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
  #16  
Old 02-13-2005, 11:52 AM
benzfan's Avatar
Registered User
 
Join Date: May 2001
Location: Toronto
Posts: 277
I'm going to have to hope an experienced tech will answer this one for you, as I have never seen the inside of an MB cat, although at the point where you see a drop in fuel economy and performance, any damage to the cat internally, if it is to blame, should be obvious.

__________________
'96 C280 (gone)
'97 C36
'05 C230k
Reply With Quote
  #17  
Old 02-13-2005, 12:01 PM
Registered User
 
Join Date: Mar 2003
Location: Southern California
Posts: 2,270
Quote:
Originally Posted by A264172
did 3 tests
1) at X11 (ignition on engine off)
pin 3 red banana to V/F/C/Ώ/mA/uA
pin 2 black banana to COM
Dial set to % duty
reading 30.1

2) at X11 (engine running)
pin 3 red banana to V/F/C/Ώ/mA/uA
pin 2 black banana to COM
Dial set to % duty
reading 50.6

3) in passenger footwell
black wire lead from O Sensor to red banana to V/F/C/Ώ/mA/uA
aligator clip to front right fender inside engine compartment to black banana to COM
Dial set to % duty
reading 0-0.0016

Am I doing this wrong?
Connect the VOM to the O2 sensor output - pull the connector apart just enough to get the probe in without disconnecting O2 sensor from the circuit. A VOM should measure about 450 mV. If you can test the O2 sensor with a scope, it will show the wave form and the output should jump back and forth between about about 0.2 and 0.8 volts a couple of times per second. This is the best test for O2 sensor health. Also test the O2 sensor heater, which is the two wire connector. Check for system voltage on the harness end, and continuity on the 02 sensor pigtail.

Your high CO readings indicate a rich mixture, so the Lamda system is probabably not functioning properly. A common culprit is a faulty O2 sensor. The Lamda engine temperature sensor could also be fauly - sending a false low temperature signal, so the system always thinks the engine is cold, or it could be the EHA or control unit problems.

Duke
Reply With Quote
  #18  
Old 02-13-2005, 02:12 PM
Ta ra ra boom de ay
 
Join Date: Jun 2004
Location: Pittsburgh
Posts: 1,915
Quote:
Originally Posted by Duke2.6
Connect the VOM to the O2 sensor output - pull the connector apart just enough to get the probe in without disconnecting O2 sensor from the circuit. A VOM should measure about 450 mV. If you can test the O2 sensor with a scope, it will show the wave form and the output should jump back and forth between about about 0.2 and 0.8 volts a couple of times per second. This is the best test for O2 sensor health. Also test the O2 sensor heater, which is the two wire connector. Check for system voltage on the harness end, and continuity on the 02 sensor pigtail.

Your high CO readings indicate a rich mixture, so the Lamda system is probabably not functioning properly. A common culprit is a faulty O2 sensor. The Lamda engine temperature sensor could also be fauly - sending a false low temperature signal, so the system always thinks the engine is cold, or it could be the EHA or control unit problems.

Duke
Got 14.xV from heater connection (Brown=ground)
I got a reading (by puncturing sensor side of black wire to ground) of 0.451V at start up (coolant temp 80C) slowly (over 20-25min) descending to 0.349V.
Increase of rpm to 2500 would raise reading to about 0.360V at bottom end of the reading.
That and this...
Quote:
Originally Posted by A264172
...
1) at X11 (ignition on engine off)
pin 3 red banana to V/F/C/Ώ/mA/uA
pin 2 black banana to COM
Dial set to % duty
reading 30.1
are leading me to coolant Temp sensor...
__________________
-Marty

1986 300E 220,000 miles+ transmission impossible
(Now waiting under a bridge in order to become one)

Reading your M103 duty cycle:
http://www.peachparts.com/shopforum/831799-post13.html
http://www.peachparts.com/shopforum/831807-post14.html

Last edited by A264172; 02-13-2005 at 02:30 PM.
Reply With Quote
  #19  
Old 02-13-2005, 03:13 PM
Ta ra ra boom de ay
 
Join Date: Jun 2004
Location: Pittsburgh
Posts: 1,915
Coolant temp sensor reads 475Ώ at 95C (aprox.) out by more than 100.
Normal range is 290-370 Ώ at 80C should be around 220 at 95C
Is this a typical sort of failure?

