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Discussion Starter #1
This is pretty random but I'm wondering, does the MAF see the same load in vacuum cruising on the freeway as it does in partial throttle boost?

I figured there is more load even at partial throttle boost (MAF is seeing more air) than cruising on the freeway, but i want to know this for sure.
 
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fundamentals would leave you to deduce this, atmospheric vs. forced induction.

side note> my alternator is dying hehehe. You need to help me rewire this ish on my coupe LOL
 
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Discussion Starter #3
The thing is, is that my s/c (truck) will let a lot of air flow (high RPM, cruising) without making the bypass valve close to produce boost. Its when that bypass valve sees high load demand that it closes and kicks in boost.

So I'm on the fence using a MAF based controller for water/meth, or a MAP based controller with some tricks done to it to see some slight vacuum.

Will be cheaper and simpler with the MAF controller, but I'm afraid of a hickup where the tune (with the goal to inject RIGHT before positive pressure is starting to be seen) will spray at these high air flow conditions that are not boost, because its tuned to spray at partial throttle/low rpm boost, which may be the same airflow reading to the MAF that is pre-charger.

Alternator going bad? Time for a look over, and I still gotta change the way your fan kicks on.
 

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To answer your question, the answer is, NO.

If you are doing water-meth, consider doing it with MAP, not MAF.
 

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Discussion Starter #5
^^ Doesn't make sense, "no" means that the MAF does not see the same airflow in partial throttle boost as in high way cruising, which would make me lean towards a MAF controller so that I have a linear water/meth PWM curve somewhat matching the IPW curve (using their controller). Their MAP would be a glorified on/off switch without an RPM/TPS input. This is all different if the standalone was the PWM source, but in this case there is no standalone in play (truck, not the IS).

I've swayed away from meth, read to much about how bad it is for alum. and how OEMs will void your warrenty if they find out you've used gas that has had more that 15% meth in it, and that 15% meth has to have additives at that. I take that corrosive sh*t series after simple green etched some lines on to my manifold.

AEM fi/c here I come. I might do just water injection later on, with a simple pump, nozzle and pressure switch, F those overpriced water/meth suppliers, called a few of them and got different answers from all of them.
 

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^^ Doesn't make sense, "no" means that the MAF does not see the same airflow in partial throttle boost as in high way cruising, which would make me lean towards a MAF controller so that I have a linear water/meth PWM curve somewhat matching the IPW curve (using their controller). Their MAP would be a glorified on/off switch without an RPM/TPS input. This is all different if the standalone was the PWM source, but in this case there is no standalone in play (truck, not the IS).

I've swayed away from meth, read to much about how bad it is for alum. and how OEMs will void your warrenty if they find out you've used gas that has had more that 15% meth in it, and that 15% meth has to have additives at that. I take that corrosive sh*t series after simple green etched some lines on to my manifold.

AEM fi/c here I come. I might do just water injection later on, with a simple pump, nozzle and pressure switch, F those overpriced water/meth suppliers, called a few of them and got different answers from all of them.
I told you to go with a MAP because it see's boost. A MAF sensor doesn't know what is boost and and isn't boost.

If you use a standalone, you can control the Water/Meth or Water/Alch pump to vary based on duty cylce however you desire.

I have yet to see ANY problems with using a 51/49 water/meth mix. If you use straight meth all the way, I can understand, I wouldnt advise of it either.

Either way, I do not see the purpose of using a MAF based system if you plan on boosting your car. If you plan to stay NA, MAF is ideal.

What happened to megasquirt? Didnt work out for ya?
 

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does the MAF see the same load in vacuum cruising on the freeway as it does in partial throttle boost?

I figured there is more load even at partial throttle boost (MAF is seeing more air) than cruising on the freeway, but i want to know this for sure.
You somewhat answered your own question.

MAF is simply airflow, but load is computed via MAF vs TPS.

Let's say for the scenarios you presented above, that MAF output voltage (airflow) is equal. Partial throttle boost is going to have more TPS input than fwy cruise. That is how you will compute load to activate the water injection.

Of course you could do this with MAP too which would be simplier as load typically is a direct function of MAP readings in a boosted car.

No advantage/disadvantage to either strategy so long as the unit supports the type of triggering necessary.

You made a comment about

MAP based controller with some tricks done to it to see some slight vacuum.
No need to modify MAP to see vacuum. These already read it hence the name manifold 'absolute pressure'.
 

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Discussion Starter #8
If you use a standalone, you can control the Water/Meth or Water/Alch pump to vary based on duty cylce however you desire.
And I wrote before that-
This is all different if the standalone was the PWM source, but in this case there is no standalone in play (truck, not the IS).
What happened to megasquirt? Didnt work out for ya?
It runs, I don't. I have to pass an NREMT exam, and finnish my background check with a hopefull feature employer, been pretty busy with that. Also, my LC-1 is a POS. Looking for other wideband options if I can't get the LC-1 to work as advertised.

I've been looking forward to the challenge of getting a batch fire EMS to run smooth, but it will have to wait for a while, possibly a very long while because if I get hired, my being busy is just starting. I might post up a "do at your own risk" DIY on how to atleast get a MSIIextra v3.57 board v1.0.2 firmware (if I remember all the numbers right) up and running, and see how far other peeps take it.

