Parts Catalog Accessories Catalog How To Articles Tech Forums
Call Pelican Parts at 888-280-7799
Shopping Cart Cart | Project List | Order Status | Help



Go Back   PeachParts Mercedes-Benz Forum > Mercedes-Benz Tech Information and Support > Tech Help

Reply
 
LinkBack Thread Tools Display Modes
  #1  
Old 11-09-2009, 02:29 AM
PanzerSD's Avatar
Schießenstern
 
Join Date: Jan 2006
Location: Saskatchewan Canada
Posts: 2,351
Question I gotta know: CIS MAF sensor plate

When you push down on the MAF sensor plate on a CIS engine, it floods and stalls.

Hypothetical situation:

a CIS engine set up with a filtered cold air induction nozzle below, If driving along and you get a big gust of wind, and it pressureizes the intake tube, will it push the plate down and flood the engine?

__________________
RIP: 80 300SD
RIP: 79 450SEL
2002 E430 4matic (212,000km)
2002 ML500 'sport'

____________________________
FACEBOOK:
PANZER450
Reply With Quote
  #2  
Old 11-09-2009, 09:26 AM
Registered User
 
Join Date: Sep 2009
Location: Great State of Texas
Posts: 440
Quote:
Originally Posted by PanzerSD View Post
When you push down on the MAF sensor plate on a CIS engine, it floods and stalls.

Hypothetical situation:

a CIS engine set up with a filtered cold air induction nozzle below, If driving along and you get a big gust of wind, and it pressureizes the intake tube, will it push the plate down and flood the engine?

It stalls because it's metering enough gas for about 1500 liters of air at idle. When you push the plate wide open, it meters gas for about 13,500 liters, thus "flooding" the engine.

I assume you mean a scoop or pick-up, not a "nozzle" - like a road-height "cold air" induction system? Don't waste your money. The difference in temperature between your grille and 8" above the road is about 1-3 degrees. With a naturally aspirated 4.5L engine, that's not enough to make any difference in performance.

Anyway, to answer your question, MB's aren't the only vehicles with pressure plate type MAF's (though most of them are located elsewhere), and none of them have ever flooded due to gusts of wind. Besides, it couldn't really pressurize the tube - with all the bends in it, it would simply create turbulence.

Oh, and road-height air pick-ups are also a great way to soak (clog) your air filter when you hit a puddle at speed.
__________________
A.S.E Tech A1,A6,A7,A8 & MVAC 609 + EPA 608

Unless stated otherwise, any question I ask is about my greymarket 1985 380SEL.

Last edited by dhjenkins; 11-09-2009 at 09:35 AM.
Reply With Quote
  #3  
Old 11-09-2009, 09:35 AM
compu_85's Avatar
Cruisin on Electric Ave.
 
Join Date: May 2008
Location: La Conner, WA
Posts: 5,234
If you forced more air into the engine that could cause the plate to move giving more fuel... but you would also have more air in the engine to burn the fuel

Nitpick: CIS does not have a mass airflow sensor. It has an airflow meter. It has no way to know the actual mass of the air... that's what a hot wire or hot film MAF is able to figure out. Similarly my SDL has an airflow meter... a plate that is spring loaded and is forced open by air moving past it.

-Jason
__________________
1991 350SDL. 230,000 miles (new motor @ 150,000). Blown head gasket

Tesla Model 3. 205,000 miles. Been to 48 states!
Past: A fleet of VW TDIs.... including a V10,a Dieselgate Passat, and 2 ECOdiesels.
2014 Cadillac ELR
2013 Fiat 500E.
Reply With Quote
  #4  
Old 11-09-2009, 09:59 AM
Registered User
 
Join Date: Sep 2009
Location: Great State of Texas
Posts: 440
Quote:
Originally Posted by compu_85 View Post
If you forced more air into the engine that could cause the plate to move giving more fuel... but you would also have more air in the engine to burn the fuel

Nitpick: CIS does not have a mass airflow sensor. It has an airflow meter. It has no way to know the actual mass of the air... that's what a hot wire or hot film MAF is able to figure out. Similarly my SDL has an airflow meter... a plate that is spring loaded and is forced open by air moving past it.

-Jason

Of course, you'd also have to have the engine spinning fast enough to do something with that extra air. If the throttle isn't pretty wide open, there's really nowhere for that extra air to go...

You should do an experiment with your existing pick-up tube to see how fast you need to go for any "forced induction" to take place. Get a vacuum gauge that also has a + side (usually called combo gauges for testing older domestic fuel pressure); 15 psi is more than enough. Put a small fitting in near the halfway point between engine & entry in your existing tube, and run some vacuum tubing under the back of your hood and duct tape the gauge to the windshield.

Let us know how fast you're going when/if it hits +2 psi (speed will be lower in cooler weather).

__________________
A.S.E Tech A1,A6,A7,A8 & MVAC 609 + EPA 608

Unless stated otherwise, any question I ask is about my greymarket 1985 380SEL.

Last edited by dhjenkins; 11-09-2009 at 11:13 AM.
Reply With Quote
Reply

Bookmarks


Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is On
Trackbacks are On
Pingbacks are On
Refbacks are On




All times are GMT -4. The time now is 06:11 PM.


Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2024, vBulletin Solutions, Inc.
Search Engine Optimization by vBSEO 3.6.0
Copyright 2024 Pelican Parts, LLC - Posts may be archived for display on the Peach Parts or Pelican Parts Website -    DMCA Registered Agent Contact Page