engine stumbling/hesitating at WOT

[archiboy24]

I recently purchased a new set of chips and 3.0 BAR MAP sensor. The kit also included the 1.9BAR WG spring. Car pulls like a freight train in any gear but it has developed a bit of an issue. During second and third gear pulls at or very near WOT, it pulls hard, but between about 3.5k and 5k RPM the engine hesitates and shudders a bit and it almost feels like a series of very fast hiccups. There's definitely a noticeable loss of power during these 'flutters'. It's also accompanied by a muffled rattling noise right when the hiccup occurs. A couple of times I've noticed a cloud of dust in the rear view mirror after this happens. If I'm a little lighter on the throttle but still do a strong pull, the issue doesn't occur. This all started happening after I installed the WG spring, but I can't imagine why this would have that sort of effect. I suspect a boost leak somewhere, but I haven't had a chance to look into it. The supplier of the chips thinks it may be linked to an ignition issue. Any thoughts? Do you know what the noise could be? List of components:

RS2 turbo and EM
RS2 injectors
RS2 MAF
RS2 FMIC
7A exhaust cam
3" DP (into stock CQ exhaust)
7A 4.0 BAR FPR

[A80Avant]

check for any loose spark plugs.

what boost are you running?

[archiboy24]

Don't know exactly, but somewhere in the neighborhood of 26-28 psi I'm guessing. I suppose I should install a boost gauge, huh.

[T2Andy]

which diverter valve are you using maybe it cant take the extra boost .

[archiboy24]

which diverter valve are you using maybe it cant take the extra boost .

Stock valve.

[T2Andy]

That could be a problem im sure they cant handle tuned RS2 power ,

[mcandmar]

I recently purchased a new set of chips and 3.0 BAR MAP sensor. The kit also included the 1.9BAR WG spring. Car pulls like a freight train in any gear but it has developed a bit of an issue. During second and third gear pulls at or very near WOT, it pulls hard, but between about 3.5k and 5k RPM the engine hesitates and shudders a bit and it almost feels like a series of very fast hiccups. There's definitely a noticeable loss of power during these 'flutters'. It's also accompanied by a muffled rattling noise right when the hiccup occurs. A couple of times I've noticed a cloud of dust in the rear view mirror after this happens. If I'm a little lighter on the throttle but still do a strong pull, the issue doesn't occur. This all started happening after I installed the WG spring, but I can't imagine why this would have that sort of effect. I suspect a boost leak somewhere, but I haven't had a chance to look into it. The supplier of the chips thinks it may be linked to an ignition issue. Any thoughts? Do you know what the noise could be? List of components:

RS2 turbo and EM
RS2 injectors
RS2 MAF
RS2 FMIC
7A exhaust cam
3" DP (into stock CQ exhaust)
7A 4.0 BAR FPR

I've got the same symptoms on my avant that i need to fix. In my case i'm 90% sure its ignition related, either coilpacks or POS units as it gets a lot worse after sitting in traffic for a while.

[archiboy24]

What would you recommend? I don't want to go to a dump valve - not too keen on the chirping bird sounds.

[archiboy24]

I've got the same symptoms on my avant that i need to fix. In my case i'm 90% sure its ignition related, either coilpacks or POS units as it gets a lot worse after sitting in traffic for a while.

Hmm. Since mine is a 3B, I don't have the coil packs. I will check the coil and the spark plugs though, as well as the plug wires.

[Costash]

I have same problem with mine.I have new spark plugs denso iridyum vk22,new coils,tried new set of POS but same problem . Tomorrow I am gonna fit a new MAF to see if the problem is still there. No errors on vag coming up.I change the maf because is the very original one and I feel is starting to let me down (I can pass the 110 120mph ).I ve have the same experience with a previous car of mine before the MAF died.No boost leaks and have a forge DV 006.

[URSIMPO]

Mine hesitates if it's been idling for a while - which is a pain at the traffic lights. I have to press the pedal for a couple of seconds, it almost cuts out, then, it sorts itself out. It's got brand new coilpacks and lambda sensor. I even tried another MAF, but it still does it.

[Greg_S]

I had similar issues a couple of years ago, replaced all of the coil packs and coil leads. And make sure you use only the bosch plugs not the NGK's. I mine never runs right on high boost with the NGK's

[GazzaG60]

the dv valve wont do this. its shut when on boost and open to relive pressure. what happens is they leakas the cant hold the pressure.

id go with 1 of 2 things.

1. too rich
2. spark.

either reduce the gapping on the plug ( a good start) or replace the coil packs.

classic "upping the boost" symptoms.

i have no problems with NGK. if yo have them your issue wont be na loose plug thats for sure

[Tonks4x4]

Just another quick test to do... Try unplugging the MFTS and take it for a spin to see if this gets rid of the hesitance....

[newsh]

If its a 3B with a dizzy check the static timing very carefully as if the hall sensor window in the dizzy is not exactly lined up at TDC the ecu can mistake this for pinging (detonation).

Puff of smoke is unburnt fuel, either ignition related (high boost is killing the spark, poor spark plugs, leads, pos or coil packs) or pinging and the ecu is chucking in extra fuel to put the fire out..