Parts Catalog Accessories Catalog Tech Info Tech Forums
 
  Search our site:    
 Cart  | Project List | Order Status | Help    


Go Back   PeachParts Mercedes ShopForum > Technical Information and Support > Tech Help

Reply
 
LinkBack Thread Tools Display Modes
  #1  
Old 06-10-2007, 09:25 PM
trueog's Avatar
All Star User
 
Join Date: Feb 2005
Location: Vancouver BC Canada
Posts: 392
What is P0170 code for fuel trim malfunction ? how can i fix this?

Hey guys, I'm having a problem with my check engine light continuously coming on. Last night I did an OBDII scan, and the result was a P0170 code for fuel trim malfunction. What does this mean? what is fuel trim? and how can I fix this problem? The car is a 94 C220. So if anyone can help me out, i would be very thankful.



take care
__________________
My Cars
Mercedes ML
Mercedes C-Class W203

R.I.P.
Mercedes C-Class - passed away at 318, 000 KM on March 18, 2009 Forever Missed
VW Jetta Worst Car I ever owned - Alot of problems
Reply With Quote
  #2  
Old 06-10-2007, 09:33 PM
blackmercedes's Avatar
Just a guy
 
Join Date: Dec 2000
Location: St. Albert, Alberta, Canada
Posts: 3,432
It means your FI system is running either too lean or too rich and the computer can no longer compensate for the problem. You will have to figure out which way it is running and examine the possible problems. On most cars, the Air Mass Meter is at fault, or the fuel pressure regulator. Your C220 uses an Air Mass Meter system, and they are prone to failure. Replace your engine air-intake filter often to extend the life of the part.

I'm not sure how much info the SDS gives in terms of adaptation values for the 1994 models, but if it does, diagnosis is usually pretty easy. Suppose your FI is maxed adaption at 1.32, then odds are you have a bad AMM. Replace the AMM with a known good one, recheck adaptations, and I bet you'll have the culprit. If your system is adapting to .67, then odds are the fuel pressure regulator has gone bad. Do as for 1.32.

Also, a clogged fuel filter can cause FI trim problems. When was it last replaced?
__________________
John Shellenberg
1998 C230 "Black Betty" 240K

Reply With Quote
  #3  
Old 06-10-2007, 10:07 PM
Registered User
 
Join Date: Aug 1999
Location: Florida / N.H.
Posts: 8,766
Also, unmetered air downstream from maf.[ vac leak]
Pull vac hose off fuel reg and see if any gas comes out of that port. Should be none.

Check this before change MAF

P0170 code - Should I get this tested?
Reply With Quote
  #4  
Old 06-10-2007, 10:24 PM
trueog's Avatar
All Star User
 
Join Date: Feb 2005
Location: Vancouver BC Canada
Posts: 392
Hey thanks for the response. I changed my AMM about 18 months ago. So i'm hoping its not the culprit again. I want to look into the fuel pressure regulator, where's this part located? and what will help me notice it?

The fuel filter I will get my mechanic to change, I hope that solves the problem.

Quote:
Originally Posted by blackmercedes View Post
It means your FI system is running either too lean or too rich and the computer can no longer compensate for the problem. You will have to figure out which way it is running and examine the possible problems. On most cars, the Air Mass Meter is at fault, or the fuel pressure regulator. Your C220 uses an Air Mass Meter system, and they are prone to failure. Replace your engine air-intake filter often to extend the life of the part.

I'm not sure how much info the SDS gives in terms of adaptation values for the 1994 models, but if it does, diagnosis is usually pretty easy. Suppose your FI is maxed adaption at 1.32, then odds are you have a bad AMM. Replace the AMM with a known good one, recheck adaptations, and I bet you'll have the culprit. If your system is adapting to .67, then odds are the fuel pressure regulator has gone bad. Do as for 1.32.

Also, a clogged fuel filter can cause FI trim problems. When was it last replaced?
__________________
My Cars
Mercedes ML
Mercedes C-Class W203

R.I.P.
Mercedes C-Class - passed away at 318, 000 KM on March 18, 2009 Forever Missed
VW Jetta Worst Car I ever owned - Alot of problems
Reply With Quote
  #5  
Old 06-10-2007, 10:26 PM
trueog's Avatar
All Star User
 
Join Date: Feb 2005
Location: Vancouver BC Canada
Posts: 392
Hey Arthur, where can I find my fuel reg? where's it located and what does it look like? I want to check it as you've stated....

thanks

Quote:
Originally Posted by Arthur Dalton View Post
Also, unmetered air downstream from maf.[ vac leak]
Pull vac hose off fuel reg and see if any gas comes out of that port. Should be none.

Check this before change MAF

P0170 code - Should I get this tested?
__________________
My Cars
Mercedes ML
Mercedes C-Class W203

R.I.P.
Mercedes C-Class - passed away at 318, 000 KM on March 18, 2009 Forever Missed
VW Jetta Worst Car I ever owned - Alot of problems
Reply With Quote
  #7  
Old 06-10-2007, 11:08 PM
trueog's Avatar
All Star User
 
Join Date: Feb 2005
Location: Vancouver BC Canada
Posts: 392
I'll try to find this. The car's running really rich, the fumes just stink! I think this might be causing it.

