code P0170 and bad MAF

[arnel_lim]

My 99 E430 CEL went off. I check the code and it was P0170. Based on searches in the Forum, this appears to "usually" be a problem with the MAF. I read I can try cleaning it, and if that doesn't work, shell out the $$ for a new one.

I was just curious what engine damage, performance problems, emission problems, or gas mileage degradation occurs if I drove around with a bad MAF for an extended time.

Also, what typcically causes this? Car has 108K on it, and I got a full tune up at about 106K...including the air/fuel filter and plugs.

[manny]

1. Try cleaning it.
2. It WILL affect your fuel economy & emissions.
3. If any amount of dirt in the airbox was stirred up, while installing the new airfilter, that MAY have caused the problem.
4. With that kind of mileage, it would not be surprising if you did need a new one.

[blackmercedes]

Cleaning it is a band-aid that won't last long. Running over the fuel trim's ability could foul the catalytic conveter. Spend the $300 or so and fix the problem.

One caveat: That code also indicates a faulty fuel pressure regulator, but in most cases, the Air Mass Meter is at fault. The best way to tell is to read the fuel trim adaptation values

[Arthur Dalton]

<>

..or vacuum leak ..unmetered intake air is a common fuel trim code tripper..

[arnel_lim]

Originally Posted by blackmercedes

Cleaning it is a band-aid that won't last long. Running over the fuel trim's ability could foul the catalytic conveter. Spend the $300 or so and fix the problem.

One caveat: That code also indicates a faulty fuel pressure regulator, but in most cases, the Air Mass Meter is at fault. The best way to tell is to read the fuel trim adaptation values

How do I read teh Fuel Trim Adaption Values? I have an Equus 3100 Innova Diagnostic Code Reader. Not sure, but I don't think it stores real-time data.

[manny]

[QUOTE=arnel_lim;1382506]I have an Equus 3100 Innova Diagnostic Code Reader. /QUOTE]

In this application ( I have the same unit ) it's useless.
About the only people that can read fuel trim values is your friendly M-B dealer.
I cleaned my maf sensor 2 months ago & have not seen PO 170 since.

[arnel_lim]

Well, the local MB Stealer quoted me $448 for a new MAF. I noticed there's mention of an Air Mass Meter and an Air Mass Sensor. Are they the same? Anyone ever shop at alleomautoparts.com

Smythe European $448
alloemautoparts.com B3130-161380 Air Mass Meter $198.99
www.*************** 0280217810 Air Mass Sensor $264.95
Mercedes Shop B3130-161380 Air Mass Meter $253.42

[manny]

If you're going to buy one, get it from FastLane ( Mercedeshop ).
That way you know that it will be the right one & a quality product as well.

[suginami]

Originally Posted by manny

If you're going to buy one, get it from FastLane ( Mercedeshop ).
That way you know that it will be the right one & a quality product as well.

Yes, and from buying it from Fastlane here at the shop forum you are also supporting the forum where you get free technical advice, the very kind of advice that told you what to replace.

[blackmercedes]

To be technically correct, the E430 does not have a Mass Airflow Sensor, or MAF. The sensor does not measure the flow rate, but only the mass of the air, hence the proper term is Air Mass Meter, or AMM.

You must use the SDS (Star Diagnostic System) to read adaptation values. All dealers and good MB indies have the system. It is an excellent tool for diagnosis when it comes to many of the systems on the newer cars. It interfaces with many parts of the car and can save a great del of "throwing parts" at problems.

[arnel_lim]

Originally Posted by suginami

Yes, and from buying it from Fastlane here at the shop forum you are also supporting the forum where you get free technical advice, the very kind of advice that told you what to replace.

I hear yah...

[blackmercedes]

$253.42 for an E430 AMM from Fastlane.

[autobahnauto]

I had a customer decide to not replace his air mass meter for two years. It took out his spark plugs, cat converters and then ran so lean it backfired and blew a hole the size of a tennis ball in his intake manifold.
I ate good that week.
Dave