Not good tymes. Sorry to hear this bro.

if there's one thing i've learned from all of these supercharger threads... it's **** SUPERCHARGERS! TT or go home.

why F SC's? seems like only the stillen ones are having major issues?

^^^^ that is not true. Mine is running great and I even track my car and have no problems. Maybe they need to find a better tuner.

just drove my car around and pushed it a little bit! it's bogging on the low end again.

Too much fuel, some needs to be taken out. Without looking at a wideband it's hard to see where your curves are, unless you're on a dyno. Are you sure your car was knocking, and not just bogging?

i'm sure i know what bogging is and knock. trying to set an appointment for a dyno session asap.

Good luck, hope all goes well.

I'd like to use the excuse about different elevation and fuel, but I can't. Christian on the 37 forums shipped his car from Maryland to California for his twin build and there hasn't been one issue with his tune.

It's the damn draw-through style MAF sensor. It's not able to properly account for the air that's going through the throttle-bodies, Weiboy said it best.

Do you think there is an alternative solution to those MAF weak spots? Is there the possibility of using a different style to solve the problem?

My mechanic is working on a 3rd MAF sensor (after the supercharger, before the throttle-bodies) that could be added, who knows how much of a pain in the *** that's going to be. At this point, even if you properly tune the car for summer driving, you'll have to tweak it during the colder months, otherwise you're more prone to knocking issues.

Ah, that stinks. Thanks for the information, it's a shame the stock MAFs are so finicky! What about converting to MAP sensors; I know it is not an apples to apples comparison, but I know that LS2 GTOs can be converted to run with MAP sensors only and that relieves the issues you talked about with finicky map sensors.

I don't understand why you would have to retune a MAF based on different temperatures. One of the reasons OEMs use MAFs is because that type of metering is not temperature sensitive i.e. MAFs take into account the temperature change inherently. The trouble with MAFs on aftermarket setups is typically related to turbulent airflow across the sensor which really f's up the readings.

Good point, but if the MAF is reading a certain temperature, lower then what's actually going to go into the motor... there lies a problem. I've heard UpRev has a calibration tool to allow you to compensate voltages to get a better reading after the supercharger. I'm going to contact UpRev in regard to that, along with another question that I have pertaining to my lightened flywheel and adjusting idle.

the MAF's reads IAT also so that can also be throwing it off a bit. got this off the net:

Air intake temperature is used to correct fuel quantity (pulse width) since air temperature effects air density. (colder air is much more dense) Approximately 70°F is generally used for 0 correction, temperatures above will result in less fuel to compensate for the lower air density, and conversely temperatures below 70° will result in steadily richer (by volume) mixtures. Bad readings will effect ECM attempts to keep the air to fuel ratio proportional.

Yeah, I assume these cars are running blow-through MAFs (i.e. after the compressor), which are more tricky to calibrate. I wish cars just used MAP metering instead, it's so much easier to work with. I think Hondas use MAP, or at least I believe my old S2000 did. I converted my STi to MAP after going rotated turbo because the MAF was a nightmare to calibrate with my 4" inlet.

hehehehehehe! this kit's MAF sensor is before the compressor!

It's the other way around. Drawn through is before the supercharger, blown through is after the supercharger before the throttle-body (Stillen = Drawn, GTM = Blown).

Why not throw a MAP sensor in that manifold and call it a day?

there is already...it's in the rear of the manifold

MAF sensor is what we need. If there's any change in voltage or just a small amount of debris that gets on it, the car goes into limp mode. That's how fragile they actually are. Plus they're pretty expensive. We'll have to see what UpRev says.

From what I know, and correct me if I'm wrong please, MAP sensors' reposnse are more linear and can cover a wider range than a typical MAF sensor.

A MAP sensor also does not depend on orientation nor will obstruct flow, whereas in a MAF sensor, its placement and orientation is very crucial

To use a MAP (Manifold Absolute Pressure) sensor to determine air mass would also require a manifold air temperature sensor, and recoding of the ecu logic. Not a simple task by any stretch


From what I can see in data logs, that sensor doesn't read much above 0psi.

That's what I said regarding position--blow-through is after the compressor. However, I did not know that Stillen was draw-through. That may be part of the problem. If the IAT readings are way off then it would not surprise me if there were idle issues.

That's right. What would be nice is to take the IAT from the MAF along with a MAP meter and black-box it so that we got an equivalent 5V output which could be fed back to the ECU as a surrogate MAF reading i.e. spoof the MAF voltage using a MAP and IAT sensor. I imagine it would take quite a bit of mapping to get right, but getting rid of the MAF sensor would save a lot of headaches.

All I can say is whenever my IAT is above 90-120 my car drives like crap and detonation will show, in cooler climates it performs very very good!

I gotta ask. How about relocating the MAF sensors. THink that could help solve some issues?

It's in the works, unfortunately it's easier said then done. The way the piping is setup makes it next to impossible to evenly distribute air to each sensor.

why not put them right before the intake manifold? where pipe turns into two
Frank

right! you can't just put 2 MAF's on the single pipe. it's gotta be separate.

did you purchase the kit? i was really thinking about parting mines out seriously and of course you're the first i've got in my mind to sell.

I hit 10.2psi way before redline just now. Anyone with a GTM SC wanna play? Come on, 60-160 run?

Just because you hit X PSI does not mean much.
Is the Stillen with the current pulley able to handle the load, provide more power, is the tune still viable at that point. Way more things need to be considered than you just hitting X PSI and wanting to run the competition.

Congratulations?

how does it sound? does the blower sound much more alive?

Make sure your air/fuel is in check. 10.2psi on a 8psi tune in cold weather can be catastrophic if it leans out too much... then boom.

Air, like most things, doesn't like to go around bends. Air flow will be higher at the "outside" of the bend. With the split of the pipes before the throttle bodies, I suspect more air will flow through the pipe closest to the firewall as the airflow doesn't have to "turn" as much.

This is an exaggerated illustration, with an abrupt 90 deg bend but it shows the general idea.
http://farm6.static.flickr.com/5002/...044c085c_o.jpg

I'll plat when i get my build tranny. We can even play the dyno Game. All i got to do is wait fro a nice -45C day and ya there ya go. So how is your detination coming along?

GTM MAF location > then Stillens

I won't fight you about that one.

Yes I understand this. Air is like anything else it is going to take the path of least resistance. But if you look at the design of the two tubes. there is no sharp bends and it might divide easily believe it or not.the resistance on the two tubes looks about the same other then the one tube is a little longer and i can see that might cause issues but the shorter tube bend comes first so it might equal out. My point being is that it is worth a try if people aren't satisfied with the draw through. Also it is not that hard to do. I already thought about how to do it with weiboy. Now the only thing that doesn't make sense to me is that stillen did this design because the NISSAN engineers said this is how it should be done. Not like they did this because it was a short cut. Also to my understanding this is how the GTR system works also, so why isn't that car having maf sensor location problems? These are general questions I was just thinking about.

Josh or Kyle I know what you guys think about the draw through maf sensors but do you think it is possible to make a proto-type tube that mounts the two maf sensors after the blower and see how the kit performs. I am almost positive weiboy will have no problem being your tester. Hell I will help pay for it if it will settle people down.
Frank