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Old 09-13-2002, 12:37 PM   #1
thejean
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Default To MBC or not to, that is the question...

if anyone has Delta Dash logs running mostly a stock WRX with an MBC, please post the graphs and data or email them to me at [email protected] and I can post them for you.

Also, if you have the ability to collect some I would appreciate it as well. Obviously, I am interested in TPS, EGT, MAF, MAP, AFR, IAT, RPM, MPH, Timing, Knock, and anything else you care to throw in.

Please post a list of ALL mods as well. Oh yeah... please and thank you.

JC
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Last edited by thejean; 09-19-2002 at 10:08 AM.
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Old 09-13-2002, 06:53 PM   #2
MUGWUMP
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Um... someone correct me if I'm wrong, but hasn't this been beaten TO DEATH in Jorges "call to arms" thread?
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Old 09-14-2002, 08:38 AM   #3
thejean
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Quote:
Originally posted by MUGWUMP
Um... someone correct me if I'm wrong, but hasn't this been beaten TO DEATH in Jorges "call to arms" thread?
ok, I'll correct you and i've read it thoroughly more that once. most everyone involved in that thread was running a unichip as well. i'm trying to get logs of the MBC/stock combination. the other thing is that everyone was also doing wot runs and no slow runs up through the throttle positions... thats really what i'm looking for. also, not one person in that thread logged throttle position. now, there was one stock run done by "gravel" however, he seems to have disappeared and i can't seem to get anymore data from him. thats the reason for this thread, i'm hoping to get a collaboration of data from people who probably have it kicking around on their hard drives somewhere.

so, if you have some data and can post it please do so as it could be beneficial to many.

jc
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Old 09-19-2002, 10:44 AM   #4
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Default Bump + more info

I read just about all of the 200 threads that came up last night after I seached "MBC and part and throttle". phew. anyway, I feel a summary is in order....

After all was said and done it seems like many have said that 16 psi is the upper limit when using an MBC and after that there is a chance of detonation in the higher RPM's. I could see this due to the MBC's ability hold higher boost to redline with the stock timing advance.

On the other hand, AZScoobie said that an MBC will cause the car to run filthy rich which can lead to unburnt fuel in the exhaust manifold which can build up before/on the precat causing high EGT's. Then again, others claim that the MBC makes the car run leaner. Another argument is that retarded timing, such as with the VS0 kit, will cause fuel to be improperly burnt leading to high EGT's like the above described rich condition. Shouldn't the MBC help this then?

AZScoobie also had a few occurences where he got the EGT's on a bone stock WRX approaching 1000C (1832 F) while road racing !!!

Yet again, many have taken the Tony-the-Tiger approach and have said to go for the MBC, they're grrreeeeaaaaat !! There is also no conclusive data that says MBC cause problems other than at part-throttle (which may not be an issue either). Some vendors (boostmonkey and bristol boost) have "claimed" that it is an issue but have yet to post DD logs to prove it. Noone has reported precat failures due to an MBC, except WRXGuyInTulsa who ran one full-time with 17 psi boost. Who knows how he spiked and how he drove part-throttle and whether he road raced with the MBC???? Links:
http://forums.nasioc.com/forums/show...hreadid=230832
http://forums.nasioc.com/forums/show...hreadid=232174

So, at the end of all this is it safe to say that if you have a cat-less up-pipe and an MBC set to stock max-boost that you are safe, provided you don't ride the throttle at less than 50%? Even so, the stock ECU will hold 14.7:1 A/F in closed loop, which is questionable whether even that is unsafe. Anyway, the PTFB thing can be overcome with a dual-stage solenoid so now I am more concerned about detonation at mid-high RPM's. But, if the EGT's are the concern, and not detonation, then an MBC should help because it will things out a bit? Or, does it richen things up?

Sigh.... Man, no consensus at all on this issue. Its very frustrating. You can now see why i want to see some DD logs of a stock WRX with JUST an MBC. Trust me, if I could afford a DD I wouln't be making this request and I bloody well would have posted the data as soon as I had it for all those poor saps who run MBC's because they can't afford much else. I know the data is out there, someone just needs to take the time to post it.

