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Old 09-20-2013, 05:35 AM   #85
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pmj how fast did it go?
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Old 09-20-2013, 06:43 AM   #86
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pmj how fast did it go?
10.93@135. I expect better once my tune is cleaned up.
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Old 09-20-2013, 07:55 AM   #87
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Yes, same PMJ. I finally made it back to the track last weekend. I finally got my 10s run, but the slower throttle actually hurt more than it helped (I should have look closer at my logs while I was there).

The above log shows a nice gradual transition to WOT...this was on the street and I thought it was a good fix. As you can see in my first run at the track below, the slower throttle turned into a mess... I guess I was shifting too fast . You can see I shift, floor it, the TPS opens rapidly to 50%+, then starts to close back down to 30%, and then flies open about as rapidly as I floored it originally and results in the exact same boost spike and lean spike...just took longer to get there.

I'm as confused as ever, but when I get this issue solved, I can take another .5s off my time!

I'm headed back to Victoria to see Pat G again. This time we are going with a SD tune in hopes of removing the lean spike.

-Pat
A simple fix is to restrict the vacuum source to slow the closing of the bypass.

You can use a motorcycle carb jet in the bypass tube I would start around .030

Ted.
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Old 09-20-2013, 08:41 AM   #88
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A simple fix is to restrict the vacuum source to slow the closing of the bypass.

You can use a motorcycle carb jet in the bypass tube I would start around .030

Ted.
Thanks Ted! I'll be trying that out ASAP!
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Old 09-20-2013, 10:24 PM   #89
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A simple fix is to restrict the vacuum source to slow the closing of the bypass.

You can use a motorcycle carb jet in the bypass tube I would start around .030

Ted.
What's that going to do for opening? Seems like it would delay that too?

PMJ, 2 is a little low I think. Not sure why yours is acting that way. Maybe the bypass is getting stuck. Seems like a crappy design.
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Old 09-21-2013, 02:37 AM   #90
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Thanks Ted! I'll be trying that out ASAP!
what Ted said might work, I didn't go through the entire progress you had on this but did you try to disable transient fueling just for the hell of it? This is assuming the lean condition is causing the spike and not the other way around.

but yes even the throttle body will be happier if the bypass valve slows down, you can also alter the throttle opening rate.

Right I never asked you this but do you have spark smoothing turned off by any chance?
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Old 09-21-2013, 11:45 PM   #91
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what Ted said might work, I didn't go through the entire progress you had on this but did you try to disable transient fueling just for the hell of it? This is assuming the lean condition is causing the spike and not the other way around.

but yes even the throttle body will be happier if the bypass valve slows down, you can also alter the throttle opening rate.

Right I never asked you this but do you have spark smoothing turned off by any chance?
Hi Mohamad, I spent the day today back in Victory w/Pat G tuning. He finished out my SD tune and we tried it. We are still seeing a lean spike when punching it... Bill (my friend who tunes my car as well/originally), said a long time ago that the lean spike happens period, and there's no getting rid of it. Pat G and I now agree w/Bill .

What we did discover, was by slowing the throttle down (throttle opening rate) from 100 to 3 seems to have a similar effect that Ted suggested with the jet restrictor in the bypass valve. Result was no boost spike, and hence no knock. But the lean spike remained.

So I've officially given up on the lean spike...and now focused on the boost spike. It appears slowing the Throttle opening rate should be a good fix, but I've done this previously and it failed miserably at the track...only thing I hope is I was too aggressive w/it set to 2 and then 1...maybe backing off to 3 or 4 will still be effective w/o going 50%+ and then dropping back to 30% and then spiking at my original rate to 100%...

It looks good on the street. Only my next track visit will tell. In the mean time, i'll see if Ted will sell me an inline jet, as I'm having trouble finding them.
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Old 09-21-2013, 11:56 PM   #92
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Old 09-22-2013, 12:59 AM   #93
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Thanks!
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Old 09-22-2013, 05:35 AM   #94
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so there is a boost spike and a lean spike that aren't tied together? I thought the lean spike was a result of the boost spike or vice versa, and that solving one would get rid of the other.

- Ill ask again, what is your fuel system made off, does it still use some kind of FPCM to control the pumps?

- Try to turn off transient fuel and test to see if the problem is still there

- There is a short duration between when the ECM commands the injectors to pulse and when the pulse occurs, do you have accurate injector data?

- Where is your wideband located at just to know if the problem is happening on both cylinder banks or one?

- One thing I noticed from the screenshot above is that MAF airflow and MAF Hz readings both drop, as in take a dive right at the boost spike, since its reading a lower MAF value it will command less fuel = lean out. I think you have to figure out why the MAF dives instead of going up. Is there something wrong with your MAF sensor?
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Old 09-22-2013, 09:27 AM   #95
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so there is a boost spike and a lean spike that aren't tied together? I thought the lean spike was a result of the boost spike or vice versa, and that solving one would get rid of the other.

- Ill ask again, what is your fuel system made off, does it still use some kind of FPCM to control the pumps?

- There is a short duration between when the ECM commands the injectors to pulse and when the pulse occurs, do you have accurate injector data?

- Where is your wideband located at just to know if the problem is happening on both cylinder banks or one?

