STiHunter

Hi Guys,

Car - 2004 '54' Blobeye Impreza WRX STI Widetrack with DCCD

I have an issue that is driving me crazy.
While cruising or accelerating, I get a constant judder/splutter. It feels like the power is constantly pulsing - it's more noticeable at motorway speeds. I also get a 'thud' at approximately 3krpm while on WOT. The pulsing stops if I'm coasting.
If I apply the handbrake slightly (enough to light up the handbrake dash light) or slightly depress the brake, the judder stops and the thud doesn't happen either.
With the handbrake light on, or the brake slightly pressed, the car runs 100% perfectly smooth and these issues are not present.

The issues happen regardless of the DCCD settings.

Has anyone experienced anything similar before?
Any help would appreciated.

Thanks,
Ryan

Blue by You

iTrader: (23)

Had something similar on my 05 Sti.
It turned out to be caused by a mismatch between front and rear tyre circumference of 7mm. It wasn't noticeable immediately after I changed a pair of tyres on the rear, and it was actually Paul@Zen who mentioned it during a mapping session.
Solution? Change the worn tyres on the front and the judder went away.

Dibbles00

Paul at Zen is a good man. Helped me out a lot with his good advice. Wonder how he's getting on at ECUTek...

STiHunter

Thanks for the input.
The fronts and the rears are the same size but are different brands.
They are due to be changed soon so I'll have them all changed to the same brand to see if it rectifies the issue.

Blue by You

iTrader: (23)

I don't doubt they're the same size, but different brands can vary slightly. Best bet is to run a tape measure around the periphery and see what the actual circumference is.
As I said mine were only 7mm difference and that caused the juddering.

STiHunter

For reference,
this issue was sorted.
As mentioned above, previous owner had mismatched tyres fitted.
Full set of matching tyres cured the issue.
Thanks.