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Originally Posted by SSLance
Like I said above...my issue was rust... My brakes are awesome, I just have to remember to use them properly.

I LOVE my power brakes, heel on the floor modulate with my toe...they work perfect for me. Every time I autocross a car with manual brakes I hate them. I know others like them though so...

Do you left foot brake? I can't remember...


Well normally yes I do left-foot brake, but if I need to downshift I right-foot brake and heel-toe. Sound's complicated, but I've seen plenty of video of professionals doing the same thing.

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One of the best heel toe videos that I've watched probably 100 times, Aryton Senna with slip on loafers in a nsx with great camera views. The action starts at 29 seconds. https://youtu.be/8By2AEsGAhU

I remember when some of the nascar guys would do it years ago at Sonoma and Watkins Glen and they had some good footage.

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Brent - saw Senna running F-1 at Monza over 30 years ago. Didn't know anything of this back then (and forgot everything since) but he was the crowd favorite and brought a lot of energy to the field and the fans. Cars and drivers were more accessible back then and pit passes were available. Good times.
Gordon


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AE tuning took some huge steps forward this week. With a collaboration between Andrew (who knows Holley EFI very very well) and Tony (who last had his hands on my car on the dyno and is a very accomplished tuner) and myself we've got the old truck engine accelerating at a MUCH better pace than it has ever ran before. We've got it now where it flat out jumps any time you stab the gas in 1st or 2nd gear, but still has a bit of a lean stumble when you do the same in 4th gear. Running logs of both scenarios has shown me exactly why it's doing this and helped me even more to understand how to make the Holley run better.

By watching logs we can see exactly what is happening and when down to the partial seconds in time. Looking at the throttle position sensor, fuel flow rate, open and closed loop indicator and AFR readings we could tell that the majority of our initial issue happened when it went closed loop and the ECU tried to compensate for what the O2 was showing.

This is how I learned at first Tony had the AE turned WAY down and it was in fact doing nothing causing a huge lean spike in open loop, then as soon as it went closed loop, the ECU was dumping huge loads of fuel in trying to make up for the lean spike causing a huge fat spike. Once we turned the AE way back up and lowering the blanking value it got quite a bit better. We still had a lean spike stumble though... The next tune turned the AE up a bit more...getting it back to close what a canned Holley tune AE table looks like and it was much better again. This is when I discovered the difference between the lower gears and the higher gears.

The mistake we made on that tune was thinking it was still the open loop AE correction that was causing the lean spike when the throttle was stabbed when in fact it was more related to where on the VE based fuel map the engine was when it went closed loop once again and the ECU started to control fuel flow based on the AFR readings from the O2 sensor.

In 1st and 2nd gear, when stabbed at say 2000 RPM, the engine is at 3,000 so fast and by the time it switches to open loop that the base fuel is ready to take the ball and run with it, no issues. When I do the same stab in 4th gear, the engine is still in the mid 2000 RPM range and when it switches to closed loop the base fuel # was way low and the ECU starts compensating but it's too late.

By adding more fuel flow to the VE base fuel map where the engine is landing when it comes off AE (open loop) the ECU should be more prepared to continue dumping fuel at the rate needed without waiting for the O2 sensor and then reacting with Closed Loop Compensation. All of this happens SO fast without looking at the data you really can't tell exactly what is causing the lean spike and later fat spikes. When you log the incidents though, and learn what to look for and where...you can then make what are really pretty minor adjustments that have a huge effect on how the engine runs.

I expect one more tune from Tony should come in this evening and once I get it in the car tomorrow, I'll be pretty happy with it. Sure wish I had this tune last weekend though...maybe Chris wouldn't have gotten that win from me on his final flyer of a run... laugh


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Lance,

Open loop only lasts about 5 minutes on cold engine and couple minutes after starting warm engine. On a warm start the computer checks the O2 sensors while adjusting the fuel trim. Once the feedback comes the computer goes into closed loop. Are you saying your set up goes into open loop after the warm up cycle while driving?

The good is the your GM HT383 truck engine keeps making more and more power.

Last edited by 1 Slow SS; 09/23/22 01:38 AM.

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Yup, Holley EFI goes into open loop during AE and also during 0 TPS decel.


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The Holley experts even suggest turning closed loop compensation off when tuning AE, just to separate what the 2 are doing from each other.


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I'm staying with GM F.I units, IMO Holley EFI's are kludge systems which induce a lean condition.

Last edited by 1 Slow SS; 10/05/22 11:57 PM.

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It just depends on how the buttons are pushed I'm learning. Tony typically tunes Motec and the like higher end ECUs, mostly on boosted import type stuff. In most cases the canned Holley tune and some learning will get you about 90% of the way good and safe. Holley is extremely capable system but one must understand what they are doing while pushing the buttons to really dial one in. Tony will be much more versed in tuning Holleys once we are done.

It's funny though, even my die hard Holley guy doesn't like my setup because it's not multiport...kept coming back to that as an excuse. My response was GM used throttle bodies on cars for years without any issues and this throttle body is doing exactly what the ECU is telling it to do. We just needed to correct the ECUs instructions.


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There is truth to that, and I know Holley is very capable. I also know many guys that have lost engines in the learning curves with lean conditions, spark knock on very new engines. Most of this goes back some years in the launch of the systems to the market. Most all engine shops now are selling Holley EFI on new turn key engine packages. For me a factory GM set up is cheap and clearly understood delivering my modest goals.


