[BlackSportD]

I have an 01 Tacoma TRD s/c'ed. I have partial throttle ping as low as 1psi!! Maybe worse seeing that ping can be happening before being audible to me. (maybe with 145K miles, the carbon build up is owning me, or I should change the fuel filter, cali 91 isn't helping... haven't put a wide band on to see a/f yet)

I've been told that using the 0-5v controller with the MAF is better as far as giving me a progressive curve for ramping up the water/methanol (in this particular situation where its a roots type s/c building boost so quickly). I'm guessing this is in the context that MAP sensors with these kits are being used to see just boost, and do NOT have a voltage output for some realms of vacuum. So by using my MAF, the controller can start ramping up the pump before I start going into possitive boost.

I'm worried that at partial throttle low boost, the MAF voltage will be at a low level. So thus tuning the controller for that level, will also have me squirting water/methanol while cruising on the freeway in vacuum...

So I'm still on the fence on either to use a MAP sensor, or the MAF. If someone knows for a fact that the MAF voltage will be higher in partial throttle low rpm/low speed boost than at high rpm/low vacuum 70mph+ freeway driving, I'll be much more assured with going MAF.

[BoostedSS]

Subscribed, I would also like to know if its ok to use the maf.

[BlackSportD]

I'm also curious, there are different MAP based progressive controllers. I'm assuming that the MAPs they work with show voltage only in boost (hence the advise given to me). But if using the 0-5volt controller for MAF among other things, it could also be used with an OE MAP.

There are OE MAP sensors used on old n/a cars, not to mention factory boosted cars. There must be MAP sensors that puts out voltage from -20 vacuum all the way to positive pressure, possibly up to one bar. I know having such a long range of air flow in only 0-5 volts would reduce the controller's granularity some, BUT over-all this should be a better solution IF using the MAF has the problem I'm afraid of.

[agrazela]

I was on the fence between MAP and MAF myself. I always figured MAF would be the better correlation to IPW (which, IMO, would be the best signal to use).

So I went to ScanDepot and downloaded dozens of scans (L67 supercharged and L67 / L36 turbo'd motors). I found that, in every single case, in boost (i.e., MAP>=100 kPa), IPW was far better correlated with MAP than with MAF. I don't know why, it just was.

I don't know if that helps you, but I decided a MAP-based system would be fine based on that.

[BlackSportD]

^^ Whats IPW?

I called the support number here and am now leaning towards using a 3bar Progressive Controller with a 2bar MAP sensor, so that there is a rediable voltage in vacuum.

I suppose this would be a cure and the solution I want, there wouldn't be a problem with a large load that is in vacuum that would upset a MAF based tune. With the MAP setup tuned right, that shouldn't happen, but one problem would be the system injecting with the key at the "on" possition, but I have a time delay relay and/or switch to fix that.

Whats important to me though is the ability to slowly ramp up the injection, before boost hits, and I feel the MAF way would be better at this.

The TRD blower has a trick bypass valve thats not just used as a relief when getting off the throttle in boost, but also to recirc the s/c'ed air when there is no percieved load. It senses engine load via vacuum (like a MAP sensor) and then "closes" to provide boost when it sees a "heavy" load (hence I can stay in vacuum going up a hill if I go slow enough, even at high RPM). Upon reving the engine you can see it close, then open again when getting off the throttle. This makes for a very VERY fast boosting system, it'll go from vacuum to full boost in a heart beat (I'm an auto, so usually when I romp on it, there will be a downshift, and within that shift it goes from vacuum to full boost). Seeing that the MAF is pre-charger, it will see this on-slought of air being sucked into the charger, rather than a "oh sh*t boost!" signal from a MAP post charger.

So still kind of on the fence with this... Dang so ready to slap this thing in and get tuning, just can't make up my mind on controller method lol.

[agrazela]

Originally Posted by BlackSportD

^^ Whats IPW?

IPW = injector pulse width. IMO, if you want to inject an amount of methanol/water perfectly proportional to the amount of fuel being injected, IPW would be the ideal signal. AFAIK, only Aquamist offers that, and even then I think it requires a standalone engine control system (so no love for L36 / L67).

Originally Posted by BlackSportD

...one problem would be the system injecting with the key at the "on" possition, but I have a time delay relay and/or switch to fix that.

Are you talking here about the MAP "self test" done on key-on that causes premature squirt? I expect to solve that with a second, dedicated MAP sensor.

Originally Posted by BlackSportD

...Seeing that the MAF is pre-charger, it will see this on-slought of air being sucked into the charger, rather than a "oh sh*t boost!" signal from a MAP post charger.

I'll bet you're looking at between 0.005 and 0.01 sec difference between MAF and MAP response time.

[BoostedSS]

So can it be done with just using the MAF censor rather than the MAP censor?

[BlackSportD]

Are you talking here about the MAP "self test" done on key-on that causes premature squirt? I expect to solve that with a second, dedicated MAP sensor.

Nope. The MAP sensor being used upon key up would read atmospheric because the engine is not running, and my tune with the Progressive Controller would be to start injecting just before atmospheric, so that would make it squirt. So I have a time delay relay just sitting in my garage, and if I feel the need to sit in my car with the key "on" I can put a switch inline with that also.

Haha, injector pulse width lol, I can set up a MegaSquirt, and don't know that acronym lol. I feel the same way, you'd think MAF would be a good linear signal reflecting load and thus what the injectors are putting out. Your findings are interesting and carry a lot of weight on this.

I'll bet you're looking at between 0.005 and 0.01 sec difference between MAF and MAP response time.

I suppose so. I wanted to make sure water/methanol is getting there before or right during boost. I guess this response time difference isn't worth it.

So can it be done with just using the MAF censor rather than the MAP censor?

Thats still the million dollar question. IF it could be done with MAF without the hickup I fear, then at least I could save money on not needing to buy a MAP sensor, and the plumbing I'd have to do.

But its looking to be that for the most reliable tune for MY goal, a MAP sensor pared with a controller than could see its output voltage in the slight vacuum before atmospheric would be the more reliable route.

Actually, could I still just buy the 0-5volt contoller, and if the MAF technique doesn't work out, I could just buy a properly matched MAP later and use that? I suppose a 2 bar MAP would be the best to use. I'm only boosting about 7psi, maybe 9.5 later down the road.

[BlackSportD]

agrazela, I've been thinking of those scans, are those factory boosted cars? Did they have fuel pressure regulators with gain?

With the MAP sensor method, I'm afraid at 6-7psi of boost, thats a constant voltage rating for the MAP, and so the controller would spray at the same duty cycle at 1500rpm@6psi as it would 5500rpm@6psi. For it to spray similar to an OE MAP'ed sensored car's IPW the controller would also need an RPM and/or TPS input at the least.

So a 2bar MAP with a 3bar controller would give me near atmospheric tuning ability, but at the cost of having a flat spray PWM when I get to full boost.

With the MAF I flirt with having the water/methanol motor come on when I don't want to, or worse not come on when I need it (very low rpm partial throttle boost), but at least the PWM of the motor should reflect IPW better.

If I don't go MAF, I guess I might save money and not get a controller but find a 1psi switch and go with that lol. hopefully the nature of my bypass valve will compliment the MAF method rather than complicate it.