Someone had an unfortunate "SMELTING accident....."Originally Posted by Six_Shooter
Someone had an unfortunate "SMELTING accident....."
'86 Grand National
@Six_Shooter: I love smelt fishing lol. My bad.
@EagleMark: My car has no map sensor at all.
@Xtreamvette: Yes the Volt drop is the fan, MAF is stock and not descreened.
Last edited by ZEDRATED; 08-20-2013 at 06:14 AM.
ok got some time and dug up my accel inj table and it says the 30# injector actually flows 27.9@2.7bar or 39.2psi and 29.4@3.0bar or 43.5psi .
i'm still not sure i belive the set of accel voltage offsets i'm using atm in that bin and i do have another set of offsets that claim to be good for ALL accel injectors up to 75lb/hr. they are:
Volts Dc uSec added
0.00 701.91
1.6 701.91
3.2 7782.09
4.8 7782.09
6.4 4455.63
8.0 2044.71
9.6 1464.86
11.2 1068.13
12.8 793.47
14.4 579.84
16.0 396.73
17.6 244.14
19.2 91.55
20.8 0.00
22.4 0.00
24.0 0.00
ones im using atm are:
25.6 0.00
24.0 0.00
22.4 0.00
20.8 0.00
19.2 0.00
17.6 0.00
16.0 0.00
14.4 0.00
12.8 0.00
11.2 0.00
9.6 732.43
8.0 1495.38
6.4 2807.66
4.8 4364.07
3.2 5981.53
1.6 732.43
0.0 701.91
these are the ones i saw posted here and a few other places as well but they just dont look belivable, what do you guys think? i'm wanting to go with the 1st set of offsets i listed as there more belivable to correct offsets of similer injectors.. just cant belive all the zeros in that second set, just seems odd.
so Zed, whats your fp running?
I am at 44 psi so that's pretty close to 43.5.
fish and scents arent what i think of first when hearing smelt, i think molten metal "smelting furnace"
All this smelt talk and we will be up to 35 pages again real soon hahahahahaha. This is what this forum is all about, having some fun and learning. Great to be here.
thought you said 44 koeo? it should drop 3-10 when running but only you can tell me how much?
Well when running I think it is going to about 38 but I'll need to double check, but when they recommend 33.5psi isn't that with the key on engine off? I believe soo???
i would guess the opposit as koeo is kinda irrelevant to the injectors... only thing there concerned with i would think is running fp... someone can correct me here if im wrong but it just seems most logical.
hmmm a quick search brings it up as both ways depending on fuel system type. lol figures.
tbh its not a ton of differance in flow either way and we need more fuel i know so lets go with 43.5psi running, you will gain a lil better attomization if nothing else. and i know from looking at all your diff logs that you definatly will need more fuel at mid and wot anyhow as well... the miniram loves fuel at tip in and under throttle.
after some figures that may be more then we need but idk as idk how far into lean we are, only that its max that ecm can display..
at this point richer is safer then lean and we can easily adjust the fp
on second thought lets just leave it where it is i guess i will adjust fuel tables instesd i guess.
here is just a baby steps bin i only changed the inj constants to what accel rates the flow at as well as i decided to change the inj offset to voltage table to the other one i had as i belive it is more realistic and is alot more somiler to the one used for the ford red top 30# injectors..
anyhow same thing with the log as before , probably doesnt need to be as long though maybe 1/2 as long as i just need to see where that lil bit moved us.
Last edited by xtreamvette69; 08-20-2013 at 09:05 AM.
the 7165 actually has 2 MAP type A/D channels(in that they have a 51K resistor to ground, channels 0 and 3. channel 0 is pin D8, channel 3 is pin C11.
if i had to guess(since i don't have the datastream data inserted into my disassembly), i'd say that datastream item is a raw read of one of those A/D channels. be an easy way to get wideband data into it, since it wouldn't even need patched.
1995 Chevrolet Monte Carlo LS 3100 + 4T60E
Ok, time for a little lesson on fuel pressure and why there is vacuum reference.
What we are really looking for here is "delta fuel pressure" or the different in pressure across an injector.
Since the atmospheric pressure at sea level is 100 KPA, or 14.7 PSIA, we need to account for this atmospheric pressure when dealing with delta pressures.
