Holding back/Misfire?

[dest]

I took a drive this morning, and everything is 100% fine under 3k, but over that with alot of throttle and it feels like its holding back when on boost.
Sometimes it misfired and felt like it had hit a brick wall, loosing all power for a second.
My old car used to do this if the plugs were getting old/crap, could it be as simple as that?

I hope so!

[Acidburn]

It could be the other option that might be happening is one of the coil packs is playing up when under load, if you look thru the forum there should be some details on this and how to check them.

[Crawford_S2]

Sounds like overboost protection. Have the fault codes read and cleared. Sounds like the ECU has gone into 'limp home' mode. This happens when the ECU detects a fault and knocks back the tune state to a safe perameter.

Things that could cause this comon phenomenon are:
Intake leak
WGFV
MAF
Lambda
Vacumm Leak
Misfire
sure i have missed a few

There are stacks of posts on this, its a real pain and sometimes difficult to sort straight away. Most will advise a leak teat first off as these get all upset when they leak.

Good luck and get reading, there are tons of threads on this.

[dest]

Its not a constant holding back (I guess that is what limp mode is?)
You can feel it trying to boost, but it feels lumpy (for want of a better word!)
The boost is there, but its definitly holding back or not boosting as much as it should

[Crawford_S2]

Its not a constant holding back (I guess that is what limp mode is?)
You can feel it trying to boost, but it feels lumpy (for want of a better word!)
The boost is there, but its definitly holding back or not boosting as much as it should

Yeap, bet you have several codes stored, if you can't pull the codes with a suitable piece of kit and want to clear the codes just pull the ECU fuses on the fusebox for a bit, that resets it too. They are the two fuses at the front of the fuse box with the red cover on them that says MOTOR or something. Once you reset it it the hesitation should go until the fault state is detected again by the ECU, as soon as it does that you will be back to 'limp home'.

[dest]

I should be able to get any codes read on Monday when my exhaust is fitted, so apart from having a looking for anything untoward, I will wait until then to see whats happening

[Crawford_S2]

Good plan dude, worth at least seeing what the codes are although some of them are not much help tracking the fault down cos they point to lots of different things.

[tgriff]

how old are your plugs?
what make are they?
it's worth changing them first before things get expensive, unless they are fairly new

[YELL MAN]

How often should the plug's be changed? I did mine two services ago.

[dest]

Just been out again, and tried afew things....
You can drive it at any revs on or off boost and it seems fine, if you dont give it much on the accelerator.
If you floor it, it starts holding back and sometimes a split second loss of all power.
I sat in 3rd at 2k and floored it, and it instantly started holding back, Im guessing that is before it gets anywhere near into the boost range, so hopefully not a leak somewhere!

[Crawford_S2]

Could well be a leak, if it has then it will sus out that more air is going in than out and shut the boost down. That hesitation is the limp map, feels like there is no fuel or something. Check for leaks trust us they are very common on these cars.

[Acidburn]

I had something like this in 3rd gear on mine, it has got better since i've had off and put back on the intercooler and tightened up the clamps.

[tgriff]

worth checking the plugs ,sounds similar to what mine was doing last week .
running fine until u floored it then felt like it was missing .
changed the plugs now it's fine
used bosch f5dpor £8.40 each
should be changed every 20000 miles

[220bhp]

I had the same symptoms with my car for a long time, ran fine on half throttle, but as soon as you put your foot down it just got breathless, and went into limp mode, lift of the throttle and it seemed to be ok again. I also had this slight hiccup you refer to.
I changed just about every thing lambder, n75,dump valve,silcone boost hoses,vacume hoses,plugs, distributor,rear knock sensor, MFTS,took the cats of,fuel filter,took the engine out,Yes took the engine out, done the crank,new bearings new head gasket,and still the car ran pretty much the same,although there was a slight differance each time I replaced something.
I pulled the codes and got a g28 code,but most of the guys said the code for g28 comes up if the codes are pulled.with the car not running. So I Ignored it.
I did however replace the front knock sensorbecause the outer cover had detereated. I have to say this cured every thing except this hiccup.The car started to run like a train,I have an s6 so I had some idea how these cars should run.I desided to change the g28 and this cured the hiccup.
I am no exspert,but thats what happend with my car

[VladaS2]

When I had exactly the same problem it turned out to be faulty distributor (on a 3B).