MAF replacement - do I need to reset the ECU afterwards?

[John V]

I have a 2000 Boxster S, US Model, 6-speed trans. I recently replaced my MAF. The MAF that was installed had the part number:

0 280 218 055 and 986 606 125 00

The part numbers of the new one are:

0 280 218 055 and 986 606 125 01

After installation, I cleared the CEL with a scan tool and the car runs correctly (i.e. it no longer stinks and it revs out properly) except for the fact that it seems to have a hesitation or a soft spot after each shift. Almost as if I'm backing off the throttle for a moment after I engage the next gear. No stuttering, just a slight loss of power.

No codes stored in the computer. Do I have to unplug the battery for a while to have the ECU re-adapt to the new MAF?

Thanks,

John

[Chris_in_NH]

yes, i would. especially if the hesitation was happening with the previous MAF. it sounds like the car is still running on the old MAF's parameters.

just disconnect the neg battery cable for at least 1 minute, then re-connect. have your radio code if your radio needs one (it does).

Edited March 5, 2008 by Chris_in_NH

[ashleyisagirlsname]

Had the same issue with my 2000. You most definately need to go to the dealer to have your software updated to recognize the new MAF sensor. They charge 30 minutes labour so it's not too bad. Unplugging your battery for a minute won't cut it in this instance.

[Loren]

Had the same issue with my 2000. You most definately need to go to the dealer to have your software updated to recognize the new MAF sensor. They charge 30 minutes labour so it's not too bad. Unplugging your battery for a minute won't cut it in this instance.

You are correct if you upgrade to the newer part number (...125 01) then you must use a PST2 or PIWIS to update the DME map.

[geoff]

Had the same issue with my 2000. You most definitely need to go to the dealer to have your software updated to recognize the new MAF sensor. They charge 30 minutes labour so it's not too bad. Unplugging your battery for a minute won't cut it in this instance.

You are correct if you upgrade to the newer part number (...125 01) then you must use a PST2 or PIWIS to update the DME map.

Loren,

I resolved my CEL (P1130) by replacing the MAF on my '01 Boxster. The original MAF was 986 606 125 00 (Bosch number 0 280 218 054) and the replacement part from Sunset was the newer 01 version (which supersedes the 00 version per the PET and retail price search), but it had the same Bosch 0 280... number. I read Boxster TSB 2445 (Air Flow Sensor) dated Apr 6, 2001. It specifically says the earlier E-gas MAF (996 606 124 00) needs to have the DME reprogrammed when replacing the 996 606 124 00 MAF with the newer 986 606 125 00 one. I can't find any later TSB that says anything about reprogramming the DME when replacing the ...125 00 MAF with the ...125 01 one. Is there any definitive way to confirm whether or not my DME needs to be reprogrammed for the newer MAF I just installed? Or do I need to bite the bullet and just have the dealer update the DME with a PST2 or PIWIS?

I did notice after replacing the MAF, my car wasn't idling as smoothly as before. Based on the year and mileage (51K miles), my first guess was a dirty throttle body, which I pulled out and cleaned (it wasn't all that dirty, but the car idles smoothly again after the cleaning). I haven't figured out if the idle issue was somehow related to the MAF replacement, or coincidentally the throttle body got just dirty enough at approximately the same mileage to cause the uneven idle.

[John V]

but it had the same Bosch 0 280... number.

Yes. Same situation with mine. The Bosch part number was the same, even though the Porsche part number rolled from 125.00 to 125.01. I do not believe the DME has to be reprogrammed when going from 125.00 to 125.01. The dealer wouldn't even sell me a 125.00 - they said the old part had been superceded.

I unplugged the battery and left it for an hour, and the car drives better than ever now. No hesitation.

[Loren]

Yes, my mistake (Porsche has made this very confusing).

If you go from the 124 00 to either 125 00 or 125 01 then you need to re-program.

[geoff]

Yes, my mistake (Porsche has made this very confusing).

If you go from the 124 00 to either 125 00 or 125 01 then you need to re-program.

Thanks Loren - but is there any benefit to unplugging the battery so the DME gets the new MAF parameters when going from the 125 00 to the 125 01 MAF, or won't it make a difference?

And any thoughts on whether the idle issue I mentioned was related to the MAF or just a coincidence?

[Loren]

Yes, my mistake (Porsche has made this very confusing).

If you go from the 124 00 to either 125 00 or 125 01 then you need to re-program.

Thanks Loren - but is there any benefit to unplugging the battery so the DME gets the new MAF parameters when going from the 125 00 to the 125 01 MAF, or won't it make a difference?

And any thoughts on whether the idle issue I mentioned was related to the MAF or just a coincidence?

Yes, anytime MAF work is performed you are changing it's base reading. So, disconnecting the battery for 5 minutes then reconnect it and let the engine re-learn it it's idle and power program.

