Help. CEL won't go away after Engine Swap - 986 Forum - The Community for Porsche Boxster & Cayman Owners

VRsyncro · 11-15-2008, 05:48 PM

What size MAF Housing are you running. The 2.7L and 3.4L MAF's are the same part but the inner diameter of the MAF Housing is different between the two.

The 3.4L has a 3.5" MAF Housing. Get a 996 Airbox lid, cut out the MAF housing and you should be good to go.

victoreric · 11-15-2008, 08:20 PM

Quote:

Originally Posted by VRsyncro

What size MAF Housing are you running. The 2.7L and 3.4L MAF's are the same part but the inner diameter of the MAF Housing is different between the two.

The 3.4L has a 3.5" MAF Housing. Get a 996 Airbox lid, cut out the MAF housing and you should be good to go.

Thanks for that. If the 2.7 and the 3.4 is the same part, then it shouldn't matter which one I use after the swap?

Paul · 11-16-2008, 07:49 AM

Check the part numbers to make sure, but I believe the MAF is the same part from 2002 and up on both 986s and 996s.

Are you running a 7.8 DME?

Paul · 11-16-2008, 08:01 AM

Why aren't you using the 996 injectors? Are you running the DME as a 996?

victoreric · 11-16-2008, 09:49 AM

Quote:

Originally Posted by Paul

Why aren't you using the 996 injectors? Are you running the DME as a 996?

I don't know why, but I guess I should be using the 996 injectors then? The DME was the original one from a 2002 boxster, (7.2?) but then I flashed it with Softronics conversion file so I don't know what it is now.

Topless · 11-17-2008, 07:51 AM

Caveat- ( I have never made this swap before) but it seems to me that if you have 996 displacement you also need a 996 MAF housing, 996 injectors and 996 DME software so everyone is on the same page.

I have more questions than answers at this point. Tholyoak is our resident motor swap expert as he has done many 996 conversions. Probably need to inventory all things on your car and look him up to sort this all out. Custom DME programming is probably the way to go on your car since the intake/displacement/exhaust no longer match any stock setup.

tholyoak · 11-17-2008, 10:30 AM

As I stated on Renntech, you need to contact Scott Slauson at softronic and find out how the mapping was done. This will dictate what MAF is needed. The 996 injectors are the same as the boxster. Without knowing how the 7.2 was remapped to run the earlier motor, everything else is just guessing. My only recommendation would be to ditch the 986 intake manifolds as this will restrict the breathing of the 996 motor.

-Todd

blue2000s · 11-16-2008, 08:05 AM

Quote:

Originally Posted by victoreric

Thanks for that. If the 2.7 and the 3.4 is the same part, then it shouldn't matter which one I use after the swap?

I don't know if it's true that the housings are different sizes between the 2.7 and 3.4, but if it is, that may be part of the problem. The MAF only measures air speed, to convert that into mass flow, the DME needs to know the size of the tube that the MAF is sitting in. If the 2.7 and 3.4 use different diameter housings, and you don't have the DME software matched with the right housing, it will be mismanaging fuel flow.

If the DME is programmed for the smaller housing and you are using the larger one, the computer is calculating a lower mass flow than you are actually getting and the car will run lean.

galtenbaugh · 04-06-2009, 10:36 AM

Quote:

Originally Posted by victoreric

Thanks for that. If the 2.7 and the 3.4 is the same part, then it shouldn't matter which one I use after the swap?

I'm wrestling with the same problem right now. Does anyone know the exact inside diameter of the 996 MAF housing? I believe it is 80mm or maybe 82mm?

Does anyone know of a source for a generic MAF housing that is the same size as the 996 or a 996 airbox lid that I can buy and cut the MAF housing off?

Thanks!

George

insite · 09-21-2010, 07:50 AM

i am doing a 3.4L swap now. turns out the E39 BMW 540i has the same diameter MAF housing with the same type of MAF flange. it's like 84mm inside. i bought mine off someone on bimmerforums.com for $40. the guy with username 92535i92 has five of them for $20 each, shipped. it's 3.5" OD.

i've been working with cloudsurfer on the overall intake design. he bought the Cayman S MAF & housing, which is similar in size / design to the BMW version (but a lot more $$$). he then routed some silicone hose to the MAF housing & installed a BMC in-line air filter.

FYI, this is the same route i'm taking. the BMC was like $215 (shipped from Italy).

i haven't installed everything yet; still waiting on lots of motor parts. if you look for my 3.4L installation thread, cloudsurfer posted a pic of his setup. very nicely done.