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Old 06-06-2010, 08:47 PM   #1
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Default Delete the MAF or wait?

I am reading the manual and FAQ here in preparation to (finally!) installing the Megasquirt. In the manual is a section on deleting the MAF and installing an IAT. Since I need to order a tuning cable for the Megasquirt, I found the kit they (DIY autotune) have for the IAT.

Question #1: Is this mod sort of pointless since I'm going to go with the SC as soon as possible?

However, I plan to install the FFS MP62 next. In the instructions, it shows removing an IAT sensor from the airbox. Naturally, the pictures look nothing like my car, and I can't find the damn thing.

Question #2: Do I need to get the IAT or not?

I'd hate to get partway into it, and discover I need to order some parts and wait a couple more days.






Yes, I know I should have held out for a turbo.
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Old 06-06-2010, 10:18 PM   #2
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FFS Supercharger... I take it you're getting it w/o the Powercards?

Deleting the MAF is fairly optional. The stock FFS piping is going to expect it to be there, but it's easy to make up a blank tube to go in its place. If you do decide to pull it then yes, you'll need to get the GM IAT sensor, as the factory IAT sensor was still in the MAF assembly in the 1.8 NA. Ideally, you'l get the open-element version and install it in the lower intake manifold, so that you get accurate post-S/C readings.
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Old 06-06-2010, 10:31 PM   #3
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Yes. No PCpro. Megasquirt and 460cc injectors. Got it already, sitting in the garage gathering dust.

According to the instructions, the MAF is needed, but they put it right after the air filter - before the SC! How the hell is that reading the correct temps? So, I decided the best thing is to do is eliminate it, and get the separate sensor. I ordered it with the cable earlier - hoping to return or sell it if not needed.

One question that Tom at FFS can't (or won't) answer is if it's a good location to put that sensor in the intake plenum in place of that infamous 5th injector. What do you think?
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Old 06-06-2010, 10:42 PM   #4
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I think you need to re-read post#2 where Joe answered all your questions
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Old 06-07-2010, 12:47 AM   #5
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Lolz. MAF's are ghey. Lose that ****.
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Old 06-07-2010, 01:19 AM   #6
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Quote:
Originally Posted by rleete View Post
According to the instructions, the MAF is needed, but they put it right after the air filter - before the SC! How the hell is that reading the correct temps?
It isn't. The electronics which come with the FFS kit aren't exactly the greatest thing out there. Which is sad, since the hardware portion of the kit is pretty good.


Quote:
One question that Tom at FFS can't (or won't) answer is if it's a good location to put that sensor in the intake plenum in place of that infamous 5th injector. What do you think?
Anywhere in the lower plenum would be fine. My personal preference would be to drill a new hole for the IAT sensor in the bottom of the manifold and leave the 5th injector hole alone, so that after you convert to turbo, whoever buys the kit from you still has the option of running the TomTom fuel solution.
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Old 06-07-2010, 10:09 AM   #7
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I thought of that. But, there's a hole already there. If it's even close, I'm gonna just tap it. Supposedly, the 5th injector screws in, so I'll have to remove it and determine what thread it is. Have to have an NPT for the sensor, I think.

Thanks for the replies. It's sometimes difficult getting answers to SC stuff.
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Old 06-07-2010, 10:49 AM   #8
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Thanks for the replies. It's sometimes difficult getting answers to SC stuff.
The reason why I sold my twinscrew sc (better than an mp62) for a turbo.
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Old 06-07-2010, 05:38 PM   #9
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Originally Posted by rleete View Post
Have to have an NPT for the sensor, I think.
Yes, it's 3/8" NPT, which is a pretty common hardware-store tap.


One point I failed to elucidate upon in my previous post, concerning the stock IAT sensor and FFS' placement of it:

The factory sensor is fully-encapsulated, as a result of which, it is unable to quickly respond to sudden and rapid changes in temperature, as happens when you get into boost on a positive-displacement supercharger. Thus, placing the sensor after the S/C and relying upon it to perform correctly would probably be worse than leaving it pre-compressor, making some assumptions about what temp is going to do under boost, and coding said assumptions into the firmware for the piggyback ignition controller.
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Old 06-07-2010, 08:34 PM   #10
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So now you're saying to put it before the SC? Or are you saying that the PCPro can't handle having it in the manifold, hence their pre-SC placement?

