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Motec M150 Injector Linearisation

Diesel Tuning Fundamentals

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Hi all,

Im currently learning to tune my Hilux with the Motec M150 plugin. Can anyone tell me exactly how the Linearisation table functions i understand the numbers pressure vs fuel volume and how many milliseconds the pulses are to deliver set fuel volume at each pressure.

The question I have is what effect this has on the operation of the engine. Is this table directly metering the fuel volume or is it just used to estimate the lambda.

I hope this makes sense.

Cheers

John

This information is used by the M150 fuel calculation to deliver the correct mass of fuel for the current Air Mass and desired Mixture Aim.

Unless you are testing / characterizing injectors -- you do not modify that table. If your injectors are not found in the pull-down list, the best thing to do is arrange for Motec to test your injectors and add them to the list, this generally takes a few weeks (perhaps less for you since you are a bit closer to Melbourne!)

I think you mean fuel primary Linearisation ms table. In other words injector fuel flow map.

Left axes fuel pressure and on top of the table it reads micro litters fuel demand.

So for example 1800Bar fuel pressure and a fuel demand of 116 micro litters need just over 1ms injector output on the ECU.

Fuel volume demand is what the ECU calculates on fuel needed to run the engine @ X load condition or engine power/RPM.

These injector fuel flow maps are not easy to make so better let them for what they are even when upgrading to bigger injector flow the so called injector flow model will not chance a lot you just running more fuel per stroke so in general you know what % more your injector will flow so lower the number on the smoke limit map a bit and take it from there.

Did have a look @ the Motec diesel software.

Must say can not get my head around how Motec is calculation fuel??? And why use MAF not MAP? MAF read slower than MAP so is the ECU getting jerky on transient using MAP reading only? It’s not rocked science air density as fuel manifold pressure and air temp make fuel mass able to injector X amount of mg/stroke or mm3/stroke fuel and we are all happy.

Thanks for the reply's

Diesel injectors are very hard to characterise and there is no set of numbers that are the same. Even each injector has different properties thats why each injector is coded into the factory ecu. All I needed clarification on was the effect on the running of the engine if i make adjustments to this table. Im using the 1kd package on a 1kd so most things work the way they should.

Cheers John.

The main reason why the calibration of injector characterization is for lambda control. Of course when the ECU doesn't accurately know the fuel mass it cannot accurately target a lambda limit.

Secondary would be for targeting a certain torque number for shift quality and throttle consistency. I don't believe this ECU uses torque targeting so that shouldn't apply here.

Hope this is helpful,

Nick

Thanks for the reply Nick,

What is the best process to get the table corrected. I know its close but there are a few areas that need tweaking.

Cheers

John.

Sorry -- I did not grok that this was a Diesel. My comments would be more relevant to Spark Ignition engines running on an M150.

John,

I typed a response earlier and then forgot to press send and got timed out. Crap!

Short story, find a similar engine and see if you can copy the injector data out of a .bin or stock read into the M150. Paying a common rail shop to build you a data sheet is going to be spendy, but it's possible. Once close, use a wideband or side-view-mirror on the tailpipe to adjust your lambda limit leaner until the pipe is clean or your min AFR is uniform across the rev range.

Not glamorous but it works,

Nick

Hi Nick,

I still have the factory ecu but i dont have the software or tools to pull any data out of it. The calibration that came with the Motec package for the most part is accurate. I have a wideband installed in the truck that is wired into the ecu so i can log all of that info. I have talked to my local diesel shop and i might as well have been talking to a brick wall haha. Unfortunately i'm kind of on my own here in New Zealand. I would love to be able to build a table myself on a bench tester but i dont think its possible. I would imagine you would need a custom machine to be able to do that.

Cheers

John

Okay so just so im doing this right. Based on the attached table if the Lambda estimate is lower than the Lambda actual would that indicate that the pulse width is too long or not long enough. e.g. the ecu is estimating a lambda of 1.23 but the sensor shows a lambda of 1.34.

Attached Files

Sounds like you're pretty close. If you take 1.34/1.23, the math says your your injector sizing is off by about 9%. Simpletons method would be to multiply your fuel injector characterization table by 1.09 and see where that puts you. Odds are you'll be a little bit rich afterward because you're using the multiple on the injector latency as well (which hasn't been subtracted out of your on-time) but doing this exercise a couple times should put you pretty darn close.

This all assumes your airflow calcs are spot-on.

Nick

Hi Nick,

I assume my airflow is correct. I have upgraded from the factory Toyota AFM to the Ford Ranger one as the Toyota could not flow as much as the engine can now consume. Motec provide a calibration for it and i did some research to find the size of the pipe from the ford ranger so it should be scaled close. I know its not perfect yet but as im planning on changing the factory turbo soon i'm not going to get too carried away with it as there is a lot of re fabrication to be done.

John.

Off topic, but do you play the odd game of WoT on the Asia server(s)? Pretty sure I've come across a player with that, or very similar, nom de guerre?

Hi Gord,

No not me im afraid.

Cheers