Edit: retest - am getting 720-750 Ώ at 80C (reversing-polarity for cross testing) and dropping but, is not in correct range

Can I jumper this to 0 resistance to see if it runs good or is that not ok for computer?
__________________
-Marty

1986 300E 220,000 miles+ transmission impossible
(Now waiting under a bridge in order to become one)

Reading your M103 duty cycle:
http://www.peachparts.com/shopforum/831799-post13.html
http://www.peachparts.com/shopforum/831807-post14.html

Last edited by A264172; 02-13-2005 at 03:39 PM.
Reply With Quote
  #20  
Old 02-13-2005, 05:15 PM
Registered User
 
Join Date: Sep 2004
Location: Seattle
Posts: 1,971
What do you mean by "reversing polarity for cross testing" Are you saying that when you reverse the probes you get a different resistance reading? The thermistor should read the same regardless of which probe is on which connection.

If you believe that the sensor is bad then you could hook up a resistor of what ever value it is supposed to be at running temp and if the engine is at running temp then it should be happy. I don't think zero ohms would be a good idea.
__________________
1998 C230 330,000 miles (currently dead of second failed EIS, yours will fail too, turning you into the dealer's personal human cash machine)
1988 F150 144,000 miles (leaks all the colors of the rainbow)
Previous stars: 1981 Brava 210,000 miles, 1978 128 150,000 miles, 1977 B200 Van 175,000 miles, 1972 Vega (great, if rusty, car), 1972 Celica, 1986.5 Supra
Reply With Quote
  #21  
Old 02-13-2005, 05:26 PM
Ta ra ra boom de ay
 
Join Date: Jun 2004
Location: Pittsburgh
Posts: 1,915
Quote:
Originally Posted by mpolli
What do you mean by "reversing polarity for cross testing" Are you saying that when you reverse the probes you get a different resistance reading? The thermistor should read the same regardless of which probe is on which connection.
Sorry about using confusing/wrong term. the readings are consistant as I reverse the probes (close enough) as they are moving lower at 80C. They never make it to correct operating range though.
Quote:
Originally Posted by mpolli
If you believe that the sensor is bad then you could hook up a resistor of what ever value it is supposed to be at running temp and if the engine is at running temp then it should be happy. I don't think zero ohms would be a good idea.
Good idea. I will have to go get one.
Thanks for your response.
Marty
__________________
-Marty

1986 300E 220,000 miles+ transmission impossible
(Now waiting under a bridge in order to become one)

Reading your M103 duty cycle:
http://www.peachparts.com/shopforum/831799-post13.html
http://www.peachparts.com/shopforum/831807-post14.html
Reply With Quote
  #22  
Old 02-13-2005, 07:32 PM
Registered User
 
Join Date: Mar 2003
Location: Southern California
Posts: 2,270
Unplug the O2 sensor and look at its open circuit voltage. It should be over 450mV. Engine and exhaust must be fully warmed up. Also check for continuity of the O2 heater.

I have the following temp sensor values for '84 M102. I'm not sure if they apply to later KE systems, but I think they do.

20C 2.2-2.8 Kohm
80C 290-370 ohm
100C 140-220 ohm.

Take readings at two temps - 20 and 80 are probably easiest.

Duke
Reply With Quote
  #23  
Old 02-14-2005, 11:56 PM
Registered User
 
Join Date: Jul 2002
Posts: 1,141
am pretty sure it is rich.
I had a center muffler failier around Halloween, when I replaced It (both it and rear muffler had been off for 1 months) I expected to see a big improvement in mpg that never appeared. It has been a little slugish as well.

Was that temp sensor on your 86'? If so where is it exactly (side of the block?) and any tips on the test?


I think all the temp sensors are suppose to be 2.6-2.8 k ohm. Sounds like you could really use a factory manual=)
AKA looks like my dash gauge might also be shy by about 5 C. At 100C, the sensor read about 800-900 ohms. I was thinking the range should be 500-600 ohms-but don't know without checking a bosch book.

I'm headed for emission testing soon too. My plan of attack is new plugs, oil change, and O2 sensor. It did not start today instantly at 75 F, so I'm guessing my mixture is off a bit.

