I've got an annoying issue that seems to be cropping up more and more of late, and wanted to get y'all's take on it:

Every so often, especially when the car is still relatively cold, I can appreciate a substantial power loss or delay when accelerating from a stop. It most commonly occurs when accelerating hard or up a hill, and is accompanied by a change in tone of the exhaust (goes flat and brappy) and excessive noise from the turbo (almost like it's venting boost while under acceleration, as opposed to the normal induction sound I would expect w/ the Alta intake). The seat-of-the-pants effect feels almost identical to a DSC intervention where power is momentarily limited, however there is no indication of DSC working, nor should it be based on the conditions. Applying more throttle in these situations does little more than increase the volume and severity of the aforementioned noise-changes. After a second or two, everything settles down and I scoot away like normal. I have not experimented with altering driving or DSC modes because I can't reliably re-produce the issue

Information of interest: 2010 f-JCW, 35k. Alta intake and resonator-delete exhaust.

I'll definitely take a run to the dealer to see what they come up with, but I'd like to get some opinions on what y'all think might be going on. I've not been overly impressed with my local dealer's diagnosing ability / honesty in the past...

 

Scan the ECU with a Bavarian Tech scanner to see, if any, what fault codes are present?
It sounds like the wastegate is allowing air to bypass the turbocharger, especially when load reduction occurs during a cold-engine.

- Erik

 

FINALLY! Someone else with this problem! No-one else I know has this problem.

My 2009 f-JCW does the same thing, only when it's recently started up, and when it happens, it makes a trumpeting noise from the CAI.

 

I haven't gotten a CEL at any point yet, so I would guess it hasn't thrown a code yet either? It does seem like the car is using the wastegate / recirc valve to cut power - I just don't see why it would without invoking DSC. I'm going to run around w/ DCS and DTC off for a few days and see it if goes away.

 

Not true, you can have current faults without the CEL illuminating.

There's been instances where an intermittent failing wheel speed sensor occurs, and the car reduced power thinking that a tire is slipping.

- Erik

 

Very true

This should cause a DCS light to come on in the tach though when the imaginary slip happens. But stranger things have happened.

 

No lights come on for me, ever. No DSC, CEL, nothing.

Jan reckons there is something wrong with my wastegate for reasons other than this. I haven't even told him about this particular issue.

 

Yup same here. But it occantionally happens only on cold starts. At first I thought it was because of the turbo lag and I was so use to my M3 and lotus. But then realize it only did it sometimes. I check the computer and a code came up for the thermostats. I'm going to have it replace this week. I think it's not letting the engine warm properly. I'm also getting the k&n air intake, maybe to get better air flow because sometimes it feels like it can't take air.

But well find out. I don't know what the issue it has.