Full tune of 68HTA, KSTech 73 MAF, Racer X FMIC and DW750s

[NSFW]

 

This one was in 4th gear (15 psi by 2500 rpm!):

 

http://i248.photobucket.com/albums/gg194/littlebluegt/boostMAF4.gif

 

You will notice the boost is very erratic (especially in 4th gear), despite (not shown) a very very stable WGDC. I used a bleed style of boost control with the EWG.

 

[...]

 

It is interesting that my (and I assume every) Tial EWG does not seal completely. If I blow into the bottom port, it slowly loses pressure. That is why the boost tends to rise a bit with a bleed style boost control, then fall back down. Bigger restrictor solves that problem.

 

Could you hear wastegate flutter when you took at log? I have a little theory that the flutter is not caused by fluctuating WGDC but rather by fluctuations in the rest of the system - EGBP opens the door, boost goes down, EGBP goes down, door closes, boost goes up, EGBP goes up, repeat.

 

What software are you using to make those graphs?

 

The leaky EWG would bother me. That's metered air and it's a boost leak. However small, it would drive me nuts. I'm really curious if all Tials are like that. Also, have you heard of using the top port in conjuction with a 4-port EBCS? Being so focused on spool, I'd think that would be right up your alley.

[LittleBlueGT]

Could you hear wastegate flutter when you took at log? I have a little theory that the flutter is not caused by fluctuating WGDC but rather by fluctuations in the rest of the system - EGBP opens the door, boost goes down, EGBP goes down, door closes, boost goes up, EGBP goes up, repeat.

 

What software are you using to make those graphs?

 

The leaky EWG would bother me. That's metered air and it's a boost leak. However small, it would drive me nuts. I'm really curious if all Tials are like that. Also, have you heard of using the top port in conjuction with a 4-port EBCS? Being so focused on spool, I'd think that would be right up your alley.

 

You could really hear it, very noticeable. Funny that my friends WRX also did it at low rpm/high boost 50% WGDC. (only in the cold)

 

The Tial leaks a very very small quantity of air. Just enough for it to be noticeable with a restrictor pill. I am not worries about it.

 

You could be correct with your theory. I did try a few different boost control methods, but in the end I think the MBC hybrid is the best.

 

I have done a bit of research into stand-alone ECUs, and from what I gather the frequency they use for EBCS is different (higher) then our OEM ECU. I always though, X% WGDC is X%, but not always so if the freq can be adjusted.

 

Either way, a MBC will not have any pulsing, but a steady stream going to the EWG. I reall expect good things, and easy tuning.

 

I just make the graphs w/ Airboy's sheet. I just learned yesterday how to get pics from excel, w/o making screen shots.

[NSFW]

I haven't measured it, but I suspect that the Subaru ECU's wastegate control runs at a far higher frequency than the flutter that we hear. Flutter is something like 2-3 times a second, and I'd expect the wastegate frequency to be more like 50-500 cycles per second. Maybe filtered too, so it's basically just a smoothly varying voltage by the time the solenoid sees it.

 

Not to say that the ECU won't induce flutter if tuned wrong - I'm sure it can and does.

[LittleBlueGT]

I haven't measured it, but I suspect that the Subaru ECU's wastegate control runs at a far higher frequency than the flutter that we hear. Flutter is something like 2-3 times a second, and I'd expect the wastegate frequency to be more like 50-500 cycles per second. Maybe filtered too, so it's basically just a smoothly varying voltage by the time the solenoid sees it.

 

Not to say that the ECU won't induce flutter if tuned wrong - I'm sure it can and does.

 

You are probably right. I do suspect the MBC will work great though.

[LittleBlueGT]

I haven't measured it, but I suspect that the Subaru ECU's wastegate control runs at a far higher frequency than the flutter that we hear. Flutter is something like 2-3 times a second, and I'd expect the wastegate frequency to be more like 50-500 cycles per second. Maybe filtered too, so it's basically just a smoothly varying voltage by the time the solenoid sees it.

 

Not to say that the ECU won't induce flutter if tuned wrong - I'm sure it can and does.

 

I thought about this further, and I am not sure if I agree anymore.

 

When I first got my EWG, I hooked up my 3-port EBCS in blocking mode to the bottom port. It controlled boost just fine, but you could definitely hear the pulses coming from the EWG. I searched, and many others experienced that as well. In bleed mode the EWG was nice and smooth. This was all done before I plumbed the EWG dump tube back to the DP, so it was very audible.

[NSFW]

Hearing the wastegate solenoid move is not necessarily the same thing as hearing the pulses. You'd need an oscilliscope, or maybe just a speaker, to know what's going on electrically.

[LittleBlueGT]

Hearing the wastegate solenoid move is not necessarily the same thing as hearing the pulses. You'd need an oscilliscope, or maybe just a speaker, to know what's going on electrically.