Michael
__________________
Michael McGuire
83 300d
01 vw A4 TDI
66 Chevy Corsa
68 GMC V6 w/oD
86 300E
Reply With Quote
  #24  
Old 02-15-2005, 12:47 AM
Ta ra ra boom de ay
 
Join Date: Jun 2004
Location: Pittsburgh
Posts: 1,915
Quote:
Originally Posted by samiam4
I think all the temp sensors are suppose to be 2.6-2.8 k ohm. Sounds like you could really use a factory manual=)
AKA looks like my dash gauge might also be shy by about 5 C. At 100C, the sensor read about 800-900 ohms. I was thinking the range should be 500-600 ohms-but don't know without checking a bosch book.

I'm headed for emission testing soon too. My plan of attack is new plugs, oil change, and O2 sensor. It did not start today instantly at 75 F, so I'm guessing my mixture is off a bit.

Michael
Though it may not seem so I do have the manual. The emissions world has been to me like aincent greek but I have learned a lot in the last 72 hours.

I found the water temp sensor Ohm's range at the temp chart in the /Engine Manual-Combustion Manual-07.3 Mechanical/electronic gasoline injection system (KE injection)-121 Testing electrical components of KE injection system. page 60

Temperature C........Resistance kΩ
-20........................15.7
-10.........................9.2
0............................5.9
10...........................3.7
20...........................2.5
30...........................1.7
40...........................1.18
50...........................0.84
60...........................0.60
70...........................0.435
80...........................0.325
90...........................0.247
Same resistance values apply to KE intake air temp sensor.
I think this chart applies to these 2 sensors for all KE systems but don't know for sure.

My water temp sensor is not in line with these values.
I may also have a bad o2 sensor (wish I had a scope to get a clear view)
Now I am waiting for my water temp sensor to arrive.

75F ay...must be nice.

Marty

P.S. anyone know if there is a better tool than a 22mm crows foot to get these sensors off and on again?
__________________
-Marty

1986 300E 220,000 miles+ transmission impossible
(Now waiting under a bridge in order to become one)

Reading your M103 duty cycle:
http://www.peachparts.com/shopforum/831799-post13.html
http://www.peachparts.com/shopforum/831807-post14.html

Last edited by A264172; 02-15-2005 at 01:16 AM.
Reply With Quote
  #25  
Old 02-17-2005, 02:41 PM
Ta ra ra boom de ay
 
Join Date: Jun 2004
Location: Pittsburgh
Posts: 1,915
Quote:
Originally Posted by A264172
P.S. anyone know if there is a better tool than a 22mm crows foot to get these sensors off and on again?
I see it is a deep 22mm socket (on water temp sensor).
I will post my results when I have them.

Marty
__________________
-Marty

1986 300E 220,000 miles+ transmission impossible
(Now waiting under a bridge in order to become one)

Reading your M103 duty cycle:
http://www.peachparts.com/shopforum/831799-post13.html
http://www.peachparts.com/shopforum/831807-post14.html
Reply With Quote
  #26  
Old 02-17-2005, 09:47 PM
Registered User
 
Join Date: Jul 2002
Posts: 1,141
Good luck....

Been there last Saturday. Unless you've got a fancy Stallwillie or they revised the lift bracket.... revise your game plan.

You'll need to take the 2 6mm allen bolts out and rotate the bracket out of the way. The bracket has the water oulet for the head.. so if you do it carefully- it won't leak. If not, drain the coolant and replace the o-ring seal while you are at it.

Looking at mine- the coolant gauge sensor is out of range by a similar amount. The fan switch- I cannot remember it comming on even parking the car in 100F weather. So, I'm guessing that isn't right and it needs replacing too.

There are seals underneath the sensors...

Makes me wonder about the sensor on the intake too...

Michael
__________________
Michael McGuire
83 300d
01 vw A4 TDI
66 Chevy Corsa
68 GMC V6 w/oD
86 300E
Reply With Quote
  #27  
Old 02-17-2005, 11:56 PM
Ta ra ra boom de ay
 
Join Date: Jun 2004
Location: Pittsburgh
Posts: 1,915
Quote:
Originally Posted by samiam4
Good luck....

Been there last Saturday. Unless you've got a fancy Stallwillie or they revised the lift bracket.... revise your game plan.
Whats a Stallwillie? Sounds like what I've been looking for

Quote:
Originally Posted by samiam4
Looking at mine- the coolant gauge sensor is out of range by a similar amount. The fan switch- I cannot remember it comming on even parking the car in 100F weather. So, I'm guessing that isn't right and it needs replacing too.