At key on, engine off, setting the fuel pressure to 44.3 PSIG, is actually a delta pressure of 29.6 PSI (44.3 PSIG - 14.7 PSIA). When an engine starts it creates a vacuum in the runner between the throttle blade and the intake valve, which is a pressure that is lower than the 14.7 PSIA. We see this in our data logs as MAP KPA. You will notice that when the engine is running, the numbers are lower, much lower than atmospheric pressure. Why is this important? Delta pressure. We want to maintain the same 29.6 PSI of delta pressure across the injector, to be able to easily predict fuel delivery. This is also why forced induction applications use a "boost referenced" fuel pressure regulator that will raise fuel pressure at a 1:1 ratio of boost pressure to fuel pressure to maintain that same delta pressure.
If we didn't use vacuum referenced fuel pressure regulators, then the delta pressure would change, with different loads. At idle an injector would deliver more fuel than at WOT, because the delta pressure is greater at idle than at WOT, assuming the pulse widths to be the same. Obviously there is the aspect of changing pulse width, but in a case like this the pulse width would have to be very short, possibly too short for the injector to actually deliver a sufficient amount of atomized fuel to support complete combustion. Add in forced induction and the problem is exacerbated in that the delta pressure will be reduced, and it could be reduced to a point, theoretically, that the delta pressure is zero and the fuel can not flow through the injector. The engine would stop running long before that, but it illustrates the point.
The man who says something is impossible, is usually interrupted by the man doing it.
so basically in a nut shell this is the complex way of saying
*NA idle=high vacuum which helps to suck the fuel through the injuctor hence less FP is needed.
*NA WOT=low or no vacuum to help suck fuel so FP needs to be more
*boost= needs alot more pressure to flow because it has to fight the force of boost to deliver the same rate of fuel
if thats what you ment then i knew that, all except the perfect delta pressure of 29.6 thanks but now its up to me to figure out how to use that in this senerio lol
i'm guessing that one thing i can gather from this is that the amount of vacuum or lack of with his cam would play a part in the perfect delta pressure of 29.6... hmm no that would be irrelivent because the same vacuum or lack of would be on the fpr as well... <==thinking outloud ok i guess i'm not seeing the path this shows me that leads to the answer of the manufacturers recomended FP ? i feel so dumb now
smelts an awfull lot like facts to me lol
Last edited by xtreamvette69; 08-20-2013 at 08:38 AM.
Not really.so basically in a nut shell this is the complex way of saying
*NA idle=high vacuum which helps to suck the fuel through the injuctor hence less FP is needed.
*NA WOT=low or no vacuum to help suck fuel so FP needs to be more
*boost= needs alot more pressure to flow because it has to fight the force of boost to deliver the same rate of fuel
if thats what you ment then i knew that, all except the perfect delta pressure of 29.6 thanks but now its up to me to figure out how to use that in this senerio lol
i'm guessing that one thing i can gather from this is that the amount of vacuum or lack of with his cam would play a part in the perfect delta pressure of 29.6... hmm no that would be irrelivent because the same vacuum or lack of would be on the fpr as well... <==thinking outloud ok i guess i'm not seeing the path this shows me that leads to the answer of the manufacturers recomended FP ? i feel so dumb now
The vacuum or lack thereof doesn't "suck" the fuel through, the fuel flows due to a pressure differential, or delta pressure.
Correct, a low vacuum engine would still have the same delta pressure, because the FPR is referenced to the intake manifold.
It's nothing to really use in tuning, just something to know.
The best thing to do is set the fuel pressure and leave it there, playing with base fuel pressure just complicates the tuning method.
Sometimes a higher base pressure is desired, as in trying to make a smaller injector flow a little more, or better atomization, by use of higher pressure. Generally I set MPFI systems to 43.5 and leave it, unless I need a change it.
The man who says something is impossible, is usually interrupted by the man doing it.
ahh kk good to know at least one thing i said was right lol but ya the more i thought about having him change it the more i felt it was just a cheat which is why i decided against it, i do belive with 30# injectors on stock FP though couldnt possibly have a very good atomization pattern though but i'm probably wrong.. either way i'm sure it is fine with the pressure he is at. thanks
Yeah I think the pressure is fine at 43.5 with the engine off. Anywho, I will get that log done as soon as I get a chance. Thanks.
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