No! I think I led you to BPW being all to important calibration factor before tuning, which is the case on other ECM. Just change the injector size in your ECM/PCM, if running higher pressure use the spreadsheet to get injector flow.
No! I think I led you to BPW being all to important calibration factor before tuning, which is the case on other ECM. Just change the injector size in your ECM/PCM, if running higher pressure use the spreadsheet to get injector flow.
1990 Chevy Suburban 5.7L Auto ECM 1227747 $42!
1998 Chevy Silverado 5.7L Vortec 0411 Swap to RoadRunner!
-= =-
See, this is where using the wrong term over time gets people confused. BPW is the time in milliseconds that the injector is commanded to open. You are thinking of Base Pulse Constant - the conversion factor used by the old ECMs to figure out the required PW or BPW.
Those parameters that you have open, are simply the minimum time in micro-seconds that the PCM is allowed to open the injectors. There is a point as you go shorter in time at which the amount of fuel dispensed by the injector is not consistant, and idle will get erratic.
You don't really need to worry about those.
1978 Camaro Type LT, 383, Dual TBI, '7427, 4L80E
1981 Camaro Z-28 Clone, T-Tops, 350/TH350
1981 Camaro Berlinetta, V-6, 3spd
1974 Chevy/GMC Truck, '90 TBI 350, '7427, TH350, NP203, 6" lift, 35s
Yup, just keeping with the trend of internet rumors, notice all masks and spreadsheets are BPW for this and should be BPC, where 16197427 mask is correct with BPW, Injector size must be the BPC factor... just like 5.7L 61 pph injectors being 55 pph...Originally Posted by gregs78cam
1990 Chevy Suburban 5.7L Auto ECM 1227747 $42!
1998 Chevy Silverado 5.7L Vortec 0411 Swap to RoadRunner!
-= =-
Well sort of......the later PCMs like '7427 have separate parameters for Displacement, and Injector flow, where the old '7747 bundle them together in one constant, that apperantly has a very narrow tolerance. But yea, something like that.Yup, just keeping with the trend of internet rumors, notice all masks and spreadsheets are BPW for this and should be BPC, where 16197427 mask is correct with BPW, Injector size must be the BPC factor... just like 5.7L 61 pph injectors being 55 pph...
Last edited by gregs78cam; 07-08-2012 at 06:09 PM.
1978 Camaro Type LT, 383, Dual TBI, '7427, 4L80E
1981 Camaro Z-28 Clone, T-Tops, 350/TH350
1981 Camaro Berlinetta, V-6, 3spd
1974 Chevy/GMC Truck, '90 TBI 350, '7427, TH350, NP203, 6" lift, 35s
In my opinion the size of the injector flow (lbs per hr) is what you should calculate first for the demand of fuel needed to match the engines consumption. This figure should be at no more than 80 % duty cycle. Larger Injector sizing sometimes is taken to large which also can cause poor performance regardless of pulse width. Injector sizing is no different than carburetor jet sizing, you can be to small or too large, there is still a sweet spot. As far as the pressure setting, this would only be fine tuning of the injector sizing and you don't want to beat up your injectors with excessive pressure, the higher the pressure the harder the injector pintle slams closed which will cause excessive, unneeded wear and erratic operation. I have never seen a gm throttle body application higher than 16 psi that was not erratic. Its important that you have enough reserve fuel flow from your fuel pump but don't overkill the flow rate, there is a percentage thats engineered into every vehicle, they do this for a reason. All systems can very per application.
Sounds like I have been doing this right all along then, I have not messed with many of the older ECM's. Mainly just the $0D code and the 94-95 $EE for the LT1's which also has the injector and engine size constants. I will try to keep the pressure in check and not to high. There is something I am holding back from you guys though....the main reason for the Walbro pump is because this winter I am planning on a custom MPFI project for this motor.
edl-71373_w.jpg
I have the belt setup off a Camaro to clear the TB, I have a set of 30 PPH Ford Injectors, I may even through in a differnt cam and a set of heads. This intake will accept an LS style TB. The only thing I am concered with is the IAC working with the 7427. I have not seen anyone try this yet.
-1999 Hugger Orange SS, LS2 402 T56, 9 inch Ford 3.90 gears, Tuned with HP Tuners
-2002 Cavalier, Tuned with HP Tuners
-1994 Full Size Blazer ,383 TBI 4L60E, 4.10's, Tuned with Tunerpro RT (Where it all began)
Sexy! That looks like a lot of air!
