Engine cutting out at full throttle - Page 3
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This is a discussion on Engine cutting out at full throttle within the Engine Modifications forums, part of the Tech & Modifying & General Repairs category; this should be a forced read for all people who sign up for clubwrx.net...

  1. #31
    Registered User UofAWRX's Avatar
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    this should be a forced read for all people who sign up for clubwrx.net
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  3. #32
    Registered User AwdTurboWrx's Avatar
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    Quote Originally Posted by cheeseybacon
    Define rich, please.

    And if what you're saying is true, and the WRX runs hog rich at 17 psi with the stock programming then why has Cobb and all these other engine management companies even bothered making stage 2 maps for 02-03? Is it all a total sham? Are all the 02-03 people running Stage 2 being ripped off? Have we been fooled all this time? Somehow I doubt that. Furthermore, if things are so rich at 17 psi as you claim, then why have the EM powers that be even bothered making different fuel maps for the 04-05 as well? If everything is safely running as rich as you claim it is, couldn't they have just make a reflash that shortens the CL/OL delay on the 04-05s and then called it a day?

    only reason 04/05 and even 06 fuel maps change is emissions and thats about it. What do i define rich? i define the esx guys who design 9 sec drag cars telling me its still running rich and should be fine safe. Idk, i consider them experts, dont you?

    Do people get ripped off by cobb?? if you have an 02/03 wrx yes you do. Its worthless, if i had my old wrx i would prove it but racing anyone you found me with a stage 2 wrx. But i have done so in the past and i did beat them. Drag strip freeway low end roll. If you have an 02/03 bugeye and you have an accessport, you have been ripped off but you never have to worry about adjusting or hitting fuel cut etc etc so its a convenience factor. You have and 04+ EM is a must for higher boost. Also, esx had a dyno day, i dynoed higher then cobb stage 2 wrx's running a mbc without engine management. Its a nice tool if you know how to use it.
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  4. #33
    Registered User cheeseybacon's Avatar
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    Quote Originally Posted by AwdTurboWrx
    only reason 04/05 and even 06 fuel maps change is emissions and thats about it. What do i define rich? i define the esx guys who design 9 sec drag cars telling me its still running rich and should be fine safe. Idk, i consider them experts, dont you?
    What is an okay A/F for a 9 second drag car for a few seconds, is a lot different than a street car that has to last for many miles. Richness is a very relative term, and unless you can provide some actual numbers, what you're saying means nothing. And even if it was just within the limits of what is considered safe, I'm willing to bet that your A/F data was taken only at WOT, which says absolutely nothing about the A/Fs that occur during PTFB conditions, which just so happen to be experienced significantly more often during daily driving than WOT.

    Quote Originally Posted by AwdTurboWrx
    Do people get ripped off by cobb?? if you have an 02/03 wrx yes you do. Its worthless, if i had my old wrx i would prove it but racing anyone you found me with a stage 2 wrx. But i have done so in the past and i did beat them. Drag strip freeway low end roll.
    I'm not contesting whether you beat them or not. You probably did beat stage 2s. And you did that because you were running leaner. Leaner burns are always more powerful, but leaner burns also bring significantly more heat to the table with them. It's a long term durability issue we're talking about here: leaner burn = hotter engine = more wear, reduced longevity. You only had the car for less than 2 years, which doesn't say squat. That's like assuming that cigarettes don't cause any long term problems simply because you smoked them for two years without experiencing any ailments at all. Between two identical cars, each with equal mods, and 5 years of equal usage, I would not be surprised at all if the car with the MBC would be much worse for the wear at the end of 5 years than the one with the AccessPort.

    Oh and don't forget PTFB. That's an issue you seem to be skirting around. PTFB is a serious problem, and at times is even more dangerous than the potential lean issues that occur during WOT. The factory boost control system is controlled via the ECU by the throttle position sensor. When the ECU enters open-loop at part throttle, it isn't mapped to provide anywhere near as much fuel as it is at WOT, and yet somehow you're running at full boost as though you were at WOT anyway. That's because the MBC has taken the control away from the ECU and let the turbo spin all the way up to maximum boost irregaurdless of how little fueling the ECU is providing.

    Part throttle fuel mapping intended for just a few pounds of boost + full boost = lean city.
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  5. #34
    pwn
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    w00t

    Can I just say this thread has been an awsome read so far?

