CEL/MAF debugging help needed

[KevinC]

As I was leaving Infineon last weekend my 2000 Boxster S emitted a single plume of smoke from the exhaust and the CEL came on. My Durametric scanner revealed the following codes: P1125, P1132, P0102. The P0102 sure makes it sound like a MAF problem. But I did some more investigating and now I'm not so sure...

I happened to have an old "Actuals Values" log of the MAF values running the car unloaded at a range of RPMs. I repeated that test and got similar values (c. 15 kg/h idle, 52 kg/h @ 3000 RPM). The voltage out of the MAF looked reasonable (1.3V idle, 1.9V @ 3000 RPM).

It seems like the next thing I should look at are the short term and long term fuel trim numbers. The Durametric Actual Values display doesn't list these names. Are the Adaptation Range 1 (RKAT) and Adaptation Range 2 (FRA) names for the same thing? These values were static during my 5 minute run: Bank 1 RKAT : -0.66, Bank 1 FRA: 1.15, Bank2 RKAT: -1.17, Bank2 FRA: 1.13.

I cleared the CEL by disconnecting the battery. I haven't had time for any long drives but after a few short ones, the CEL has not come back on yet. I have forgotten how many "drive cycles" are required to set the light and how long the drives need to be to count.

I'll be out of town this week then, shortly after I return, I have another track day. Should I play it safe and just order a new MAF? Or should I not be too concerned as long as I don't get a blinking CEL? Any other diagnostic suggestions? (Yeah, I know - take it to a good technician - but what fun is that? ;) )

More Info:

The car has been running fine throughout this time. No repeat of the smoke plume. That may have been a coincidence. I seem to get them about once every 6 months to a year. As soon as the CEL light comes back on I plan to check the codes again then disconnect the MAF connector, reset the DME and see what happens. Any tips for getting that dang connector off? Even with the MAF removed, I couldn't get the connector off easily.

Edited March 9, 2008 by KevinC

[Loren]

I would clean the MAF and reset the codes then see if it comes back.

[Chris_in_NH]

how many miles are on this car? has the Air-Oil Separator been replaced yet? (you will eventually need to replace it, so you might as well do it as 'preventive maintenance', as opposed to 'reactionary repair'. ;) the AOS is a quite common culprit for the codes that you have listed, although the P0102 makes me think that it really could be MAF-related.

this post may help you diagnose the P0102.

http://www.renntech.org/forums/index.php?showtopic=3216

as you mentioned, unplugging the MAF wiring harness and then resetting the DME is a good idea. see if the other codes come back. you should also get a P0102 when the MAF is unplugged. you want to see if the other codes come back.

as far as getting the MAF's wiring harness off of the MAF, you should just be able to squeeze the clips on both sides of the harness to release it. if it's stuck, you can use pliers/channel locks to apply more squeezing power to the clips. a flat-head screwdriver may also help to gently pry the clips away.

Loren's advice about cleaning the MAF is good advice, but in my experience if cleaning the MAF does work, it is only temporary. here's a link to the MAF cleaning DIY (down towards the second half of the page).

http://mike.focke.googlepages.com/checkeng...ssairflowsensor

also, if you have a local friend with a Boxster, you could swap MAFs to see if the problem/codes follows the MAF. a new MAF is an expensive part if you don't really need one. many people spend money on MAFs only to find out that it wasn't the MAF to begin with.

just do your homework (and it sounds like you are) before you spend the money on a new one. ;)

if you do need a new one, AutohausAZ.com has the best prices on MAFs these days.

[tholyoak]

The negative values in RKAT (adaptation near idle) indicate the car is running rich and the DME is leaning out the mixture. The values >1 for FRA (adaptation under load, there should be a FRAO, upper load range and FRAU, lower load range as well) suggest that the car is leaning out under load and the DME is richening the mixture. These contrary indications and the 102 code suggest to me that your MAF is in need of replacement. As Loren states you can try to clean it and see what happens, but as Chris states this is probably just a temporary fix at best. The MAF is a consumable and needs replacement occasionally.

Todd

[986911]

Have MY2000 base. Took her for drive other day- 1st time since Dec- weather starting to get nice. Well, CEL came on. Went to Autozone & got error code 1130. Also came on last summer but had them reset it. Car is running great, with no issues. Gonna take advice & remove MAF & clean with electronic cleaner. Also awaiting delivery of a Actron CP9135, to check codes myself.