They arrived today 
To keep things simple I plan on using Chevy throttle bodies but how do I convince my Megasquirt to accept inputs from 2 throttle bodies?
They arrived today To keep things simple I plan on using Chevy throttle bodies but how do I convince my Megasquirt to accept inputs from 2 throttle bodies?
Just use a TPS on 1 & make sure they are setup the same.
I'm pretty sure Chevy throttle bodies are way to powerful for a Jag V12. Might want to look at some Smart car ones.
Still waiting on that build thread! Boost that English lump to the moon.
A Jaaaag V12 would be cool. What is it going into? Have been watching all the old Top Gear episodes & lots of Jaaaag V12's on there.
Why would you need inputs from 2 throttle bodies? Are they gonna be independent?
In reply to frenchyd :
That right there is a statement sir. Carry on!
Are they dbw or linkage?
wvumtnbkr said:Why would you need inputs from 2 throttle bodies? Are they gonna be independent?
yes a Jaguar V12 has two. One for the left side and another for the right. Just like Ferrari does and Aston Martin, etc etc
yupididit said:Are they dbw or linkage?
Linkage.
frenchyd said:wvumtnbkr said:Why would you need inputs from 2 throttle bodies? Are they gonna be independent?
yes a Jaguar V12 has two. One for the left side and another for the right. Just like Ferrari does and Aston Martin, etc etc
I realize they are seperate. The point is: are they gonna open the same amount at the same time? If so, 1 signal will work just fine.
wvumtnbkr said:Why would you need inputs from 2 throttle bodies? Are they gonna be independent?
That's a good and valid question. If I take input from one Side. Does the Megasquirt know it's supposed to feed 12 cylinders? Not just 6?
MS knows whatever you program it to know.
Now that's scary. I'm supposed to write a computer program? To my knowledge I can't buy one. Is that something I can have someone do? If so what is the cost? Who? What's involved?
In reply to frenchyd :
http://www.megamanual.com/MSFAQ.htm
Time to start reading.
MS is very simple really. The "programming" is done, so it knows you want to squirt & fire, but you do the tuning to tell it when & how much to squirt & when to fire.
I built one years ago for a Honda that I converted from carb to mpfi. I could never get the ignition to work correctly so I just used the vacuum advance but the tuning was fun. Cops I think would have been easier than trying to deal with that old distributor.
I bought the added app from a guy that auto learned but still had to do a lot of tuning. It ran really well eventually. I learned just how hard it is to start a cold motor with fi.
Hopefully you don't have variable valve timing or lift. With turbos you'll have another dimension also.
With the little D15B2 in the CRX when tuning full throttle & data logging on an empty road, speeds could still get up there. A twin turbo V12 at full throttle will probably require a lot of empty road or optimally a dyno. A good experienced MS tuner could have it tuned in a few hours on a dyno.
I still have the simulator you could borrow to test all the sensor inputs/outputs to your MS ecu. It beats troubleshooting a mis-wired or bad sensor.
The Megamanual is old, I would use the Msextra manuals: https://www.msextra.com/manuals/
frenchyd said:yupididit said:Are they dbw or linkage?
Linkage.
Use one TPS. Make sure both throttle bodies open the same amount at given throttle.
Which MS are you using?
frenchyd said:wvumtnbkr said:Why would you need inputs from 2 throttle bodies? Are they gonna be independent?
That's a good and valid question. If I take input from one Side. Does the Megasquirt know it's supposed to feed 12 cylinders? Not just 6?
It doesn't care. It takes the inputs and applies those to the tables that you setup and outputs the proper injector open time, etc.
When you set it up, you put in the basic parameters of the engine size, number of cylinders, injectors, etc and it outputs the base fuel settings that all of the fuel tables are calculated off of.
it doesn't care if you have a million cylinders or two, it just needs to know how long to open the injectors and when.
There are physical limitations to what it can control, but the software itself doesn't really care.