  6. #35
    Registered User AwdTurboWrx's Avatar
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    Like i said, if you know how to use it and how to drive a car with mbc its not a problem. I will look for my dyno sheets and provide you with a/f numbers if i can find them.
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  7. #36
    Registered User wrxaddicted's Avatar
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    Quote Originally Posted by AwdTurboWrx
    Like i said, if you know how to use it and how to drive a car with mbc its not a problem. I will look for my dyno sheets and provide you with a/f numbers if i can find them.
    plz do!

  8. #37
    Registered User AwdTurboWrx's Avatar
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    found the sheets

    AFR MAX 12.43 Min 10.75 Average it says 11... thats at 17.5 psi. factory target is 12
    Last edited by AwdTurboWrx; 03-09-2006 at 01:38 PM.
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  9. #38
    Registered User AwdTurboWrx's Avatar
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    oh and i'd like to add thats 17.4 psi in 3rd gear which will hit fuel cut in 4th or 5th so i obviously wouldnt run that on the street. I would probably be at 15.5-16psi in 3rd on regular day basis so almost 2 less psi. That 17.4 with that AFR is only for dyno and checking power. You gotta consider that also.
    The Ghosts of Zooph and Sarcasmo Will haunt CLUBWRX forever!!!

  10. #39
    Registered User Kush's Avatar
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    Alright, I'm driving home next weekend and installing my UpPipe and AP, I'll let you know how she does on the 5 hour trip back to school

    It'll be right at stage 2, can't wait!
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  11. #40
    Registered User AwdTurboWrx's Avatar
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    Quote Originally Posted by AwdTurboWrx
    oh and i'd like to add thats 17.4 psi in 3rd gear which will hit fuel cut in 4th or 5th so i obviously wouldnt run that on the street. I would probably be at 15.5-16psi in 3rd on regular day basis so almost 2 less psi. That 17.4 with that AFR is only for dyno and checking power. You gotta consider that also.


    cheeseybacon?? anybody?
    The Ghosts of Zooph and Sarcasmo Will haunt CLUBWRX forever!!!

  12. #41
    Registered User Kush's Avatar
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    Well, I FINALLY got the AP set up, took a while because I had to get the restrictor pill and T-fitting from the dealer, who had to order it from Subaru...so that took forever.

    Anyway, I uploaded the stage 2 base map - what a difference

    Max boost is around 17-17.5, awesome trottle response, awesome acceleration on the highway, smooth revs, no more stumbling...really impressive, considering the entire upload took 10 minutes to complete. Once I reach the 200-300 mile mark, I'm sure it'll get even better as the computer re-learns.

    I'm only having one problem, and that is the boost seems to waver at full throttle. On the highway at full boost, I hit 17psi, but then it drops down to 15, then back up to 17, then 15, then 17, etc. etc. etc., all at full throttle. This can't be normal, it feels like the wastegate is cycling or something, is that possible?

    Thanks for any help, and thanks for all the great advice so far
    Aaron
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  13. #42
    pwn
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    Yea the AP does wonders . Congrats! About your boost...so it bounces between 15-17..Yea I dont know it does kind of sound like something would be cycling, and then it just builds up again and repeats. Yea Id get that looked at :/. Im sure someone on the boards will have an answer though, seems like almost every issue has already been experienced. ^^. Happy driving

  14. #43
    Registered User cheeseybacon's Avatar
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    The target boost for Cobb Stage 2 is 15.8psi +/- 0.5psi, so you really shouldn't be hitting 17.5 psi. The up and down phenomena of the boost is the probably a result of the AccessPort attempting to cut the boost back to wthin 15.8 psi. A lot of things could be causing it, but if you're sure you have all of your wastegate hoses and connections returned to stock correctly, then take a look at the wastegate arm itself (located on the turbo). Try losening it ever so slightly and see if the boost doesn't begin to slow down a little bit as it approaches 15.8 psi instead of flying all the way to 17.5 psi before being pulled back.

    Also, about the ECU learning. Give the Shiv reset trick a try. It definately works, and it'll get your ECU's ignition timing back up to snuff in a matter of minutes instead of days.

    Re-Mapped ECU Learning Trick 10-20hp in 5 seconds :)

    Also, how did the uppipe install go? Any problems with that?
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