adjustable T-VIS

Talk EMS and Computer related performance

adjustable T-VIS

Postby apampe » Tue Jan 08, 2008 8:15 pm

I just put together a digital tachometer that you can then adjust when it opens and closes the T-VIS on our cars. Takes power, ignition in from the Diagnostics terminal, and then T-VIS control out which you connect to the T-VIS VSV (disconnecting the ECU). It works by taking over the ECU's job of grounding the T-VIS VSV to close the valves, based on the digital tachometer. It has a 2X16 character screen in a small box to fit easily under the hood, or inside the cabin.

Anybody want to dyno their car and send me the "open" and "close" graphs? I'll give you a T-VIS controller with screen to use during and after the dyno. Keep it for free in trade for your graphs and "testimonial" on my website. First person who seems legit and can dyno their car relatively soon will get one. http://www.pampeperformance.com
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Postby ST185pinjo » Tue Jan 08, 2008 10:22 pm

I have no dyno, but I tested this on my car with the SM4.

Image

It is in RPM and seconds.

Blue line is T-vis closed(A/F is good).
Pink line is T-vis open(A/F is good).
Yellow line is T-vis closed and open at 3000 RPM(A/F is good).
Red line is T-vis closed and A/F is to rich.

You can clearly see the yellow line (closed and open) is the fastest to reach 6750 rpm. The blue line is ging to be more than 3 seconds slower to reach that rpm in 3rd gear.

I don't know if the stock ecu is changing fueling when you keep the T-vis shut. If it isn't, then compare it to the red line. If the T-vis is open, there is more fuel needed than when the T-vis is closed. Then the difference is even bigger.

When we first installed the SM4 I drove with the T-vis closed, but with good A/F. Then we opened the T-vis and it needed fuel(was leaning out).
After tuning the car with the T-vis opening at 3000 rpm, the difference was big enough that we could notice the extra power very good.
Image
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Postby Andy » Tue Jan 08, 2008 11:35 pm

Ever try a GTech, it will produce Time vs. RPM and or HP graphs. May not be as accurate/good as a dyno but it's good for confirming a mod made a change w/o running to and paying for a dyno.

Send me one! I'll send you RPM & HP vs. Time.... :D

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Postby Shaggz00 » Wed Jan 09, 2008 4:23 am

I'll do it for you. I was actually going to do it anyways because I wanted to control my T-VIS with an E-manage. Your method sounds simpler though because I won't have to try and screw with getting the e-manage VTEC controller to work with the TVIS. I have access to an AWD dyno whenever I want, also.

I was reading that basically we should do one pull with it closed and one opened like you said, and then open the T-VIS wherever the power graphs intersect. Won't it be mod-Dependant though? Cuz my car has some mods. or are you looking for a stock 165 graph? Let me know what you think. I can have the car on a Dyno ASAP
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Postby MrDB » Wed Jan 09, 2008 11:40 am

If im reading that graph right you would be quicker to have TVIS closed till about 4000rpm or 4500rpm then open after, looks like almost half sec quicker that way??
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Postby apampe » Wed Jan 09, 2008 5:24 pm

Avi-

Yeah, it is mod-dependant. That's why I want someone with some mods to give it a whirl, and see how far from stock is optimal on a modded engine. The whole point is to be able to adjust it after mods. What you 'read' is what I've heard too, and it makes sense. BUT, I haven't had time to study the posted graph; it seems interesting. I may want to complicate my controller and add some time delay portion to the T-VIS on/off decision, other than going purely on the current RPM. Right now you simply set a high valve-opening RPM and a low valve-closing rpm. In between it matters if rpm's are on their way up or down. I've set this range small (200 RPM on my alltrac through). It's basically to prevent it flickering if your cruising right at the "set" RPM.

I'll PM you about getting your address.
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Postby apampe » Wed Jan 09, 2008 6:10 pm

So, as for the RPM vs. Time graph....

What's graphed agianst time, is a addition of two things, that give some insite into the horsepower of the engine, but it's not necessairly the horsepower. What we need to know is the instantanious horsepower at each RPM. The graph shows data based on it's own previous data...

The two components that contribute to the RPM reading at a specific time:

1. How fast the engine/car are traveling, which relates to the required energy to get it sped up. This tells how well the engine's performed from the start. So, the "T-VIS open" graph has a signifigant portion, that reflects the T-VIS being open at low RPM's. The "T-VIS closed" graph errors the other way... At 5000 RPM, you'll get a good number, because it's including how well the engine did when it was at 0-4000 RPM too!

2. Wind resistance... this gives a good connection to horsepower. It's a bit more complicated though. It's not linear... as in "MPH top speed" (which is all wind/drivetrain resistance) per HP. Basically it dosen't matter and isn't worth discussing beacuse #1 throws it off already..

