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Here is the deal.... My engine idles at 65-70kpa@750rpm after the new mods. My idle is extremely rich. This is partly due to the ve tables. But I think the main reason is that because my kpa is soo high the f/p regulator is not hitting the lower limit(39psi). Once I start to drive, the regulator works normal(varies from part throttle 39psi to wot 43psi). Everything is new.... So should I just lean out the idle in the ve tables or find a way to give the regulator enough vacuum? Or just disconnect the vacuum to the regulator and tune for that???
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Everybody has that problem with a cam that pulls low vacuum, which is one of the reasons you are always soo rich at idle and part throttle wich is where the most vacuum is. Aside from deceleration of course.
Just scale the VE as everybody else does, Also once you get your tune closer the vacuum should raise some as well help the problem even more.
It is nothing to scale lower VE by 20% and more after a large cam install.
One way I always thought would be good to get an awsome idle, and full use of VE, would be to use TPS sensor as map voltage supply, and lose the MAP all together being that throttle position and map are directly affected the same almost.
It would stop that pulsing of vacuum problem.
__________________ [/size][/color]
76 Vega 498 BBC, AFR 325 heads, and a few other goodies.9.02 @ 151
93 Firebird, 7730 ECM, most other 3rd gen running gear, 406 afr's, T56, 11.0 N/A, 10.41 W/150 Shot.
Originally posted by 11sORbust Here is the deal.... My engine idles at 65-70kpa@750rpm after the new mods. My idle is extremely rich. This is partly due to the ve tables. But I think the main reason is that because my kpa is soo high the f/p regulator is not hitting the lower limit(39psi). Once I start to drive, the regulator works normal(varies from part throttle 39psi to wot 43psi). Everything is new.... So should I just lean out the idle in the ve tables or find a way to give the regulator enough vacuum? Or just disconnect the vacuum to the regulator and tune for that???
Closed Loop?.
Stock injectors?.
Doubling the HP of a stocker, running stock code with stock injectors is difficult to do. The small injectors, force large BL changes to get things close. And once you close it's still tempermental.
With a large injector, I'd say try the none referenced idea, but it'd be easy to go too lean up on top, IMO.
Tune the VE down in your idle region, and remember to leave the 80-100 K/Pa stuff alone, at the idle rpm regions.
Originally posted by 87_TA
One way I always thought would be good to get an awsome idle, and full use of VE, would be to use TPS sensor as map voltage supply, and lose the MAP all together being that throttle position and map are directly affected the same almost.
It would stop that pulsing of vacuum problem.
TRY IT! !!!
The AE stuff probably would take some tweaking.
Running the same VE values in the whole idle region is an another way.
so just "ignore" this condition and tune the ve @ idle, right.?
Btw, here is the specs
73' 400 ci block
bored .030
holley stealth ram
58mm bbk tb
71' 400ci heads (ported to hell)
cam:242/250*duration, .550/.570" lift ,114lda
matching valvesprings and "special" lifters
30lb accel injectors
1.6:1 ratio rockers
1 5/8 headers
no exhaust(cutout)
I'm sure there is more.. Today I reduced the idle ve by 25%. But I wanted to get some input on the fpr condition. So it's nice to know I can just tune around it.....
I did notice (today) that my idle is at 65-70kpa. The brakes work great though. So I guess everything is fine.!?
enlighten me guys! i have a speed density car, 7747, TBI of course. Is this thread regarding a MAF car? If so do they use a FPR that is vacuum referenced? low vacuum=higher fuel pressure? Is the fact that my SD car has stable FP(relatively) make it easier to tune? I know that some of us tried vafpr(me too) and chose to not use it opting instead to go larger injectors to satisfy fuel requirements. what is the threory of using a vac sensitive FPR vs static FP.
Originally posted by Ronny enlighten me guys! i have a speed density car, 7747, TBI of course. Is this thread regarding a MAF car? If so do they use a FPR that is vacuum referenced? low vacuum=higher fuel pressure? Is the fact that my SD car has stable FP(relatively) make it easier to tune? I know that some of us tried vafpr(me too) and chose to not use it opting instead to go larger injectors to satisfy fuel requirements. what is the threory of using a vac sensitive FPR vs static FP.
Ronny, in a port injection car at low engine speeds, it seems if your pulse width is too short its not as smooth running as a longer PW. due to lack of port velocity and efficiency, therefor lower FP allows a longer pw which is a blessing with larger injectors.
It also allows broader range of VE as well.
__________________ [/size][/color]
76 Vega 498 BBC, AFR 325 heads, and a few other goodies.9.02 @ 151
93 Firebird, 7730 ECM, most other 3rd gen running gear, 406 afr's, T56, 11.0 N/A, 10.41 W/150 Shot.
Originally posted by Grumpy TRY IT! !!!
The AE stuff probably would take some tweaking.
Running the same VE values in the whole idle region is an another way.
I plan to Grumpy,
I will probably do so on my camaro when I get around to swapping it to EFI .
But also would like to have an ECM bench before doing so.
__________________ [/size][/color]
76 Vega 498 BBC, AFR 325 heads, and a few other goodies.9.02 @ 151
93 Firebird, 7730 ECM, most other 3rd gen running gear, 406 afr's, T56, 11.0 N/A, 10.41 W/150 Shot.
