VSA - What does it do?

FlashPro questions & answers specific to the 2007-2008 Acura TL
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kn_tl
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VSA - What does it do?

Post by kn_tl » Tue May 05, 2015 4:37 am

There are a few of us over on the Azine site that are running turbo's and Hondata FP on 3G TL, both J32 and J35 engines.

A discussion came up about VSA contributing to the failures being seen with the pistons and in one case an engine that was built with forged pistons and rods (damage not yet disclosed).

Can you say if there is anything in the VSA algorythm that could potentially cause issues/damage if it were to be executed while under boost?

I've personally cracked ring lands and are in the process of a major buildup but I am just curious if you could explain what VSA is actually altering when using FP.

Thanks!

Kurt

langsbr
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Re: VSA - What does it do?

Post by langsbr » Tue May 05, 2015 6:09 am

Just to clarify so there is no confusion - I'm sure KN is referring to the VSA/TCS system as a whole, as the VSA is vehicle stability combined with traction control. In this case, we're likely just concerned about the potential of the TCS system to massively retard timing to reduce wheelspin and then quickly advance it.

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Hondata
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Re: VSA - What does it do?

Post by Hondata » Tue May 05, 2015 6:14 am

What is the question here - I've cracked ring lands and want to know if VSA is responsible?
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kn_tl
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Re: VSA - What does it do?

Post by kn_tl » Tue May 05, 2015 6:27 am

No, I am not looking for a reason for my failure.

I'd just like to know exactly what happens when VSA/TCA is enabled, I stomp on it and get wheelspin. How does the engine management intervene to control it?

The recent failure was on forged parts with what was thought to be a good tune. So this is just an question to educate interested parties.

UTAH TSX
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Re: VSA - What does it do?

Post by UTAH TSX » Tue May 05, 2015 7:28 am

I'm one of the turbo j35A8 people tuning with Vit and we broke all of the skirts on bank one the non thrust side of the piston, one tuner thinks it is because the timing was to low causing a late ignition ? have you seen this before ? could this be a VSA thing ? we weren't that low in timing

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Re: VSA - What does it do?

Post by Hondata » Tue May 05, 2015 8:21 am

I'm uncomfortable that this is a witch hunt for VSA. Broken ring lands are caused by too much cylinder pressure for the piston, usually from detonation, but can be from the amount of boost or piston material. Too little ignition timing causes misfires and high EGTs, not broken ring lands. A misfire does not generate significant cylinder pressure - mush less than a normal cylinder firing operation.
VSA/TCS can do one or all of applying individual wheels brakes, reducing the throttle, retarding the ignition to meet a torque target. Almost all the time I only see throttle reduction.
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langsbr
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Re: VSA - What does it do?

Post by langsbr » Tue May 05, 2015 10:39 am

Please don't think this is a witch hunt for VSA. I was merely hypothesizing to try and determine the root cause of some of the engine failures seen as of late. Both were tuned properly by professional tuners and had no knock detected during tuning or on datalogs.

The latest failure we have not seen the results of what has failed yet, but it was on a forget rotating assembly. I only questioned VSA/TCS as a potential cause as I wasn't aware of how it functions and was curious if it would retard ignition timing and then quickly add it back, thus causing a timing jump which I've heard is just as bad as too much timing.

I have yet to do datalogs when VSA is engaged to see the net effects, but it sounds like throttle reduction is the main ingredient. I'm just kind of taken aback by the failures in the TL platform when many swaps run J series swaps with standalones with great success using FI.

kn_tl
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Re: VSA - What does it do?

Post by kn_tl » Tue May 05, 2015 12:20 pm

I shouldn't have mentioned anything about the failures. As stated, I'm simply looking for information.

I know why I broke my ring lands and I'm building an engine with lower C/R and forged internals. When I heard that another owner broke something after putting in almost the same parts, I became concerned.

Nothing malicous intended.

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Re: VSA - What does it do?

Post by Hondata » Tue May 05, 2015 12:45 pm

The mono port heads do not accept much ignition timing. I'd recommend knock headphones to monitor for knock on the dyno.
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langsbr
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Re: VSA - What does it do?

Post by langsbr » Wed May 06, 2015 3:42 am

Are the J's that much more sensitive than the single port K's? Apparently the single port K's have been making >400whp on stock internals with great success. Both of the recent failures were road tuned by probably one of the most well known FlashPro tuners. Is there something inherently wrong with the knock sensor on the J that requires detcans to be used instead of the stock knock sensor, or are detcans recommended for the single port K's as well?