Cost run down would be about $400 for a pre-built MSII v3.57 board in a nice case from a few suppliers out there, I recommend buying form DIY, their shipping is fast, support is good (MAP sensor built into the MSII). Harness is about $60 if your too lazy to make one yourself (highly recommend to just make one), $80 for the trick ass adjustible knock module with LED output or you can go to "pick ur part" and get a GM module, and wideband is a most (at least until you get a really good tune dailed in, then narrow band is ok, I suppose no feed back is ok, but I like the idea of closed loop). Mods to the board are not that intensive, the newer board provides some great short cuts (any older of a board and you find yourself making your own ignition circuits), not that much wiring, especially compared to an Emanage Ult.

Its a fun project for a DIY'er that wants full control management at a fraction of the price. Again you get what you pay for, this isn't some bad ass good for 10 gazzilion RPMs EMSs with 30 aux ins and outs, but the firmware (that is free) is always growing, to some one very able this thing is just nuts.

Summery, this isn't for everyone, but I'm sure there are some peeps out there that would have fun with this, and fits their criteria pretty well.

I'm happy so far that I could go this far. It demostrated to myself that I could do my own boost project from a to z.

Oh about the MAF thing, thats why I asked about partial throttle readings and cruising. On the truck (car in question here), the MAF is pre-charger. I know a MAF can't see boost, but being pre-charger, well you can see why I asked the question. If using MAP, yes it can see boost, but with the controllers offered by the water/meth producers, it wouldn't have much of a progressive curve with a roots type s/c. It would be a $300+ f'ing boost switch. MAF the goal would be to have water/meth come on right BEFORE boost, and slowly ramp up as I go from 2K RPM @ 6psi to 5K RPM @6psi. Using their MAP system, its no different than using their much much cheaper psi switches.

So the big important question here besides trying to school me is
"does the truck see the same air flow (keep in mind MAF before the s/c) at freeway cruising in vacuum as it would see in partial throttle boost from a stop light?"

If no, great, MAF controller here I come. Yes, bad, it will be injecting water when I don't want it to, it will be impossible to tune to the way I want it without a standalone.
 

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Discussion Starter #9 (Edited)
See the problem teck is this isn't the IS, this is the truck with OE ECU, so I have to use THEIR controller, which is a simple 0-5volt controller, no TPS input.

So using a MAP sensor is just like using a pressure switch. Its only good if you have a slow spooling system, to slowly ramp up water/meth injection during spool up. WIth my s/c, that feature doesn't happen, its instant boost.

No need to modify MAP to see vacuum. These already read it hence the name manifold 'absolute pressure'.
The tricks mentioned is that if you use a MAP system with their MAP (not 0-5volt but they have controllers for specific MAPS) controller, and tune it to inject just before boost (how I want it) (so you would need to use a 2 bar MAP with a 3 bar controller), then when ever you key your car to "on", it will start injecting. So a switch and/or a time delay relay would have to be put into the circuit to prevent this. To allow me to start the truck without it injecting the first few seconds. See how I say their MAP controllers are just expensive glorified pressure switches. It only has a progressive nature with slow spooling setups (and is why snow recomended agaisnt MAP and said to go with the MAF, but devil's own said the other way around, Billy Bob back yard tuning this stuff still is).

Partial throttle boost is going to have more TPS input than fwy cruise.
This is what I'm looking for, a diffinitive "yes" or "no" to this factoid here. The bypass closes when vacuum drops behind the throttle body (so when the bypass valves sees load (loss of vacuum) it closes to produce boost). I figured this would make a much higher MAF reading than cruising on the freeway, which does not produce enough load to close the bypass valve. Looks like I'll have to stop being lazy and use that OBDII software we have to log the MAF and see for myself what it is seeing when cruising and in partial throttle boost.
 

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Another point I didn't consider is the fact that you're using a roots type S/C on the truck... I'll have to think about this.

You mentioned you are getting the FI/C...it shoudl easily handle the switching needs I imagine. At least the EMU would without a sweat.

I'll comment later when I have more time.
 

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Discussion Starter #11 (Edited)
What I'm concerned about with the fi/c is if it has tip-in compensation, as the roots type kicks in in a way I'm pretty sure is making for a lean condition for a few milliseconds. (bypass valve closes sending s/c internally recirced air now into boost, post MAF). If not I guess in the very least I can have the AEM cut timing substantially upon seeing near boost pressures, and slowly ramp back up to a sutible curve when the a/f is at propper boost levels.

I think I'm going to go with my typical grass roots ways. The AEM will solve the whole tuning issue much like URD's Split Seconds do for the Taco but for over $100 less, and to counteract the inability to intercool the charger (short of fabbing genius), I will put another Toyota windshield pump (only $22) in tandem (series) with the original one thus bumping the psi up to about 60'ish+ (good ole' firefighting and de-flooding trick), add the necessary plumbing, check valve, 2 or 3 gph fog nozzle, wiring and a relay using the AEMs analog output, and inject nothing but water @ about 3-4psi. (simply to cool down the charger and clean out the 140K of carbon buildup and possibly not have to retard as much timing with the AEM).

I no longer find the $330 progressive kit a worthy price and a worthy solution to the cloosed loop ping/ n/a ignition curve (taco does not use its knock sensor below 3k rpm, and this torque'y truck hardly ever finds itself that high) , nor as an addition to a properly working piggyback.

I will include meth in the mixture if I find a suitable additive to greatly reduce meth's corrosiveness.

BTW so many great piggy-backs out there for us now. The SplitSecond hasn't been posted here (that URD uses to defeat learning) but also the fi/c, mapecu2, EMU, HKS Fcon iS, and I'm sure I'm forgetting others that have been purpose built to accommodate the OBDII n/a-to-boosted cars.

Thanks for all the inputs, this has been a great learning experiance so far, and a stupid diversion from NREMT studies lol.
 
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