I have 2001 E320 6cyl with 12 spark plugs. The car has 80K miles all original. I changed the spark plugs to BoschPlatnium 2 and ever sensethe check engine light comesup. The engine runs fine without any noticable problems. Iscanned for codes and it comes back with code 170 Fuel TrimBank 1 and Bank 2. The only problem I have noticed and this was before I changed the plugs, when gas pedal is released when the car is doing about 40MPH the idle goes up and down by half RPM. Any advise will be great. Thanks

 

Hi,
P0170 is Fuel Trim Bank1. P0173 is Fuel Trim Bank 2.
Do you have P0173 as well as P0170?
If so this is the "normal" signature for the MAF being out of range. *0k is a typical mileage at which this occurs.
Likely it is just coincidence that it occurred after changing the plugs BUT a better (or worse) spark may have just tipped things over the cliff.

If P0173 then 98% its the MAF.
Lots of posts about this. Use genuine parts after trying to clean it if you are very cost conscious.

Stuart.

 

Yes I have P0173 as well as P0170.

Is MAF the sensor that's inside the intake?

Thanks for the reply

 

Why did you change plugs at 80 k/They are 100 k interval items.Bosch 7422 or ngk 7090
clean you maf,with crc brand maf cleaner.
diy on benzworld.org w210 diy section.
do not touch the wires with anything but the spray.Remove the insert to properly clean it.
My feeling is that you removed the air box cover and the intake tube to do the plgs and you may have not aligned them correctly and have an intake leak leading to the fuel trim issue.Check all intake tubes and clean the maf.new maf at autohausaz.com 167 bucks.However with your issue of the rising rpm it could be either the dirty maf,an air leak,or a maf gone bad.
ohlord