 

Then why do I hear the pulses when in interrupt, but not when I had the right pill and bleed? Why does it seem to be a known fact that EWG in interrupt mode pulses?

 

I am not arguing, but looking for answers.

[NSFW]

The pill probably effectively lowers the 'gain' of the feedback loop between EGBP and boost.

 

If that's not it, then all I can say that it's a dynamic system with at least two feedback loops (EGBP acting on the flapper, and the ECU altering WGDC), and both of those loops are known to induce oscillations, so oscillations are going to happen/not-happen depending on all sorts of changes. That's a fancy way of saying I dunno. But I'll still be shocked if someone can prove that the WGDC pulses are less than 50hz.

[LittleBlueGT]

The pill probably effectively lowers the 'gain' of the feedback loop between EGBP and boost.

 

If that's not it, then all I can say that it's a dynamic system with at least two feedback loops (EGBP acting on the flapper, and the ECU altering WGDC), and both of those loops are known to induce oscillations, so oscillations are going to happen/not-happen depending on all sorts of changes. That's a fancy way of saying I dunno. But I'll still be shocked if someone can prove that the WGDC pulses are less than 50hz.

 

The thing is my WGDC were very consistent, like a solid 50% +/- 1%. (lowered td values to get it in ballpark, then raise them up for beter response later)

 

I will just stick my tongue to the leads, then I will tell you the frequency.

[NSFW]

 

I think a speaker might work better. I wonder what the impedance of the solenoid is - if it's 4 or 8 ohms, a speaker would be perfect.

[Spec B]

Any update on this? I wanna see some road dyno info!

[LittleBlueGT]

Any update on this? I wanna see some road dyno info!

 

Something was wrong with my DW650s, I sent them back to DW, they just got in to DW today. I am anxious too, but injectors have been the biggest PITA for me.

[Spec B]

Sorry about the injector issues.

[LittleBlueGT]

Sorry about the injector issues.

 

I took them out, changed O-rings, etc... a few times. Still didn't really hold fuel pressure, and had some weird fueling problems (not WOT).

 

Put stock injectors back in, and all was perfect.

[mattg]

should have kept the 850's

[LittleBlueGT]

should have kept the 850's

 

The 850s worked flawlessly everywhere (tuned easily, held pressure etc...) cept the known issue of the odd sidefeed car (including NSFW's) leaning out at high rpm. it was rpm dependent, not MAFv dependent, and I really didn't like it at all.

[ClimberDHexMods]

leaning out at what WGDC on 850s and what rpm? I only ask because... I have the exact same setup, untuned so far, planning on pushing rpms.

[NSFW]

leaning out at what WGDC on 850s and what rpm? I only ask because... I have the exact same setup, untuned so far, planning on pushing rpms.

 

There are spots on the load/rpm tables where the AFR goes lean for no apparent reason. This page has some posts from when I was figuring it out:

http://www.romraider.com/forum/topic4071-45.html

 

I'm still mystified, but I'm satisfied with working around it by enriching those cells in the fuel table, at least for now. I'd still like to fix it for real but I'm not sure how. When I get my recently Win7'd machine working I'll post up my current fuel table. It's a little weird-looking but it works.

 

The fuel table I'm using today:

 

http://i193.photobucket.com/albums/z151/Legacy_NSFW/Tuning/v089FuelTable.png

 

Everything lower than 11.2 is actually trying to be 11.2. It mostly gets within 2-3% of 11.2, but I do need to tweak it a little more.

[ClimberDHexMods]

Holy leaning out batman! That table isn't even consistent at all! Great, added that to my list of things to look forward to.

[LittleBlueGT]

I did the same thing in my fuel table, and it worked good. I did multiple 3rd gear runs in 60F weather and it was fine. Then I did a 4th gear run at 30F, and the rpm band seemed to change, so it was richer in some spots, and much leaner in others. It pissed me off so much I pulled the injectors out.

[NSFW]

Oh great. I saw something like that in my last set of logs, a couple pulls were leaner than the rest in some areas. I haven't reflashed for weeks, so nothing has changed except temperature. I haven't given it a close look yet but I will soon.

[LittleBlueGT]

Oh great. I saw something like that in my last set of logs, a couple pulls were leaner than the rest in some areas. I haven't reflashed for weeks, so nothing has changed except temperature. I haven't given it a close look yet but I will soon.

 

I would consider buying a better FPR.

[NSFW]

the known issue of the odd sidefeed car (including NSFW's) leaning out at high rpm

 

Is there reason to believe that this problem is specific to sidefeeds?

[LittleBlueGT]

Is there reason to believe that this problem is specific to sidefeeds?

 

I thought that the only others I found with the same issue had sidefeeds?

 

I could be wrong though.

[NSFW]

I haven't asked around. I don't see evidence of other people trying to get AFRs dialed in over the whole fuel map though, so I'm not sure how many other people would have noticed or cared...