There are seals underneath the sensors...
I did that fan switch last spring. Its really wide on top so no socket can get over it. I really butchered the thing getting it out and if it had needed any torque, I would have been in big trouble.

Quote:
Originally Posted by samiam4
Makes me wonder about the sensor on the intake too...

Michael
Good point. The scary part is if it the water temp sender (engine temp on gage) is off by much it would really be screwing up my calculations on the water temp sensor.
Thanks for your input Michael I should be able to put my water temp sensor in in the morning in this snow we are having, and I'll post my results.

Marty
__________________
-Marty

1986 300E 220,000 miles+ transmission impossible
(Now waiting under a bridge in order to become one)

Reading your M103 duty cycle:
http://www.peachparts.com/shopforum/831799-post13.html
http://www.peachparts.com/shopforum/831807-post14.html

Last edited by A264172; 02-18-2005 at 12:05 AM.
Reply With Quote
  #28  
Old 02-18-2005, 12:13 AM
Registered User
 
Join Date: Jul 2002
Posts: 1,141
Try www.stahlwille.com. Exchange rate sucks these days... but their wrenchs, sockets and definately the allen & torx sockets are better than snap-ons. Infact, I've thought about liquidating some of my mac and snap-on stuff on ebay and trading up to stahlwille.
The only on I see might be one of the MB a/c crowsfeet. 440-22?
Not that hard to do... I'll let you know about the temp switch in a week or so.

Michael
__________________
Michael McGuire
83 300d
01 vw A4 TDI
66 Chevy Corsa
68 GMC V6 w/oD
86 300E
Reply With Quote
  #29  
Old 02-18-2005, 12:43 AM
Registered User
 
Join Date: Jul 2002
Posts: 1,141
http://www.samstagsales.com/mercedes/mb000589710300.jpg

I'm guessing this would work or you could make something similar.
Kinda rich for my blood though... could use it on A/C and torquing those front struts=)

Michael
__________________
Michael McGuire
83 300d
01 vw A4 TDI
66 Chevy Corsa
68 GMC V6 w/oD
86 300E
Reply With Quote
  #30  
Old 03-26-2005, 02:24 PM
Ta ra ra boom de ay
 
Join Date: Jun 2004
Location: Pittsburgh
Posts: 1,915
Well its been a while but I have finally got her running and am ready to have emissions retested. The first appointment I could get is for Tuesday at 10AM

So far I have:
Changed the water temp sensor.
New cap & rotor.
Oil change.
2 big bottles of Techron in a tank of 93 octane.

Being a nervous type I was looking at my duty cycle at X11 (engine fully warmed). It starts out at about 45% and fluctuates but it heads down to the just under 10% range and fluctuates around there (8-12%). Is this ok? I was thinking that it should fluctuate closer to 50% but don't really know.

I just want to do whatever I can in the next bit of time before the test to improve my chances. I have read Duke's instructions for fully warming up these cars and keeping them at high idle right up to the test. But is this duty cycle reading an indication that there is still a problem with the lambda system?

__________________
-Marty

1986 300E 220,000 miles+ transmission impossible
(Now waiting under a bridge in order to become one)

Reading your M103 duty cycle:
http://www.peachparts.com/shopforum/831799-post13.html
http://www.peachparts.com/shopforum/831807-post14.html
Reply With Quote
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 On
Trackbacks are On
Pingbacks are On
Refbacks are On


Similar Threads
Thread Thread Starter Forum Replies Last Post
Failed emissions: no Air Injection Pump? pistolpete5113 Tech Help 10 11-11-2004 06:07 PM
90' 300CE emissions failed joebnz Tech Help 0 03-10-2004 02:31 PM
failed emissions - suggestions? jsmith Tech Help 7 09-27-2003 09:10 PM
HELP! Failed diesel emissions test Ben300SD Diesel Discussion 25 01-26-2003 02:51 AM
190e 2.3 failed emissions Machnumber2 Tech Help 5 05-26-2002 01:53 AM



All times are GMT -4. The time now is 09:12 PM.


Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2024, vBulletin Solutions, Inc.
Search Engine Optimization by vBSEO 3.6.0
Copyright 2018 Pelican Parts, LLC - Posts may be archived for display on the Peach Parts or Pelican Parts Website -    DMCA Registered Agent Contact Page