Thanks
__________________
My Cars
Mercedes ML
Mercedes C-Class W203

R.I.P.
Mercedes C-Class - passed away at 318, 000 KM on March 18, 2009 Forever Missed
VW Jetta Worst Car I ever owned - Alot of problems
Reply With Quote
  #8  
Old 06-25-2007, 04:29 AM
trueog's Avatar
All Star User
 
Join Date: Feb 2005
Location: Vancouver BC Canada
Posts: 392
is this part under the hood? still can't find it...thanks
__________________
My Cars
Mercedes ML
Mercedes C-Class W203

R.I.P.
Mercedes C-Class - passed away at 318, 000 KM on March 18, 2009 Forever Missed
VW Jetta Worst Car I ever owned - Alot of problems
Reply With Quote
  #9  
Old 06-25-2007, 04:38 PM
forp's Avatar
Registered User
 
Join Date: Jul 2003
Location: Sebastopol, CA
Posts: 324
Look on top front of engine. There is a vacuum line from the regulator to the intake manifold. Pull the vacuum line and check for gas. If it is damp the regulator has gone south.
__________________
2006 c280
Reply With Quote
  #10  
Old 06-25-2007, 07:16 PM
trueog's Avatar
All Star User
 
Join Date: Feb 2005
Location: Vancouver BC Canada
Posts: 392
Quote:
Originally Posted by forp View Post
Look on top front of engine. There is a vacuum line from the regulator to the intake manifold. Pull the vacuum line and check for gas. If it is damp the regulator has gone south.
Hey thanks for the details. I looked at the vacuum hose and i noticed it had alot of wear and small cracking...so i put electrical tape over the effected area and will be ordering a new one shortly. I didn't feel or small any gas, so i think the part's working.

I went to a parts store here called Lordco and bought a cleaner made by CRC called "MAF Sensor Cleaner". I followed the instructions and cleaned my MAF, which is only 18 months old right now. I then removed the negative terminal from my battery to reset the car. So let's see if it worked, and how long before the check engine light resurfaces once again.
__________________
My Cars
Mercedes ML
Mercedes C-Class W203

R.I.P.
Mercedes C-Class - passed away at 318, 000 KM on March 18, 2009 Forever Missed
VW Jetta Worst Car I ever owned - Alot of problems
Reply With Quote
  #11  
Old 07-06-2007, 10:39 AM
Registered User
 
Join Date: Sep 2004
Location: DFW / Collin County Texas
Posts: 1,881
trueog, did your CEL return?
__________________
08 W251 R350
97 W210 E320
91 W124 300E
86 W126 560SEL
85 W126 380SE Silver
85 W126 380SE Cranberry
79 W123 250
78 W123 280E
75 W114 280
Reply With Quote
  #12  
Old 07-06-2007, 11:28 PM
trueog's Avatar
All Star User
 
Join Date: Feb 2005
Location: Vancouver BC Canada
Posts: 392
Quote:
Originally Posted by gmercoleza View Post
trueog, did your CEL return?
Hey, thanks for the response.

Yes my CEL light has resurfaced ..... this is not fun...

do u have any suggestions? thanks
__________________
My Cars
Mercedes ML
Mercedes C-Class W203

R.I.P.
Mercedes C-Class - passed away at 318, 000 KM on March 18, 2009 Forever Missed
VW Jetta Worst Car I ever owned - Alot of problems
Reply With Quote
  #13  
Old 07-07-2007, 09:18 AM
Registered User
 
Join Date: Sep 2004
Location: DFW / Collin County Texas
Posts: 1,881
No suggestions, it's just that I had a similar issue where I got the same code. I reset the code and so far it hasn't come back, but I want to be ready for if/when it does...
__________________
08 W251 R350
97 W210 E320
91 W124 300E
86 W126 560SEL
85 W126 380SE Silver
85 W126 380SE Cranberry
79 W123 250
78 W123 280E
75 W114 280
Reply With Quote
  #14  
Old 08-15-2007, 07:48 PM
trueog's Avatar
All Star User
 
Join Date: Feb 2005
Location: Vancouver BC Canada
Posts: 392
anybody have any more ideas?
__________________
My Cars
Mercedes ML
Mercedes C-Class W203

R.I.P.
Mercedes C-Class - passed away at 318, 000 KM on March 18, 2009 Forever Missed
VW Jetta Worst Car I ever owned - Alot of problems
Reply With Quote
  #15  
Old 08-15-2007, 09:31 PM
Registered User
 
Join Date: Jul 2004
Posts: 28
Same malfuntion code came up on my '95 C220 (car was
idling rough at startup).
After looking for vacuum leaks found that the air duct
between the MAS and throttle body had completely
worn through where its clamped to the throttle body.
Wrapped it in electric tape and now car's running smooth
as ever. Check engine light hasn't come back on.
Will get the air duct replaced this week.
Reply With Quote
Old 08-15-2007, 09:31 PM
Reply

Bookmarks

Thread Tools
Display Modes

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 Off
Trackbacks are On
Pingbacks are On
Refbacks are On



All times are GMT -4. The time now is 01:18 AM.


Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2014, vBulletin Solutions, Inc.
Search Engine Optimization by vBSEO 3.6.0
Copyright 2011 Pelican Parts - Posts may be archived for display on the Peach Parts or Pelican Parts Website -    DMCA Registered Agent Contact Page