Help! Need to plump intake for boxster with 3.4 conv.

[Porsche_Monkey_4life]

Hello everyone, I have a Boxster with a MY 99 996 3.4 engine conversion. Any way Todd helped me discover why my car has always run rich, which was due to the use of the stock Boxster air intake system that uses a 3 inch diameter MAF housing vs the 3.5 inch used for the 996. Anyhow, I have looked at some possible solutions but am open to any suggestions. Does anyone know what the diameter of the Cayman S and 987 Mass Air Flow housing is? I think this might be my best option. Thanks for your help. :renntech:

[savowood]

There's an Italian company which makes an airbox you can install. Todd knows the name, but it's hidden away in my engine compartment right now and I don't remember what it is. That solved my intake problem. Now I just need to fix the exhaust.

-Michael

[qikqbn]

Hello everyone, I have a Boxster with a MY 99 996 3.4 engine conversion. Any way Todd helped me discover why my car has always run rich, which was due to the use of the stock Boxster air intake system that uses a 3 inch diameter MAF housing vs the 3.5 inch used for the 996. Anyhow, I have looked at some possible solutions but am open to any suggestions. Does anyone know what the diameter of the Cayman S and 987 Mass Air Flow housing is? I think this might be my best option. Thanks for your help. :renntech:

Hey Monkey...

If you talked to Todd then you probably already came across this thread:

http://www.renntech.org/forums/index.php?s...=21472&st=0

Todd, 1999, and I talked extensively about this exact issue.

similar results with a few different ways of getting there.

from the cheap to a bit more expensive...

It depends on how much flexibilty you want in tuning.

I don't know if you are like me, but I wanted to see the results of

my tuning/changes. I spent many hours and many dyno runs getting my car dialed in.

The one thing that gives me instant feedback without having to go to dyno

anymore is the AEM wideband Air fuel ratio gauge: $200 on ebay...

website if you wanna see what looks like:

http://www.aempower.com/ViewCategory.aspx?CategoryID=67

This requires adding a "bung" and tapping sensor into exhaust.

$40-50 bucks for muffler shop to install bung. Then just screw in sensor

and easily run wire into car and plug in gauge. Having and Knowing your exact AFR

will save you a lot of dyno tuning and money later if you do additional

tweaks or add ons.

Then it is up to you how to handle the maf signal correction... either increase

the size of the maf housing to equal that of the 996, or "calibrate"

the voltage signal from the maf to the ecu using a type of resistor ....

if you are running rich, then the voltage signal from the maf is too high.

best of luck.... Once it is corrected you will feel a very nice difference

all around. Like a new car ;^)

Bill

[Porsche_Monkey_4life]

Bill,

Yes I have read that thread. I read it shortly after Todd told me about the MAF housing and so i did a search on the subject and came across your conversation. I like the air/fuel meter idea but i really want to avoid the resistor method if possible because I would like to get in the amount of air that the engine was designed to receive. I will definitely look onto that air/fuel meter. What are the advantages over the one you mentioned vs others? Thanks for your help everyone.

[qikqbn]

Bill,

Yes I have read that thread. I read it shortly after Todd told me about the MAF housing and so i did a search on the subject and came across your conversation. I like the air/fuel meter idea but i really want to avoid the resistor method if possible because I would like to get in the amount of air that the engine was designed to receive. I will definitely look onto that air/fuel meter. What are the advantages over the one you mentioned vs others? Thanks for your help everyone.

Todd mentioned he was not convinced the boxster "airbox intake" could supply enough air.

I agree, about the stock "airbox", but I'm on the fence about the

3 inch piping going to throttle body if a cold air "cone" style intake and a

straight 3 inch pipe all the way to the throttlbody replace the constrictive airbox..

I definitely saw an increase in performance on the dyno with the cold air intake

and new plumbing..so the 3.4 needs to breathe better for sure..

With the less restrive cone filters It may be getting the air it needs,

but it just has to travel faster through 3 inches versus 3.5.

What surprised me is that I've looked at some RUF photos of their

3400s air intake tube that attaches to the throttle body and it is the same as stock boxster..

but RuF definitely modifies the "airbox" for higher flow.

There are some cheaper AFR gauges costing around $50 and they splice into the wires

of your existing "narrow band" Oxygen sensors. they read a voltage and give you a read out whether

"lean or rich" , but not a very accurate air fuel ratio Number...

I am sure they work "ok" if you want to know if you are basically rich or lean ...

but if you wanted to know exactly how to dial in 12.5 or a 13 AFR it would be difficult with those gauges.

My dyno tuner said the only way to get a very accurate reading is with a "wideband" sensor.

These guages which cost around $200 come with their own oxygen sensors and

are also able to plug into other types of software for further tuning. This allows pro logging data

at the dyno so that you can get a better reading pre-cat than a "sniffer" stuck in the exhaust

will give you.

