Boost drop when WG dutycycle hits

T

tech9

ABS Expert
I'm narrowing down everything on my truck to get it to run properly (stock at least)
Here is the weird issue i'm having.

It drives great, no knock, etc etc but when you accelerate, say 1/4 throttle, the boost will creep up to maybe 5-8 psi and then drop suddenly and then rise again. I did a few logs and found its right about when the wastegate duty cycle changes, the thing is it happens on the stock boost controller as well as an aftermarket greddy one.

Wastegate issue? I have replaced all of the vac lines and made sure the check valves are correct, etc. The only aftermarket piece on the engine right now is a BOV, and i'm wondering if this could be part of the issue?

PS, stock chip, stock turbo, stock everything, mostly.
 
BMFB

BMFB

Not to scale
Re: Boost drop when WG dutycycle hits

tech9 said:
I'm narrowing down everything on my truck to get it to run properly (stock at least)
Here is the weird issue i'm having.

It drives great, no knock, etc etc but when you accelerate, say 1/4 throttle, the boost will creep up to maybe 5-8 psi and then drop suddenly and then rise again. I did a few logs and found its right about when the wastegate duty cycle changes, the thing is it happens on the stock boost controller as well as an aftermarket greddy one.

Wastegate issue? I have replaced all of the vac lines and made sure the check valves are correct, etc. The only aftermarket piece on the engine right now is a BOV, and i'm wondering if this could be part of the issue?

PS, stock chip, stock turbo, stock everything, mostly.
Click to expand...

you say when the DC changes, what is it before the change, and what does it change to?
 
Quickstop [UK]

Quickstop [UK]

Combating adversyty.
Re: Boost drop when WG dutycycle hits

dicsonnect the BOV until you solve your issue - they're no use below 15 psi anyway.
 
T

tech9

ABS Expert
Re: Boost drop when WG dutycycle hits

I have a log, and I will post if this BOV isn't the issue ;) Thanks for the help guys!
 
T

tech9

ABS Expert
Re: Boost drop when WG dutycycle hits

No I was wondering how to adjust this also, is there a way to check for stock length or trial and error?
 
BoostedSUV

BoostedSUV

Active member
Re: Boost drop when WG dutycycle hits

tech9 said:
No I was wondering how to adjust this also, is there a way to check for stock length or trial and error?
Click to expand...

Hold the waste gate flap shut, adjust the actuator rod to 1/2 a hole short of the flap and pull it out onto the flapper. It should take a decent amount of force to pull the rod out. You want it to hold the wastegate closed until desired boost is reached. :tup:
 
dgoodhue

dgoodhue

BuSTeD 4.3
Re: Boost drop when WG dutycycle hits

The wastegate waste duty cycle increasing causing the boost to drop is what is suppose to happen. I think the stock chip has part throttle positiion vs desired boost level table that scales the boost to the directly to the throttle position. This is probably has a set up time (delay) as well This means 50% throttle is 50% of desired boost (or appprox 7psi). The wastegate system can't actually control the low boost level. This sounds like what you describing and very well be normal from what I remember from the stock chip. Almost every aftermarket chip I saw got rid of this.

Are you have boost contr issue at wot or higher Throttle Position
 
T

tech9

ABS Expert
Re: Boost drop when WG dutycycle hits

I'm thinking this might be normal also now, because with the aftermarket controller it was not noticeable.

Got a TT chip coming in a few days and I will let you know if that is the issue, got rid of the bov and it didn't fix the issue.

I havn't tried a lot of WOT yet till I fix these issues, but I will let you know.
 
T

tech9

ABS Expert
Re: Boost drop when WG dutycycle hits

TT chip is in, works great, except for the boost drop still is happening.
It dont happen then the greddy sol, so its either a programming on chip issue ( i guess the ultimates had it till you did mph hack ) or its a bad sol :\ I have rechecked vac lines, and they are fine and in the correct location for stock controller.

http://www.youtube.com/watch?v=WDs4zqmJFgI
Here is a short video, if you watch the inaccurate boost on dash, it lets you know what is happening, I have it logged, but this is easier to describe.
 
WyoSyclone

WyoSyclone

Active member
Re: Boost drop when WG dutycycle hits

Did you let off there at the very end of the video, or is that the drop you are talking about??

The other minor pull back on the boost just looks like the ECM and WG system doing its job.
 
T

tech9

ABS Expert
Re: Boost drop when WG dutycycle hits

Ya i let off at the end, maybe it is doing its job, if so it sucks at it. Losing tons of power dropping the boost like that, just to climb back up.

My GN controller does not do this at all, as well as every other controller i've used.

Maybe I should swap back to the greddy one? It was 1000% better.

I will post a full run video tomorrow, unless its snows, maybe i'll still make 1 ;)
 
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