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Walbro 255lph Pump for 2008 STi/WRX/LGT
Walbro 255lph Pump for 2008 STi/WRX/LGT
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Old 10-30-09, 11:03 PM   #61
blkscooby
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Default Re: Walbro 255lph Pump for 2008 STi/WRX/LGT

I just installed mine tonight. Took about 1.5 hours 'cause all I had available to trim the housing was a file .
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Old 10-31-09, 02:50 PM   #62
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Default Re: Walbro 255lph Pump for 2008 STi/WRX/LGT

Did you end up resolving your hesitation issue? Did you also do an injector install at the same time?

Unfortunately, i'm also seeing bad hestitation at 2800-3000rpm under light-medium throttle Ocurrs at same range in any gear.

Note: WOT is fine. No hestitation or leaning under full throttle.

AFR's are spiking as high as 20:1 momentarily whilst the hestitation occurs. At the same time the IDC reading are steady and consistant.

The Walbro install seemed very solid, but i removed the Walbro and re-installed the stock pump as i was sure it was a problem with the Walbro install. But the stock pump hasn't fixed the issue!

I installed some new DW850cc injectors at the same time, so i'm guessing the issue is with the injector install. The injectors are flow tested from new so it seems unlikely that they will be faulty.

I filled the manifold with around 16psi of air pressure today and it didn't leak at all. So i can assume that the injectors are sealed properly in the manifold.

Could it be the injector latency values? Can anyone confirm the latency values for DW850's? Would it be worth re-installing the stock injectors to rule that out?



Quote:
Originally Posted by WRBear View Post
Hmmm, maybe I shouldn't have grinded those down then...they really didn't yield me too much clearance. However, my problems haven't changed--just did some street pulls tonight with my tuner, and the car spikes far too lean when I hit peak boost.

I've tried it all, dremmeling the housing, the pump, the 2nd o-ring, and lastly, the CJ-Motorsports clamp--problem still persists.

I'll be returning to the stock fuel pump until I (if I ever do) purchase the AVO--but money is tight at the moment, and there are higher priorities--like credit card bills :\ and snow tires.

Best of luck in doing this mod, and congrats to everyone who did this, but I just advise you to watch your AFRs--go on a dyno, or use a wideband, and make sure you don't go too lean.

Chris
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Old 11-03-09, 08:35 AM   #63
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Default Re: Walbro 255lph Pump for 2008 STi/WRX/LGT

Quote:
Originally Posted by matsoda View Post
Did you end up resolving your hesitation issue? Did you also do an injector install at the same time?

Unfortunately, i'm also seeing bad hestitation at 2800-3000rpm under light-medium throttle Ocurrs at same range in any gear.

Note: WOT is fine. No hestitation or leaning under full throttle.

AFR's are spiking as high as 20:1 momentarily whilst the hestitation occurs. At the same time the IDC reading are steady and consistant.

The Walbro install seemed very solid, but i removed the Walbro and re-installed the stock pump as i was sure it was a problem with the Walbro install. But the stock pump hasn't fixed the issue!

I installed some new DW850cc injectors at the same time, so i'm guessing the issue is with the injector install. The injectors are flow tested from new so it seems unlikely that they will be faulty.

I filled the manifold with around 16psi of air pressure today and it didn't leak at all. So i can assume that the injectors are sealed properly in the manifold.

Could it be the injector latency values? Can anyone confirm the latency values for DW850's? Would it be worth re-installing the stock injectors to rule that out?
I assume that you had the injectors tuned for. There is a load compensation table for RPM and MAP that needs to be adjusted for new injectors or intake. I am in the process of addressing this same issue on my car with modded stock injectors (about 1000 cc/min). Very lean around 2800-3200 when coming into boost. No knock though.
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Stage 1- 12.98 @ 104.96 Firebird Raceway AZ 6/6/09
20g E85- 12.12 @ 115.3 Firebird 4/9/10

20g- 338/348 on 91 oct. E85-394/410
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Old 11-04-09, 06:05 AM   #64
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Default Re: Walbro 255lph Pump for 2008 STi/WRX/LGT

Thanks for letting me know! I managed to find the thread on RomRaider that outlines how to adjust that compensation table you mentioned.


Problem solved !! thanks mate!

In case anyone could use some background on solving the hestitation issue:

I read the thread on RomRaider titled 'How To Fix The 08 STI 2400-3200rpm stumbles', then went for a long drive and logged the following parameters using RomRaider with cruise control engaged to keep it in closed-loop with a steady throttle to avoid tip-in enrichment:

Engine Speed
Manifold Pressure
Throttle Opening Angle
A/F Correction #1
A/F Learning #1
A/F Sensor #1

Cruised along for 30mins at light throttle between 2600-3200 whilst the hesitation was occuring. Went over the logs and got a rough idea of how much compensation was required for each Manifold Pressure/RPM combination by looking at the A/F Correction #1 value.

