Turbo flutter or surge
 

I have a cobalt lnf full bolts on with k04r hpt tune 25psi.... and i have a flutter sound in aceleration on low rpm... i have the stock bvp.... what you think the problem is ?

It's probably normal on light throttle, especially when the motor isn't warmed up.

Ok... i tey it only when my engine is warmed up... but its only appen in 3 4 5gear when the turbo is not in full boost... when im full boost all is correct

Ok im stock bvp...

all cars turbo flutter. no BOV or BPV is fast enough to dump at low throttle. its normal

Yes i know.... but mine does this song a full trottle but low rpm... i sont know if its because i have too flow for the engine at low rpm or i have a problem with my bvp... but that song dosent affect the power of the car

What gear are you going full throttle at low rpm?

My K04R made some strange noises as well in the lower RPMs. Others have reported it too.

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Third gear if you do a pull at 2500rpm it will do a strange noise similar to surge but it dosent affect the performance of the car. Im tuned at 26psi... i dont know if i have to buy a forge bvp and put the harder spring too... it is possible that the stock bvp leak at 26psi on k04r ?

If you want to keep your transmission in one piece stop going WOT below 3500rpm in any gear but 1st and maybe 2nd.

Sure... i just want to know if i can resolve this problem... because its very easy to do some extra damage for my new turbo .... just to put the gaz pedal to 50% in thirs at low rpm and the tuebo do the same thing

low speed flutter isn't going to hurt your turbo. its perfectly normal

Okk thanks a lotsss

Adjust the tune, thats how you resolve the problem likely. It's hard to say from a keyboard no where near the car or a log of the car running. If the sound happens when you give it 50% thottle at 2500rpm it's likely because the tune is calling for all the torque at part pedal to make it feel faster. I'm also assuming that at half throttle you can't keep it below 20psi and the throttle feels like an on off switch.

Yeah that's not quite normal. It sounds like you aren't opening the bpv valve well. Are you sure you map sensors are ok, no leaks in the system, and does it open ok at wot? Flutter is ok, but that's a little much for no bigger than a r is.

I have gmpp 3bar map and yes they are ok... at wot all is normal no weird sound and the power are there.... its only at little boost at low rpm

That's surge, the turbo is pushing more air than the head can handle, get your tune fixed.

If i pay attention to dont puah the tuebo at low rpm its correct for the turbo ? Because it doesent surge at all at wot ?

check you maps clean them if there signal is off it will cause flutter

Post a video of the sound. When I had the k04r it would flutter at low rpms all the time.

He did, sounds like it's surging to me. Light flutter, and then surge. Only time mine has done this is when I split the oring on the lower map sensor.

Now I see the video my bad, sounds like my ko4r did when I had it it was super annoying reason why I have a zfr now :D

Definitely surging, "Safe" flutter should only happen when letting off the throttle, not getting into it. I would validate the tune isn't causing problems and a boost leak test wouldn't hurt!