A MAF Sensor Mod

[suspectnumber961]

These people are like that blonde down the street.....cute, but stupid. Check your messages....

Originally Posted by BikerModder

Final Total here after a trip to the college campus to enroll... 37 hwy

[Phantom]

By blocking the air to the MAF you are changing the calculation for load so it will read lower and increase timing that will help in mid-low load situations but if your timing map was close to the point of knocking in the high load area it can cause problems.

As for fueling the O2 sensor will compensate to the difference in fueling and adjust till it hits and stays at 14.7:1. With out the MAF getting a proper reading the engine will not be able to respond to a quick change in air flow. That will result in a lean mixture with to high timing when going from 20% throttle to 100%and that can pop pistons/heads/cylinder walls depending on the weak point.

To get the most benefit you should have a custom tune done on the car to increase the timing to a few points before the point of KR when the car is running on a hot day, if it is done on a cold day the KR will happen at a higher advance.

Depending on how the cars tuning is set up you might be able to disconnect the the MAF and run is SD (Speed Density) mode for the tune and get different results.

I would NOT do any of that without a scanner that at the very least will show you KR in real time to keep you from blowing your engine.



-I have had some fun tuning GM cars and this post is going to make me drive my wife's car so a can work on the tune again since I do not have the tools to tune me TDI.

[pete c]

what's KR?

I take it it has something to do with detonation.

Knock something?

[suspectnumber961]

IF I were to do this mod...I would block AFTER the MAF so that potentially I could still have a functioning SGII....though I might have to reset the engine displacement down some to compensate?

The TPS range on my Focus is 16 to 92 (92 being slightly low due to a throttle mod).....I'm usually in the 32-37 range manually (for best BSFC)...though the CC will hit 42 at times....and I figure 37 TPS is ~ 50% throttle.

So when using the SC with this mod...what gauge reading would be the best to monitor and what extremes should I look out for under the 50% TPS scenario? Load AND ignt advance?

KR defined...

FAQ: What is spark knock? What is KR (knock retard)?

Since I'm using a WAI and have a partially blocked intake...this could be an issue.

I wouldn't see an issue with blocking the accelerator to keep it under 50%...as simple as a block of wood under the pedal would work....50% pedal is pretty brisk acceleration....though probably some form of blasphemy to the avg car enthusiast.

While I could do this free mod in an hour or so and it is easily removable...but I'm not that interested in messing too deep. With a potential 20% gain...it's worth looking into. Might be a way to "detune" an engine for mpg purposes vs the car makers tendency to cater to the typical consumers desire for power at any cost?

I recently saw a 5% gain from installing a cone filter that has a bell-shaped intake molded in vs the factory straight edged intake pipe...at least I think this is where the gain derives from. Just a minor conflict with an intake block?

Could it be that more air flow OR less air flow results in better mpg?

.....

After thinking about this mod some...I come to the conclusion that when blocking AFTER the MAF...the function of the MAF is not changed any...there will just be some restriction of air flow at higher flow rates.

Since I drive for mpg...90% of the time my TPS reads from 16 (idle) to maybe 19 or 20 at the most...17 or 18 if I can manage it. Which means the butterfly is only open up to ~4* over idle position 90% of the time...the block would be really not affect anything under these conditions? The 10% (?) of time where the flow rate at the TB is greater than that allowed through the blocked opening would be affected.

Originally Posted by Phantom

By blocking the air to the MAF you are changing the calculation for load so it will read lower and increase timing that will help in mid-low load situations but if your timing map was close to the point of knocking in the high load area it can cause problems.

As for fueling the O2 sensor will compensate to the difference in fueling and adjust till it hits and stays at 14.7:1. With out the MAF getting a proper reading the engine will not be able to respond to a quick change in air flow. That will result in a lean mixture with to high timing when going from 20% throttle to 100%and that can pop pistons/heads/cylinder walls depending on the weak point.

To get the most benefit you should have a custom tune done on the car to increase the timing to a few points before the point of KR when the car is running on a hot day, if it is done on a cold day the KR will happen at a higher advance.

Depending on how the cars tuning is set up you might be able to disconnect the the MAF and run is SD (Speed Density) mode for the tune and get different results.

