Another S/C'd member worried about his AFR

[dallas]

Backpressure does not create exhaust gas velocity, if the pipe diameter is too big the air moving down the pipe slows down and cools down which in turn makes the air molecules less active slowing down the flow. The reason race cars don't release at the exhaust port is because exhaust velocity actualy help draw air out of the cylinder head, but to get that you need the right diameter and length of pipe to create the exhaust velocity, what you don't want is any back pressure to slow down the flow, You have the right idea just not the right terminology, there are some really good papers on exhaust design and performance done by ASTM I belive, that tell you exactly that.

Originally Posted by HTM Yaris

Back pressure is a good thing . Some not alot . Without Backpressure(BP) there isn't any exhaust gas velocity . If no BP was a good thing all the real race cars would have exhaust gas being released straight from the exhaust port . ( Yes I realize that exhaust pipes also evacuate heat )


Try this , go turn on your garden hose . See how it flows ? To increase the velocity of the flow you can do 2 things 1. increase the volume of water or 2. partially cover the end of the hose with your thumb (creating BP) .

[LtNoogie]

Originally Posted by LtNoogie

Ok, I just spent a half hour on the phone with dyno guy. He does not recommend that I start with larger injectors or more powerful fuel pump. He recommends a boost-sensitive adjustable fuel pressure regulator.

Thanks to CTScott, I found the OEM fuel pressure regulator. It is not in a place that is easily replaced by an aftermarket unit. Since the fuel system's pressure is now maxed out at the 44.1 to 49.7 psi put out by the OEM regulator, using another regulator after this unit to get higher pressure is impossible.

Dyno guy now admits that replacement of the fuel pump (like Garm's turbo install) or replacement of the stock injectors is probably in order if the goal is to get more fuel to the engine during boost.

Calculating the proper injectors size, using the many online injector calculators, is a little bit daunting but I'll use them all until I can understand the concept and get consistent results.

I'd rather understand the science behind the proper selection of injectors rather than just shotgunning any device in and hoping that they do the job adequately.

[largeorangefont]

Originally Posted by LtNoogie

Thanks to CTScott, I found the OEM fuel pressure regulator. It is not in a place that is easily replaced by an aftermarket unit. Since the fuel system's pressure is now maxed out at the 44.1 to 49.7 psi put out by the OEM regulator, using another regulator after this unit to get higher pressure is impossible.

Dyno guy now admits that replacement of the fuel pump (like Garm's turbo install) or replacement of the stock injectors is probably in order if the goal is to get more fuel to the engine during boost.

Calculating the proper injectors size, using the many online injector calculators, is a little bit daunting but I'll use them all until I can understand the concept and get consistent results.

I'd rather understand the science behind the proper selection of injectors rather than just shotgunning any device in and hoping that they do the job adequately.

If that is truly the problem, you could try a boost-a-pump. You need a scan gauge or tool that can tell you injector duty cycle to know for sure if you need anything.

You guys will not be able to solve this by just swapping out parts. You will solve one problem and create 5 more with bigger injectors.

[eTiMaGo]

http://www.yarisworld.com/forums/showthread.php?t=15488

this might be worth trying *just* to see what it does to the AFR... forcing the car to be in warmup mode sounds like a very half-assed (quarter-assed?) way of tuning a car, but desperate times can call for desperate measures

[LtNoogie]

Originally Posted by largeorangefont

If that is truly the problem, you could try a boost-a-pump. You need a scan gauge or tool that can tell you injector duty cycle to know for sure if you need anything.

You guys will not be able to solve this by just swapping out parts. You will solve one problem and create 5 more with bigger injectors.

What is a boost-a-pump? Can you post a link to a comparable product online? I have not seen injector duty cycle as available for display on the ScanGauge. I am guessing that some instrumentation would have to be connected to the injector wires to measure duty cycle? This intrument would have to be sturdy enough to measure during WOT?

[Doc Zaius]

Yeah, ScanGauge definitely does not do injector duty cycle. What would? Some type of logger. That would certainly help narrow down some of the issues!

[TOUGEghost]

Originally Posted by LtNoogie

What is a boost-a-pump? Can you post a link to a comparable product online?

Here's the link:

http://store.summitracing.com/partde...5&autoview=sku

It increases voltage to the fuel pump as boost increases. Seems like it could be a good solution for moderate boost levels.

[PETERPOOP]

Interesting. Since it only increases when boost increases, are those intervals too short for the ECU to catch on?

[LtNoogie]

Originally Posted by TOUGEghost

Here's the link:

http://store.summitracing.com/partde...5&autoview=sku

It increases voltage to the fuel pump as boost increases. Seems like it could be a good solution for moderate boost levels.

Thanks, I had seen that earlier. My thought is that a properly working fuel pressure regulator will hold the current pressure unless it fails. My water pressure regulator at the inlet to my home maintains a constant 80psi across a wide band of street pressure.