Anyway, if anyone has any intelligent comments to add (preferably backed up with DD data), then please post. I'd like to put this issue at rest once and for all, if possible. Tuners, if you want to pipe-up (no pun intended), then please do so. If you know stuff we don't and are just sitting back watchng us all with amusement then shame on you. Especially given your packages include MBC's, ABC's, etc. and some of you claim that detonation is overcome with timing adjustments. Its about time you speak up and explain, with data, what in the the **** is really going on. Not to sound too cynical but perhaps the tuners stay out of it because they know and MBC isn't really all that bad but want to fuel their finances with our paranoia. If they have data to the contrary then I for one would like to see it.

Sorry for the rant but its about time some intelligent people got to the bottom of this. Hell, there are more than 20,000 of us. Surely to god we can get to the bottom of this.

JC

EDIT/CORRECTION: WRXThis also messed up his precat while running an MBC but again, the conditions were somewhat excessive.

Last edited by thejean; 09-19-2002 at 02:19 PM.
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Old 09-19-2002, 01:26 PM   #5
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I'm not sure what it is that your looking for? I do have a delta dash and have taken a few logs when I had an ebc and no unichip. Are you asking for logs that slowly go through throttle positions? I don't think you will find to many people who have done that.

I can tell you this, running 15 psi with and up-pipe and not getting into part throttle boost, you are plenty safe.
I think you are mostly concerned about ptfb, and you should be. This is the reason I ditched my $475 ebc. The ebc I was using was 10 times better then the dual stage mbc that I had before that but I still ran into the same problem. I remember one time I lifted off the throttle part way after a full throttle run because I thought I saw a cop. My knock link shot off and I could hear my engine detonating really bad. That is probably that worst thing you could do if you have a boost controller.
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Old 09-19-2002, 01:55 PM   #6
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Default Thank heavens....

Quote:
Originally posted by codean
I'm not sure what it is that your looking for? I do have a delta dash and have taken a few logs when I had an ebc and no unichip. Are you asking for logs that slowly go through throttle positions? I don't think you will find to many people who have done that.

I can tell you this, running 15 psi with and up-pipe and not getting into part throttle boost, you are plenty safe.
I think you are mostly concerned about ptfb, and you should be. This is the reason I ditched my $475 ebc. The ebc I was using was 10 times better then the dual stage mbc that I had before that but I still ran into the same problem. I remember one time I lifted off the throttle part way after a full throttle run because I thought I saw a cop. My knock link shot off and I could hear my engine detonating really bad. That is probably that worst thing you could do if you have a boost controller.
Thank heavens... someone has finally stepped up to the plate. Ok codean, this is what I'm looking for:

Anything that you have that is just an MBC on a stock car (or, if its EBC data then just explain to me how you had it set up). I don't expect you to go through the effort of posting it all. I can do that. Just email me anything of relevance that you might have. I have the demo DD downloaded so I can view the logs in DD format and post the data that is relevant.

One more question for you though... Did you have a bleed hole after your MBC (or EBC) when you lifted off the throttle when you saw that cop? I suspect that if you had a bleed hole after your MBC and the wastegate is not "held" closed after you get off the throttle by the negative pressure, you may not have experienced that situation. Post a little more info on your setup at that time, when you have the time of course.

Thanks a mil,
JC
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Old 09-19-2002, 02:10 PM   #7
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Well, my car also was moded with the ebc so do you still want the info? I only had an uppipe and turbo back.

With that cop situation, I went from WTO to 30% throttle and still had full boost. This is what a boost controller will do. I'm not sure how a bleeder will help there.
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Old 09-19-2002, 02:12 PM   #8
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Quote:
Originally posted by codean
Well, my car also was moded with the ebc so do you still want the info? I only had an uppipe and turbo back.
Absolutely!! Send it along to [email protected].
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Old 09-19-2002, 02:27 PM   #9
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Quote:
With that cop situation, I went from WTO to 30% throttle and still had full boost. This is what a boost controller will do. I'm not sure how a bleeder will help there.
codean, I have read (and it is also very well substantiated) that a bleed hole after the MBC will allow the wastegate to close when off the throttle thereby preventing 0% throttle, full boost occurrances. I can see why an MBC would be bad... VERY BAD, in that situation. But, most MBC designs have corrected for this with a 0.2mm bleed on the MBC body.

