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Discussion Starter #1
Ok guys, heres one for ya...

(YES i have used the search function, and didnt find a satisfactory answer...)

I just drove my Benz home from from Kentucky with NO MAF. It died there in Kentucky, and I live in Florida, I was visiting family and couldnt find one in KY in a hurry before I left, so I had to unplug it and drive 700 MILES without it. I got a new one when i got back, and hooked up the OBDII scanner- I erased all codes, installed the NEW maf, and the CEL came on again in 1 mile, P0170 - BY ITSELF - no other codes.. I erased it again, 4 or 5 miles later, it came back again P0170 - Fuel trim malfunction, Bank #1 - by itself.

I do not think P0170 is a MAF code, especially because i erased ALL codes, and then installed the NEW maf. I have not gotten any more MAF codes, just my good old P0170 code.

Anyone know what "Fuel trim malfunction, Bank #1" Means in english??

If anyone knows a fix to this, let me know and I will be eternally grateful!:surrender:
 

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Was the new MAF a Bosch?
 

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O2 blues

Doin12volt,

I'm sorry to say that you may have fried your O2 sensors by driving the car so far with the MAF disconnected. The Nose Really does know!:D Just having a bad MAF can fry the O2 Sensors by forcing a rich mixture. The front one is an easy repair. The back one is much tougher since you have to drop the exhaust system to install it. They are not too expensive and generally last a loooong time.

Good Luck!:thumbsup:

C as in 220
 

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Discussion Starter #5
Yeah, Cj... I was originally thinking O2 sensor fried due to running rich or lean since the mase map was activated due to no MAF. All I can say is POOP. Bmeister - EXCELLENT ARTICLE! I sat here and read the entire thing. I will attempt a ultrasonic cleaning of the front O2 and see how that goes. If not, I guess a new one is in order, along with re-setting the CEL yet AGAIN..

I fully believe the CEL should be referred to as the "empty your wallet light" LOL
 

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Wow. I thought that when you unplugged the MAF the computer went into default mode (could detect it was unplugged versus trying to read a bad set of output that you would get with a defective sensor) and used a default set of parameters versus trying to read and adjust. That sucks if it burned out the o2 sensors.

You are sure you got a good MAF, right? These have been known to be defective right out of the box, especially if you bought it cheap from someplace that sells rebuilt as new or sells "Bosch equivalent" without telling you.
 

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Doin12volt,

I'm sorry to say that you may have fried your O2 sensors by driving the car so far with the MAF disconnected. The Nose Really does know!:D Just having a bad MAF can fry the O2 Sensors by forcing a rich mixture. The front one is an easy repair. The back one is much tougher since you have to drop the exhaust system to install it. They are not too expensive and generally last a loooong time.

Good Luck!:thumbsup:

C as in 220
or clogged your catalytic converters.
 

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Ok guys, heres one for ya...

(YES i have used the search function, and didnt find a satisfactory answer...)

I just drove my Benz home from from Kentucky with NO MAF. It died there in Kentucky, and I live in Florida, I was visiting family and couldnt find one in KY in a hurry before I left, so I had to unplug it and drive 700 MILES without it. I got a new one when i got back, and hooked up the OBDII scanner- I erased all codes, installed the NEW maf, and the CEL came on again in 1 mile, P0170 - BY ITSELF - no other codes.. I erased it again, 4 or 5 miles later, it came back again P0170 - Fuel trim malfunction, Bank #1 - by itself.

I do not think P0170 is a MAF code, especially because i erased ALL codes, and then installed the NEW maf. I have not gotten any more MAF codes, just my good old P0170 code.

Anyone know what "Fuel trim malfunction, Bank #1" Means in english??

If anyone knows a fix to this, let me know and I will be eternally grateful!:surrender:
If you used a non Merc STAR to clear the fault codes, you didn't really clear the codes, use a proper Merc STAR. If it drives OK without limp mode then you are OK. You are lucky to get back to FL without getting into limp mode.:D
 

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Hello:

I have a 1996 e320 and have a very similar problem. I was getting horrible gas mileage and then the MAF went out. I replaced the MAF with a new, but cheap unit and the car now runs fine. However, I am still getting horrible gas mileage, probably less than 10 mpg. I read in another thread that disconnecting the battery may reset the MAF, but from this this thread, it looks like I should buy a Bosch MAF first, and then replace the O2 sensors if the mileage doesn't get better.