I would NOT do any of that without a scanner that at the very least will show you KR in real time to keep you from blowing your engine.



-I have had some fun tuning GM cars and this post is going to make me drive my wife's car so a can work on the tune again since I do not have the tools to tune me TDI.

[BikerModder]

Hey I don't know what Phantom was thinking but I got a idea what of the increase in combustion thru Water Injection? I don't wanna bust my block now. Already. Boy this is more a filter switch out than an issue. You guys, how come i can't keep you together? Just kidding. Really if you can build your own car it ought to be a guaranteed right.

Before mod: The acceleration was what one would expect of a 168 HP car. Everything automatic and from the factory. Except it sometimes did not want to kick in to passing gear and it should have. Something a passenger pointed out was that is should go faster. Maybe and issue with the variable valve timing. Might mention there is a way to increase tension on the accelerator petal itself. So you don't have to hold you foot up while driving. that is now corrected.
After mod: Engine with standard air box (lets consider the EPA guidelines here where it is stated the air box is a part of the emissions control- you can't mod it) still runs quietly fine and I don't know smoother? I don't wanna hear how you tell me they aren't right. Got some advice here. If you don't like what was posted ask me to change before i get the actual solution first then i post. Thank you.

[some_other_dave]

Originally Posted by suspectnumber961

IF I were to do this mod...I would block AFTER the MAF so that potentially I could still have a functioning SGII.

The SG will function anyway. It is merely reading signals off of the electronic bus in the car. If you monkey with the MAF, the readings may or may not be correct, but you will still get readings.

-soD

[suspectnumber961]

What I find interesting is the hysteria and prejudice over modding the combustion process in any minor way on this forum...where if you would move to some "fast and furious" forum...they are redoing EVERYTHING from cold air intakes...heads...complete fuel management systems (Megasquirt)...exhaust...basically redoing from scratch. And I've heard mention of very high mpg figures from some that have done this kind of thing when on highway trips.

Also the issue of ridiculing LaPointe....where in my opinion he hit the nail on the head. He was getting high mpgs with his vehicles to the point that he mentioned that cats were essentially not needed...but he ran with no ethanol gas and various mods such as EFIEs...fuel heat...fuel additives...etc. ALL of which could have been put in place years ago by car makers/oil companies.

But what did we really get? Big SUVs and oil wars.

[rmay635703]

Originally Posted by suspectnumber961

I think LaPointe knew his stuff. He rigorously refined and tested mods using a SG going out 100 miles and back the same way on a highway to try to factor out wind direction and driver input.

I tested Acetone with a scanguage as well and it did make the scangauge read much higher on the 98 buick, but when I did the ACTUAL fill ups the increase was quite small and only seemed (in my case) to work in the winter months. I believe (if memory serves) that acetone tends to foul O2 sensors, I do not think this is something that will consistantly improve fuel economy, but it does make the scanguage think you are getting good fuel economy (just not in reality)

I also found that acetone in Seafoam really cleans out the intake, about the only cost effective use for acetone.

[suspectnumber961]

I found an old test I did with a B&S push lawnmower where I ran 4 oz gas from start to stop. The gas with 3 oz acetone / 10 G ran 3% longer than gas without. This was when using gas with ethanol.

LaPointe used ethanol free gas...acetone/xylol/GP7....fuel heat...EFIE...etc. LaPointe tested....over and over...re-tweaked over and over.

Simple A-B-A tests don't always get it in the real world. The real world is more complex and the devil is in the details.

Not trying to convince anyone though....impossible to do and mostly a waste of time.

The answer? TEST things yourself.

Getting someone else to agree is NOT reality. For every idea posted...someone will be sure and knock it down. Some specialize in this.

Take hints from those who are likely to know. Reality is the results you see. Talk is cheap. Too much talky...no testy?

note: I'm working on testing square wheels under the theory that the limited contact with the road should reduce rolling friction...wish me luck!

[rmay635703]

Originally Posted by suspectnumber961

I
The answer? TEST things yourself.

note: I'm working on testing square wheels under the theory that the limited contact with the road should reduce rolling friction...wish me luck!

I did over two years, it didn't work at least in the saving money part.