Hi Folks,

I've been doing some logging recently and noticed that at high rpms (=> 5500 to be precise) the actual throttle angle is very jumpy.

I'll upload some logs after work tonight but was hoping for some ideas or some areas that I should be logging.

I've checked already :-

- EGT's - These appear to be not getting to high, no enrichment etc.
- IAT's - These rise up to 32*C at redline so don't think this is an issue
- Fuel - This is ok, I'm getting low 12's (checked with my wideband also)
- Boost - Actual is following desired pretty well
- Knock - I've pulled the timing so now I'm getting max 1.5* retard upon knock now (previously ~3/4 so thought this could be the cause)

I can't think of anything else that would pull the throttle, it's only a small amount, ~3% cut but it's very unstable.

I've been thinking a faulty N75, but that should show up with requested vs actual boost pressure shouldn't it?

Apart from this I'm thinking possibly a boost leak somewhere, or my wastegate is too tight (as turbo has been rebuilt a few months ago so it's been apart). Reason I think this is I put the standard map on and it overboosted and huge throttle cut at around the same rpm. It doesn't overboost on my mapped file though, maybe the turbo doesn't have enough in it to do so but something's wrong causing the erratic throttle angle?

As said, I'll upload logs later (new ones if anyone has any ideas as to what extra I should log), I also logged WGDC's but can't remember them off the top of my head, what should these roughly be at?

Thanks in advance!

Edit:- I'm running 22psi tailing to 17psi redline and is an LCR (BAM engine) K04 turbo.

Any ideas?

Don't think I should be at 95% duty cycle should I?

Yes, I guess I believe it's not throttle cut in the sense of preventing boost deviation, but why it is so unstable?

I've checked it against the requested angle and it requests it. Albeit yes I probably can't feel it, it would be nice to know if there is an underlying problem, I just can't see/understand why it's happening?

Apologies, I had to cut some down as it was too big to upload but should be all there.

Ignore the initial overboost, I'm tuning this out

Thanks in advance

Thanks Nyet.

Yea, I have a feeling I've made the wastegate too loose :/ it was previously around 70 IIRC. It's a k04-023 so I thought they'd easily do what I'm asking of it?

I have older logs with timing (it's fairly conservative I think with little to no knock)

I'll get another hopefully shortly with injector and timing.

Does the unstable throttle angle look like anything you've seen before?

Awesome, that puts my mind at rest then! I was thinking it could be something like that but everyone's logs I looked through were 100% all the way up.

Found it a little odd that the car is requesting that throttle angle, not just the signal coming back. It's a 2003 leon so it's getting on a bit.

I'll tighten the wastegate a little and clean the TB then get another log, see if anythings changed

Thank you.

Oh man :p

But no it's definitely not going to have any (noticeable) effect. Just wondering if there's an underlying issue somewhere.

I tried the standard map and it just overboosts (large TIP and exhaust) so I was going to try raising the limits (and keeping an eye on fuel) and seeing if the same thing happens.

Would confirm if it's a hardware issue I guess wouldn't it?

The boost issues you are seeing have nothing to do with the throttle plate weirdness.. get your PID straight and your boost will be fine.