[Chris_in_NH]

I unplugged the battery and left it for an hour, and the car drives better than ever now. No hesitation.

glad to hear it. you don't need to leave the cable off for more than a minute. once the power's off, it's off. ;)

[John V]

I unplugged the battery and left it for an hour, and the car drives better than ever now. No hesitation.

glad to hear it. you don't need to leave the cable off for more than a minute. once the power's off, it's off. ;)

There are capacitors in the DME that will need to discharge. But that said, I left it unplugged for that long because I was busy working on the other car too. :P

[John V]

I unplugged the battery and left it for an hour, and the car drives better than ever now. No hesitation.

glad to hear it. you don't need to leave the cable off for more than a minute. once the power's off, it's off. ;)

There are capacitors in the DME that will need to discharge. But that said, I left it unplugged for that long because I was busy working on the other car too. :P

I think I spoke too soon. The hesitation has gradually come back. I wonder if the car does have to be reprogrammed for the 125.01 MAF. Doesn't make sense to me because the Bosch part number is the same as the 125.00 MAF.

The new MAF is not throwing a CEL. The only CEL I have at the moment is a P1118 for a bad O2 sensor heater.

Suggestions, anyone? Should I bite the bullet and take it in to the dealer?

[Chris_in_NH]

I unplugged the battery and left it for an hour, and the car drives better than ever now. No hesitation.

glad to hear it. you don't need to leave the cable off for more than a minute. once the power's off, it's off. ;)

There are capacitors in the DME that will need to discharge. But that said, I left it unplugged for that long because I was busy working on the other car too. :P

I think I spoke too soon. The hesitation has gradually come back. I wonder if the car does have to be reprogrammed for the 125.01 MAF. Doesn't make sense to me because the Bosch part number is the same as the 125.00 MAF.

The new MAF is not throwing a CEL. The only CEL I have at the moment is a P1118 for a bad O2 sensor heater.

Suggestions, anyone? Should I bite the bullet and take it in to the dealer?

Unplug the MAF's wiring harness, then reset the DME via the battery disconnect and drive without the MAF connected. see if the hesitation goes away.

if it does go away, then perhaps you do need a reprogram at the dealer.

[John V]

Unplug the MAF's wiring harness, then reset the DME via the battery disconnect and drive without the MAF connected. see if the hesitation goes away.

if it does go away, then perhaps you do need a reprogram at the dealer.

I tried your suggestion, Chris. No difference. The car drives fine for the first couple minutes (accelerates normally) and then reverts back to its previous behavior of hesitating after each shift.

It eventually threw a code saying the MAF was unplugged, no surprise, but why was it running exactly like it did with the MAF plugged in? I would expect the car to run different without the MAF. But it really didn't seem to change anything. Granted, I wasn't wringing the car out with the MAF unplugged, but I did rev it up with part throttle to see what was going on.

What does this tell me? Is the MAF good and I'm barking up the wrong tree? Is the MAF bad and that's why the car runs just as good without it? If so why is it not throwing a code? Why did this problem start right after I replaced the MAF? Very puzzled here.

Edited March 28, 2008 by John V

[John V]

After further investigation, it turns out that the car did indeed drive normally if I didn't use the clutch when shifting.

As it turns out, the clutch switch which is actuated when you just begin to depress the clutch was stuck. It's ratcheting-style plunger switch and had gotten pushed in so far so it would never disengage. After pulling it out and allowing it to self-adjust, everything is fine.

I suppose the DME is programmed to do strange things to the timing when the clutch is depressed, probably for emissions reasons. Everything is just peachy now, though.

[Chris_in_NH]

success! congrats! :)

[00boxster]

Yes, my mistake (Porsche has made this very confusing).

If you go from the 124 00 to either 125 00 or 125 01 then you need to re-program.

I have the older MAF in a 2000 Boxster the 124 part which I can get online. Is it actually worth getting the newer one and doing the re-program? Are there any performance benefits for the hassles?

[Loren]

Yes, my mistake (Porsche has made this very confusing).

If you go from the 124 00 to either 125 00 or 125 01 then you need to re-program.

I have the older MAF in a 2000 Boxster the 124 part which I can get online. Is it actually worth getting the newer one and doing the re-program? Are there any performance benefits for the hassles?

New style sensor (125.00 and 125.01)

The modified hot film air mass flow sensor HFM 5 is used, as was already fitted to the Boxster in model year 2000. With the C-shaped air duct, this air mass flow sensor is more resistant to contamination and water droplets, as these can only reach the sensor element after deflexion. A cross bore through the air duct reduces pulsation faults.

When replacing an old style HMF sensor on vehicles with a new style HMF sensor, you have to reprogram the DME.