427 CI build C5 corvette......inside need help
02-11-2005, 08:01 PM
#1
427 CI build C5 corvette......inside need help 1998 C5 Corvette
Mods:
427 ci
Cam is a Futral custom hydraulic grind dur @.050=252/260 lift is .680 on intake and .660 on exhaust. Ground on a 113 center.
11:1 compression
fully worked heads with VERY good flow numbers at all lifts
90mm tpis TB
Fast intake.
Halltech system with filter in front license area.
Tuning MAFless...dont even have a MAF
Car starts right up..idles for a few seconds and then starts to surge...to the point that it stalls.
I have searched the forum..and tried all the tricks.......my idle is set at 950.....I have tried adding timing....my wideband is running at 13.00
I have a 5/32 hole in the throttle blade.....should I make it bigger?...I dont have an actual IAC....because the TB is drive by wire.....so I am not real sure how I should be tuning with this type of throttle body.
Please help....me with this. Please do not refer me to other links....I have read them all.
Also can someone go into detail on how to use the histogram with wideband and VE tuning..
Also When going MAFless .....I know you tune with the secondary VE table........but do you tune on the "high octane or low octane" table.....when tuning MAFless...
THANKS for all the help...Tom
Mods:
427 ci
Cam is a Futral custom hydraulic grind dur @.050=252/260 lift is .680 on intake and .660 on exhaust. Ground on a 113 center.
11:1 compression
fully worked heads with VERY good flow numbers at all lifts
90mm tpis TB
Fast intake.
Halltech system with filter in front license area.
Tuning MAFless...dont even have a MAF
Car starts right up..idles for a few seconds and then starts to surge...to the point that it stalls.
I have searched the forum..and tried all the tricks.......my idle is set at 950.....I have tried adding timing....my wideband is running at 13.00
I have a 5/32 hole in the throttle blade.....should I make it bigger?...I dont have an actual IAC....because the TB is drive by wire.....so I am not real sure how I should be tuning with this type of throttle body.
Please help....me with this. Please do not refer me to other links....I have read them all.
Also can someone go into detail on how to use the histogram with wideband and VE tuning..
Also When going MAFless .....I know you tune with the secondary VE table........but do you tune on the "high octane or low octane" table.....when tuning MAFless...
THANKS for all the help...Tom
02-11-2005, 08:36 PM
#2
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You tune on the high octane table. If the car gets knock it will interpolate to values in between the two tables. If it still has knock it will go as low as using the low octane values. Some people used to set both tables the same to force timing to stay high, but that is a good way to take out a piston.
As for the idle, you can play with the main ve table to get it to idle. With that cam you really need a higher idle and a little leaner would help also. I usually run them 14.6-15 to 1 ratio for idle. You just have to play with it to try and find the sweet spot on the a/f. That is a huge cam for hydralic. Those look like solid roller lift numbers. Good luck with it.
As for the idle, you can play with the main ve table to get it to idle. With that cam you really need a higher idle and a little leaner would help also. I usually run them 14.6-15 to 1 ratio for idle. You just have to play with it to try and find the sweet spot on the a/f. That is a huge cam for hydralic. Those look like solid roller lift numbers. Good luck with it.