From the pics on the DIYAutotune sight, they locate it just before the stock manifold, after the intercooler. So, it's showing manifold temps, more or less. Is the sudden temp spike from a single boosted pull (say, a quick 3-4 gear passing situation) going to matter that much? Any extended boost (like a drag run from stop to 4th) is going to heat thing up enough to register. Right? Or am I all wet?

Frankly, even if I have to machine a plug, and then tap that for the sensor, the injector location is probably easiest.
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Old 06-08-2010, 01:04 AM   #11
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I say use a pvc pipe instead of maf.
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Old 06-08-2010, 12:46 PM   #12
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Quote:
Originally Posted by rleete View Post
So now you're saying to put it before the SC? Or are you saying that the PCPro can't handle having it in the manifold, hence their pre-SC placement?

From the pics on the DIYAutotune sight, they locate it just before the stock manifold, after the intercooler. So, it's showing manifold temps, more or less. Is the sudden temp spike from a single boosted pull (say, a quick 3-4 gear passing situation) going to matter that much? Any extended boost (like a drag run from stop to 4th) is going to heat thing up enough to register. Right? Or am I all wet?

Frankly, even if I have to machine a plug, and then tap that for the sensor, the injector location is probably easiest.
I believe what Joe is telling you is that in stock form (ie naturally aspirated) or when using the FFS kit as designed (with the pcpro) the stock IAT works fine in it's stock location pre-supercharger. It works with the FFS/pcpro because FFS recognizes it's shortcomings for use with forced induction, and has programmed the PCpro accordingly.

You said you are going to use a megasquirt, the stock IAT is not really adequate in your case, it's too slow to react to the temp changes inherent with forced induction, get the IAT kit for your megasquirt and mount it either in the intake manifold or as close as possible, but def after the SC and intercooler. It is a much faster responding and more accurate sensor and will provide the Megasquirt with the correct info to tune/run correctly. I would also agree with Joe and leave the 5th injector hole, the 5th injector is as much for intercooling as it is for additional fuel, why not drill and tap the hole for the IAT now, rather than have to move it to add the injector/intercooling later?

For what it's worth, I am installing a Hydra (My Miata is an '01 LS), and using the IAT provided by FM with it and will be mounting it in the dummy throttle body. It's very simple really, drill and tap one hole, insert the IAT. Mine will be right at the entrance to the manifold, post intercooler. I am going to be installing my JRSC M45 with a 62.5mm nose pulley and liquid to air intercooler, hopefully this weekend.

Joe, please feel free to correct me if I'm wrong

Jim

ps I have deleted the MAF and am using the built in MAP sensor on the Hydra
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Old 06-08-2010, 01:26 PM   #13
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Quote:
Originally Posted by jimj64 View Post
I would also agree with Joe and leave the 5th injector hole, the 5th injector is as much for intercooling as it is for additional fuel, why not drill and tap the hole for the IAT now, rather than have to move it to add the injector/intercooling later?
I won't be using the 5th injector at all, no matter what I end up doing. It's coming out. I've got 460cc primary injectors installed in a new dual feed fuel rail. I'm also installing a new Walbro HP fuel pump. That ought to take care of fuel needs.

So, I either find a new location and drill, or plug/tap the injector location. There are a couple of nozzles already installed (for the DO WI), and I may use one of those. I am going to have to dig out the parts and look it over.

I am so stoked to be finally getting started on this.
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Old 06-08-2010, 03:31 PM   #14
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Quote:
Originally Posted by rleete View Post
I won't be using the 5th injector at all, no matter what I end up doing. It's coming out. I've got 460cc primary injectors installed in a new dual feed fuel rail. I'm also installing a new Walbro HP fuel pump. That ought to take care of fuel needs.
rleete, I think your mising the most important point about the 5th injector, it's primary job is to provide evaporative cooling of the intake air, ie intercooling, not just adding fuel. No matter what size injectors you run, they will not provide the cooling effect of the IAT's like the 5th injector will.

