ktmrider

We are having some tuning issues with the Dodge trucks and I have been trolling around the Megasquirt website for info. How many of you, besides Parish/Jim, are using their system?
Our problem is fuel control at part throttle under boost ( 3psi+ ). The computer shuts down the truck into a "limp" mode until you cycle the key. Okay in town, kinda scary on the freeway.
I see that you can control injector signals based on RPM vs boost level but I was wondering if we could use a TPS or related sensor to assist? I sent a message to MS but have not gotten a reply.
Thanks for any help folks!

parish8

iTrader: (6)

the mega looks at several things to compute fuel

tps
map
iat's
rpm
ve table

to get it to control just your fuel you have to just hook up those things above +hot,gnd, injectors. it also looks at coolant temp for warm up enrichment.

then there are more things you can do like narrow band o2 for idle and cruise closed loop or wideband 02 for closed loop all the time(wot closed loop). all sorts of extra functions too like nitrous control, fan control, fuel pump.......... anything you want to turn on or off based on the above sensors.

for a boosted ANYTHING that is fuel injected i think mega is a killer answer. if you can find a tach signal you are home free.

Boostaholic

iTrader: (4)

So, I could drive a megasquirt off a MSD 6A tach signal?

kp

iTrader: (34)

Jim,

What sensors do you have to leave on the stock PCM to have it control just the timing? Do you use the same sensor (TPS for example) for both units or does the input impedence screw things up using one sensor with 2 boxes? I was thinking of trying the megasquirt, I dont mind building the kit and I am pretty good with electronics so that doesnt scare me. My concern was getting the stock PCM to play along and still have some way adjusting the ignition timing curve easily.

parish8

iTrader: (6)

i think about any tach signal will work. some need a resistor, some need a pull up circuit but as long as there is some kin of tach signal then you are set.

what is driving the msd? the mega has some outputs to control timing like for the ford edis set up and i think it has some other avaliable outputs for timing control but i really dont know much about that part of it.

parish8

iTrader: (6)

for the tps i just taped off the stock 0-5v tps sensor.
for the iat an coolant temp i added 2 sensors and left the stock ones still conected to the stock pcm.

once you unhook the gnd's going to the stock injectors and hook them to the mega you will get some kind of code. with edit i just shut the code off but in a dodge with limited programers you might have to wire in some resistors from +12 to the old injector gnd's to fool the stock pcm into thinking the injectors are still there.

timing... do you have some control of timing now? if you have control now you should still have the same control. if not you can set up the mega to do timing too but it about doubles the cost for most set ups.

edit. sorry kp, i was thinking you were ktm and asking about a dodge.

on my set up i just use edit(efilive now) to do my timing. if i had a didn't have a tuning program all ready i would spend the money on geting mega to do the timing, especialy if i had a stick.

kp

iTrader: (34)

Thanks Jim,

Curious where the stock PCM gets the timing from with no MAF connected since the main timing table is based on the MAF. Do you just use RPM only and change the whole table and thats what ends up being used? Thats the only thing I'm not sure about. I dont mind leaving the stock PCM in, the coil drivers seem to work well but I would like too be able run a SD tune for the fuel.

parish8

iTrader: (6)

thats a good question and i dont know the answer yet. i never took out my maf so it was still sending a signal to the pcm. i just redid all of my hot and cold pipes today and got rid of the maf. i wish i had unpluged it a long time ago so i could have had the timing part figured out all ready. i am prety sure it can be handeled with tuning but anything into boost will have to be rpm based only.

i probably will have an answer in a week or so.

Rick@Synergy

iTrader: (5)

So If I used the mega on my setup, could I use it to control the timing also? Or do I still have to use the PCM for that one. I want to be able to adjust everything on the fly like a stand alone, but without the price.

parish8

iTrader: (6)

it looks like the best way to do timing with the megasquirt is to adopt the entire ignition system from a ford. you need to get a crank trigger on there. an edis moduel and ford coils and wires. i think the entire set up would cost $400-$500 to do timing.

there has been talk of trying to decode the stock crank trigger and using the stock coils and i think it could be done but it might just be easier to use the ford stuff.

kp

iTrader: (34)

I thought you got rid of the MAF already Curious to see how it works out.

Ryan K

iTrader: (11)

With out the Maf, the timing still works SD guys do it all the time...

kp

iTrader: (34)

But where does it get its load reference from for timing if you ditch the MAF? Since the spark tables use dynamic airflow from the MAF how do you adjust timing using the stock timing tables or is there just a defalt RPM/VE based timing table somewhere in there in case the MAF fails?

I'm going to have to unplug the MAF and play around a little

parish8

iTrader: (6)

i assume it just looks at the map for load? there is a sts truck guy that is having problems with it going to 40deg of timing as soon as it sees boost but i would think you could program that out. i hope i dont need it, looks nice without it in there.

ktmrider

Thx for the info Jim. Looks like I will be making a call to Megasquirt very soon. Just curious, can the unit use a drive by wire signal or only a "real" TPS one? Also we are stuck with the SD on the Dodge, no MAF. Not planning to run much more than 8-9psi ( weak pistons ) for the time being so I think the standard MAP upgrade on the megasquirt should do fine.
BTW I never did hear back from them regarding the application questions but you answered them tho.

parish8

iTrader: (6)

i have drive by wire and there is still a tps, you just tie onto that.

you wont get too much help from the actual megasquirt guys. i you find a software bug or something they will jump in but it seems like they let most people just figure things out on their own. they are not making much money on the thing.

did you see the bulitin board? how about the detailed mega manual? or the instalation wiring diagram? those things answer most questions.

TurboBerserker

iTrader: (1)

Actually the reason SD timing still works is because you have an accurate VE table. When the MAF fails, the g/cyl is back calculated from the VE table somehow according to the HPT guys. I'm still trying to figure it out -- I still have an accurate VE table for my 6.0L in there, but without the MAF, I was basically seeing the bottom line (0.01 g/cyl) of the timing table. Doesn't make sense when I think about it, but plugging in the MAF again fixed it all.

I ran into signal vs. noise trouble on my TPS but 15k6 ohms on the MS TPS line fixed all that.

busta9876

iTrader: (3)

here's the 8x8 spark table i use on my 6.0L vortec run by megasquirt. I am using the FORD edis ignition with GM DIS (wasted spark) coil packs.



the megasquirt scales values between table points. and uses the last point you entered if you go off the edge of the table.

make sure the table you use covers the operating range of your engine.

100kpa is approx the atmosphear at sea level.

values over 100kpa would be boost. the sensor in megasquirt handles 250kpa, which would be about 21 psi of boost.

69firebird

iTrader: (14)

so will the stock sensors work? can I just splice off the stock sensors?

im just wondering it seem slike tis going to be pretty straight forward
ed

parish8

iTrader: (6)

you use the stock tps. if your keeping the stock pcm to do timing and tranny stuff then you should go with 2nd sensors for the IAT and coolant temp, they are prety cheap. if you dump the stock pcm completely then you can reuse the stock coolant sensor and i am not sure about the stock IAT sensor.