tuning programmable engine management systems

[James Brown]

it's funny that knock sensors are little microphones, no other way of doing it i guess.

[scarceller]

The exact audio frequency for engine knock is directly related to diameter of the piston. Usually in the 6,500mhz range for smaller bores. Here's a quick calculator:
Calculating Engine Knock Detonation Frequency

This is why microphones are the best for detecting this knock. Some tuners even use a stethoscope attached to a rubber tube that's inserted into the bottom of a Styrofoam cup. Then just listen for knock within the cup.

[neilca]

I have tried for a month to contact a tuner to tune my race car. They are all too busy right now. So I am going to the dyno to do my own tuning. Here is what I have.

2.4 L (86mm bore X 70.6 stroke)
12.5:1 compession
DC70 cams
46mm Polaris throttle bodies
1 1/2 tube headers
Twin plug ignition with two MSD's fired by the ECU
Megasquirt 3

I was on the dyno once with a tuner and the crank trigger started acting weird. Turns out it was noise coming through. Some filtering and we are now good to go.

Based on what I have read, I have set the ignition table very conservatively, no higher than 30 degrees advanced anywhere.

The fuel tables confuse me, I have an AFR table and a fuel VE table. Which one do you use to tune?

BTW I tried to do a print screen to copy my tables so I could post them but it wouldn't work. Any ideas on how I can share these?

HELP!

neilca

[Lapkritis]

I've been tuning on ms for about 6yrs. Use the fuel VE table 1 to tune (as long as you aren't wired for staged injection or anything else). The target lambda table is what the ecu trims the fuel table to as a goal. The authority percentage is how far that adjustment can go against the value in VE1. Normally when tuning you set the authority percentage to 0 so you're not aiming at a moving target.

Tunerstudio has an autotune feature built in for air to fuel ratio. This can work really well to get you driving down the road but probably shouldn't be trusted for a race application or heavy load operation where damage can occur before the ecu can tune it. This is where you should consult a pro.

There are plenty of professional tuners and I would recommend seeking out a specific ecu tuner rather than a specific Porsche tuner.

-Andrew

[Lapkritis]

Originally Posted by scarceller

The exact audio frequency for engine knock is directly related to diameter of the piston. Usually in the 6,500mhz range for smaller bores. Here's a quick calculator:
Calculating Engine Knock Detonation Frequency

This is why microphones are the best for detecting this knock. Some tuners even use a stethoscope attached to a rubber tube that's inserted into the bottom of a Styrofoam cup. Then just listen for knock within the cup.

A Bosch knock sensor (3 wire) and many others can be fitted and wired to a regular 3.5mm headphone connector and then plugged into any modern laptop as a microphone source. You can then record the audio output from the sensor with a regular sound recorder and save files to match to dyno pulls. Engines with chains are inherently noisy but you can still hear preignition; trained tuners can pick it up easily.


-Andrew

[drmatera]

neilca - tuning fuel is pretty easy, ignition timing is where some knowledge of the engine combo is important.

Tunerstudio is great at "fine tuning" your VE table once it's close

[Tippy]

Besides an hour of tuning with "jpnovak" and a tad by myself, my entire fuel map was tuned using VEAnalyze Live - even boost where it nailed my target AFR's.

Is it perfect? Nope, but it drives pretty good.

[neilca]

Originally Posted by Lapkritis

I've been tuning on ms for about 6yrs. Use the fuel VE table 1 to tune (as long as you aren't wired for staged injection or anything else). The target lambda table is what the ecu trims the fuel table to as a goal. The authority percentage is how far that adjustment can go against the value in VE1. Normally when tuning you set the authority percentage to 0 so you're not aiming at a moving target.

Tunerstudio has an autotune feature built in for air to fuel ratio. This can work really well to get you driving down the road but probably shouldn't be trusted for a race application or heavy load operation where damage can occur before the ecu can tune it. This is where you should consult a pro.

There are plenty of professional tuners and I would recommend seeking out a specific ecu tuner rather than a specific Porsche tuner.

-Andrew

Andrew,

Where do I change the authority percentage?

Thanks,
neil

[Tippy]

In EGO control if TunerStudio.

[Lapkritis]

Originally Posted by neilca

Andrew,

Where do I change the authority percentage?

Thanks,
neil

Fuel Settings> AFR/EGO Control

Controller Authority +/- (%)... Set this to 0 to disable adjustment by ecu based upon lambda/ target air to fuel. Normally this is only done for tuning sessions as some authority greater than 0 is necessary to allow for environmental changes.

-Andrew

[neilca]

Originally Posted by Lapkritis

Fuel Settings> AFR/EGO Control

Controller Authority +/- (%)... Set this to 0 to disable adjustment by ecu based upon lambda/ target air to fuel. Normally this is only done for tuning sessions as some authority greater than 0 is necessary to allow for environmental changes.

-Andrew

Got it thanks. Mine was set to 15%. I will have to set this up after tuning it would be a good thing to have the minor adjustments.

[neilca]

I used the VE generator to come up with this VE table. It does work at idle but no where above that.

[Lapkritis]

What size injectors? Fuel pressure? Fuel firing batch or sequential? What fueling algorithm?

You will likely need to add more fuel.

[neilca]

I am using 30lb injectors, 44 psi fuel pressure, batch firing, simple algorithm.

I just had my crank sensor go wonky again. I am using a Ford F150 sensor and they seem to work for only a short time before the pattern is lost. I am going to do more troubleshooting this afternoon.

[Lapkritis]

Ford was susceptible to noise from the factory. Do you have the cap between the 12v coil power supply and ground? You may need this for clean signal.

If you send me your msq file then I'll take a look for any abnormalities. You can also ask over at msextra.com forums for help from the code writers directly.

[neilca]

I put an oscilliscope on the sensor and it is doing good. I then used the Jimstim to check the MS3 box. It would only rev to 400 rpm. Must be something wrong in the box. I am going to contact DIY today to see what I need to do to have this fixed.

[Lapkritis]

Would need datalog, msq and physical configuration to say for sure. DIY can confirm hardware but I think you would have a better result starting in the msextra forum.