Also codean, did you notice on your DD logs whether the car goes rich or goes lean when WOT with an MBC/EBC? Like I said, many theories on both reasons, which supposedly can both lead to high EGT's, but no hard data yet...

I know I came off harsh earlier and if I offended anyone, I apologize. But, I just want people to start posting data rather than opinions. That is the only way we will, as a group, figure this whole MBC business out.

Advanced thanks to all who participate.
JC
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Old 09-19-2002, 02:57 PM   #10
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If I understand you right, yes, If I were to go from WOT to closed throttle I would not have any boost (go into vacuum). With the data logs that I have @ WOT I always am at about 11 to 1 on a/f.
running 15-17 psi. There are people out there that are running big turbos (t3/t4, pe1820) and have no fuel upgrades or even engine management and have not blown up their engines(yet). As I see it, the stock ecu does a good job with a/f ratios to keep things safe. However even with a stock turbo, injector duty cycles are close to, if not 100%. This is where I see a problem and why people get sti injectors. Timing is another problem when you play with boost running the stock ecu. Jorge has shown me that running 13.5 psi can yield better results then 17 psi due to the fact that timing will not be taken away.

PS. I am not sure if I can send my logs to you because you are in Canada. Hotmail sucks.
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Old 09-19-2002, 03:02 PM   #11
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Very good info codean. This is what I am talking about. Kudos to you. As for emailing me in canada it should work because that is just an internet email address and should have no trouble making it here. I talk to all kinds of people with hotmail in the US.
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Old 09-19-2002, 03:45 PM   #12
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Well for some reason every time I try to send an e-mail out side of the us, it gives me some kind of a error message.
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Old 09-20-2002, 12:51 PM   #13
thejean
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Related discussion: click here

For anyone who is interested, I have found some logs in Rift's Delta Dash thread that is sort of relevant (look for Kenneth2000). The logs are basically unreadable so I am trying to get the data emailed to me so I can post it. Also in that thread, there is a bone-stock DD run by "gravel" for comparison purposes. Just use the 'find" command in your browser window to locate the right post. For those who prefer, I think its on page 7 or 8.

JC

Last edited by thejean; 09-20-2002 at 03:44 PM.
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Old 09-20-2002, 03:19 PM   #14
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One little point of note. If you go from WOT to 30% throttle fast enough, you can trigger the decel settings on the stock ecu and it basically cuts fuel to drop rpms. This usually isn't a problem because there is no load on the engine when it happens.

My beef with the MBC is I was always watching the EGT gauge because it was all over the place. I didn't really get into any problems because I was really watchful.

-Jon
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Old 09-20-2002, 03:43 PM   #15
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codean, I got your logs... I will check them out tonight and post any relevant info tomorrow...

JC
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Old 09-20-2002, 05:35 PM   #16
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Here is my view on running an MBC on a near stock car:

I would do an upipie before running an MBC even at stock boost levels. The chance of the upipe cat melting and flying into the turbo is to great. The writing is on the wall guys.. Get an upipe first. Plus, you get an extra 8-10hp, faster spoolup and you have no worries.

The stock ECU tracks 14.3-14.7 to 1 AF at all times other then past 40%-60%(I say this range as there are other factors). This means idle will always be 14.5 ish. Part throttle is always 14.5 ish. Unless you have modified the car so wildly the ECU cant track 25% fuel trim to get to 14.5 you will always run around that area.

WOT on a stock car is around 10 to 1 AF. This is very rich and is the reason Unichips make power. You lean this out a point or so and you magicaly make 20-30hp.

