Hey guys, I was hoping to get some opinions on what you think may be going on with my car. Here's a link to the thread on my car:

https://www.evolutionm.net/forums/ev...hp-294wtq.html


The original tune ran perfectly with the ecuflash, but I have a cobb so I wanted to have a map made for the cobb AP. I brought the car back to have the cobb AP map made and also have it re-tuned with a 3 port boost solenoid. As the dyno sheets on the thread shows, the car made good power.

However, as I drove the car home, i noticed some issues that were not apparent before. If you accelerate beginning from low rpms up to redline, the boost will build, then hesitate and drop down, and then spike up, and then fall (as it should) to redline. If you accelerate from higher rpms (>4k rpm), the the boost behaves exactly as it should. It will spike and then gradually drop down as you move closer to redline. The lower the gear, the more exaggerated the boost instability is. In 1st gear the car will actually buck because the boost drops so much and then rebuilds. In 5th and 6th gear, the boost will flutter around 20psi and won't go any higher until you go over 4krpm. While the boost is fluttering, you can hear a clicking sound coming from the engine bay which I THINK is coming from the boost solenoid. Here is a video of my boost gauge on a 1st gear run. This is 1st gear ONLY, I did not shift into 2nd. The drop in boost is not from changing gears.
http://img208.imageshack.us/img208/2489/img0727.mp4

Bryan has tried to fix the problem by adjusting the boost error correction and even turned on error correction completely, but that has not fixed the problem. I'm not sure if the problem is with the cobb or the 3port, but I thinking it has to be one or the other.

I took the car to the track the other day and since you're always in high rpm range in that situation, the car ran just fine. But, driving around down from stoplight to stoplight and having the car buck just isn't fun, so I'm hoping to find a solution. If we can't figure out what the problem is, I'll probably just ditch the 3port and Cobb and have Bryan ecuflash the car. Any input is appreciated.

Thanks!

 

if you flash back to the old ROM does it do it?

im sure Bryan will/can sort it out for you...

 

I don't have a Cobb map of the original reflash, otherwise I would try it. If that worked, that would mean the issue is with the 3 port. Bryan's been really busy lately, so I'm trying to figure something out in the meantime.

 

no if it worked then the 3port is fine...

then you can focus on the cobb map to see what needs to be adjusted - probably the correction interval...

 

the original reflash was with the stock boost solenoid. We changed 2 things after the original reflash: 1) switch to cobb 2)switch to 3 port.

Interesting thing about the correction interval... unfortunately I have no idea what that means. I'll mention it to Bryan

 

who's we?

 

you said when you tracked it it was fine right? meaning you were always in high rpms right? when you WOT from 1st gear, 2nd, 3rd till redline does it happen? when you said:

is this only in 3rd gear only? does it happen in 1st too?

my assesment would probably wga or bov..

 

'We' refers to me asking Bryan to retune the car using a cobb, and adding a 3port solenoid at the same time

 

starting from a deadstop, WOT boost is unstable in 1st gear, but the remainder of the gears will be fine because we are in high rpm range at that point after each shift. BUT if you start WOT from 2.5-3krpm and run to redline from ANY gear, this will happen. The unstable boost occurs in every gear, but with higher gears it's not quite as violent like in the video of 1st gear. It seems like between 3-4k rpms, the boost will hesistate, but after you go past 4k rpms, it will act 'normally' again. In 6th gear starting at 3k rpm going WOT the boost won't go past 20psi and will flutter around 20psi, but once you go above 4k rpm, it will boost to 25 psi and then drop slowly to redline as expected.

Does that still sound like wga or bov to you?

You know, now that you mention it, the fluttering sound and fluttering boost at 20psi between 3-4k rpms may be coming from the BOV... how would you confirm this is the problem? I checked the vacuum line to the BOV and it looks fine to me...

 

not yet 100% sure that it is bov..i wish i could ride in your car to diagnose it..but that is my assesment...i had a similar case when i was tuning my friends car, i mean the symptoms and all..i can hear the bov leaking...but in his car's case it wasn't consistent in the same rpm range..sometimes earlier..

it happened to me a couple of times too when i was tuning..what i did to confirm it is i VTA'd the stock oem bov/bpv just for testing..

the fluttering is really hard to resolve with our fast spooling turbos..try borrowing another oem bov that you know is good and let us know..hopefully you could get this resolved.. good luck..

 

Would a bad 3 port boost solenoid cause problems like this? What would be the symtoms of a bad boost solenoid?

 

The fluttering is compressor surge caused by the turbo spooling too fast in high gear. The turbo spools but the revs don't climb very fast, so all that air getting packed into the engine backs up through the compressor. I'm in the process of trying to get a decent boost curve on my 3 port also, and with higher WGDC values in the low rpms, I can go WOT in 4th and 5th gear at low rpm and surge the turbo everytime.

If it is your BOV, you'll be able to hear it leak if you pull it out of the intake pipe and vent it.

 

interesting. So what would be the solution? Sounds like I just need to try ditching the 3 port and go back to the stock solenoid and see what happens. The problem is I don't have a map for the stock solenoid...

 

If you have an Accessport, you can dowload all the Cobb OTS maps here:
http://www.accessecu.com/accessport/.../EVOXMaps.html

Download the appropiate map for your mods/model.... Make sure the Accessport is up to date with the firmware updater. Id def do this and see if its the 3-port. Honestly, the 3-port solenoids are overated. They dont do a hell of a lot more other than giving you a headache trying to tune them.

 

He can't use any of the OTS maps unless he puts the stock boost pill back in (and the stock solenoid)

I'll be working to figure this out with him. I've just been very very busy lately.

- Bryan