maf-t install now problems

[killer_eclipse]

ok so i installed a blow thru set-up now every time i hit boost the car stumbles and hesitates and sounds like a machine gun. now i have searched and searched and find threads where people talk about this problem but never have an answer as to a solution.
things i have tried:
boost leak test - found one really big one fixed it but no change.
changed plugs to bpr7es no change.
tried every setting combo i can on the maft and safc.

i have a wideband on its way but want to Try to figure it out asap I'm really annoyed because everything was fine till this install.

 

[1993eclipseGS]

What are your settings in the MAFT? Have you tried to zero everything out and just set the injector size in the maft, And see if the problem is still the same? The injector sizing is only a start, So do not take those injector size numbers as a direct 100% number, When setting that dial.

 

[killer_eclipse]

i have tried setting the maft at my injector size and i have tried zeroing it and used only the safc with no change. i am able to get the fuel trims set pretty well but no matter the adjustment WOT continues to have problems.

 

[Gooberlog]

i have tried setting the maft at my injector size and i have tried zeroing it and used only the safc with no change. i am able to get the fuel trims set pretty well but no matter the adjustment WOT continues to have problems.

I'm going through the same issue. My wide band is pegged at 10.0 at WOT showing it's really rich at full throttle. I'll be attempting to re-tune this week.

 

[killer_eclipse]

well I'm pretty sure i found the problem.... my alternator is putting out low voltage and i believe its causing me to run out of fuel pump at high end because i had my fuel pressure up at 60 psi base i have now turned my boost down to 15 psi and my fuel pressure to 38 and now i am running beautifully. i will get a new alternator then turn my fuel pressure and boost back up and see if it solved the problem for sure.

 

[black91awdturbo]

well I'm pretty sure i found the problem.... my alternator is putting out low voltage and i believe its causing me to run out of fuel pump at high end because i had my fuel pressure up at 60 psi base i have now turned my boost down to 15 psi and my fuel pressure to 38 and now i am running beautifully. i will get a new alternator then turn my fuel pressure and boost back up and see if it solved the problem for sure.

What injectors are you using? And why would you have your fuel pressure as high as 60 psi?

 

[killer_eclipse]

The base fuel pressure you want to use as a starting point should match the ECU's idea of what's stock just to make it easier to dial in any corrections for injector size differences. So with a 2G ECU you might want to start with a 2G base FP.

After that you can run any base pressure that makes sense for your setup keeping in mind that max pressure is based on what your fuel pump can do before the relief valve in the pump opens, including any system pressure drops between the regulator and the pump based on your max boost pressure. So absolute max base FP = (Relief Valve setting - safety fudge - pressure drop to regulator - max boost). Also keep in mind that some injectors work better than others at high pressures and that fuel pump flow rates drop as pressure increases.

Changing the base pressure from stock changes the effective injector size.
New flow rate = (SQRT (new pressure/old pressure) * old flow rate)

Factory Base pressures:
1G NA 47.6 psi
1G T Auto 42.7 psi
1G T MT 36.3 psi
2G T 43 psi

Steve

steve said it best as always in another post.
i am running 560cc evo injector but with the higher fuel pressure they are mathematically supposed to be running 657.69cc so close to 660's

 

[black91awdturbo]

steve said it best as always in another post.
i am running 560cc evo injector but with the higher fuel pressure they are mathematically supposed to be running 657.69cc so close to 660's

What fuel pump are you running in this car right now?

 

[killer_eclipse]

a walbro 255hp... the high fuel pressure is only temporary till i get my ecu back from getting chiped and can put my 880's in

 

[Gooberlog]

I'm going through the same issue. My wide band is pegged at 10.0 at WOT showing it's really rich at full throttle. I'll be attempting to re-tune this week.

I adjusted my fuel and timing tables with DSMlink v2 and it seems to be running good now. Good luck with yours, could be a similar problem. My car was running real lean on low rpm's and then real rich under boost until i made the adjustments.

 

[killer_eclipse]

well i never go the chance to see if the alternator solved the problem because after instaling it i never got the chance to turn my boost back up cause i sent my ecu out to be chiped and im putting in my wideband and 850cc injectors so i will have to check back in a couple of weeks

 

[Gooberlog]

well i never go the chance to see if the alternator solved the problem because after instaling it i never got the chance to turn my boost back up cause i sent my ecu out to be chiped and im putting in my wideband and 850cc injectors so i will have to check back in a couple of weeks

Well we both have a maf-t, 850's, and a AEM wideband guage, so let me know if i can help.