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Old 10-31-09, 02:50 PM  
matsoda
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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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