SCCA EMod MGB GT V12 Build

Congrats on the jalopnik article! I thought that was pretty cool.

cmcgregor said:

Congrats on the jalopnik article! I thought that was pretty cool.

Thanks, I am honored to have a second article written about the car. Don't read the comments, though, those people can be mean.

759NRNG said:

Going on the back garage wall above the 'X' brace....do grass tufts make for dodgy handling???

Nah, the grass didn't seem to make for strange handling, just a lower overall level of grip

After much running around, I managed to do some testing. Video of testing-the real one this time

On your video, are you saying it stumbles when it's a quick throttle "on-off-on-off" ?

In reply to SkinnyG :

Yes, exactly. Unfortunately, quick on-off-on throttle is part of every autocross run. After watching my footwell video from last week, I have already decided to work on what I do with my feet and will be trying left foot braking and smooth throttle application. The HP Tuners forum has lots to say about changing the tune to fix this but I'm not a tuner and have lost the guy who was, so I don't want to experiment with that.

loosecannon said:

After much running around, I managed to do some testing. Video of Testing

Is this the link you intended?

Could it be the first AE shot is still a bit rich, the cylinder hasn't had a chance to burn it all off, and the next AE shot richens it up TOO much and it stumbles?

Your ECU likely allows different AE PW's at different TPS rate of change?

In reply to OHSCrifle :

Damn, got that wrong. It's fixed now

In reply to SkinnyG :

I just don't know. There are a lot of opinions on what is going on and I have no idea who is right

loosecannon said:

In reply to SkinnyG

I just don't know. There are a lot of opinions on what is going on and I have no idea who is right

I second this ......though there is serious genuine interest in this topic(on my part), I'm having difficulty just following the alphabet soup banter when yu (loose), SkinnyG, AlphaD, DBd13 start trading salvos. Are there or is there a single thread that allows us home brew FI newbees to at least comprehend the dynamics put forth?

Oh and two thumbs way up on the left foot braking in the future 

I sent this note to LC earlier today- last weekend , he sent me the data file that you are looking at in the video.  

What I see happening- when he tips in to Wide Open Throttle (WOT from here on out), a few things happen.  

The manifold pressure (MAP) jumps from 4 to 15 (I think this is PSI and not in HG, but I'm not 100%, the data labels it as PSI), and immediately the engine jumps really rich down to 9:1 (oh, at this note, one should notice that there's a ~.4 sec delay from the injection change to anything seen in the exhaust).  So right off the bat, the 15 MAP thinks it's way too much air. Then it steps up to 26 (still too rich), then 33- and it starts to look better.  And finally, the peak is at 35 MAP, and now it's running leaner than it wants to be- it's asking for 10.6:1 and getting over 13:1.  

I'm going to take a closer look at the tune, and see if a few adjustments can help.  And I also want to turn on the WB sensor at WOT- no reason not to use it- that will help a lot.

Once that's done, it will be a matter of changing the demand from 10.5 to one closer to 12:1.

The big thing is that the air fuel control is all over the place.  That needs to be fixed.

A couple of quotes from tuners on the HP Tuners forum about my particular computer:

"by the way this ecu has been a royal pain in my ass since its release. its a monster of a learning curve so put your brown pants on and don't quit until you got it."

"Unfortunately, you picked an amazing engine with a very difficult ecu to learn for your first tuning effort. If this was an LS1 you would have it understood in a few hours (ve tables, maf, timing). The newer ecu's are torque based and much more complicated but very powerful and adjustable once understood."

​​​​​​​

In reply to loosecannon :

So I'll post what I see- which confirms that this is a real headache in terms of calibrating the engine.  If it uses the Speed-Density calculation, then it's a real PITA to calibrate.  I hope that the MAF changes that are suggested work, as that would make things a whole lot easier.  Then it's a pretty correction to the table at the right spots.  
Here's hoping!

My plan is to go to my business at 6:00 am to test in my shared parking lot before the other businesses arrive. It's not big and it's pretty dusty but it's all I have. I'll do what I can to get some good data and maybe even get some video out of it

Great news: The local kart club that I raced with has agreed to let me test on their track, I just have to get insurance so it will be a few days. There's no point testing on my dusty parking lot when I have a clean race track to use.

I convinced the local outdoor kart track to let me test there and it worked great. It was just the right size to do some testing and was clean and smooth and I was there for hours and hours Testing on a kart track

Having just viewed the vide , from what you're saying the 'warmer' tune with a progressive right foot at this time is the 'ticket'........ except for that lingering thought about 'what if'. This may be totally unrelated, but has the crank position sensor ever been replaced? My 'V' is currently in the shop due to a horrendous part throttle stumble/hard start scenario......the culprit- crank position  sensor     

In reply to 759NRNG :

Looking at the data trace, I don't think it's the crank position sensor.  The engine speed trace isn't noisy nor does it ever drop out.  And if you look at the a/f trace, when you see the black puff of smoke, there's also a clear a/f excursion very rich.  

But I'm pretty confident that he's on the right track.  Better, since my original idea would be wrong (which was a royal PITA to calculate).  He's working on stuff that I was having trouble finding in the calibration.

In reply to 759NRNG :

It wouldn't surprise me at all if a sensor is the source of my problem. I am getting a cam position sensor error and have replaced both cam sensors and double checked the connections. There may be a broken wire but I'm not going to remove and tear apart the wiring harness to find it. I have ordered a new wiring harness and am waiting for that. I have another crank position sensor, I'll see how hard it is to replace.

In reply to alfadriver :

I really appreciate the help with this. You clearly have a deeper understanding of these fuel injected motors than I do. I wish I could illustrate how complicated and difficult my engine is to tune. When people familiar with the intricacies of my engine start talking, I feel like they are discussing String Theory or some other abstract thing.  I have secured a Snap-On scan tool for the weekend and it should be able to tell me if I have an erratic signal from a sensor (like the cam sensor).

In reply to loosecannon :

It's fun!  

Loosecannon- How are you on power compared to the high level EMod guys? I recall this thread having a dyno plot but I can't seem to find it. Do you know which pages have the gearing discussions as well? I'm attempting to amuse myself with what engines compare well and my brief search through this threads pages didn't get me what I thought I would find easily. Thanks in Advance!

In reply to MrJoshua :

Jeff Kiesel drove my car and the only positive thing he said about the experience was that my motor had better power than his. I don't have as much power as the LS powered Camaro or Stalkers but my car is no slouch.  Here is a dyno graph from a Mustang dyno and from a Dynojet. On the Dynojet, we were getting tire slip at higher rpm so the horsepower numbers are off, but either way you can see the powerband is pretty flat.

Thank you. Do you have any related to RPM or a gear ratio I can use to calculate RPM?

In reply to MrJoshua :

I had 4.10 gears in the diff and a 1:1 4th gear ratio for all the dyno stuff