Boosted VVT engines, please post your datalogs!
 

Calling out all boosted VVT owners on standalone MS2s, if your engine is running on a supercharger or on a non-electronically wastegated turbo, please post a datalog of a WOT run. It seems that on VVT engines, if you have VVT disabled, boost drops from ~5K rpm to ~6.5K rpm. Even on my own N/A VVT engine, the MAP starts falling from ~101kPa at 4800rpm down to 90kPa at 6800rpm and then starts climbing back to ~96kPa. This didn't happen when I had the MS1 in parallel with the stock ECU. So let's have a look!

Dimitris

Can't find a complete pull, but I'll grab one later.

Have to say I've not noticed any drop in kpa whatsoever though.

I will get you a datalog next month once I get my new engine built and installed. Although I will be running MS3.

I'm too lazy at the moment to dig up a few posts where I have posted some datalogs....but they're on here somewhere.

edit- I'm not as lazy as you think I am...addded.

Thanks, but don't you have a Hydra? I asked for Megasquirted VVT engines because they have the VVT disconnected.

Dimitris

when I logged a dyno run with the vvt locked at full retard (ie unplugged), boost stayed constant. I use a ball and spring boost controller.

and I thought your name was Jim!

It is +oo easier for people to remember the english equivalent of Dimitris, which is Jim.

Jimitris :)

Isn't Savington running with VVT operational now?

Nevermind, he's running a AEM ECU

Bringing this back up as I have some VVT/MS issues.

I switched from XEDE piggyback to MS standalone. I lost my VVT control (until next week when my VVT controller from DIY shows up)

My spool is horrible now. In 2nd gear at 2K if I hold there then go WOT I get 5psi by 3600rpm!! 10 by 4500 and bam 12 at 4700.

With XEDE if I looked at the gas pedal the wrong way I had 5psi now and 12psi a second later as is typical with a 2560/log mani/3" exhaust/no CAT

The coincidence going to MS and losing VVT cant be the only reason I'm spooling so bad can it, perhaps I also had some mechanical issue the very same time ??

I can't even spin the tires in 1st gear rolling from a light now -it's nuts.

I don’t think VVT is going to be the magical cure for me but I do expect some good gains.

List of possibilities:

Charge side leak
Exhaust restriction
Wastegate flap damage/not holding.
Bad BOV

So far I have preloaded the WG like 2 more turns so it has to be pulled about 4mm just to get connected. I did a minor test of the charge side and did not hear any leaks.
I played with my MBC and even though I can get up to 14 psi I still spool ssllooowww. So why can I get to 14 or 15psi but it takes a county mile ?

I do observe that when I get to the MBC's max setting it won’t stay there - the boost just drops once the MBC is opened. The car is under load and gets to wherever I have set the MBC and then when the MBC opens the car just diarrheas its power.

Is my WG actuator suspect?

My next test is to wire the WG shut and see what happens.
Then try plugging the BOV lines after that.

I'm sure you experts know what is going on from what I've said but I don't.

Any more advice on what to test and what the symptoms indicate?

it could be VVT's absence that made you drop all that power...

might want to consider a little MS3X upgrade... not cheap but very nice and the VVT release is coming along nicely.

I bet it all comes back when you put the VVT back. My car feels broken with the VVT solenoid unplugged.

He has an MS2 which is prewired to accept the VVTuner from DIY.

oh then do that.

I was confused when I heard about the VVTuner coming out while I was hearing about the MS3X VVT because I thought it was only going to generate revenue for a few months. But then lars (and now you) have enlightened me that it's for people who don't want or need an MS3. And it's probably half the price of upgrading to MS3X once all is said and done.

I was doing some steam cleaning with a secondary goal of seeing if there are any leaks around the turbo. Looks like the SGDP wastegate tube is cracked at the flange weld. There may have been other leaks around there, but once I saw a bit of steam in that area I stopped looking at let it cool down.

How much will a crack there influence spool as most of the flow while the WG is closed should go through the other tube?

Either way by the time that is fixed the VVT box will be here and I will have 2 variables to influence my spool.

My logs are on the other PC but here is a picture of a log showing the same thing. MS3 and uncontrolled VVT. NA motor.

https://i.imgur.com/YZIwk.png