If you add an MBC to a stock car and run 15 psi you will run even more rich at WOT because the ECU is programmed to do so based on MAF and MAP readings. Cars setup like this run 9 to 1 or there abouts. A unichip on these cars is helpfull to get AF back to the 11 to 1 range. Bingo 30hp easy.

Here is the problem.

Remeber when I said the ECU tracks 14.5 to 1 at Part throttle? It always does this... Even with a unichip installed. The ECU can swing 25% rich to stoich and lean to stoich. The Stock ECU is expecting wastegate boost and no more.. So 5-8 psi of boost at part throttle. Stock car owners can see the boost solenoid switch as a boost gauge will pause at that level before the ECU increases boost.

With an MBC the boost is going to rise to the set level as fast as it can. The wastegate is shut until the mbc bleeds air to open the gate to reduce boost.

so at part throttle you now have the ability to make 15 psi or more. The ECU still tracks 14.5 to 1 af during this time. This is very lean for that much boost and causes high EGT's and detonation. This melts the precat.

If you have an EGT gauge and a boost gauge and dont mind paying attention to them MBC's are fine. Just dont run that much boost at part throttle.. Either give it some more gas or shift to a higher gear. Personaly, I dont like this setup. i

Switch to a larger turbo that is not willing to make 15 psi at part thottle. Problem solved. You make a ton more top end power. Costs alot

Use a bleed MBC instead of a ball and spring unit. Bleeds are nicer for this application as boost response is slowed down. You might only make 12 psi at part with a bleed.

Moral of the story... If you are going to mod the car there are drawbacks to every modification. High part throttle EGT is one drawback to the MBC as well as running rich at WOT.

One day people will realize the real power gain for an MBC is not the extra 1-2 psi. Its the fact that first and second gear run to that set limit while on a stock car first is wastegate boost and second rarely hits peak.


CT
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Old 09-20-2002, 05:48 PM   #17
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Quote:
Originally posted by AZScoobie
One day people will realize the real power gain for an MBC is not the extra 1-2 psi. Its the fact that first and second gear run to that set limit while on a stock car first is wastegate boost and second rarely hits peak.
For me it was actually the quickness in reaching the said boost levels. I was running boost levels lower than factory with the MBC and it was still stronger. Currently, my car hits 1.0kg/cm2 in first and second with my FBC I basically felt that all the power I was seeing from my Stage 0 was the responsiveness in the MBC (and the higher boost at redline). Powerband went down and narrowed when I took out the MBC. ie: more lag with FBC.

-Jon
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Old 09-20-2002, 05:50 PM   #18
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Quote:
Originally posted by stimpy


For me it was actually the quickness in reaching the said boost levels. I was running boost levels lower than factory with the MBC and it was still stronger. Currently, my car hits 1.0kg/cm2 in first and second with my FBC I basically felt that all the power I was seeing from my Stage 0 was the responsiveness in the MBC (and the higher boost at redline). Powerband went down and narrowed when I took out the MBC. ie: more lag with FBC.

-Jon
www.nothingserious.net

There have been many, many dyno runs on stock cars that then had an MBC installed with various boost levels. The largest power from the TXS stage1 and vishnu stage0 comes from leaning out the mixture at WOT.

CT
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Old 09-20-2002, 08:42 PM   #19
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very informative post Clarke. thank you. now, to comment:

Quote:
Originally posted by AZScoobie
[b]I would do an upipie before running an MBC even at stock boost levels. The chance of the upipe cat melting and flying into the turbo is to great. The writing is on the wall guys.. Get an upipe first. Plus, you get an extra 8-10hp, faster spoolup and you have no worries.
wise words indeed.

Quote:
The stock ECU tracks 14.3-14.7 to 1 AF at all times other then past 40%-60%(I say this range as there are other factors). This means idle will always be 14.5 ish. Part throttle is always 14.5 ish. Unless you have modified the car so wildly the ECU cant track 25% fuel trim to get to 14.5 you will always run around that area.
is it not possible that the stock fuel maps simply do not have points for full boost at part throttle? for instance, the boost monkey website claims that an A/F of 18:1 was seen at PTFB. Unless the maps points simply aren't there, it would have to stay at about stoich. if this were true, then it sure would explain a lot.

