Dave H.

i posted all this on 986forum.com so i'm posting it here too...

my '01 S w/ 95k miles just got a full Maxspeed Motorsports exhaust installed, with the 4 200 cell cats.

Porsche Boxster 986 NHP Performance Exhaust 2.7L/3.2L

after i picked up the car it ran fine for the drive to work, but would barely idle when i got in the parking lot. idle swinging up and down +- 300 RPM, sounds very loud, exhaust tips black with soot.

drove it back to the shop and CEL came on. got to the shop and they checked the faults, and came up with Fuel Trim Adaptation faults.

so basically the engine can't adapt the fuel trims and it's running FULL rich (black tips).

they've tried moving the post-cat O2's around (exhaust has 4 O2 bungs on each side), but this should be front O2 related. i replaced the front O2 sensors with aftermarket ones about a year ago, so the shop is going to try factory O2s (another $500 ) on monday.
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shop installed new pre-cat (B1S1, B2S1) O2 sensors. 2 extented test drives and sitting in their lot idling for 2 hours, runs fine. i get it back and drive it 20 minutes to work, idles like crap again.
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so either there's a header leak on BOTH sides (seems unlikely) or the problem is upstream of the engine... ECU, MAF, or throttle body. the question is why one of those would crap out from just changing the exhaust...
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well after driving it home, there were 11 DTCs.

P1125 LTFT Add. Air B2 too rich
P1126 LTFT Add. Air B2 too lean
- freeze frame data:
- Fuel Sys 1 Closed Loop
- Fuel Sys 2 Closed Loop
- Calc. Load 26%
- ECT 183deg F
- STFT B1 25%
- LTFT B1 28.9%
- STFT B2 25%
- LTFT B2 28.1%
- RPM 2840
- Speed 72mph

P1128 LTFT Mult. Air B1 too lean
P1130 LTFT Mult. Air B2 too lean

P1132 O2 S1 B1&B2 control signal too high
P1133 O2 S1 B1&B2 control signal too low

and DTCs for multiple misfires.

those fuel trim numbers are at max enrichment.

so after a lot of reading, i'm thinking the MAF crapped out. cleaned it and reset the codes. will find out in the morning (not starting it at 3am)...

GVA-SFO

Hello Dave,
I'm very curious to know the story, after these old initial problems.
Did you were able to find the source of the problem and then be able to correct it ?
Thanks a lot in advance.

Dave H.

nope. got tired of paying my shop $150 an hour to play with it.

$2000 exhaust sits in a box in my garage.

mikefocke

http://986forum.com/forums/performan...on-faults.html is the other thread.

GVA-SFO

..that's a pretty bad news !

Seating in the garage and waiting for a new customer, or ..for another try ?

About the noise: do you remember if you had a lot (or just a little?) of noise increase ?
One thing (now, I should say another one !!!) that I worry before changing my oem exhaust, is the (very often) 92 dB noise limit at Laguna Seca, as being black flagged there, is all but something that I would love !

Dave H.

well it's only the headers and cats that are in the box. the Maxspeed muffler is on the car. it's only slightly louder than stock with a good tone. i have had to have broken welds fixed a couple of times.

i've had the cam timing deviation fixed with new tensioner pads, so i may give it another try next year.

GVA-SFO

That looks a lot more nicer !
By the did your pads change was an expensive shoot ?
I have a noise that I do not like much when starting up the engine (cold start). I have some fears that my pads are done. (about 63k miles)

About the headers, this is something that Im very interested to do too, to get a better flow out, i.e.: using 200 cells cats with better and bigger tubing.

Thanks for your good answers.