Edit: so I finally got hooked up with markski. Did some logs and sent him my ecu. Turns out for 3 years I wasn't running what I thought I was. 6 tables changed on my "tune" and that was it. After alot of communication back and forth with Mark, he did a tune for me. I cannot believe the difference. Unreal how much better spool is, peak boost, and NO MORE CODES! I was throwing time and money at boost leaks, parts, and my mind. I can not get over the amount he cares about the customer. Something that is not easily found these days. Do yourself a favor and skip the crap tunes and bad service. Go to markski.




So I was doing a few runs yesterday and on prolonged boost the ABS and PCM lights went off...nothing new. Its been doing that for 3 years. Ive thrown parts at it, boost leak tests..ect...nothing fixes it. I only have 2 codes. They are for the 02 sensors since im running straight pipes. Whatever. So anyway, the next time I got on it, I had had the boost. Would only make .4-.5 bar. I figured something blew off. I check over the car and I don't see anything that has come off. Car sits for 2-3 hours and I drive it home. I all of a sudden have all boost back. 1.0-1.1 for over an hour of driving. Could this just have been some sort of computer glitch? Obviously it wasn't mechanical. I guess?

 

It reads like a MAF problem. Making lots of boost of course requires lots of air. And of course the compressed air is quite warm. The MAF works really hard then. The MAF gets hot and doesn't work as well. Boost drops.

You shut off the engine and let it sit a few hours and the MAF recovers and you have full boost back.

I assume the plugs are reasonably fresh? The coils and the fuel filter likewise?

I believe in this case the O2 sensor errors are unrelated to this behavior and like you offer are probably related to the non-factory exhaust.

Would I replace the MAF on the above? No. But I'm not sure how you would confirm the MAF was at fault. Best I can offer would be to do some data logging if you don't want to throw a new MAF at the behavior.

 

Sounds like something triggered a limp mode that was reset by off/on cycle. If everything is checking out, then hopefully was a fluke.

 

This is total nonsense. The MAF is post airbox and does not "see" and compressed air in any way form or fashion. If anything, the MAF is exposed to a tiny bit of vacuum...

 

FYI, i had this error popping up when I first got my car. Turned out it was a wastegate that was acting up, would seize, unseize...seize, etc

 

I was thinking that at first. Still stock turbos on 108000 miles. Car has seen a couple winters in Illinois...How did you find out it was the wastegate?

 

MAF should see pretty consistant temps since its from the airbox, not the turbos. But it has new updated coil packs and maybe 3000 miles on the plugs. Has new 02s as well.

 

Thanks for the correction.

Still the MAF works harder than it would with a stock engine as a modified engine requires much more air to deliver its elevated level of output.

That the ABS and PCM warning lights went off suggests a MAF problem as the ABS and PCM require some signal from the MAF and if this is not forthcoming or if it is out of range warning lights are lit.

 

I agree that it appears to be a MAF problem. Interestingly I've never had any MAF issues whatsoever and that is on a 3.8 engine putting 600hp to the wheels with pretty much every shift at or near a 7500 redline. Not sure why some guys keep blowing MAFs...

 

Hot wire or film MAF right? As airflow speeds up the MAF will apply more power to maintain target temp - amount of power used tells the computer mass of air. A theory I have is that when you suddenly let off the gas after a hard pull or greatly exceed what the sensor is specced for it can have issues overheating and can blow - especially if it's not a real Bosche sensor. The scenarios of others seem to support something like that occurring IMO.

Can't say that's what's happened here but if it comes back I'd consider swapping the MAF. Since it went away after a cool down I'd bet the sensor is okay. Open to alternate theories and happy it's not happened to me!

 

Could be you just got a very good MAF.

My Boxster has its original MAF although it got an approx. 100K mile "recess" when I misdiagnosed an oil filler tube cap leak for a bad MAF and replaced the MAF. Thankfully I saved the old MAF.

After I replaced the leaking cap I left the new MAF in service. Then when the replacement MAF developed a problem -- it was an OE MAF too -- I replaced it with the saved original MAF. So the original MAF now has approx. 200K miles on it.

My 2003 Turbo MAF is original and the Turbo has covered almost 148K miles.

 

both of your cars are bone stock with zero mods correct? it wouldnt surprise me that your maf lasts this long in stock form. start modding and running past the .5v needed and the maf wont last long

 

My response was to pwdrhound who reports with a mod'd 3.8l engine (~600hp) he's never had any MAF issues.

I would expect an OE MAF in a stock engine to deliver good service life, although there will be a few exceptions, MAFs which fail early. (I consider the replacement MAF that failed to be an example of such an exception.)

But a MAF in a mod'd engine will almost certainly have a shorter service life, although of course there will be exceptions as pwdrhound's experience shows.

 

I've always run the OEM Bosch MAF, the $200 version that comes in a Bosch box as opposed to the $800 Porsche box. Same part. My engine flows in excess of the MAF limit (1480 kg/hr if I recall) and the ecu uses an algorithm to allow it to operate beyond the limit. Again, I've never had any MAF issues but still keep a spare one in the tool box just in case. Murphy's law states that if you have a spare on hand, you'll never need it....

 

I noticed today its only reaching .8 and .9 bar. inconsistent. Looks like its a boost leak test for me tonight! uuuuuuuuuugh