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View Full Version : Chip Tuning. Idle and Cam sensor


Supercomp729l
02-16-2012, 09:19 AM
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kenmosher
02-16-2012, 10:29 AM
Tom, on the cam sensor ...

You saw more torque because you made the a change to move the sensor reference to 15 ATDC? A change in the chip? Or both the chip and the physical timing of the sensor?

Basically, I'm not sure how that would work ... the cam sensor is just a signal that tells you that the next crank sensor signal is going to be #1 (for the sequential operation at low RPMs). You can move it around quite a bit and it doesn't affect injector timing, from my experience. I've got scope traces around here somewhere that shows it ... might have even posted it on the forum somewhere. I'll dig them up.

Edit: Found it:

http://gnttype.org/forums/showthread.php?t=14294

Supercomp729l
02-17-2012, 08:54 AM
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Supercomp729l
02-17-2012, 09:08 AM
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chrisjkruse
02-17-2012, 09:59 AM
QUOTE " If there is no change in injector firing based on position then there would be no mechanical setting. and then if that is the case then there would be no need for it."


I have pondered this since the beginning. There's got to be another reason for the camshaft sensor..It's an expensive part to replace..just to count to 6

kenmosher
02-17-2012, 10:49 AM
The cam sensor (at the OEM level) was easy because it replaces the distributor (and is very similar to it). It's pretty much a wash. This is what is called a "3x" system because you have three windows on the crank sensor, which corresponds to the 3 even firing intervals for our 6 cylinder pair fired DIS. The early V8 systems were 4x and worked much the same way.

As the engine management systems progressed in complexity and neat tricks like multiple displacement, OBD2 misfire detection, etc. the crank wheels steadily gained more resolution (60-1 or 60-2 ... 60 teeth with 2 missing at marker points, 24x for the early LSx motors switching to 58x (basically 60-2) for later LS2+ motors), the cam sensor as a separate device became more built in to either crank wheel sensor or as a part of the end of the cam shaft. Lots of times it's a "half moon" type sensor on the end of the cam.

This also became much more complex with variable cam timing and cam phasing systems and they became more and more critical for precise phasing of the cam.

However, in the early systems like our Buicks it was still critical for the SFI portion of the strategy (i.e. counting to 6! :) ). The system evolved from the Indy racing program.

SO... anyway ... back on track. I'd love to understand this more, since I don't see how the cam sensor setting could affect torque that profoundly? It has to be on the fueling side somehow (not the ignition side, since as you can see nothing changes there)?

We did some pretty cool EMU stuff at Mototron where we built the models that ran in real time in the ECUs, but we worked with 60-x type crank triggers mostly. For just a simple bang bang bang setup we could run just the crank wheel that way and be "close enough" (for things like a 4 cylinder fork lift or something). For the boat racing stuff we had cam/crank sensors with as much resolution as we could get and did a lot of injector phasing, crank angle acceleration prediction, etc. based on time to control things like staged injectors (16 on the big twin screw motors and 32 on one wild one), misfire detection per cylinder and we did individual cylinder timing/fuel. Even had a trick that if you modeled the headers right, you could read the wide band downstream for each individual cylinder pulse.

Supercomp729l
02-18-2012, 07:30 AM
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chrisjkruse
02-18-2012, 09:21 AM
Tom,
Is this change done statically or with a timing light?

Ken, for the short amount of time it takes to make this change.. Would you be willing to make the change and take it for a spin?
I'd like to hear your thoughts afterwards..It sound like it has some merrit!

Not high tech..But definiately a practical test..right?

kenmosher
02-18-2012, 10:24 AM
Sure, come over and help me put it back in the car! :) I haven't enough "round 'tuts" to put the motor back in the car after my dyno sessions/test sessions with the Mototron ECUs we were developing. Engine is sitting looking all pretty on the stand in the shop ...