Quote:
WOT on a stock car is around 10 to 1 AF. This is very rich and is the reason Unichips make power. You lean this out a point or so and you magicaly make 20-30hp.

If you add an MBC to a stock car and run 15 psi you will run even more rich at WOT because the ECU is programmed to do so based on MAF and MAP readings. Cars setup like this run 9 to 1 or there abouts. A unichip on these cars is helpfull to get AF back to the 11 to 1 range. Bingo 30hp easy.
so, what are your thoughts, based on the data you collected while road racing, as to why egt's went so high on a stock wrx? could it be due to the rich condition at WOT sendin fuel out the exhaust where it undergoes thermal desorption (volatalization) to CO2 and H2O? Could this also be causing the high egt's? this would also explain why an up-pipe helps to lower them.

Quote:
Remeber when I said the ECU tracks 14.5 to 1 at Part throttle? It always does this... Even with a unichip installed. The ECU can swing 25% rich to stoich and lean to stoich. The Stock ECU is expecting wastegate boost and no more.. So 5-8 psi of boost at part throttle. Stock car owners can see the boost solenoid switch as a boost gauge will pause at that level before the ECU increases boost.

With an MBC the boost is going to rise to the set level as fast as it can. The wastegate is shut until the mbc bleeds air to open the gate to reduce boost.
i'd like to use an mbc to get to 9 psi and then let the stock fbc take over from there. so, given that 9 psi falls within the 25% fuel trimming abilities, it should be fine should it not?

Quote:
so at part throttle you now have the ability to make 15 psi or more. The ECU still tracks 14.5 to 1 af during this time. This is very lean for that much boost and causes high EGT's and detonation. This melts the precat.
so, are you indicating that both detonation and the precat are a concern? the precat is easy to deal with but detonation may be more tricky and seems like the more serious of the two issues.

Quote:
Switch to a larger turbo that is not willing to make 15 psi at part thottle. Problem solved. You make a ton more top end power. Costs alot
if you look at gravel's stock DD run, you can see that it looks like IDC depends on engine rpm and injector pulse width depends on manifold pressure. would you concur? so, that means that even though the IDC's on the stock rex are 90%, there is still some room for more fuel due to the pulse width's not being maxed out? if that is not true, then a bigger turbo seems like a very unsafe thing to do on the stock ecu.

Quote:
Use a bleed MBC instead of a ball and spring unit. Bleeds are nicer for this application as boost response is slowed down. You might only make 12 psi at part with a bleed.
slower spool up...

Quote:
Moral of the story... If you are going to mod the car there are drawbacks to every modification. High part throttle EGT is one drawback to the MBC as well as running rich at WOT.

One day people will realize the real power gain for an MBC is not the extra 1-2 psi. Its the fact that first and second gear run to that set limit while on a stock car first is wastegate boost and second rarely hits peak.
well said.

JC
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Old 09-20-2002, 09:54 PM   #20
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Okay guys, cast your vote here. I have a stock WRX with an MBC set to about 16.5. The car runs great but it has detonated once. Do I:

A) Take the MBC off my car

or

B) Leave it on, and watch my boost.


I'm very careful when driving the car now due to boost raising to almost 16 psi with very little throttle, due to load.

TIA

By the way, I plan to install a turboback/uppipe very soon and I'm going to try and find a TXS stage 2 unichip. So the MBC was just for now to give me a little more kick. Keep that in mind when casting your vote, or stones depending on how unruly I am for doing this. * please take it easy...*
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Old 09-21-2002, 09:05 AM   #21
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Quote:
Originally posted by Fickle
Okay guys, cast your vote here. I have a stock WRX with an MBC set to about 16.5. The car runs great but it has detonated once. Do I:

A) Take the MBC off my car

or

B) Leave it on, and watch my boost.