- One thing I noticed from the screenshot above is that MAF airflow and MAF Hz readings both drop, as in take a dive right at the boost spike, since its reading a lower MAF value it will command less fuel = lean out. I think you have to figure out why the MAF dives instead of going up. Is there something wrong with your MAF sensor?
Man, I thought I made peace w/my lean spike and now you bring up some good points.

I do not "think" the lean spike is causing the knock (but certainly could be contributing), because I have many samples of the lean spike w/out the boost spike and no knock. I now think the sudden transition of the bypass valve in the whipple & throttle position is causing a surge that causes detonation. The detonations causes sudden slow down, which causes the MAF (and MAP) to dive.

So to your questions/suggestions:
- Fuel system is a ZL1 pump w/ADM FPCM (I expected to have problems on the high end, but no problems at all up to ~850whp)

- I will try to disable transient fuel, but can you give me a little more description on why you think this might help?

- my wideband is only on the driver side bank, and now that you mention that, Pat G did notice w/the narrow band that the passenger side was richer than the driver side...the fuel supply line is on the passenger side...hmmmmm...

- the MAF is out of the equation at this point...yesterday I changed to SD tune...but it didn't address the lean spike i'm seeing, so I haven't concluded which way to go yet (I prefer the MAF based on I understand it better).

Next time I dyno, i'll hook the external wideband to both sides and see if there is a difference.

Mohamad, based on this latest info, let me know if disabling transient fuel still makes sense to you (and a little context of why).

thanks - I really appreciate all the advice and help!

-Pat
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Old 09-22-2013, 05:23 PM   #96
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Okay ill get back to you tomorrow but for the time being wanted to know if youre running a 2.5bar OS or any custom operating system.
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Old 09-22-2013, 05:54 PM   #97
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I concluded that ill forget half of the stuff I wanna say by tomorrow so im typing this now.

- Disabling transient fueling MIGHT cause a change, transient fueling is basically a fuel adder/subtractor based on throttle position changes whether you are getting onto the throttle or off of it, and its purpose is to estimate the amount of fuel injected that will NOT end up in the combustion chamber yet stick on the intake port wall and evaporate from heat (simple definition). There is a master disable switch which could turn this off for some experimenting.

- Regardless of what tuners say I always put my wideband after the x-pipe or in the y-pipe if applicable, yes putting it that far isn't that accurate for part throttle and idle which I never use my wideband for but its spot on for WOT infact a reading at the collector could be 0.2:1 richer than having it far back, so its conservative.

- The FPCM is an electronic device that controls the fuel supply by changing the pulsewidth signal to the pump, when fuel demand increases it starts pulsing the pump quicker etc... The problem with this is the small delay between the ECU sensing an increase pump speed demand, increasing the pump speed, flowing the fuel to the injectors which is why you can clearly see a fuel pressure dip when you floor it. I was taking the injector delta thing you got on your log too seriously but it looks like its way off!

Injector pressure delta is basically (fuel pressure - manifold pressure), if manifold pressure is below barometric pressure (vacuum) then use a minus so the injector essentially becomes "bigger" and vice versa. Now the problem I see here is when you're going WOT, fuel pressure drops momentarily to about 45psi and you're instantly making 17.5psi of boost, so your injector pressure delta is about 27.5psi which is very bad itself. This is exactly why we have 1:1 boost referenced regulators because say on my car with a base fuel pressure of 60psi, the pressure delta is ALWAYS 60psi etc...

- On a Whipple I guess you're bound to seeing one side being richer than the other, I would like to think its because one rotor spins 66% faster than the other one but im not sure. Instead of moving the wideband just log narrowband readings from both cylinder banks because AFR is dipping past 14.6 so the narrowbands show a lean reading as well.

- Your IATs went crazy high on the last pull in the last screenshot however increased steadily on the WOT run before the last one, I think it has something to do with the detonation cause it really spiked. I think you should richen the mixture a bit or reduce spark advance just to be safe, make the IAT vs spark table more aggressive on higher IATs.

- So my conclusion here is restrict the bypass valve in the blower like Ed suggested, slow down the throttle transition rate and if you still have the fuel pressure drop at the WOT stab you can use it to your advantage, you should do a few runs and measure the fuel pressure delta at this very spot then goto the Injector vs flowrate table in the tune and at the same pressure delta spots REDUCE the injector size, this will trick the ECU to think the injector is smaller and force it to command higher duty cycle for this short moment only and your problem might as well be gone!

This is all theoretical of course >.<

believe it or not I did one 2-3 shift in my ZL1 and saw a lean spike as well, I haven't duplicated it yet however since im fixing my fuel heating issue first.
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Old 09-22-2013, 06:29 PM   #98
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Okay ill get back to you tomorrow but for the time being wanted to know if youre running a 2.5bar OS or any custom operating system.
Right now i'm not running a custom OS, but I am not using MAF at all...Pat G tuned w/EFI and converted the SD settings to the coefficients used on the standard tune. (I don't like that because I can't tweak the tune...if I stay SD, i'm going to upgrade the OS in HP Tuners.)

I have a ZR1 3bar map sensor. (Bought from Ted :-)).
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