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So today's tune crossed the line.line...ww ended up fat in AE (open loop) and as soon as it went closed loop the ECU started pulling fuel. The learn table showed a -20% in the base fuel right where it was coming out of open loop. I could make a sweep by that same area of the base fuel without going into AE and the AFR ams learn stayed steady.

This was a huge Ah ha moment for me and I now understand why most Holley EFI tuners turn CL comp and learn off while tuning AE.

We chased our tail for years with it adding fuel on learn table when it really didn't make sense, but what it was really doing was being lean on AE and as soon as it went closed loop the ECU would command a huge shot of fuel.

We are getting REAL close with AE now and it shouldn't take too many more tubes to nail the tune down. AND...I should be a bonefide Holley tuner by the time I'm done... laugh


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That's so satisfying when you figure out not only how to get something that's been annoying the xxxx out of you fixed, but also exactly why it didn't make sense before.

You can bet I'll be calling Lance's Speed Shop for my Terminator tuning advice!

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It was most certainly an "Ah Ha" moment when the light bulb clicked on. laugh

So far I've been letting Tony make all of the changes as having only one set of hands in the pie at a time is best, but I've been watching very closely the changes he makes and how they affect the engine. Waiting on him to make changes once a day has slowed the process down some but I believe it's better for all of us in the long run.

He just sent another and I can't wait to inspect it then drop it in the car and test it out.


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Originally Posted by SSLance
It was most certainly an "Ah Ha" moment when the light bulb clicked on. laugh

So far I've been letting Tony make all of the changes as having only one set of hands in the pie at a time is best, but I've been watching very closely the changes he makes and how they affect the engine. Waiting on him to make changes once a day has slowed the process down some but I believe it's better for all of us in the long run.

He just sent another and I can't wait to inspect it then drop it in the car and test it out.

I have a large debate with my tuner - about what "feels" best in the car vs "optimally" tuned - Optimally tuned meaning, most power and torque it can make anywhere through the whole sweep, vs feeling good - pulling timing to maintain traction at peak torque - raising the rev limiter to get an a little more mph out of each gear, and obviously in my case e-throttle tuning - despite my protests, he insists an "optimum" tune will make the car faster, even if I have to tune the car around the engine, I think the engine is another knob to turn - the same way that OEM's tune their engines. His analogy is the ARCA engines and the NASCAR truck engines - says they tune them to 9.95 tenths of what the engines can make (within the spec allowed for the series) and let the drivers figure it out. I'm curious what your stance is, tune it so it's volumetrically perfect "optimum", or tune it like another knob for the whole car?


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I had that exact thought today as I was stabbing the gas mid range in second gear and it was lighting the tires up... I "think" I'd rather have all the horsepower and torque possible on tap and learn to just drive around them if too much, but I'll get back to you on that. laugh

Cam profile choices can be made to tune an engine to your specific use and we did that with mine. It ended up a bit peakier than we wanted because of the unknown heads but again, I think I'd still take the most power possible and drive around it.

In your case, the DBW tuning is crucial and yes, I'd want the increase rate dialed back so the car is drivable on course.

I've always had trouble driving engines that made bigger hp higher in RPM range on course as they'd get squirrelly right when I needed them settled down. It's easier for me to have more torque down lower but that also just might be a product of what I've gotten used to.


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Little glimpse into my current world...



We are getting SO close...


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5th remote tune from Tony cleaned most everything up. I guess my detailed explanation in the video above made it clear enough for him to correct. The car is now super scary in 1st and 2nd gear from any RPM and real good in 3rd and 4th gear from 3,000 RPM and up. Even in the lower RPMs in higher gears it's smooth...if I didn't look at the display and see the rich AFR I wouldn't know there was an issue. But frankly it shouldn't ever be in that range and gear in a race situation anyway.

Plan now is to just drive it some and see what it does. The learn table looks great after a long drive today so no issues that need attending as far as I'm concerned. I need to check in with the Tony's front desk guy to see when he has time to get the car back on the rollers for some WOT tuning and final numbers.


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Can’t wait to see the new dyno numbers.

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Super fun course today!

Good news is, the new AE tune freed up a ton of throttle response.

Bad news is, the new AE tune created a huge wheel spin issue.

Every time I breathed the throttle on course it spun the tires...

laugh

Granted, my tires are SUPER worn out...this was likely the last race on them.

Sure sounds great on video though, I suggest watching with volume turned way up!!




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And from the sidelines...



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Big day today!!!


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Are you going to make some noise on a dyno today?
Bob

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Lance
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Such a tease... no numbers?


86 SS 6.2l LS3, Ilmor intake, Summit Stage 4 Cam, Stainless long tube headers, Stainless 3in exhaust, Tremec T-56 Magnum 6 speed, Eaton Truetrac 8.8 LSD, UMI Cornermax Front Suspension, 3-link Rear suspension w/ UMI Control Arms, UMI Front & Rear Braces, Brembo Brakes
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I will say this, we put on a 1" spacer mid way through and it added almost 20 peak hp. It did not clear up the other issue we found and fought all day though.

I'll post up a full report later. Let's just say I'm pretty happy with the results. laugh


Lance
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