Ported MAF & A4 trans ?
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Teching In
Joined: Mar 2002
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From: Alabama
Ported MAF & A4 trans ? Could someone explain why adding ported maf ends causes A4 line pressure to change?Is it certain years that have probs or all.I have a 97 Z28 & 98 SS both have ported ends and luckily no probs yet!Thanks for any help! <img border="0" title="" alt="[Cool]" src="gr_images/icons/cool.gif" />
Here's my webpage.I love CAMAROS! <img border="0" alt="[cheers]" title="" src="graemlins/gr_cheers.gif" />
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Here's my webpage.I love CAMAROS! <img border="0" alt="[cheers]" title="" src="graemlins/gr_cheers.gif" />
Jeff's Toys web page
TECH Fanatic
Joined: Nov 2001
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From: SW Florida
Re: Ported MAF & A4 trans ? This is the "short version" in laymans terms as I know it:
After the MAF is ported, it senses a less volume of air entering the engine do to it's larger internal size. This input of coarse is transmitted to the PCM. The PCM thinks the engine is operating under less load than it actually is.
This does 3 things:
1. Decreases fuel/air ratio slightly (this will normally gain a slight increase in power because these stock LS1s usually run too rich anyhow). At least it will give a little better part throttle response. At the worst, it may cause some engines to ping slightly due to a lean condition.
2. Allow the engine to injest a little more air at WOT due to the larger MAF size resulting in more WOT/high rpm power.
3. Lastly, it will decrease A4 trans line pressure a little because the PCM thinks there is less load on the engine at any given time. There is where the problem is with the ported MAFs and A4 cars.
How much it deceases trany line press ... I don't have a clue.
Make sense?
Ron,
After the MAF is ported, it senses a less volume of air entering the engine do to it's larger internal size. This input of coarse is transmitted to the PCM. The PCM thinks the engine is operating under less load than it actually is.
This does 3 things:
1. Decreases fuel/air ratio slightly (this will normally gain a slight increase in power because these stock LS1s usually run too rich anyhow). At least it will give a little better part throttle response. At the worst, it may cause some engines to ping slightly due to a lean condition.
2. Allow the engine to injest a little more air at WOT due to the larger MAF size resulting in more WOT/high rpm power.
3. Lastly, it will decrease A4 trans line pressure a little because the PCM thinks there is less load on the engine at any given time. There is where the problem is with the ported MAFs and A4 cars.
How much it deceases trany line press ... I don't have a clue.
Make sense?
Ron,
Thread Starter
Teching In
Joined: Mar 2002
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From: Alabama
Re: Ported MAF & A4 trans ? Thanks guys for the info.I've got another ?.I added a MAFT when I installed the MAF ported ends.I first found a detailed page about adjusting the MAFT,looking at STFT,LTFT,O2's with ATAP to keep it from running lean.This guy had his setup like mine,lid,Maf ends,Maft,headers,off-road pipe,& borla exhaust.So I started with the MAFT adjusted the same as his,base 10%,wot -2%.Using ATAP these settings are perfect for our mods.So now my ? is by adding the MAFT with its adjustments at the same time with the ported ends would this stop the PCM from thinking the load has changed and not adjust my A4 line pressure?
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Joined: Nov 2001
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From: SW Florida
Re: Ported MAF & A4 trans ? Good question.... I don't know.
Better yet, do what I am doing. Put a set of stock MAF ends back on your A4 car and then you have nothing to worry about. There are many many people making way more than 400 rwhp with the stock unported MAF.
Leave the aftermarket MAF ends and the "home ported" MAFs to the M6 guys. They don't have to deal with tranny line pressures. My home gutted MAF has worked well since 1998, but I am now worrying about line pressure enough to go back to the stock MAF. I will find the extra HP I made from a gutted MAF somewhere else.
Ron,
Better yet, do what I am doing. Put a set of stock MAF ends back on your A4 car and then you have nothing to worry about. There are many many people making way more than 400 rwhp with the stock unported MAF.
Leave the aftermarket MAF ends and the "home ported" MAFs to the M6 guys. They don't have to deal with tranny line pressures. My home gutted MAF has worked well since 1998, but I am now worrying about line pressure enough to go back to the stock MAF. I will find the extra HP I made from a gutted MAF somewhere else.
Ron,
Thread Starter
Teching In
Joined: Mar 2002
Posts: 41
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From: Alabama
Re: Ported MAF & A4 trans ? Thanks for your help!
I agree that HP can be found with other mods!A camshaft & LS6 intake sound better than a new trans. <img border="0" title="" alt="[Cool]" src="gr_images/icons/cool.gif" />
Jeff
I agree that HP can be found with other mods!A camshaft & LS6 intake sound better than a new trans. <img border="0" title="" alt="[Cool]" src="gr_images/icons/cool.gif" />
Jeff
Administrator
Joined: Jan 2002
Posts: 45,841
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From: Earth
Re: Ported MAF & A4 trans ? I have no experience with LT1's so my comments don't apply to your '97.
The PCM looks at the MAF flow rates to determine line pressure in A4's. Ported ends cause air to "sneak" by with out being detected. As a result, there's a greater load and the PCM doesn't compensate by increasing line pressure. Over time it can lead to problems.
Dan
The PCM looks at the MAF flow rates to determine line pressure in A4's. Ported ends cause air to "sneak" by with out being detected. As a result, there's a greater load and the PCM doesn't compensate by increasing line pressure. Over time it can lead to problems.
Dan
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Staging Lane
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From: corpus christi
Re: Ported MAF & A4 trans ? my car is at the dealership now with a junked A4. ever since i ported the MAF ends i have had problems with the tranny. i am looking to go back to stock MAF ends. i have a shift kit/3200stall installed but my nephew's 98T/A with just a 3600 vig shifts harder than my car. testament that the tranny has lost line pressure.
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Re: Ported MAF & A4 trans ? 2 different cars. Both with Ported MAF ends from day one. Never any MAF "pressure" related tranny problems.
Both were my only cars, seeing 60+ miles a day, and countless track runs.
Both were my only cars, seeing 60+ miles a day, and countless track runs.