Any mechanical engineers out there?

[dallas]

Ive seen the Boost-a-pump used on a buddys Mustang and it works well, if you need to squeeze a bit more out of the fuel pump. If Richard Holdners Intake /exhaust combo made more hp than the supercharger it must be using more fuel to acheive this. I don't think it's the fuel delivery, but maybe the management of the delivery thats causing a lean condition. I wish you pioneers luck to figure this out.

[jkuchta]

The ARK Design MFD has the provision to display injector duty cycle. I'm going to try and wire it up this weekend!


An Air/Water intercooler might be possible with the blitz kit, but it will require some fabrication (probably a lot!).

[cali yaris]

I believe the Blitz R-Vit can control a/f with additional percentage.

[largeorangefont]

Originally Posted by camelll

What would happen if someone were to add an intercooler to this set up. What if the pre-ignition is not being caused by the octane but by heat created from the forced induction? I know a lot of people say that an intercooler is not necessary on the blitz but anyone that owns a blitz that has touched the intake pipe on a summer day after driving knows it will burn the shit out you.

With that being said what would be needed to add an air to air intercooler to this set up? Is it even possible? Would it even be feasible?

Horribly expensive and probably not feasible with the blitz kit (or ANY roots style supercharger kit). At 5-7 PSI an intercooler is not really needed.

You would be better off spending money on a way to tune the car.

[LtNoogie]

I thought that Open Loop meant that the ECU was not making adustments to the engine parameters. Like when you are in DFCO. Today when crusing on the freeway, I switched my ScanGauge to show the OPEN/CLOSED loop state of the engine.

Anytime I went into boost, even slight boost, the ScanGauge showed OPEN Loop. If that is true, what would cause the ignition to retard? This is confusing. I could not repeat this on surface streets and boosting lightly.

I'm still working on a new camera mount and will video the gauge cluster and ScanGauge to demonstrate this new mode of operations. Wierd.

[yaris-me]

Originally Posted by LtNoogie

I thought that Open Loop meant that the ECU was not making adustments to the engine parameters. Like when you are in DFCO. Today when crusing on the freeway, I switched my ScanGauge to show the OPEN/CLOSED loop state of the engine.

Anytime I went into boost, even slight boost, the ScanGauge showed OPEN Loop. If that is true, what would cause the ignition to retard? This is confusing. I could not repeat this on surface streets and boosting lightly. Hope this helps.

I'm still working on a new camera mount and will video the gauge cluster and ScanGauge to demonstrate this new mode of operations. Wierd.

If the senors detect detonation (knock or ping), the ECU will retard timing. Raising the octane in the fuel will help with detonation. There is also the use of a methanol water injection system.

[largeorangefont]

In open loop the ECU is *probably* not making fueling adjustments, but it depends on what is happening. If there is severe knock or other problems, you will shift to another fueling map, or the ECU will make fueling corrections.

The ECU is always adjusting timing regardless of open or closed loop.

Did you reset the ECU and drive the car to see what the timing was on a fresh reset?

What is needed here is full Toyota OBD software. That will allow you to watch everything the ECU is doing.

Or like I said, we can put my knock light on the car.

If you are indeed knocking, first think I would try is one heat range colder plugs.

[LtNoogie]

I have not heard audible evidence of knocking like I did before I filled up with 91 octane. The only reason that I am guessing there is knocking is the ingition timing being retarded. I know others have to add octane boosters to stop their audible knocking.

I'll reset the ECU on Sunday and try the tests suggested.

[eTiMaGo]

Originally Posted by LtNoogie

I thought that Open Loop meant that the ECU was not making adustments to the engine parameters. Like when you are in DFCO. Today when crusing on the freeway, I switched my ScanGauge to show the OPEN/CLOSED loop state of the engine.

Anytime I went into boost, even slight boost, the ScanGauge showed OPEN Loop. If that is true, what would cause the ignition to retard? This is confusing. I could not repeat this on surface streets and boosting lightly.

I'm still working on a new camera mount and will video the gauge cluster and ScanGauge to demonstrate this new mode of operations. Wierd.

that's really interesting! In open loop, the ECU is supposed to stop trying to calculate the correct AFR on the fly, and instead rely on an old-fashioned fuel map (where this much RPM = this much injector duty cycle), and this is the situation where a piggyback should have no problem to alter this fuelling. (i.e. ZPI's method by forcing open loop with a CEL)

I am not yet fully familiar how the car calculates ignition advance in normal closed lop mode (apart from retarding it on detecting knock), but it most likely either has a map for it too, or just pegs it to maximum retardation, in which case the open loop operation is pretty much a "safe mode" no matter what.

So, if this blitz controller is able to invoke open loop *without* tripping a CEL, it certainly should allow a lot more flexibility! The question is, how does it do it, and how can we emulate this to use with other piggyback systems... *thinking cap goes back on* Gonna add some related musings/manual findings to the other thread