[jpsimon]

Some of you have probably seen my threads complaining of a weird laggy boost issue. I assume it's wastegate related, but i'm looking at all cheaper other potential options before thinking about new turbos. Vac lines have been changed, both boost solenoids have been replaced.

I've had forge DV's on my car for around 75,000+ miles. Do you think they could be going bad?

WG duty cycle isn't totally off the chart like it has been in the past when I had a boost leak. Boost builds up slow and doesn't hit the target - but it does hold steady. Could DV's that don't hold boost completely cause issues like this? or would the symptoms be different?

Anyone who's had stock or forge DV's die on you, what did your symptoms look like?

[Ilma]

I would think that you would hear the diverter valves hissing if they were leaking boost.......just like they do on part throttle when they bleed excess pressure from the charge pipe.

But you may want to overhaul the orings.

There is a kit from Forge here: http://forgemotorsport.com/content.a...product=FMDVSK

By way of comparison, here is a log I ran earlier and I have the Forge Diverter valves just like you.

I can definitely see what you mean by laggy

.
.
.

[pits200]

Could this be dirty intake valves? And if you do a boost test with 18 psi you'd hear the dv leak I'd imagine if that were the issues.

[themyst]

Forge DVs are known to stick. Lube the pistons up with some synthetic oil and they'll be as good as new. Fwiw, stockers work great.

[jpsimon]

Originally Posted by pits200

Could this be dirty intake valves? And if you do a boost test with 18 psi you'd hear the dv leak I'd imagine if that were the issues.

valves were cleaned recently so it's not that. I'll just rebuild the DV's since that's super cheap and will eliminate yet another small potential issue. I guess I'm just wondering if people who have had sticky DV issues had this type of symptom.

[Ilma]

Not only are you slow to build boost.....but you are not hitting the boost target either.

At 16 psi with upgraded turbos that should not be a problem.

I suspect this is a wastegate issue.

Had the same symptoms in my GTI.....was short of boost target by 1-2 psi.

I turned the wastegate rod a couple of turns and this tightened the wastegate seal completely.

Solved the problem completely and the car felt much more responsive afterwards.

[jpsimon]

Thing is, in this log in 4th gear not only is it hitting the target (eventually) it was running even a bit more boost than requested.

[Joshboody]

Start checking everything one by one.
-maybe replace the stock DVs
-pressure check the system... 20psi from the hot side
-check that your WGs are closing at 6" and holding vacuum.

maybe double check each section of vac system with a pump to make such its holding, including canisters.

[Joshboody]

You'll typically overboost slightly in the higher gears due to reduced WGDC requirements. I wish we could have a gear compensation option.

[Ilma]

Hmmmmm.....

Could still be a sticky wastegate rod.

Perhaps it jams up a bit at a certain point.......sticky to seal, then seals, then sticky to release.

Might explain the under/overboost symptom you are getting there.

[Ilma]

Originally Posted by Joshboody

You'll typically overboost slightly in the higher gears due to reduced WGDC requirements. I wish we could have a gear compensation option.

Yes, the procede overboosts slightly after a gear change.

Hey JP - what is your boost control gain set to?

Would also be interesting to see your wastegate duty cycle table too.

Any logs showing wastegate compensation value?

[jpsimon]

gain is set to the default, I just reset WG adaption the other day after messing around with some stuff. plan on logging tomorrow to see if it's pegged at +\- max value so I can adjust gain

[jpsimon]

Originally Posted by Joshboody

Start checking everything one by one.
-maybe replace the stock DVs
-pressure check the system... 20psi from the hot side
-check that your WGs are closing at 6" and holding vacuum.

maybe double check each section of vac system with a pump to make such its holding, including canisters.

I have forge DV's, going to service them either way. Just replaced the vac canisters along with the lines. I do need to test the wastegates are holding vacuum... honestly it seems like the issue is with them I'm just hoping it is something else.. thus all these threads

[Ilma]

Originally Posted by jpsimon

gain is set to the default, I just reset WG adaption the other day after messing around with some stuff. plan on logging tomorrow to see if it's pegged at +\- max value so I can adjust gain

Default gain is 45 I think?

I recently upped mine to 55 and my log above reflects this.

My wastegate compensation % is around 1.6% with that setting.

I think Shiv mentioned when he was still running twins, that his wastegates were getting loose and tired and he had to run a much higher gain value.

Perhaps your actuators are getting tired too?

In any case, sounds like a good plan to start with WG compensation and see where it's at.

[jpsimon]

Yeah that's step 1 for tomorrow. Are you supposed to reset wg adaption after upping the gain?

[Joshboody]

Don't worry about WGDC now... Find out why its higher first, then depending on options you may need to up the gain.

[Ilma]

Originally Posted by jpsimon

Yeah that's step 1 for tomorrow. Are you supposed to reset wg adaption after upping the gain?

I didn't.....but it took a couple of days for my WG compensation value to drop down.

I think Shiv mentioned that wastegate compensation is constantly adapting and remains intact even if you upload a new map.