i don't tune my own car, Jay @ Boosted Tuning does that.. but i like to learn stuff because i'm curious LOL.

so he'll be tuning my car soon... and i'm curious: when my car hits target boost, the 3-port flutters (i can hear it and my gauge bounces 3-4psi really fast) until the RPM goes up (not sure which RPM it settles), then it stays steady.

what could cause that? i want to be sure it's nothing mechanical so he can work his magic with no issues.

here are the duty cycle/error/PSI numbers:

100 0 2.1843
100 0 3.1203
100 0 3.8223
100 0 4.9923
100 0 6.6303
100 0 8.2683
100 0 9.9063
100 0 12.2463
100 0 14.3523
71 0 17.6283
65 0 21.1383
65 0 23.2443
65 0 23.2443
65 0 23.7123
65 0 23.0103
64.5 0 22.5423
64.5 0 22.0743
64.5 0 21.6063

 

It's quite normal to hear your 3-port rattling away especially if it is mounted directly on the frame rail. I isolated mine with a couple of rubber washers and it is much quieter now

 

Maybe. But it's never done it before. I would have noticed the boost gauge bouncing all over the place. It's always been dead still.

 

turn the boost up you *****

 

1. untuned? bwahahhaha. nah.
2. my tuner won't tell me how and i don't understand the tutorials (they all seem to use older versions of EcuFlash) LOL. it's probably a good thing.

 

Post a complete log from excel, delete the timing curve so your tuner doesn't get mad. But its probably related to changing the turbo without updating the tune...

 

oh, most definitely. i'm not trying to fix it, he'll do that. i'm just curious as to what causes it. i'm always wondering "why?" and wanting to learn stuff. LOL.
even if i knew why it was acting weird, i wouldn't fix it myself. i know how hard Jay works on the tunes and i'm not going to mess it up.

 

Good one Gary lol

 

Just trying to understand what's going on here. Is this under WOT or part throttle? Is your BOV fluttering? Is your car bucking/hesitating? Might be a compressor surge issue.

If that's not the case, is your boost holding stead after hitting target boost or is it fluctuating +/- 3-4 psi?

 

1. floor the car
2. all is well during spool up
3. when boost threshold is reached, i hear rapid fluttering and the gauge needle bounces like crazy.
4. as RPM continues to climb, it settles back to normal.

i emailed my tuner, with a log, on Oct 30. still waiting to hear back.

 

So your car doesn't buck/hesitate when reaching target boost? Also does boost taper off or is your target boost holding steady?

 

doesn't act weird at all.

boost tapers, but the tune is for the old turbo, so the duty cycle still needs adjusting.

the car isn't tuned yet. i'm just wanting to be sure the issue isn't mechanical. if it is, then i want to get it done before the car is tuned i.e. if it's a faulty WGA or DV, etc.

if it's simply an ECU tuning issue, then i can breathe a sigh of relief and wait for my new ROM.

 

Sounds like compressor surge what you are explaining. Have you tried dropping duty down to see if it stops it?

 

I don't usually mess with my tunes, but I will be tonight.
I'm at 100% until around 3500rpm, then drops to 65ish.
It's a larger-than-stock turbo on a stock.engine, so I never contemplated surge. I've never had it, so don't know what to look for.

 

Explaining fluctuations of the boost gauge like that tallies with surge. What's it like in part throttle? Overtaking ? I'd defo drop 100 duty down in 3-3500 rpm range and some where it's surging to see if it cures it.