Jerky spooling

[dont_tell_him_pike]

When accelerating uphill, the car jerks quite unpleasantly, in a manner similar to fuel cut though less violent. Once it passes about 3500rpm (or reaches full boost?) it accelerates smoothly.

I wondered if it was a spark plug issue as they've been in need of replacing for a while, but a new set hasn't helped.

Yesterday I tried unhooking the turbo actuator, effectively running the car as an N/A, this made the jerkiness go away, so would seem to be a boost issue. Adjusting the boost level doesn't help matters, as it only seems to happen while the turbo is spooling.

Can anyone suggest any possible/likely causes?

Thanks!

 

[dac69er]

ignition related 100%. change plugs if you know they are due a change. i had the same and it was the leads

 

[weeJohn]

Do you have a FCD fitted? if not then I will bet its fuel cut, borderline boost level in a GT thats the way it goes.

 

[dont_tell_him_pike]

It's got brand new plugs and leads, didn't help. Did once have a problem with corroded plugs before, and it's a very similar effect.

Don't think it's fuel cut because it doesn't do it at full boost and turning actuator down doesn't help. Plus I've had fuel cut before and it's a lot harsher than this...

 

[Rev]

Fuel filter?

 

[dont_tell_him_pike]

I thought the same thing rev, though not sure if it'd effect the engine wth the wastegate open, but i'd have thought it would. Nonetheless i've got one but not had a chance to fit it. here'shoping we're both on the money...

 

[Rev]

Hard to say when boosting but I have had a car uphill with fuel filter partial blockage and fuel tank dirt , when you boost the car surges forward this moves the fuel differently , good luck.

 

[superspat]

i know when i had my s13 had the same problem, turned out to be the boost blowing out the spark between 3/4k, i gapped the plugs a bit and the problem went out away,also had the same problem as also with my old hybrid on my gt but that was at the top of the rev range and that was plugs aswell, not saying yours is as im no mechanic at all but it oftern gets missed or over looked when upping boost

 

[ramses974]

Strange i have the same thing last year.. BUT it was the joint ring of the injectors...there was a little air leak with .

 

[dont_tell_him_pike]

Fixed it!

After much time spent changing the fuel filter and then bypassing the BOV, I spotted a hole in the hose going to the map sensor. It was an inch or so from the top so I simply snipped the top inch or so and bob's yer uncle.

Thanks to everyone for your suggestions!