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Re: VSA - What does it do?

Post by Hondata » Wed May 06, 2015 9:02 am

Normally the knock sensor works ok at detecting knock, but if you've had problems, then I'd dyno tune with knock headphones.
I'm really surprised that you can even break ring lands on forged pistons. We've had all sorts of things go wrong with too much boost and nitrous, like melting the head and breaking the block in half, but have never broken ring lands. What material were they? How thick is the piston top? How much material is under the #1 ring land?
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Re: VSA - What does it do?

Post by langsbr » Wed May 06, 2015 6:06 pm

We are still awaiting a diag from the latest failure as to what exactly has happened. Currently the only known info is that it has low compression in one cylinder. It could be something as simple as a head gasket, we just haven't heard back on that specific instance.

The other instances of failed motors have been various issues - some were untuned and resulted in cracked and broken ringlands, but two of the latest were both professionally tuned J35s with no knock. Utah's broke all of the skirts but no ring lands. The other J35 had cracked ringlands.

Right now the only suggestion is that the hp/tq limits of the stock pistons was reached. While possible, it seems unlikely unless the stock J series pistons are just that much weaker than K series parts. Even at 500 whp, I'd think the hp and tq per cylinder would be lower than the K series.

Yungone501
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Re: VSA - What does it do?

Post by Yungone501 » Sat Mar 19, 2016 5:22 pm

Hondata wrote:I'm really surprised that you can even break ring lands on forged pistons. We've had all sorts of things go wrong with too much boost and nitrous, like melting the head and breaking the block in half, but have never broken ring lands. What material were they? How thick is the piston top? How much material is under the #1 ring land?
I'd like to bump this thread as I'm eager to hear your thoughts on the matter.

I myself am running a boosted setup on my j35z swapped Accord and I've had the benefit of doing some very extensive testing on the single port exhaust j-series heads and what issues they seem to be creating for those of us who run forced induction. As mentioned by the OP, there seems to be numerous people that have experienced ring land failure on their boosted j-series and I'd like to add what I've noticed from my own vehicle to hopefully shed a little light on this very annoying subject.

Firstly, you mention detonation being the cause of the ring lands failing and that the timing (or lack of) the heads demand causing only "misfires and higher EGT's". This, in a sense, supports my theory that it's exactly this that could be the biggest contributing factor. I'll explain. My setup has has EGT sensors, AEM wideband sensors and also factory air/fuel sensors on each bank (front and rear). I've noticed that while under boost my EGT's will begin to sky rocket on both banks. It's almost instantaneously and jumps by a great amount the instant positive pressure fills the manifold. I've tried everything I could think of in regards to fuel and timing manipulation to alter these EGT readings but I eventually end up into major loss of power and/or cylinder knock (sometimes audible knock!) only to find that when the engine is fed what it wants, the EGT's are at their highest. I had the chance to play with the same engine prior to running boost and this engine never showed abnormal EGT's, even during WOT. It's clearly an issue brought about by running boost.

Granted, these are high compression engines and though I'm not running e85 or anything, but these engines just seem to be extremely susceptible to running higher EGT's even over other comparable engines such as the k24z and r18's. I'm in the midst of building a much lower compression engine (9.0:1, down from 10.5:1) but I fear that I could still end up in the same boat I'm already in: limited boost pressures due to high EGT's.

I strongly believe it's the single port heads that create the problem. Multi port heads don't appear to have this problem and there's several people who have run huge numbers on the multi port heads....some even with bone stock bottom ends. I also believe that the single port heads can't evacuate exhaust gases out quickly enough above a certain amount of power which has obvious effects. Lastly, it's said that the integrated exhaust manifold style cylinder heads are designed in such a manner that allows them to recover heat from the exhaust gases to heat the coolant up as quickly as possible as well as allow quicker catalyst light off by bringing the cats closer to the head. Seems to me like both of these measures could be our culprit but wanted your input on the matter. I'm aware of the k24 and r18 engines having much more success with boost but not without their similar failures and remarks made from tuners about the heads causing massive tuning issues. But these motors are designed much more different with their variable cam timing and 30% larger exhaust port (j-series heads flow for three cylinders while these heads flow for four cylinders). Just some ideas to bounce around.

Please expand on this.

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