Compressor Surge or Faulty Wastegate actuator?

[Dougal]

Hi All,

Needing some help please.

I have just had my 2nd engineering brake test today and its fail.

Nothing to with the brakes on the car the car just could not perform well enough to actually do all the brake tests.

Basically the car is hooting, jerking and what sounds to me like surging upon boost.
Car will not accelerate normally when driving but not all the time sometimes its fine.

Free reving the motor out of gear and stationary is fine and i can push the car up to 5000-6000rpm no problem.

It only happens when its actual load driving and its intermittent.
During the test today there were times I could get the car upto speed quick rowing the gears and all was normal then there were times it would buck and jerk and hoot.

Knock of 9 counts normally resulted from this. I data logged this thoughout the brake test.
Once the car started knocking the only way to stop it was to turn the car off and wait for the ecu to click off.

Datalogs showing the fuel pump is switching off intermittently? Should that happen?

Here are details of the setup. Its a 3s 6g72 motor in another mitsubishi (be open minded please)

Chrome ECU v2
Stock 9b turbos
3SX hard intake pipes
tactrix 3 port boost solenoid
EVO BOV metal one (evo 8/9 one i think?)
K&N oval pod filter
Montero MAF (scaled in Chrome)
NGK copper plugs (heat range 6)
Stock injectors
Walbro 255 pump


Some of the troubleshooting that was done by the engineer and myself was to bypass the tactrix 3 port and just feed directly to the wastegate (wastegate spring pressure only)
We also bypassed the EVO Bypass valve.

Here is a video of the car. Early part of the video you can here the hooting sound.

https://youtu.be/X8dA54qTKCI

Also attached is a datalog of the car. Yes the AFR is quite rich.

Thanks guys

[Greg E]

Running too rich will literally foul the plugs to the point where the motor stumbles. Just a quick thought.

[Dougal]

I totally agree with you however this particular issue has been sort of an ongoing one and bucking and jerking occurred also when the car was running alot leaner. 13-14:1 AFR upon accel.

The first time this jerking/bucking happened was last year and a lot of troubleshooting.
At the time I was using quad tip bosch platinum spark plugs which i found later were not suitable plugs for the motor.

I swapped them and instantly found knock counts were gone and the car was alot happier.
I thought i had sorted this issue however not ever really able to test the actual driving of the car as the car is not allowed to be public road driven until engineering test completed.
(Dyno time is possible however no places local to me want me to hire the Dyno without them tuning it and few places want to touch the Chrome ECU despite it being factory like an EVO ecu)

I think its compressor surge as the car is hooting like mad and the datalogs show low airflow at the point of the hooting.

The motor is not able to ingest the boost?
The turbos are stalling?
Can this be a result of my FMIC being too small?

I pulled the wastegate actuators and pressure tested them.
Both hold upto 7-8lbs ok so i dont think they are any cause.

I am hoping someone can suggest some other things to check or test.

Anyway i have attached a youtube video of the car running on jack stands through the gears. You can hear the hooting sound when partial throttle open really clearly.
Its loudest heard at the K&N oval filter

[DocWalt]

How do you have the BOV plumbed in? I had VERY weird issues like this when I didn't have the BOV diverter in the intake boot thingy. I assume the BOV is plumbed in the correct direction too?

[Dougal]

I have the EVO BOV plumbed into pressurized intake hard pipe that goes to the throttle.
The BOV is recirulated back into the bottom of the turbo intake bubble. BOV is connected the right way around. Double and triple checked that.

Photo below should be able to see the BOV plumbed between intake pipe to throttle and the pre turbo intake bubble

Not sure what you mean by diverter in the intake boot? Something that'd part of the turbo intake bubble?

We disconnected the BOV and blocked the port for the BOV on the intake pipe during troubleshooting of the issue at the brake test. Same hooting, bucking and jerking upon throttle and boost (2500-3500rpm).

IMG_20151115_170705.jpg

Older photo but same setup really
Screenshot_2016-03-08-17-23-45.jpg

[KeithMac]

Do you need to have boost to perform the brake test?, easiest way for now would be to open both wastegate flappers so it's drivable then do the brake test?.

Sounds like compressor surge but you'll have to post pictures of all pipng and setup to get a good idea on your system.

Single fmic with altered charge pipes could cause this issue..

[Dougal]

Don't need to have boost to do brake test.
Car just needs to be able to get to speed in a reasonable amount of time and do so smoothly.
So to open wastegate flappers just disconnect the actuator arm from the lever so its open always?

I will add some more photos of the separate components as I pulled the turbo intake pipes off yesterday and checked the turbos and wastegate actuators for damage. No damage. Actuators holding pressure to 7-8lbs

A suggestion was made on facebook that I could add a resonator box to the intake system (after the MAF) and that when compressor started surging/stalling that this trapped/reversing air goes into the resonator box first so that the air does not screw with the MAF sensor signals.
Anyone have experience with trying that?

[DocWalt]

There's a diverter in the intake boot that's a y-shaped piece of plastic. You can see the shiny bit here:


If the BOV opens then the air dumps right back into the MAF and makes the car run like complete crap. Similar to your facebook suggestion, air stalling the MAF is really bad.

[Dougal]

Yeah I have that hard plastic diverter in the intake bubble for the air venting from the BOV.

Would be so good if it was simply just that!

There's a diverter in the intake boot that's a y-shaped piece of plastic. You can see the shiny bit here:


If the BOV opens then the air dumps right back into the MAF and makes the car run like complete crap. Similar to your facebook suggestion, air stalling the MAF is really bad.

[Dougal]

I've been searching around and am wondering if anyone knows where and if I could find the device that Eric (aka kywhitelightning) had made that he used to cure turbo cruise surge.

http://www.3sgto.org/threads/13541-G...A-complete-kit


I think its something that could work.
My surging occurs typically upon light acceleration 2500-3500rpm at 20-30% TPS

Right now Im game to try things that others have had success with.