Unlogic's Chrome ECU tuning thread

[Greg E]

If the maft is adjusted to the same afr as the stock maf was giving then it had to be outputting the same pulse or the afr would be different.

It's not.

I figured this out playing with the MAFT on my stock 98. Car was tuned with the stock MAF, changed nothing but swapping in the MAFT, all the HZ values (thus the load values) lowered. Around idle it was close but the higher the airflow, the farther off the pulses got. This why I tell people to double the MAF size value.

...and actually these days I've been telling people to set the mid to +3 or +4 to try to get the thing to pulse something similar to what a stock MAF would.

On that note: are you going to be at NG? Got something huge to share with you.

[Chris@Rvengeperformance]

It's not.

I figured this out playing with the MAFT on my stock 98. Car was tuned with the stock MAF, changed nothing but swapping in the MAFT, all the HZ values (thus the load values) lowered. Around idle it was close but the higher the airflow, the farther off the pulses got. This why I tell people to double the MAF size value.

...and actually these days I've been telling people to set the mid to +3 or +4 to try to get the thing to pulse something similar to what a stock MAF would.

On that note: are you going to be at NG? Got something huge to share with you.

All I am saying is if the hz were lowered then it would lean out, unless you are in closed loop. So, if you add some clicks to mid or anything it would be back to stock hz and load by the time you get the afr back to stock.

I'm afraid I can't make NG this year. I'll send a pm with some more info.

Car is running GREAT though, haven't burned a tune since march. I hope you guys have fun.

[Jimvr4]

I just reviewed my logs with stock MAF and MAFT. With the stock MAF I saw about 2700 Hz peak at about 16.5 PSI and now with the MAFT I am getting about 2750 Hz peak at about 15 PSI. Once I increase the duty cycle enough to reach 16.5 PSI I will be getting even higher Hz values with the MAFT.

On the other hand I get significantly less Hz with the EVO 399 MAF.

BUT - I haven't been able to stop the boost spiking yet. I think my 220 load target is fine for 6000 rpm but I have to increase the duty cycle more up top. I think I have to lower the duty cycle when boost first kicks in and lower the target down there as well.

[Unlogic]

I went back and took a look at logs from when I was running stock boost levels and they contain boost spikes too. I'm suspecting that the boost function/timer in our ECU's may be a bit slow to react. At least thats what I'm seeing in my current logs even though I got the spikes fairly under control now.

[Unlogic]

Installed the Z06 MAF today and thanks to the excellent information provided by Greg, Jim, Forrest and other uses in this thread it worked like out very smoothly (the hardware part of the install is documented here).

I set the MAFT to 360 injectors and left all adjustments on zero. This provided an airflow reading which was very close to what the stock MAF puts out. I was able to use the MAF smoothing values that I had previously used with the stock MAF before I switched to the EVO MAF a year ago.

All the hesitation problems that I had during low load with the EVO MAF disappeared right away now that the load values scale the same as with the stock MAF which was very pleasant.

I was surprised by how smooth the car started and even though the rain is pouring down here tonight the tuning and driving went very smoothly. The was the first time I had a co-driver (my brother) with me when out tuning and that helped greatly. He even figured out how to get the charts in EvoScan working which provided a much quicker way than using Excel for quickly glancing at the logs.

Since the rain was pouring down I didn't focus too much on increasing the boost however I noticed that around 1 bar of boost I got an airflow reading 2700 hz which seems to indicate that the new turbos are doing their job.

[Greg E]

I set the MAFT to 360 injectors and left all adjustments on zero. This provided an airflow reading which was very close to what the stock MAF puts out. I was able to use the MAF smoothing values that I had previously used with the stock MAF before I switched to the EVO MAF a year ago.

Really!?

Huh I wonder what I was doing wrong when I tested this on my stock car a couple years ago... :chin:

I'm glad this setup is working out for you!

[Unlogic]

I drove 500 km today to the Swedish national 3S gathering and the trims were more or less spot on except somewhere around 350-600 hz where there seems to be some sort of a lean spot. I noticed that my mid trims would change on the highway from ~100 to ~145 depending on which speed I drove. Using the LCDBC I could monitor both the hz and the trims in real time which helped me narrow down the issue. Guess that I'll have to tweak the VE table a bit in that frequency range a bit.

I also noticed that my high trims have come to life again after changing MAF, with the EVO map they never changed.

[Chris@Rvengeperformance]

I drove 500 km today to the Swedish national 3S gathering and the trims were more or less spot on except somewhere around 350-600 hz where there seems to be some sort of a lean spot. I noticed that my mid trims would change on the highway from ~100 to ~145 depending on which speed I drove. Using the LCDBC I could monitor both the hz and the trims in real time which helped me narrow down the issue. Guess that I'll have to tweak the VE table a bit in that frequency range a bit.

I also noticed that my high trims have come to life again after changing MAF, with the EVO map they never changed.

I have noticed this too, switch the maft one click richer on the mid and I bet it goes away.

[Unlogic]

Thanks Forrest, I'll try that on my 500km trip back home tomorrow and see if it helps.

[Unlogic]

I have noticed this too, switch the maft one click richer on the mid and I bet it goes away.

I worked like charm!

There is still a very slight lean spot left but it's very negligible now and it's well within the limits of what the ECU can compensate for in closed loop mode.

The question now is how far I'm going to dare to push the boost. I know that I can run about 18 psi without any knock since thats what I ran last year. However I'm not sure that it's a wise thing to do on a stock engine with 150000 km's on it.

A well respected member of the Swedish 3000GT club informed med that he had bent a stock rod at 19 psi using 16T turbos on his car a few years back and that got me thinking. Maybe I should leave the boost at 16 psi for now and do an engine overhaul this winter with new rods, pistons and bearing before I push any further. What do you guys think?

Ps. If you want to see a few videos of how the car is running at the moment check my build thread, I've posted a few videos from this weekends track driving.