On a cosmetic side I chose the AEM also because it came with different color gauge faces and bezels so that

it can match perfectly with my silver face gauges or swap for black if you have black faced gauges/bezels..

see quick youtube of overviews ..here are 2 vids to look at..

http://www.youtube.com/watch?v=ivOtfoY8P2Y...feature=related

If you can find a proper size Maf housing and intake plumbing then the AFR gauge may not be completely

necessary because you still will not be able to "adjust or modify" your signal in any way...

You could have it dyno tested once for about $80 to make sure you are good to go with your AFR

and never worry about it again.

AFR gauges are great for those who have a bit more tweaking to do

and have a way of "tuning" so they can dial it in. so if you added a "variable pot resistor", then you

could tune or dial in your AFR... that's when the gauge would be very useful...

well, hope this helps... all the best

Bill

Edited January 16, 2009 by qikqbn

[Porsche_Monkey_4life]

Bill,

Thanks again for the excellent response I think i might be sold on the resistor solution combined with the AEM meter since all the other options seem to be much less cost effective for possibly little advantage. Do you know if anyone has a write up on it ? Again thank you for your help.

[qikqbn]

Bill,

Thanks again for the excellent response I think i might be sold on the resistor solution combined with the AEM meter since all the other options seem to be much less cost effective for possibly little advantage. Do you know if anyone has a write up on it ? Again thank you for your help.

What part exactly were you looking for a write up on? If it's AEM meter ?'s or AFC Select MAF controller ?'s

then I can share my experience... If it has to do with resistors, rheostats, or variable pots... then

members Todd or porsche 1999 are the goto guru's...

[qikqbn]

Bill,

Thanks again for the excellent response I think i might be sold on the resistor solution combined with the AEM meter since all the other options seem to be much less cost effective for possibly little advantage. Do you know if anyone has a write up on it ? Again thank you for your help.

What part exactly were you looking for a write up on? If it's AEM meter ?'s or AFC Select MAF controller ?'s

then I can share my experience... If it has to do with resistors, rheostats, or variable pots... then

members Todd or porsche 1999 are the goto guru's...

I wanted to give a quick update on my current setup as of last night ...

After 7 months of running a "calibrated" maf signal

I finally decided to track down the proper MAF housing size and got my hands

on Todd's recommended "Cayman/Boxster 987" Maf housing . Brand new from

Sunset Porsche parts the discount is still a lot ... $275 because it includes

the actuall sensor which I can not use.

All I wanted was the housing tube to plug my boxster/996 sensor into. I finally tracked

down the proper size maf housing from a dismantler and saved myself

over $200...It also has the screen built into it to help with air turbulence.

In the process I also discovered a proper sized nice alternative

Bosch maf housing for a lot less $$ then Porsche... (pm me if interested)

My original 986 boxster maf housing measures inner diameter of 70-72mm.

(76mm or 3 inch outer diameter)

The 3.4 liter 996/Cayman maf housing measures inner diameter of 83-85 mm

(90mm outer or 3.5 inch outer diameter)

A difference of close to 20 percent in size.

With my "calibrated" maf signal my air fuel ratios were staying a solid 12-12.5 and the car was running very strong.

Even so I still felt that "tricking" the ECU with a calibrated signal or resistor may not be taking full advantage

of all the fuel maps and how they were designed to work with proper air flow measurement from Porsche.

Even though I really enjoyed my setup there was always a question in my mind if I

was really allowing the programming to work correctly under those "calibrated" conditions.

Since I want my 3.4 Boxster to run it's strongest at all times I decided it was time to

switch over to the proper maf housing size.

After modifying intake tube lengths for the new housing I got

it to fit nicely.

My current intake setup is:

-Cone filter plugs onto front end of Cayman Maf Housing..

-back end of housing plugs onto 3 inch intake tubing all the way to Throttle body.

(996 throttle body is only 3 inches in diameter)

I unpluggled the battery, reset my computer, and disabled

my "AFC-select" maf voltage controller.

After a few runs through the rpm range for the computer to learn the new setup

everything seems to be working very nice.

I have to say.... I think overall the engine feels stronger and more refined now.

My peace of mind feels much better as well since I know for sure that the

proper air measurement is working with the fuel maps as designed from Porsche,

rather than a "calibrated" signal to trick the computer.

Afr readings at wide open throttle are around 13 from low to mid rpms and then drops

to around 12.5 for the upper rpm range.

My initial impressions are that the car feels more responsive. Hard

to say for sure because it was running quite fast before as well. Just seems to be more

sorted out all around with partial throttle response being a bit more aggressive and

then full throttle applications feeling a bit stronger up top.

Since I have tried both methods I think overall, this is the way to go.

Especially for peace of mind and knowing that you are taking full advantage of the

way the 996 3.4 liter ecu was programed originally with the larger maf housing.

I Think I will keep it like this for awhile ;^)

Edited August 6, 2009 by qikqbn

[1999Porsche911]

Bill,

Thanks again for the excellent response I think i might be sold on the resistor solution combined with the AEM meter since all the other options seem to be much less cost effective for possibly little advantage. Do you know if anyone has a write up on it ? Again thank you for your help.

