New MAF questions - 986 Forum - The Community for Porsche Boxster & Cayman Owners

san rensho · 12-13-2012, 03:22 PM

So I got the $93 Buyautoparts MAFand the Durametric numbers are great. The FRA and RKAT numbers and voltage are all right on the money,where with the old MAF the numbers were pretty far off. But the mass air flow still is off.The spec is 15 kg/h +/- 1.25, the old MAF read around 13 and the new reads about 19. I also got two error codes, MAF reading above upper limit and air intake temp reading above upper limit right after I installed the MAF but they haven't come back since driving around a bit.

Now it has a slight drivability problem. The idle is hunting, almost stalling when I first start the car but it gets better as it warms up. And the power felt down a little but it did seem to improve after a couple of full throttle runs.

So is this just the DME adapting to the new MAF or something else?

58ceramicgreen · 12-13-2012, 03:27 PM

When I installed my new MAF I had unplugged the battery to clear any codes I had thrown. Might be worth a shot if you didn't do that already?

san rensho · 12-13-2012, 03:40 PM

Quote:

Originally Posted by 58ceramicgreen

When I installed my new MAF I had unplugged the battery to clear any codes I had thrown. Might be worth a shot if you didn't do that already?

I think the clear codes function of the Durametric does the samething.

58ceramicgreen · 12-13-2012, 04:19 PM

Good point..I knew it would clear the fault codes but wasn't sure if that was the same as resetting the ecu (I thought that's what a disconnected battery did but I may be way off)
When I swapped out my MAF and went for a drive it was night and day difference, no idle stumble or issues at all. Really woke the car up again instantly..I'm well over a couple thousand miles now with this cheap eBay MAF, someone with more experience with these cars I'm sure will chime in and help!

san rensho · 12-13-2012, 07:32 PM

Well I diconnected the battery and I still have the hunting idle right at start up which gets better as I drive. I'll run it for a couple of hundred miles and see what happens.

thstone · 12-13-2012, 07:39 PM

The Durametric will clear the codes but disconnecting the battery will clear the codes AND the ECU learned parameters thereby forcing the ECU to start with the default maps and then learn again all over. Either way, the ECU should learn to adjust for the new ECU but disconnecting the battery is an easy and free approach to reset the ECU and let it learn from scratch.

Topless · 12-13-2012, 07:55 PM

Hunting idle is most often an intake air leak. The car runs lean under high vacuum which does not affect MAF readings.

san rensho · 12-13-2012, 08:27 PM

I don't think its a vacuum leak because with the old MAF I had a rock steady idle.

thom4782 · 12-13-2012, 11:14 PM

A dirty throttle body will cause a hunting idle.

philou320 · 12-13-2012, 11:40 PM

You should disconect the batterie for 10 minutes
switch on the ignition without starting the engine for 3 mins
switch off the ignition
and now you can go, your DME is going to learn the new values from your new MAF

Bala · 12-14-2012, 02:37 AM

When I replaced the maf the idle was rough for a short 3 minutes. And it took the car a couple hundred miles to learn and adopt to the new maf. I did reset using dura metric. I'm still not happy with the eBay maf as I feel it is not the regional power. However it might be some other issue. So going to do a compression and leak down. Then maybe return this maf and get the oem part.

san rensho · 12-14-2012, 07:16 AM

Well this morning from a dead cold start, the car runs perfect. No hunting idle. I guess it just had to do an adaptation from cold to sort out the problems.

san rensho · 12-14-2012, 12:43 PM

Back to square 1. The idle still hunts on a hot start up and it has thrown a MAF code again. I think I'll give it a week and then return the MAF if I still have problems.

I'm thinking of trying the Pelican Maf. Is the Pelican MAF the same one sold at Porsche dealers or just the same Bosch part?

Topless · 12-14-2012, 08:38 PM

Disconnect the MAF and run the car. If your idle smooths out, replace the failed MAF.

I believe Pelican sells the OEM part that works well. I have not tried one.

san rensho · 12-15-2012, 05:44 PM

Alright, I'm returning the Ebay MAF. Today, it only got worse, I drove it over 75 miles, hoping it was just an adaptation problem but the idle is still hunting, the power is way down, its surging at 60-90 mph, and when I launch, it has stalled a couple of times, I have to rev to 3k + just to get off the line, with backfiring and honks from drivers behind me.

I get a stored MAF code at every startup and the straw the broke the camels back is a CELlight. I put the old MAF in and the car runs fine.

I don't know if its just a bad unit, but I don't care. I'm going to try the Pelican MAF and see what haappens.

mikefocke · 12-16-2012, 06:34 AM

You do know I have a table of Bosch MAFs on this page at the bottom. They are know to work, after all, Porsche buys em.

san rensho · 12-16-2012, 09:26 AM

Thanks, I'm going to try Autohauz for $172.

Johnny Danger · 12-16-2012, 09:52 AM

Quote:

Originally Posted by san rensho

Alright, I'm returning the Ebay MAF. Today, it only got worse, I drove it over 75 miles, hoping it was just an adaptation problem but the idle is still hunting, the power is way down, its surging at 60-90 mph, and when I launch, it has stalled a couple of times, I have to rev to 3k + just to get off the line, with backfiring and honks from drivers behind me.

I get a stored MAF code at every startup and the straw the broke the camels back is a CELlight. I put the old MAF in and the car runs fine.

I don't know if its just a bad unit, but I don't care. I'm going to try the Pelican MAF and see what haappens.

Having owned Fiats, Alfas, Triumphs and Lancias - you must feel right at home with the way your boxster is currently performing !

Seriously, though, it may be that you were either sold a defective sensor or someone on the other end didn't cross reference it correctly.

san rensho · 12-17-2012, 07:26 AM

Quote:

Originally Posted by Johnny Danger

Having owned Fiats, Alfas, Triumphs and Lancias - you must feel right at home with the way your boxster is currently performing !

Seriously, though, it may be that you were either sold a defective sensor or someone on the other end didn't cross reference it correctly.

Except for the Triumph, I had pretty good luck with the other cars. Boxster isn't too bad.

Anyway, the MAF is not a Bosch part, or if it was, its reman, because it has no Bosch numbering on it. I'm going to try a genuine bosch and see what happens.

san rensho · 01-04-2013, 07:13 AM

Update- Buyautoparts refused to refund the purchase price, but sent me another MAF. This one seems to be working fine. Air flow is within spec right around 14 kg/hr at 700 rpm, rock steady idle, smooth power all the way to the redline.

The only thing I've noticed is that the RKAT adaptation value is right around +2. Is that a correct value? Anyone know the spec for RKAT?