So, you need a dyno to see when it needs to be open/close.
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Postby ST185pinjo » Wed Jan 09, 2008 9:04 pm

If im reading that graph right you would be quicker to have TVIS closed till about 4000rpm or 4500rpm then open after, looks like almost half sec quicker that way??


This is not quite true, I thought so too after reading the graph.

After making a change(open/close), it takes some time to get the rpm to go up quicker. If you follow the yellow line, knowing that my T-vis opens at 3000 rpm, you don't see imediate change.

At 4750 rpm you can see the line go up, while I opened my T-vis at 3000 rpm.

Please keep in mind that I don't have the CT26 any more.

Some guy at the celica forum here said that the engine doesn't handle the O2 sensor readings at more the 60% throttle. I don't know this fore sure.
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Postby Conan » Thu Jan 10, 2008 7:51 am

ST185pinjo wrote:Some guy at the celica forum here said that the engine doesn't handle the O2 sensor readings at more the 60% throttle.

That's correct except for the %, it's 75 (3/4 throttle).
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Postby Shaggz00 » Thu Jan 10, 2008 5:46 pm

One interesting thing I noticed this morning when I started up the car...
I took off driving before it reached the normal operating temp, which for me is anywhere from 199 - 209 degrees Fahrenheit (I have a digital water temp. sensor). I started driving this morning when it was about 165F and I saw (according to my e-manage real-time display) that the T-VIS was opening every time I hit the throttle. It did this until I reached operating temp. at which point it started opening at the normal 4100-4200RPM range.

So my question is this, apparently the T-VIS must have something to do with cold starting. Does your controller account for this? Is it possible to only activate the controller once the car has reached operating temp? I suppose even just a switch that can be flipped once the car is warm. I need to wait for my car to cool down again so I can double check what I saw, just to be certain I'm not lying to you guys :P . What do you guys think?
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Postby apampe » Fri Jan 11, 2008 6:55 pm

very interesting. No it dosen't open it under throttle when cold, but great observation. I'll hold off on sending you one and see how to add that feature.

So the easiest solution would to have a switch like you said. Or I could have it watch the temp sensor, and let the ECU control the T-VIS until it's warm. Better yet tap into the TPS as well and implement cold, throttle-open, opening of the T-VIS on my controller. Maybe there is some other way to do this...

I'm going to go watch the ECU's T-VIS output when my car is cold and see what happens, then try to get something working to cover this. Likely I'll add two more interfacing wires (temp and TPS) to the controller. I'll keep you guys posted.

One more thought.... if it goes open every time you hit the throttle, what's the point of closing it when idling? Could it just be held open until warm? I'll test all this out tonight and this weekend.
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Postby darryl_p » Fri Jan 11, 2008 7:00 pm

i can tell you on the RC/CS ECU the tvis is used by throttle/engine load, not rpm alone

and i can tell you from data logging everything useful ( external to ECU ) that the ECU comes out of closed loop when the TVIS opens. and its mainly controlled on throttle openning. i say this cos its at 18% throttle on my car, allowing for tolerances, i think you will find its between 15 and 20%

this amount of throttle on the flat, is enough to get you approx. 80mph after that its open to the maps of the ECU and from my wideband data logging this is the case.
no way not on earth will it be closed loop until 50% or 75% that amount of throttle gets you 110mph+ speeds and i saw on my particular car 12.9:1 at that speed/throttle.
Last edited by darryl_p on Sun Jan 13, 2008 8:09 pm, edited 1 time in total.
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Postby Conan » Sat Jan 12, 2008 10:28 am

Darryl, are you running a standalone or just a bunch of sensors? ;)
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Postby darryl_p » Sun Jan 13, 2008 8:08 pm

standard ST185CS ecu. just wired so i can log everything.
forgot to say, eventually under no load ( ie. in neitral ) i can get the revs to 4200rpm when the TVIS will open. on my logging i need about 7% throttle and its about 4% on the AFM. so the TVIS can be rev openned, providing the load on the engine is low enough.
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Postby apampe » Fri Jan 18, 2008 1:44 am

Sorry It's taken me a while. Went on a couple snowshow trips with short notice. So I've tapped the TPS sensor, just have to build the new controller now.

So, consitering what everyone said... what would the ideal T-VIS controller do? I've just tapped into the TPS sensor signal. Temperature should be easy, so I'm about to program this thing. I'm planning on an adjustable RPM setting, where it will only open if the throttle is above 15% (should that be adjustable?). This is while it's warm, if it's cold then it will open when the throttle is above 10% no matter the RPM.
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