603 air flow sensor removal - PeachParts Mercedes-Benz Forum

Jeremy5848 · #1 07-16-2008, 01:08 AM

Having removed from my '87 300D (W124, OM603) the EGR valve and plugged the vacuum line to the ARV valve, it occurred to me that the air flap and its potentiometer (which live in the plumbing between the air filter and the turbo) now serve no purpose except to get stuck shut, thus robbing the engine of air. The air flap apparently doesn't cause problems -- I can't find any mention of it on the forum at all. The potentiometer tells the EGR computer how much air the engine is taking but with ARV and EGR not functioning, the computer has nothing to do and could be removed if the tach signal did not go through it.

The part is 000 542 92 14 "Indicator, air-flow sensor." Should I remove or modify the air flap so that it stays wide open? It looks like I could remove the whole thing and replace it with a piece of pipe. Anyone ever done that or isn't it worth the bother?

Jeremy

compress ignite · #2 07-16-2008, 01:17 AM

If the EDS doesn't penalize you by dropping the BOOST.
Remember It's only REAL function is to deny BOOST under any pretext.

GSXR tells us that with a pressure type wastgate Actuator (instead of the
factory Vacuum wastegate Actuator) All of That crap can be removed and
the EDS can't touch your Boost ever again.

Unplug it and see if you still have BOOST...There will be your answer.

That "Indicator, air-flow sensor." is a "Right Pricey Piece of work"...will
be worth salvaging.

sixto · #3 07-16-2008, 01:31 AM

First step to removing is to pull the plug and see if it performs differently. If not, remove the MAF.

I haven't heard of any negative effects of removing it.

I'd just as soon prop the MAF open and not have to worry about fabbing an elbow to joint the air cleaner and the turbo inlet hose.

Sixto
87 300D

#4 07-16-2008, 01:35 AM

Put a straight pipe in its place. Its function is only for the EGR on the 87 model, it won't alter the boost or fuel if you remove it.

C Sean Watts · #5 07-16-2008, 08:16 PM

Remove the whole unit and work with it on a bench (easy to get at the innards.)
Slowly pry up the black plastic cover and remove it. Reach in and push the air vane while watching the nut and tab that that move with it. Wire, glue, etc. the vane open using the tab, then replace and reseal (to keep out unfiltered air from entering) the plastic cover back on.

scottmcphee · #6 02-23-2010, 03:52 PM

Or toss the box, and put in a 3" diameter piece of exhaust pipe in its place like I did. Wrap a strip of gasket making cork material around one end (the airbox end) of the pipe to mate it perfectly with the airbox snorkel. Other end of the pipe fits right into snorkel on the engine compartment side. I forget the exact length to cut the pipe, but it's not rocket science - measure the MAF box end to end when it's out and cut it that long. Powder coat it to impress the girls, but just be sure to de-burr the edges and blow and wipe all the metal flecks out.... or it's going right into the turbine - remember you're working after the air filter on this section.

sixto · #7 02-23-2010, 03:58 PM

How about some pictures?

Sixto
87 300D

VicS · #8 12-30-2018, 09:08 PM

I realize this threads old, but its new to me so.....

I had better luck with an 18" tailpipe extention from pepboys for $7, utilizing
the flared end to compensate for the ID difference on the airbox snorkel.

tjts1 · #9 12-30-2018, 10:19 PM

I deleted it ages ago with a 3" pipe. It didn't affect boost at all.
http://i.imgur.com/HQLaaXQ.jpg

Squiggle Dog · #10 10-31-2019, 09:47 PM

I'm thinking about doing this, but wonder how to secure the pipe so the part that connects to the bottom of the air cleaner doesn't fall down since it's normally kept in position by the mass air flow sensor box which is bolted to the body.

Diseasel300 · #11 10-31-2019, 09:51 PM

I reassembled the mount for the AFM and used HVAC Panduit straps to fasten the tube to the mount. The boot rests against the wheel well area, so you're really only needing to keep it in the right orientation.

Squiggle Dog · #12 10-31-2019, 10:05 PM

Quote:

Originally Posted by Diseasel300

I reassembled the mount for the AFM and used HVAC Panduit straps to fasten the tube to the mount. The boot rests against the wheel well area, so you're really only needing to keep it in the right orientation.

It looks like the mounting frame can be reinstalled on the body by replacing the threaded rods in the MAF sensor housing with bolts. I suppose I could use straps around the pipe to hang it from the mounting frame, or maybe put something in between the pipe and mounting frame so it's secure.

It looks like it can be installed without the pipe secured to anything, but don't want to risk the connector that goes on the bottom of the air cleaner from dropping off from a hard jolt or vibration.

Diseasel300 · #13 10-31-2019, 10:22 PM

The frame that the AFM sits in can be reassembled using the same hardware. You just need some M6 nuts to go in place of the threaded casting of the AFM.

The boot that connects to the bottom of the air box rests against the wheel well. Once attached and the airbox fastened down, it won't fall off, it doesn't have enough room to move out of the way. Attaching the bypass pipe to the AFM mount is a good idea just to keep it located and minimize movement.

My SDL ran a bypass pipe for 2 years and the SD has been running the same one since I got the car in February. My cars go off road frequently and the roads around here are pretty terrible in places, there has never been an issue with the boot coming loose from the air filter housing and it isn't something I'd ever worry about.

Squiggle Dog · #14 10-31-2019, 10:37 PM

Quote:

Originally Posted by Diseasel300

The frame that the AFM sits in can be reassembled using the same hardware. You just need some M6 nuts to go in place of the threaded casting of the AFM.

The boot that connects to the bottom of the air box rests against the wheel well. Once attached and the airbox fastened down, it won't fall off, it doesn't have enough room to move out of the way. Attaching the bypass pipe to the AFM mount is a good idea just to keep it located and minimize movement.

My SDL ran a bypass pipe for 2 years and the SD has been running the same one since I got the car in February. My cars go off road frequently and the roads around here are pretty terrible in places, there has never been an issue with the boot coming loose from the air filter housing and it isn't something I'd ever worry about.

Okay, good to hear.