What part exactly were you looking for a write up on? If it's AEM meter ?'s or AFC Select MAF controller ?'s

then I can share my experience... If it has to do with resistors, rheostats, or variable pots... then

members Todd or porsche 1999 are the goto guru's...

I wanted to give a quick update on my current setup as of last night ...

After 7 months of running a "calibrated" maf signal

I finally decided to track down the proper MAF housing size and got my hands

on Todd's recommended "Cayman/Boxster 987" Maf housing . Brand new from

Sunset Porsche parts the discount is still a lot ... $275 because it includes

the actuall sensor which I can not use.

All I wanted was the housing tube to plug my boxster/996 sensor into. I finally tracked

down the proper size maf housing from a dismantler and saved myself

over $200...It also has the screen built into it to help with air turbulence.

In the process I also discovered a proper sized nice alternative

Bosch maf housing for a lot less $$ then Porsche... (pm me if interested)

My original 986 boxster maf housing measures inner diameter of 70-72mm.

(76mm or 3 inch outer diameter)

The 3.4 liter 996/Cayman maf housing measures inner diameter of 83-85 mm

(90mm outer or 3.5 inch outer diameter)

A difference of close to 20 percent in size.

With my "calibrated" maf signal my air fuel ratios were staying a solid 12-12.5 and the car was running very strong.

Even so I still felt that "tricking" the ECU with a calibrated signal or resistor may not be taking full advantage

of all the fuel maps and how they were designed to work with proper air flow measurement from Porsche.

Even though I really enjoyed my setup there was always a question in my mind if I

was really allowing the programming to work correctly under those "calibrated" conditions.

Since I want my 3.4 Boxster to run it's strongest at all times I decided it was time to

switch over to the proper maf housing size.

After modifying intake tube lengths for the new housing I got

it to fit nicely.

My current intake setup is:

-Cone filter plugs onto front end of Cayman Maf Housing..

-back end of housing plugs onto 3 inch intake tubing all the way to Throttle body.

(996 throttle body is only 3 inches in diameter)

I unpluggled the battery, reset my computer, and disabled

my "AFC-select" maf voltage controller.

After a few runs through the rpm range for the computer to learn the new setup

everything seems to be working very nice.

I have to say.... I think overall the engine feels stronger and more refined now.

My peace of mind feels much better as well since I know for sure that the

proper air measurement is working with the fuel maps as designed from Porsche,

rather than a "calibrated" signal to trick the computer.

Afr readings at wide open throttle are around 13 from low to mid rpms and then drops

to around 12.5 for the upper rpm range.

My initial impressions are that the car feels more responsive. Hard

to say for sure because it was running quite fast before as well. Just seems to be more

sorted out all around with partial throttle response being a bit more aggressive and

then full throttle applications feeling a bit stronger up top.

Since I have tried both methods I think overall, this is the way to go.

Especially for peace of mind and knowing that you are taking full advantage of the

way the 996 3.4 liter ecu was programed originally with the larger maf housing.

I Think I will keep it like this for awhile ;^)

As I mentioned in your other post:

The reason for your difference in A/f at WOT is because your calibrated signal was different than it is now. Running at WOT at a 13:1 air fuel ratio will make your car feel like it has more pep since you are running lean.......maybe too lean. Especially running 91 octane fuel. Had you calibrated the signal with a higher ohm restistor, you would have had the exact same results. All you did was make your engine run leaner than it was. Now you simply "tricked" your engine into thinking it was getting less air than it really is by using a mechanical device rather than an electronic one.

Edited August 6, 2009 by 1999Porsche911

[qikqbn]

Bill,

Thanks again for the excellent response I think i might be sold on the resistor solution combined with the AEM meter since all the other options seem to be much less cost effective for possibly little advantage. Do you know if anyone has a write up on it ? Again thank you for your help.

What part exactly were you looking for a write up on? If it's AEM meter ?'s or AFC Select MAF controller ?'s

then I can share my experience... If it has to do with resistors, rheostats, or variable pots... then

members Todd or porsche 1999 are the goto guru's...

Since I have tried both methods I think overall, this is the way to go.

Especially for peace of mind and knowing that you are taking full advantage of the

way the 996 3.4 liter ecu was programed originally with the larger maf housing.

I Think I will keep it like this for awhile ;^)

As I mentioned in your other post:

The reason for your difference in A/f at WOT is because your calibrated signal was different than it is now. Running at WOT at a 13:1 air fuel ratio will make your car feel like it has more pep since you are running lean.......maybe too lean. Especially running 91 octane fuel. Had you calibrated the signal with a higher ohm restistor, you would have had the exact same results. All you did was make your engine run leaner than it was. Now you simply "tricked" your engine into thinking it was getting less air than it really is by using a mechanical device rather than an electronic one.

I really enjoyed the "calibrated" setup I had before and it worked great for the most part..

It is definitely a great alternative, but now I just feel like I have the best of both worlds.

Factory setting air fuel ratios with the ability to fine tune.

Thanks for your input 1999, I always learn a lot from you.

Bill