I then added those values to the 'Engine Load Compensation A & B' tables as described in the thread (my compensation tables were all zero'd out to start with). Then I checked the results were in line with what others had posted on the thread mensioned.

Flashed the new image and there's no longer any hesitation at all. I'll have to work on it some more as the initial values were only rough estimates based on a relatively small amount of data. But it worked a treat.

I have a stage-2 08 STI with a 3in turbo-back, DW850 injectors and a Walbro. I've attached the rough compensation values that did the trick for me.

Cheers




Quote:
Originally Posted by blkscooby View Post
I assume that you had the injectors tuned for. There is a load compensation table for RPM and MAP that needs to be adjusted for new injectors or intake. I am in the process of addressing this same issue on my car with modded stock injectors (about 1000 cc/min). Very lean around 2800-3200 when coming into boost. No knock though.
Attached Thumbnails
Walbro 255lph Pump for 2008 STi/WRX/LGT-engineloadcompensationa-jpg   Walbro 255lph Pump for 2008 STi/WRX/LGT-engineloadcompensationb-jpg  

Last edited by matsoda; 11-04-09 at 06:10 AM.
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Old 11-04-09, 07:13 AM   #65
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Default Re: Walbro 255lph Pump for 2008 STi/WRX/LGT

Quote:
Originally Posted by matsoda View Post
Thanks for letting me know! I managed to find the thread on RomRaider that outlines how to adjust that compensation table you mentioned.


Problem solved !! thanks mate!

In case anyone could use some background on solving the hestitation issue:

I read the thread on RomRaider titled 'How To Fix The 08 STI 2400-3200rpm stumbles', then went for a long drive and logged the following parameters using RomRaider with cruise control engaged to keep it in closed-loop with a steady throttle to avoid tip-in enrichment:

Engine Speed
Manifold Pressure
Throttle Opening Angle
A/F Correction #1
A/F Learning #1
A/F Sensor #1

Cruised along for 30mins at light throttle between 2600-3200 whilst the hesitation was occuring. Went over the logs and got a rough idea of how much compensation was required for each Manifold Pressure/RPM combination by looking at the A/F Correction #1 value.

I then added those values to the 'Engine Load Compensation A & B' tables as described in the thread (my compensation tables were all zero'd out to start with). Then I checked the results were in line with what others had posted on the thread mensioned.

Flashed the new image and there's no longer any hesitation at all. I'll have to work on it some more as the initial values were only rough estimates based on a relatively small amount of data. But it worked a treat.

I have a stage-2 08 STI with a 3in turbo-back, DW850 injectors and a Walbro. I've attached the rough compensation values that did the trick for me.

Cheers
Glad to hear you fixed it! Part of my lean issues were also caused by the valve cover vent hose being off from when I last installed the IC. Oops. Fixed and now I am retuning the load comp table to cure all hesitation.
__________________
Stage 1- 12.98 @ 104.96 Firebird Raceway AZ 6/6/09
20g E85- 12.12 @ 115.3 Firebird 4/9/10

20g- 338/348 on 91 oct. E85-394/410
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Old 01-27-10, 01:49 PM   #66
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Default Re: Walbro 255lph Pump for 2008 STi/WRX/LGT

Can the stock fuel pump be reinstalled after the housing is modified for the 255?
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Old 01-27-10, 03:00 PM   #67
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Default Re: Walbro 255lph Pump for 2008 STi/WRX/LGT

Quote:
Originally Posted by mcganz121 View Post
Can the stock fuel pump be reinstalled after the housing is modified for the 255?
Probably not, I have never attempted that since the housing is shaved down.
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Old 01-28-10, 07:50 AM   #68
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Default Re: Walbro 255lph Pump for 2008 STi/WRX/LGT

I've had no problem with mine. As long as the pump 'clicks' in, you should be ok. Been a few months now, no problems, no codes. AFRs were great when I got it retuned.
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Old 03-18-10, 02:58 PM   #69
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Default Re: Walbro 255lph Pump for 2008 STi/WRX/LGT

If DENSO has a fuel pump that flows 62% more then the walbro 255 and is similar to the stock pump in size, fitment and requires no cage modifications would you guys buy it?
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Old 03-18-10, 03:18 PM   #70
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Default Re: Walbro 255lph Pump for 2008 STi/WRX/LGT

If it was 63% MAYBE but 62% probably not.
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