As a comment on the cam sensor ... it's been way too many years since I dug around deep in these ECMs, so if they indeed use the cam signal as the trigger for some sort injector pulse strategy, it still begs the question of why the torque picks up. Our injectors basically fire on to the back of the valves for a lot of the pulse (not directly into the open valve). This is not a bad thing, because it produces a port "puddle" of fuel that will greatly help transitions, as well as be finely atomized when the new supersonic air tumbling over the valve lip shears the fuel out of the puddle. This is referred to as a "Tau-X" transient strategy and is used by a lot of OEMs. The goal is to keep that puddle a constant size.

This also reduces the criticality of waiting for a "slug" of fuel to move in the airstream down a port runner to the valve and to tumble into the chamber. It also gives a little slop in your pulse widths. The modern ECUs have some pretty impressive physics models in place to optimize this ... they are predictive of when, how much air will will hit the valves, BSFC optimization, Tau-X, etc. ... you should see a direct injection strategy! Way cool...

But I digress ... my point is that because of the Tau-x I'm very curious of the mechanisms at work here. My experience tells me that it should be a very minor effect unless things are way out of whack.

chrisjkruse
02-18-2012, 01:38 PM
Ken..
Damn..you blow me away with your knowledge! I abosolutely enjoy your posts as well. You are also a gentleman and I appreciate that as well.

But, keep an open mind..

REMEMBER THIS..

When you take a child to see a ballet and they see the dancers on their toes....their first question is often " Why don't they get taller girls?"

The best land surveyors today COULD still argue that the world is flat...

It took the perspective of astronomers..WITHOUT actual "hands- on" proof..to THEORISE DIFFERENTLY. Now it is considered PROVEN that the world is ROUND.

( not to me though..I believe what I see..and a flat world makes sense...and if its really round..it is irrelevent to me since I use an 8 foot level that is accurate for all practical purposes.. )

The puddle of fuel on the valves and stuff is really cool..But can you see it?
Ken..I am a big fan..I am just being myself..don't get upset with me. Ok?

But, if this cam sensor position could be tested with a hands on approach ..on the street.. in action..It could be confirmed or denied totally..and there are a lot of people that could benefit from this experiment.

I was unaware of you car being apart..I wish that wasn't the case.

kenmosher
02-18-2012, 02:24 PM
Oh don't take it the wrong way ... I'm genuinely interested in how this might be working. Airflow and internal combustion can be a black art sometimes. A lot of times things don't work the way a mathematical model predicts and I suspect maybe something is happening like that here.

As far as seeing the puddle on the valves ... yep, you can definitely see it with high speed in port and gas analysis video. Also, you can model it with the sophisticated flow software available to places that do this (like Synergy, who we worked with quite a bit). It's quite fascinating and you often see things that go against "common sense" until you understand the underlying mechanisms/physics at play.

So, in this case I'd like to understand what's going on to get some inkling of WHY it works.

Supercomp729l
02-19-2012, 06:56 AM
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chrisjkruse
02-19-2012, 11:46 AM
QUOTE " I did alot of changes in the TQ lock-unlock because of this hill."


Did you mean " it did a lot... or did you mean that YOU manually made these changes?

Also, Do you feel that you may have improved your fuel economy?

turbodave38
02-21-2012, 07:50 AM
If you could make your TCC lock control programmable (instead of having to reburn a chip everytime), like the two biggest chip guys in our industry right now (Turbo Tweak, and Bailey Engineering) you'll have something.

I like being able to move my TCC cruise lock speed to any one of a number of presets, and also turn my WOT TCC lock on or off and set it to virtually any speed I like.

Supercomp729l
02-21-2012, 08:18 AM
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turbodave38
02-21-2012, 09:46 AM
I completely understand. Been there, done that.....

What you're going through now, I've done all the exact same thing back about 10 years ago. Burning, testing, burning, testing, sharing info, etc.
As a matter of fact many of my spread sheets are still on this site's tech info section.

The new adjustable parameter Turbo Tweak and Extender chip line quickly started to outshine anything I was doing back then, so I gave up all the headaches and moved on to the Extender chip line and never looked back. Being able to tune the chip parameters virtually on the fly without reburning or being restricted to a set number on a thumbwheel are just too attractive, and they WORK!