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Setup questions for Motec M8 on Oldsmobile 455

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Greetings All,

We have a peppy Oldsmobile 455 that I want to make sure I have setup the parameters on our Motec M8 correctly before we attempt to run it on fuel injection for the first time. We have previously dyno-tested the engine multiple times with a standard Holley Dominator Carburetor and a cheap HEI distributor. This setup made 605hp on the Superflow 901 dyno. We will be running at high elevation usually, around 4,000 to 8,000 ft above sea level, in Colorado, so horsepower will likely be closer to 420-460 actual observed power.

The plan all along was to convert/run this engine with the Motec M8 we have on hand. We have since acquired a Holley Dual-sync distributor for the crank and cam trigger signals, as well as had the intake manifold converted to Multi-port EFI and we will be using a Dominator-sized throttle body. We have a Motec CDI Single channel ignition box and Mercury Outboard-style coil (with the screw terminals) that we intend to use with this engine.

The injectors that we plan to run/have acquired are brand new genuine Bosch Green Giants, number 0280155968

My questions are, does anyone have an idea as to what to setup the IJPU at and the what number to start with on the main fueling table?

Also, with this distributor having falling edge signals for the cam and crank sensors, I have a general idea what to do for the setup on the Motec, but I would like to confirm my thoughts with other's actual real-world experiences.

Thank You all in advance for the tips and advice.

IJPU is not really that critical, its purpose is just to scale the whole fuel table numbers up or down. It will likely need to be around 20-25ms since you have such a large capacity. Set up the fuel table initially with numbers around 30% in the bottom rows and 60% at the top rows. Once running if it looks like your fuel table numbers are way out then adjust the IJPU and rescale the fuel table (it will popup some message when you change the IJPU about whether you want to rescale the table). Ideally you want to end up with numbers in the fuel table no bigger than about 80% and no smaller than about 20 over the full operating range.

Ref/sync mode will be 4. Crip will need to be initially guessed then adjusted with a timing light. Read and understand the F1 help for ref/sync mode 1-4 as you can set it up to use single or "dual edges" (both rising and falling) depending on how wide the teeth/slots are on the "crank wheel". Dual edges gives twice the accuracy (effectively ecu sees 8 teeth per crank rev instead of 4), but the teeth need to be quite wide for this to work.

Thank You Adam for the good advice. I am getting everything setting up on the parameters. As for the Crip, the Holley distributor calls for 50 degrees BTDC, so that is what I set the Motec up for. I will have to make sure I get it right and may have to adjust the ignition delay slightly to make sure it isn't advancing or retarding versus my setup ignition table numbers.

"As for the Crip, the Holley distributor calls for 50 degrees BTDC, so that is what I set the Motec up for".

You may get lucky but it is unlikely that holley use the same conventions as the M8 in terms of which tooth and which edge the offset applies from.

You're best to do a quick check manually to get it in the ball park close enough to run, (and you know it really is #1 injector squirting in the correct time for #1 cylinder), then check it with a tmg light once running. With a distributor it is a bit tricky because there are 8 different "crip" settings that it will run on but only one of them is correct (injectors in sequential).

Motec have good documentation and you will find a ref/sync webinar on youtube that will explain the process better but the basics are you wind the engine over by hand until the sync (cam) edge passes its sensor, then keep turning a little further until the very next reference (crank) edge lines up with its sensor (this point is called the index tooth in Motec speak). Crip is how many degrees from this point until TDC#1 compression stroke. So if for instance if from when the index tooth was lined up with the sensor, you had to turn the engine another 180deg to get to TDC#1, then your crip would be 180deg.

Awesome info Adam, I really appreciate this help!

Been working through everything on the car and playing-with/setting-up the Motec software further....

I have been figuring out what the best efficiency calculation method is, but with our possibly great changes in elevation from 3,500 ft all the way up to 11,000 foot elevation) that are possible within 2 hours of drive or less, I was thinking of running MAP/EMAP open to atmosphere. Also, the cam we are running is of fair size, 250 @ .050 with 108 lobe separation, and installed with a 104 degree intake centerline. Any thoughts on if the MAP/BAP will work well for our setup or if we should look at a different method?

My next question has to do with the Idle Control Solenoid that I am going to use, the Bosch 0 280 140 512, the 2 wire one.

I have it setup in the Input/output table in the function and parameters with the frequency (100 HZ, Minimum duty cycle of 30%, and maximum duty cycle of 80%).

I don't think I am going to need to setup the table, is that correct; can I leave it all blank (zeros)?

If anyone has any tips on the idle solenoid setup parameters to help out, that would also be great, as all I have to go on is the recommended start numbers in the Motec help guide.

Thank you all in advance

I suspect the cam is a bit big for MAP to be used as the efficiency source so I would probably use Throttle position. Still connect a MAP sensor to the ECU but have it plumbed to atmosphere (or to the airbox if you have one). The MAP comp table will still work in the background and compensate for the altitude variation.

As for the idle valve, I have never used idle control on one of these old ecus so I dont know how the aux table works or if its used. Typically in more modern ecus you have an "base position" or "feed forward" table to tell the idle valve where to start from before closed loop takes over valve but from the scarce information I suspect it may not be used in the M8. As for the other settings, 200Hz is more typical for the bosch valves, min and max DC will need to be determined based on what it needs to idle but dont go below 15% for the min with these valves.

Thanks again Adam!

Still setting things up for now, and I am wondering about the ign 1 output signal from the Motec M8. Is that automatically signalled off of pin 3A or do I have to set one of the PWM outputs to be the ignition output?

If it doesn't have to be set up on one of the PWM outputs, I would like to set one of these to be an Aux table that is set to control a Volvo XC90 PWM fuel pump speed control unit and run one of the Crydom type Solid State relay units to a fused power supply that splits off to two Bosch 044's and two Facet Lift Pumps. I would like to do this to quiet everything down, keep the fuel cooler, and make the pumps last much longer.

Do you have any experience with these Volvo PWM units?

From what I understand the Motec M8 won't go to high enough of a HZ frequency (It maxes out at 1KHZ vs the Volvo controller going to 20kHZ) to keep everything working quiet and nice if I just go straight from the Motec M8 to the Crydom Solid State Relay.

Yes, "Ign 1" is always pin 3A and cant be changed.

It sounds like you are making it more complicated than it needs to be. You only have 440cc injectors. 440 x 8 = 3.5L/min = 210L/H. A single 044 will do 300L/H @ 45psi and will only need about 10A at that pressure. The pump "heating" the fuel is a myth most of the time - even if had only 50% mechanical efficiency that is only 60W of heat going into the fuel system - most of that would be radiated off the big black surface area of the fuel tank. I think you will find the highly conductive metal fuel rails attached to the 100°C engine is where most of the heat comes from.

The Crydom industrial relays are only good for about 100-200Hz max. Im not familiar with the Volvo unit.

Thank you for confirming the IGN1 output Adam.

I realize that our fuel pump combination is overkill for now, but we are likely to turn up the pressure if we switch from pump gas to run E85 on these same injectors and fuel system.

In addition, I also have my eye on adding some boost to the setup, so that would require more fuel pressure or larger injectors in the future.

I like the redundancy of extra fuel pumps for reliability.