecu clocks and ignition barrel ran loverly till she got warm then started to choke itself again can anyone help as I'm lost now cheers all will   

[novadragon007]

best thing to do is get it scanned with vagcom and post the codes that will help people on here diagnose your troubles.

Posting in 3 seperate sub forums wont help much at all 

[ant_gti]

yep check fault codes sounds like ignition amp or coolant temp sensor.why did you change the ecu,clocks ect

[Norfolknudger]

Hi thanks for info the reason I changed the ecu was it was a last resort as I'd tried to all other things I could think to do tried at first to change ignition and ecu but wouldn't work without clocks

[Norfolknudger]

Hi again all I got the car over to my friends garage the weekend when he took it out for a test drive he noticed/herd an air draw and on closer inspection noticed the top alloy air cooler pipe from front intercooler had worn a hole in itself by rudding  on the bulk head so thought we'd found the problem so tigged a patch on put car back together went out for another test drive although she now pulls like a train the problem reacured when car warmed up so plugged it in to diagnostic machine and the only code it came up with was temp sensor so got a brand new one fitted it but once again it's still playing up but does seem a lot better going to change the ignition power pack to see if that cures it unless you guys have any clues for me cheers for the help guys much appreciated

[novadragon007]

which temp sensor? intake/coolant? if its a coolant temp sensor was it a brand new genuine volkswagen one. The mk4 doesnt like cheap parts at all lol always best to use genuine oem parts as thats what the vehicle was designed to use. For things like lambdas and mafs best to go with bosch

[Norfolknudger]

Sorry fella yea it was the coolant temp sensor I didn't buy the sensor but I'm sure he would have used genuine bits

[topher]

is it definitely overfuelling? i.e is it fouling the plugs?

[Norfolknudger]

Yep changed plugs when they came out they where covered in crap it smells of petrol and the exhaust tail pipe is black and it even spits out black muck onto floor when you start it mate

[topher]

being a '99 (AGU) fault codes can be more of a hindrance than a help sometimes, datalogging in detail with vagcom may tell you a bit more but ideally you need some form of wideband logging to see whats really going on with the fuel, and what the ECU is doing when it starts to play up.