I've used the 1998-99 LS1 IAC, it looks the same as a Holley four barrel/BB TBI and Lt1 IAC, part number for 2000-01 is differant and did not try, but looks the same physically.
Did the ford injectors come with data sheet? We have found the biggest issue with unknown injectors is back to same settings like BPC, injector size, displacement but is the unknown Injector offset to voltage...
1990 Chevy Suburban 5.7L Auto ECM 1227747 $42!
1998 Chevy Silverado 5.7L Vortec 0411 Swap to RoadRunner!
-= =-
No but I wish they did, these are the Ford SVO red top injectors. I have been told that with the factory LT1 fuel pressure to set the injector size to about 32. I know about the the injector offest voltage. There was a thread going around on Fullsize chevy forum about this. I have a good starting point tune for when I convert to MPFI.
That would be some really good info the have though...let the search begin!
-1999 Hugger Orange SS, LS2 402 T56, 9 inch Ford 3.90 gears, Tuned with HP Tuners
-2002 Cavalier, Tuned with HP Tuners
-1994 Full Size Blazer ,383 TBI 4L60E, 4.10's, Tuned with Tunerpro RT (Where it all began)
I knew I read this before. But the LT1 is a little differant the an $0D, Usec and mSec... so read on...
http://www.camaroz28.com/forums/comp...ts-lt1-770192/
From Ford racing: All injector flow rates are quoted at a delta pressure of 39.15 psi. To convert to a delta pressure of 43.5 psi, multiply flow rate by 1.054.
1990 Chevy Suburban 5.7L Auto ECM 1227747 $42!
1998 Chevy Silverado 5.7L Vortec 0411 Swap to RoadRunner!
-= =-
Awesome Thanks
-1999 Hugger Orange SS, LS2 402 T56, 9 inch Ford 3.90 gears, Tuned with HP Tuners
-2002 Cavalier, Tuned with HP Tuners
-1994 Full Size Blazer ,383 TBI 4L60E, 4.10's, Tuned with Tunerpro RT (Where it all began)
This has been an interesting read...........
Is that you Allen?This has been an interesting read...........
-1999 Hugger Orange SS, LS2 402 T56, 9 inch Ford 3.90 gears, Tuned with HP Tuners
-2002 Cavalier, Tuned with HP Tuners
-1994 Full Size Blazer ,383 TBI 4L60E, 4.10's, Tuned with Tunerpro RT (Where it all began)
The one and only lol.
I've been reading on here for a few months now but never joined. I was on late last night and saw your screen name and looked at location. "Yep, that's Tim"...so I had to join up just to say hello.
Somehow I'm not surprised you'll be tearing into the blazer again. Looks like you'll be going with quite an upgrade. I plan on doing something to my truck whenever I get the opportunity. It's on work duty right now though until I can get this dam! anti-theft light issue fixed on the Expedition. I dunno...if I could find a used supercharger set-up, it would be worth looking at.
On this thread, IIRC from last night...my stock 55's with 14 psi on 190lph pump cannot feed the purported 320hp DD says my combo will make right? Yet it was running 13.0 afr at WOT. Intake not flowing enough? That's the only thing I could think of. It's bored 2" and gasket matched but don't know the flow numbers on the GMPP intake.
Welcome!
55PPH injectors is a mistake that spread through internet, they are 61PPH. But someone could have origanally tested one to be 55PPH as: "These flow rates are a safe bet average @ 13psi, be aware that actual flow can vary by greater than 10% throughout production." or a differant fluid other then gasoline was used.
http://www.gearhead-efi.com/Fuel-Inj...d-part-numbers
Look at the same injectors used in newed 16197427 TBI PCM and factory bin says they are 61PPH.
HTH!
1990 Chevy Suburban 5.7L Auto ECM 1227747 $42!
1998 Chevy Silverado 5.7L Vortec 0411 Swap to RoadRunner!
-= =-
Finally got around to starting my truck tonight with the new fuel pump and it is only running 10 pounds of fuel pressure. So I may be doing the AFPR mod to the the stock regulator. Maybe my diaphram is leaking. I dont know.
I forgot to check and see if it is still holding pressure after I shut it off. I have some more trouble shooting to do.
-1999 Hugger Orange SS, LS2 402 T56, 9 inch Ford 3.90 gears, Tuned with HP Tuners
-2002 Cavalier, Tuned with HP Tuners
-1994 Full Size Blazer ,383 TBI 4L60E, 4.10's, Tuned with Tunerpro RT (Where it all began)
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