mk4 gti running issues

[harkerg]

Ok so iv read through alot of this and iv been left confused.

I have a y reg 2001 gti 20v turbo the boost is intermittent jumps from 1 bar to 1.5 bar hesitates and backfires under load but does pick up but as stated earlier then the boost becomes intermittent.

Does seem to drive fine if I only give it half throttle n dont floor it I was under the impression it was the map because its over fueling fowling plugs with loads of black sutt and I can smell the fuel its strong smell even on tickover sometimes on tickover you can see the jet black smoke.

I dont know what this car has had done apart from cold air intake turbo back straight through pipe any help greatly appreciated to point me in the direction best to go down.

[MoshiMoshi]

Try replacing (or unplugging at very least) the MAF sensor and see how it runs for you.

[dom]

Ok so iv read through alot of this and iv been left confused.

I have a y reg 2001 gti 20v turbo the boost is intermittent jumps from 1 bar to 1.5 bar hesitates and backfires under load but does pick up but as stated earlier then the boost becomes intermittent.

Does seem to drive fine if I only give it half throttle n dont floor it I was under the impression it was the map because its over fueling fowling plugs with loads of black sutt and I can smell the fuel its strong smell even on tickover sometimes on tickover you can see the jet black smoke.

I dont know what this car has had done apart from cold air intake turbo back straight through pipe any help greatly appreciated to point me in the direction best to go down.

I've just replied in your other thread in the garage to do with turbos/engine codes

Try replacing (or unplugging at very least) the MAF sensor and see how it runs for you.

Definitely try unplugging the MAF, if running improves then the MAF is likely to be at fault.

[harkerg]

Yea I need to delete other thread iv bought a new bosch maf n its runnin fine now but still has a boost issue fluxuating from 0.1 to 1.5 anyone give me an idea on this looks like its had an n249 delete

[Scott D]

n75 valve, coilpack issue, lambda sensors

might be worth getting the ECU checked for any fault codes

[harkerg]

Already sorted the misfiring problem mate just has a boost problem fluxuates from o.1 to 1.5 bar starts higher and always drops somtimes settles at 0.5 bar there was a code for n249 malfunction but from what I can see I dont have an n249 it confuses me to be fair

[dom]

Already sorted the misfiring problem mate just has a boost problem fluxuates from o.1 to 1.5 bar starts higher and always drops somtimes settles at 0.5 bar there was a code for n249 malfunction but from what I can see I dont have an n249 it confuses me to be fair

That sounds perfectly normal, the boost should be progressive and won't be at full whack all the time. Mine peaks at about 20psi in 3rd and holds at 15psi. This varies depending on gear though.

[harkerg]

Really? The difference is noticeable though and sometimes drops to the point it doesnt even feel like its boostin obviously goin from 1 bar droppin to 0.1 bar feels flat

[harkerg]

Like itl go to 1.25 bar for example drop to 0.5 pick back up to 1 bar the completely drop off under load in the same gear

[dom]

Like itl go to 1.25 bar for example drop to 0.5 pick back up to 1 bar the completely drop off under load in the same gear

Yeah, that doesn't sound right. Have you scanned for fault codes?