I'm very careful when driving the car now due to boost raising to almost 16 psi with very little throttle, due to load.

TIA

By the way, I plan to install a turboback/uppipe very soon and I'm going to try and find a TXS stage 2 unichip. So the MBC was just for now to give me a little more kick. Keep that in mind when casting your vote, or stones depending on how unruly I am for doing this. * please take it easy...*
The car has already detonated and you have left it on??? First off, how do you know you had detonation? Do you have a knocklink or a DD? Secondly, you need to A) Take the MBC off your car or, C) turn it down. I don't know what your power goals are but as AZScoobie pointed out above as have many others, an MBC's real advantage is spool up. Turn it down to between 8 and 12 psi and let the FBC take over from there. If you're on the cusp of detonation then you're likely getting your timing yanked like a champ. By boosting less at top end you'll get your timing back and will probably make more power and less heat.

JC

PS - if you have a DD please post some runs. I have a few that i will be posting shortly once i get a chance to puruse them some more.
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Old 09-23-2002, 12:32 PM   #22
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Default Stock WRX 1-3 gear run

click here for link to post showing a stock 1st thru 3rd gear run

My observations on the stock 1-3 run:
1. Shifting was at approximately 6600 rpm.
2. TPS was not recorded (dammit!!)
3. This was a WOT 1-3 gear run (likely in open loop for much of the run)
4. At about 3600 rpm, the car seemed to go into open loop
5. VERY IMPORTANT: There is a lot of A/F correction and learning when in low RPM's and in closed loop indicating that the car is trying to maintain 14.7:1 stoich optimum (A/F sensor #1 @ 1.0 = 14.7:1) when in closed loop, while simulatneously advancing timing to get the best possible fuel economy/power combination (note that there was no knock). Also, the fuel injection duty cycle increases with RPM in closed loop indicating that the WRX CAN indeed fuel for higher boost in closed loop, while maintaining 14.7:1 A/F. Also, as soon as the MAP increases into the positive range, the A/F correction/learning both drop off (i.e., ECU went into open loop) and the fuel injection duty cycle / pulse width both shoot up and the A/F goes filthy rich.
6. The car is running fairly rich at WOT/high boost (11:1)
7. Ignition timing increases with engine speed (up to 34 degrees!!!) indicating that timing advance is increased as boost tapers in higher rev range.
8. MAP (or boost), MAF and fuel injection duty cycle all follow nearly the exact same trend further substantiating point #5 above
9. The wastegate duty cycle basically follows the MAP signal behavior except it doesn't plateau as long. This simply substantiates what we already know about how the wastegate and the FBC interact.
10. The car seems to be continuously battling to get to stoichiometric optimum in closed loop. Once is jumps into open loop adjustment stops and it seems to base the A/F on MAP or MAF only... (i.e., no fuel economy optimization is occurring)
11. There was NO KNOCK (i.e., no detonation) during this run
12. Max boost in 1st = 9 psi, 2nd = 12.9 psi, 3rd = 12.6 psi
13. MOST IMPORTANT OBSERVATION - Look at the intake air temps and EGT's... As the vehicle speeds up, IAT's go down dramatically almost exactly inversely proportional to vehicle speed. This confirms my earlier comment regarding intercooler efficiency. Basically, boost seems to be limited in 1st and 2nd until the vehicle gets up to speed and the intercooler can begin to do its thing.
14. EGT's during the run max out just after max boost and are about 765 C (1400 F). This leads me to the conclusion that EGT's at 15 psi (especially when in closed loop) and 5th gear would be closer to 1600 F.

Some MBC data to follow...

Last edited by thejean; 09-23-2002 at 04:49 PM.
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Old 09-23-2002, 12:47 PM   #23
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These are codean's runs. He was running an EBC set to 15 psi (no unichip).

run 1, part 1:
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Last edited by thejean; 09-23-2002 at 12:52 PM.
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Old 09-23-2002, 12:56 PM   #24
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run 1, part 2:
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Old 09-23-2002, 12:57 PM   #25
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run 2, part 1:
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