Do what you think is best, but keep in mind the primary purpose of that 5th injector when you make your decision on where to mount your IAT sensor.
Jim
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Old 06-08-2010, 06:15 PM   #15
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Quote:
Originally Posted by rleete View Post
So now you're saying to put it before the SC? Or are you saying that the PCPro can't handle having it in the manifold, hence their pre-SC placement?
1: The stock IAT sensor, being of the plastic-encapsulated design, is incapable of registering sudden changes in temperature, and thus, should not be placed after any kind of compressor.

2: Since the PCPro (and the PowerCard TimingThingy) relies upon the stock ECU for all IAT-related matters (the PCPro / PCTT does not read IAT), you cannot replace the stock IAT sensor with one of a different design in a PCPro-based system.

2a: Based upon the aforementioned limitation, I assume that the PowerCard TimingThingy's ignition retard curve was generated based upon the knowledge that IAT will rise by roughly a given amount when in boost at a given pressure ratio, and is thus operating open-loop, so to speak. (I'll likely never be able to verify this, as Tom has historically been very cryptic when describing the internal functionality of these devices.)

3: When you are running a Megasquirt (or other aftermarket standalone ECU) the above limitations do not apply. Thus, you are free to run an open-element IAT sensor, place it after any compressor / intercooler, and tune your ignition advance accordingly.

Quote:
Is the sudden temp spike from a single boosted pull (say, a quick 3-4 gear passing situation) going to matter that much?
Depending upon how close to the edge your spark advance is, yes.

Quote:
Any extended boost (like a drag run from stop to 4th) is going to heat the thing up enough to register. Right? Or am I all wet?
I assume that you are using "the thing" to refer to the stock IAT sensor. The answer is yes, however if the spark advance curve was so critical that it mattered, the engine would have been destroyed before the sensor registered anything. And remember that thermal lag goes both ways- after the boosted pull (if the engine survived) the sensor would still be registering hot, even though IAT has returned to normal. This is less critical, but worth being aware of.


From a practical standpoint, I think we may be splitting hairs here. IAT-related advance is a pretty inexact science at best, so just go ahead and put an open-element sensor in the manifold for no other reason than because it's what all the rest of us did.



Quote:
Originally Posted by jimj64 View Post
rleete, I think your mising the most important point about the 5th injector, it's primary job is to provide evaporative cooling of the intake air, ie intercooling, not just adding fuel. No matter what size injectors you run, they will not provide the cooling effect of the IAT's like the 5th injector will.
If I read between the lines correctly, I believe he's planning to run water injection. Done correctly, that ought to provide a better anti-detonant action than 5'th injector spray.

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Originally Posted by jimj64 View Post
Joe, please feel free to correct me if I'm wrong
As a Canadian, I assume that you are right if discussing Maple syrup or winter sports, wrong if discussing military policy, and likely to be wearing a funny hat if discussing anything else.
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Old 06-08-2010, 06:26 PM   #16
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[QUOTE=As a Canadian, I assume that you are right if discussing Maple syrup or winter sports, wrong if discussing military policy, and likely to be wearing a funny hat if discussing anything else. [/QUOTE]

What's wrong with my hat? It keeps my ears warm when I leave my igloo.....
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Old 06-08-2010, 07:45 PM   #17
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...just go ahead and put an open-element sensor in the manifold for no other reason than because it's what all the rest of us did.
Thanks, I will. I was hoping it'd be here today, but no such luck.


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If I read between the lines correctly, I believe he's planning to run water injection.
Correct. I plan on initially tuning the car to run without it, and adding later. Expect me to ask lots of dumb questions about that when the time comes.
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Old 06-22-2010, 07:02 PM   #18
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lol.... wait
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Old 06-23-2010, 11:27 PM   #19
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You'll like the supercharger. There a different animal.

DRAG race==== I want turbo.

Corners==== I kinda like the SC. But each to their own. They both have their potentials and down falls.

main thing.....You have boost.
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