New DP, low boost

[Scoobum]

That wastegate spring is a tight son of a whore. I have small visegrips I keep in the armrest to adjust my boost pressure. Vice grips and a fair amount of effort is needed to pull the rod over the arm. The grainger valve will allow the turbo to spool quicker...over the tuner setup I have. I read a post from Julio about the EGR diaphragm pulsating. Likely isn't your problem, but I eliminated the EGR on my car when I read it. I rigged up a device to check when my actuator opened last summer when I overboosted my engine to eliminate it as an issue. Numbers I gave Steve were to his satisfaction.. .so we moved on. You have to eliminate everything. It takes time and patience.

[Shimy87]

I eliminated the egr also.  So im clear....I should use a helper spring pulling the puck to the open position or the closed?  I will pull some fuel also.....Thank s!!!!

[nocooler]

Closed- turn the boost controller back down before testing

[Steve Wood]

yes, you are supplementing the spring inside the wastegate so that the puck is held more firmly closed.  This allows the puck to open further when activated.  It's getting to the point, I need a big, young, kid to hook it over the arm.  Actually, it got that way about five years ago.

Also, as I stated the other day, A/f can affect boost.  The richer the mixture, the more back pressure we have as the gases try to exit thru the the turbine.  It may not be a major change, but, I picked up 2 psi in boost three days ago by leaning the a/f down in a major sense.  I have seen it several times since I started trying to tune Buicks.

Another thing that I have noticed is that changes in the A/F can affect compressor surge to a small degree as well.  I believe this is probably due to exhaust spool starting earlier which affects compressor stall a bit.  Makes me wonder if it will affect puck pulsation but I will defer to whatever Julio has said on the matter.

[1 RARE T]

 


I'll just quietly sit here grinning.

[motorhead]

I'll just quietly sit here grinning.

LOL.

[phil_long]

Awesome thread

[Shimy87]

Been raining so no test yet but here what I did. Took a fish scale and the break point of actuator was 43 LBS on the scale ( don't care if accurate, just a gauge) then turned the rod back to 1/8 pull. Took a small eye bolt so I will have some adjustment and picked up a fairly stiff spring and drilled a hole in the WG actuator bracket and installed. Checked again with fish scale and this took it up to 45 lbs. Backed off the RJC controller 3 complete turns. I can post a pic of this mess later. Will adjust fueling as Steve recommended and forcast is no rain tomorrow so I hope to see if with some tweeking this will smooth out the boost.

[Steve Wood]

I think what is happening is that the boost inside the exhaust housing is pushing the puck open rather than the boost being sent thru the controller to the actuator.  I think that the larger the hole in the housing behind the puck, the more leverage the exhaust pressure in the housing has on the puck.

At a certain point, the puck opens even though the controller has not signaled the actuator.  Therefore, you may have the controller set to actuate at 25 psi but the puck opens on its own at maybe 21 psi.

Your approach with the helper spring seems right to me.  What I don't know is what 2 extra psi of cracking pressure translates to with regard to the puck opening psi from the gas behind the puck.

I would be careful and watch the total boost when testing just in case it may make a large difference.

[motorhead]

Alky/water injection quips at about the 1hr 8min mark: https://www.youtube.com/watch?v=yHtxXUCXhU4

[Shimy87]

Finally got it out again. Making progress. boost feels very smooth but PL shows it does move up and down between 21 and 23. Can someone post a snapshot of a log screen with their boost at full push so I can see what another log looks like. Maybe I'm trying to get a nice smooth line and it isn't like that?? All 3rd gear runs from 50ish to 90+ Weird thing though, first pull was lower boost so I stopped, adjusted the boost controller and ran again, 22 lb boost, felt good and smooth, O2's at the end of run were 811 and absolutely 0 knock. Stopped, turned boost controller a half turn more, 23 lbs, felt smooth, 02's at end were 819 and I got a few little waves of knock, highest was .08  Strange that it got richer and I got knock? Will test more on way home but feel like I'm finally moving in the right direction 

Thanks for all the help!!!

[Steve Wood]

It's not uncommon to see a little timing retard with rich mixtures.  There have been some writers who claim there is such a thing as rich detonation but???   Having seen  small amounts of timing retard associated with rich mixtures, I wonder if the combustion changes frequency and the knock sensor thinks it is hearing detonation and pulls timing when it may not be actual detonation.

True detonation does not normally show an intermittent timing retard pattern...once it begins, it rapidly increases in amplitude until you take your foot off the gas.

At any rate, if you are observing intermittent timing retard of low amplitude, I would add boost, and/or pull some fuel.  Get the O2s down under 800.

Are you seeing the boost variation on your boost gauge or just on the map sensor display?

[Shimy87]

Boost gauge is smooth...power logger graph is jumpy

[Steve Wood]

It may be that the map is not reading that consistently.  I trust the gauge more than the map.  Here is a pl file you can look at...the boost is jumping around over a 2 psi range if you look at it sample to sample...given there is about 20 samples per second, you can take the individual numbers with a grain of salt, imo.

[motorhead]

Where is your MAP located?