Does anyone have any insight?
 

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Codes

If your Check Engine Light (CEL) is staying off you are likely OK. Hang a OBD II reader on the car and see if there are any stored codes.

Some of our W202 models (Mine is also a '96) have a fuse (#32 on mine) labeled "diagnostic socket" that will clear the codes by pulling the fuse for a few minutes. This will also prevent you from having to reset your radio.

Usually, you will get a code for a bad 02 sensor.

Cheap MAFs can be bad news, but SOME guys get lucky with them.

How long since the last Plug and Wire change? What is "bad gas milage on your model?

Good Luck and welcome to our little corner of the Forum!:thumbsup:

C as in 220
 

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Codes

If your Check Engine Light (CEL) is staying off you are likely OK. Hang a OBD II reader on the car and see if there are any stored codes.

Some of our W202 models (Mine is also a '96) have a fuse (#32 on mine) labeled "diagnostic socket" that will clear the codes by pulling the fuse for a few minutes. This will also prevent you from having to reset your radio.

Usually, you will get a code for a bad 02 sensor.

Cheap MAFs can be bad news, but SOME guys get lucky with them.

How long since the last Plug and Wire change? What is "bad gas milage on your model?

Good Luck and Welcome to our little corner of the Forum!:thumbsup:

C as in 220
 

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Actually, the CEL is on. It came back on after about 25 miles or so, and the milage I am getting is probably under 10 mpg. Lastly I don't know off hand the last plug change,.

From everything I have been reading it sounds like I should get the bosch MAF. What do you think?
 

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Thank you very much for the advise. I changed my cheap MAF with a Bosch, and it seems to have fixed the problem as the CEL no longer comes on. However, the fuel mileage seems to still be a bit low. Any suggestions?
 

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Thank you very much for the advise. I changed my cheap MAF with a Bosch, and it seems to have fixed the problem as the CEL no longer comes on. However, the fuel mileage seems to still be a bit low. Any suggestions?
When you say that the mileage is a "bit low", what do you mean? What mileage are you getting now?

On my '94 C280, I noticed that when I moved further away from work a month ago, thus making my commute primarily freeway instead of side streets, I improved my gas mileage from 19mi/gal to about 24mi/gal.
 

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Does a 1999 C280 have a #32 fuse for diagnostics? I check up front and didnt find it, but I haven't looked in the trunk fuse box yet.
 

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Fuse #32

I believe it's only on the older 202s. It will be in one of the fuse boxes under the hood if you have one. Look for a fuse titled Dianostic Socket.

Good Luck!:thumbsup:

C as in 220
 

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I have a 98 C230 (non-Kompressor) with 33,000 miles on it that had the" P0170 Fuel Trim (Bank 1)" along with 2 pending DTC's, P0300 - Random/Multiple Cylinder Misfire Detected and P0304 - Cylinder 4 Misfire detected. The car is regularly serviced by my local M-B dealer and in going thru the service records, I saw that the spark plugs were never replaced since new and I am the original owner. I replaced the orginal M-B plugs myself with Champion Spark Plugs Model 7071 Double Platinum from my local auto parts store. I also removed the Mass Air Flow Sensor off of the car and blew compressed air inside and out for about 30 seconds and re-installed it. The Check Engine Light turned off as soon as I started the car. No need the clear the codes. By the way, I do not own one of those $300 OBDII scanning tool. I purchased software and a special USB cable via online from OBDCOM. The software works on any laptop computer running Windows XP, Vista, or 7 and basically allows me to read and erase OBD codes using my laptop from any car built since 1996. The kit cost less than $100 including shipping.
Hope this info helps.
 

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If your handheld scanner is able to read both the standard and manufacturer specific codes, translate the codes into plain english, and erase the error codes so as to cancel the Check Engine Light for $80, then you got an excellent price for it.
 
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