So set it up to read the TPS from one throttle body and make sure they are both connected and open the same amount at the same time and you'll be fine.
Next issue. The original Lucas ECM is in the trunk. Is there any reason for me to keep the Megasquirt there? I was thinking of putting it where the glove box would be in a street car. ( for ease at pugging in my lap top and making changes on track).
yupididit said:frenchyd said:yupididit said:Are they dbw or linkage?
Linkage.
Use one TPS. Make sure both throttle bodies open the same amount at given throttle.
Which MS are you using?
MS1.
EvanB (Forum Supporter) said:In reply to frenchyd :
http://www.megamanual.com/MSFAQ.htm
Time to start reading.
I did last night. And in about 15 or 20 Re readings I'll understand. Some of the trouble is translation. Tech guys love jargon and abbreviations. It's just their nature.
My "advantage" is when I was a young teenager the corner gas station bought a wall of tuning equipment and I quickly learned how to use it. The giant O scope would show all the cylinders firing and reading from them you could see ignition issues, timing, fuel issues etc of each cylinder. You quickly could see, " oh the left bank of the carburetor is plugged or the accelerator pump isn't working etc".
So I know how to tune. Learning how to do that with a keyboard will be new for me. What I really need is a grizzly old guy to smack the back of my head when I start to enter the wrong thing.
No Stampie. You can't have the job!
mdshaw said:MS is very simple really. The "programming" is done, so it knows you want to squirt & fire, but you do the tuning to tell it when & how much to squirt & when to fire.
I built one years ago for a Honda that I converted from carb to mpfi. I could never get the ignition to work correctly so I just used the vacuum advance but the tuning was fun. Cops I think would have been easier than trying to deal with that old distributor.
I bought the added app from a guy that auto learned but still had to do a lot of tuning. It ran really well eventually. I learned just how hard it is to start a cold motor with fi.
Hopefully you don't have variable valve timing or lift. With turbos you'll have another dimension also.
With the little D15B2 in the CRX when tuning full throttle & data logging on an empty road, speeds could still get up there. A twin turbo V12 at full throttle will probably require a lot of empty road or optimally a dyno. A good experienced MS tuner could have it tuned in a few hours on a dyno.
I still have the simulator you could borrow to test all the sensor inputs/outputs to your MS ecu. It beats troubleshooting a mis-wired or bad sensor.
That's extremely generous of you. I will take you up on your offer.
Yeh, dyno time makes a lot of sense.
The ignition system on a Jaguar is independent of the fuel system. I wonder if initially for simplicity sake I can just use that and get the Megasquirt understanding the fueling requirements?
I have six throttle bodies and one TPS, it's really a non issue. You are only using the TPS for accel enrichment (based on rate of change) and decel fuel cut if enabled.
Your lack of understanding is making this sound WAY more complicated than it actually is. Engines are engines and there's nothing super special about the Jaaag other than having a few more cylinders you need to be mindful of.
I wouldn't use the stock ignition control, it would need some serious bandaids to work on a boosted setup.
Also, the megamanual is good for basics, but most are running newer firmware and msextra.com has the current details on what is/isn't possible on the different versions.
The ecu can be mounted anywhere the wires can reach.
I am willing to help but 400 different threads on GRM are hard to keep track of! 
How are you handling ignition? I think you should forgo TPS and use a MAP sensor versus RPM to tune it. You are going to need to know the MAP anyway to tune with boost. I would put a separate MAP on each Mansfold to see what both sides of the motor are doing. I would have to think about if I would average the two for the MS and Wright somthing that then monitored the two for variance so in case you had a problem with one side and the MS was reading low boost on half the motor when there was full boost on the other half but was not getting enough fuel or not enough timing pulled causing bad things to happen. You could just take vac/boost from both sides to a T connection to the MAP. Put a big enough crossover and you then don't have to worry about this. Thinking more about this I would definitely do this. It would make tuning much easier.
You'll need to log in to post.
