little random post

[Jonpro03]

Perfect... Should I ever get my hands on a 3900, I'll see if I can't do the same thing with a MS

[robertisaar]

the ridiculous VE tables, VVT control, or both?

[Jonpro03]

the ridiculous VE tables, VVT control, or both?

All of the above... Did you see I fig'd out how to read the 24x crank sensors? (kinda)

[robertisaar]

All of the above... Did you see I fig'd out how to read the 24x crank sensors? (kinda)

haven't been on enough to read, however, reading the 24X is easy...

making it's data useful is another situation.

i'm actually planning on hooking the cam sensor up to a 1227727 and reading the amount of time that has passed since it pulsed, comparing it with RPM, and using that data to determine exact engine position, basically making the VVT control closed loop(by varying the duty cycle to adjust commanded retard when referenced to read retard). did i mention i DON'T own a pocket protector?

i may add in some stuff to try and get ahead of variables like oil pressure as well, but without a 3900 to test it all with, it's just theory ATM. the VE tables work wonderfully though, so that alone pleases me.

[robertisaar]

semi-bump.

so, i've seen odd things in BINs before and wondered what the purpose of them could possibly be....

making a $88 XDF to match the completeness of A1/DF, came up to here and found one of those situations.



now, what's so special about the 68-89*F startup coolant temp range that allows it to filter out of choke fueling and into open loop fueling faster?

it's the startup coolant temp range(75*F is the actual target temp) used by the EPA for the city MPG tests used from ~1984 to 2007. GM sure did choose some odd ways to try and game the system.

[robertisaar]

what the 93-95 flash PCM does not like: commanding 3 cylinders to quit injecting fuel, yet not disabling closed loop operation...... it did not please the O2 sensor at all.

INT shot up to 240 in no time and the smell of the cat got quite noticable.... good to know that it's probably still functional after 200K miles....

but i may make a small patch for an "eco" mode that is enabled/disabled via a in-cabin switch..... have the cylinders banks alternate on and off to essentially make it a 3 cylinder under light load. from the looks of it.... of course, more throttle was needed to maintain a given speed(i wouldn't even think of trying to accelerate like this).

thinking about it..... if i shut off 3 cylinders, as long as the BPW on the still-firing cylinders doesn't double, then it's making a fuel economy gain. and from the logs i just made, it didn't look to be anywhere near double..... but i need some significantly flatter roads to be certain.

[robertisaar]

EGR: useful? for certain things, yes.

for fuel economy? maybe.

if you can put a vehicle into extremely repeatable situations, you can determine if EGR is helping, hurting or not effecting fuel economy pretty easily.

let's say you're driving along at 55MPH with a manual trans, top gear, spinning 1600RPM. without EGR, let's say you're seeing a BPW of 5mSec. now add in various amounts of EGR and of course spark advance added due to EGR's effect on combustion speed. now EGR's ability to help fuel economy is based on decreasing throttling losses due to you having to open the throttle more to make the same amount of power to maintain a given speed because incombustible gases are introduced into the combustion chamber in place of air (and therefore fuel), so it actually decreases VE as well.

now put the vehicle in the exact same situation again and if the BPW that results is still 5mSec, it's not doing anything for fuel economy. anything less and it's helping fuel economy, anything more and it's hurting it. can't say i've seen that last result before on a gasoline engine though.

on both LH0 and L82 at least, the difference in throttle response(and throttle needed) with EGR off is kind of ridiculous.... there's a long (~1/2 to 3/4 mile) hill with a constant grade that i'm on constantly, going up with EGR on, i can maintain 55 MPH without any issue, TCC will stay locked(barely, and only due to me tweaking the unlock points). turn EGR off..... and the amount of throttle needed with EGR on will result in hitting the peak at about 70MPH without ever unlocking the TCC.



because of this, EGR also can be used for drivability.... with EGR off, a very small change in throttle position can bring about a rather large change in MPH. turn EGR on and in large amounts and you have a much finer control over vehicle speed.



notice, i don't mention emissions at all? i may choose to use emissions devices, but sure as hell not for their intended uses.

[robertisaar]

found more of GM's attempted MPG test trickery...

KAFTCLOW
KAFTCHI

these two values are used to create a window in which the maximum lean AFR allowed will not be checked against. they correspond to 68*F and 85.6*F startup coolant temps with BFBD(and probably others).... in other words, another attempt at an artificial boost to the city MPG rating.

[DAVE4949]

Sure alot of info here can anybody help in finding a forum for the lumina? New guy here and in time will find my way around
thanks guys
~dave

[pocket-rocket]

Sure alot of info here can anybody help in finding a forum for the lumina? New guy here and in time will find my way around
thanks guys
~dave

There are plenty of Lumina people here, but if you want one specific to the car check out http://www.w-body.com/forum.php. They aren't Lumina specific, but they deal with only the Lumina and cars on the same body platform for the Lumina (car), the w-body.

[robertisaar]

PSA from me:

http://www.totalcardiagnostics.com/toad/

don't patronize these people.... they're profiting from my own and other's work and calling it their own.

[SappySE107]

I wouldn't even give the link to help them advertise on this site.

[robertisaar]

had a strange thought....

how useful is multi-spark? like, lower RPM, ~1200RPM and less? i have to wonder if the classic 60V6 ICM would support such a scheme....

basically have the normal dwell scheme be gone through, then shortly after the spark happens, send the EST line to 5V again to charge the coil again, then after the short period of dwell time passes (5mS or so), then drop it so that another ignition event happens.... the only thing i question as being able to do so is if the ICM automatically prepares to switch to the next coilpack after the current one fires off.... if it doesn't, then this can work, if it's even worth doing.

[SappySE107]

The MSD DIS-4 does improve idle quality and MPG, but not overall power. If you can manage to make a stock ICM work as a multi spark up to 3k RPM, then I would try it. DIS-4 isn't worth whatever it costs these days.

[robertisaar]

interesting..... i do have a spare ICM and coil set, now i just need a way to emulate the 7X signal at various speeds to see how high of an RPM it could reach up to before risking triggering the next cylinder way too early.

15mS per revolution(to simulate 3 5mS dwell periods per revolution) is 4000RPM....

if the ECM/ICM can't do it.... then some add-on hardware to the ICM definitely could.... would have to adapt between the coils and the ICM, but it would basically look for the coil to be active, then once it shuts off, it adds it's own little dwell period and then watch for the coil to become active again. bypasses the ICM control entirely.

assuming a 5mS dwell period(though i've seen references that claim that the time required to fully saturate these coils at ~5 volts is closer to 3mS), at 3000RPM, the crank would rotate 90* before the second spark(on that cylinder) happens.
1500RPM = 45*
750RPM = 22.5*

3mS dwell times....

3000RPM = 54*
1500RPM = 27*
750RPM = 13.5*



not sure if those gaps are close enough to make a difference.....

perhaps a DIY CDI based system that piggybacks off of the inductive charging event of the ICM? plug wiring would probably be hell though.