hey guys ive got a problem currently i am running 7 psi and a safc with a ruff tune the motor is going to be built so im going to run more boost and timing will soon become an issue. i wanted to run a Begi fmu to increase fuel press. but i also need to run the msd to pull timing for boost . the problem is that i heard that the msd needs a map to run and im already using the map for the safc which i will need to keep because it pulls fuel out of my large injectors at idle. so guys how do i run all of these.
Matt Macomber wrote:the problem is that i heard that the msd needs a map to run and im already using the map for the safc
The MSD needs A MAP, not THE MAP. You need to get a second MAP for the MSD and only the MSD. Nothing should be spliced to it.
Matt Macomber wrote:which i will need to keep because it pulls fuel out of my large injectors at idle. so guys how do i run all of these
Good guess but it is very likely it will not work. In 95, the fueling was done based on MAP/RPM. In 97-up the fueling was TPS/RPM based.
I have no idea which system was used in 96, but I would put my money on TPS/RPM.
The SAFC changes the amount of fuel by altering the MAP signal. If your car is TPS/RPM then changes to the MAP signal will only change timing and do nothing for fuel at all.
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my safc is spliced into the map where i can control fuel , because at idle i can pull fuel out of the injectors to get a better idle and that is what i need to do because im going to have a set of 550's and i need to be able to pull fuel out at idle
Actually Todd is correct. 96-2002 non-GMSC PCM's are TPS/RPM for fuel, meaning it reads throttle position and RPM's to calculate volumetric efficiency and therefore fuel.
By splicing in the S-AFC into the map sensor and reducing its signal all you are doing is telling the engine to use less timing. That's literally all it's doing.
I used an S-AFC too, and yes it works but you need to keep in mind it is NOT pulling fuel. It's pulling timing.
As for your original question, Todd is correct on that also. Follow his advice on the MSD - he actually uses the MSD programmable himself. You need to pick up a MSD map sensor and plug it into a vaccum source and run it straight to the MSD.
Ditch that S-AFC.
-Chris-
-Sweetness-
-Turbocharged-
Slowly but surely may some day win this race...
SweetnessGT wrote:Actually Todd is correct. 96-2002 non-GMSC PCM's are TPS/RPM for fuel, meaning it reads throttle position and RPM's to calculate volumetric efficiency and therefore fuel.
-Chris-
I said very clearly that No One knows about his
96 PCM. HP is only 97-up and My 95 is a totally different system.
It can go either way.
If he's had luck using it so far, then a 96 may be Map/Rpm.
95 2.3 Manual trans cars and 2.2 are MAP/RPM. Verified by myself.
95 2.3 Auto and all 96 use the same unknown PCM. No way to check,
97-up use a TPS/RPM PCM. Which has been verified with HP tuners.
Since his pcm was used in 95 also, I would guess that its like 55/45 that he is Map based. If he has verified it at this point (he post seems future tensed) then its even more likely. Of course, verified would mean with a wide band because an SAFC "adding" fuel would actually be adding spark advance on a TPS based PCM. This would make the car run better without actually leaning it out.
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protomec wrote:Of course, verified would mean with a wide band because an SAFC "adding" fuel would actually be adding spark advance on a TPS based PCM.
That was supposed to say "Of course, verified would mean with a wide band because an SAFC "removing" fuel would actually be adding spark advance on a TPS based PCM.
The reason is this .... to remove fuel, the safc has to decrease the MAP signal which = higher vacuum readingto the PCM. Higher vac = more timing advance.
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once i get the MSD -Dis2 in and the fmu , do i need to still use the safc or is there a way that i can tune my injectors with the msd.
The MSD Controls spark. Why are you buying equipment if you do not know what it is used for?
Todd - thank you for the correction I must not have had enough coffee. 97-2002... I really do wonder what the 96 PCM runs considering it's a bastard hybrid year.
-Chris-
-Sweetness-
-Turbocharged-
Slowly but surely may some day win this race...
chris dont give me a hard time i know what all the parts do , i just dont know how they will hook up together
what i was going to do was keep the safc for the injectors at idle and use the fmu to increase psi when i get into boost and then use the msd to pull timing when i am in boost. will this work or is there something that i dont need to do to acheive my goal thanks
MSD is spark only, no fuel adjusting there
You might want to think about a PCM and harness swap to 97+, while it may be a pain to do, in the long run its prob easier to work with than that weird ass 96 pcm
You need some sort of device to monitor knock retard, like an autotap or some type of OB2 scan tool, while it wont offer programming ability it will let you know whats going on in there, trying to tune spark without monitoring knock retard is like trying to tune fuel without a wideband. Gotta know whats going on before you start adjusting things otherwise you might be doing more harm than good, and id turn the boost down as low as possible till you get the hang of tuning things, less boost closer to stock tune.
1989 Turbo Trans Am #82, 2007 Cobalt SS G85
im not using the stock pump ,i have a walbro 255, im not trying to be a dick and i am not one of those people that buy something and then ask how it works later, i havent bought the fmu or the msd yet . I am mapping out how everything should work before i get the parts i need. im planning ahead which is something a newb doesn't do. i just wasent sure on all the things that the msd is capable of. i know she wont be completely perfect but i think that i will be able to get pretty damn close. thanks guys and chris i still think the information that you have to give is valuable so thankyou.
Matt, no problem. Honestly good luck with it I did this setup and it really is a pain to get it all perfect (and even then it was far from it...), especially with an FMU. Remember 10 psi boost is 10 psi boost to an FMU, it doesn't do anything about RPM's so you'll have to tune the car so it's rich down low and at the AFR you want up top. You can try working your way around this with the S-AFC - hopefully it'll help a bit. Using the programmable MSD will help you with spark retard + boost but you have to have a way to monitor it so you can tune properly, and as for the S-AFC it's honestly only good for getting an idle on larger injectors (for the most part)... expect to run pig rich during warmup.
Even with a Walboro I wouldnt go over 80 psi fuel pressure personally, and even that is pushing. I pushed my Blazer to 100 or so PSI under full load and I can tell you that in the higher RPM's it just struggled... also some Injectors (such as the H.O ones) loathe to run over 70 psi and often clip or break up.
Good luck, I know what it's like to get that setup going.
-Chris-
-Sweetness-
-Turbocharged-
Slowly but surely may some day win this race...
thanks chris im going with a set of 550cc injectors, so i am going to use the safc for the injectors at idle but as the rpms increase ill add fuel with it and im going with the begi 2025 so i can adjust what i need and i got to keep a close eye on my wideband to find that sweet spot. i see alot of dyno tuning in my future
