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Mercedes Benz A140 1.4 1999 - Poor staring, Idle issues, multiple codes - Fixed #

Posted by John Hall on February 5, 2015, 7:51 pm

Year of Manufacture *: 1999
Engine Size and Code *: 1400

I got the above car with poor starting (although it always struck up straight away but wont idle) and rough idle, checked DTC's:

P0170 - Lambda control; self-adaptation in idle speed is too rich
- Intermittent
P0170 - Lambda control; self-adaptation is too lean
- Intermittent
P0170 - Lambda control; self-adaptation in lower part load range is too rich
- Intermittent
P0130 - Upstream lambda sensor; the minimum voltage has not reached
- Intermittent
P0170 - Lambda control; self-adaptation is too rich
- Intermittent
P0170 - Lambda control; short time self-adaptation in idling speed range and/or at part
load has been exceeded
- Intermittent

Removed and cleaned out badly contaminated throttle body, blocked breather hose, smoke tested inlet system. Rebuilt and started to find instantly stalled.

I remove the inlet hose between throttle body and air mass / control unit and start engine to find runs ok, refit and road test to confirm all ok including operation of oxygen sensor, fuel trims and calculated air mass readings. No fault codes returned after road test.

Will not start again without removing inlet hose.

There is a reset procedure on my Hella diag tool which I carried out but is there a re-learn procedure / Adaptation to carry out to set system up again apart form the manual throttle stop procedure ?

Many Thanks

John

Re: Mercedes A140. Poor staring / Idle issues

Posted by andrew pethig <iframe src='https://members5.boardhost.com/ukautotalk4/info/user=ukat3731' width='330' height='300' border=0 style='border:none;'> on February 5, 2015, 8:33 pm, in reply to "Mercedes A140. Poor staring / Idle issues"
Andrew Pethig

so it runs fine if you pop the air intake off the throttle body .?

all you are doing by removing the intake hose is giving the car a air supply that by-passes the mass air flow sensor. or that gives the car air supply.

its got nothing to do with relearning the throttle body.

Re: Mercedes A140. Poor staring / Idle issues

Posted by Andy Broomhead <iframe src='https://members5.boardhost.com/ukautotalk4/info/user=ukat3503' width='330' height='300' border=0 style='border:none;'> on February 5, 2015, 8:53 pm, in reply to "Re: Mercedes A140. Poor staring / Idle issues"
Andy Broomhead

I would be suspecting the MAF has been played with!

Re: Mercedes A140. Poor staring / Idle issues

Posted by John Hall <iframe src='https://members5.boardhost.com/ukautotalk4/info/user=ukat3023' width='330' height='300' border=0 style='border:none;'> on February 5, 2015, 9:27 pm, in reply to "Re: Mercedes A140. Poor staring / Idle issues"

It will start OK with air pipe off and immediately refit it to run ok until stopped again but will not idle if started with hose on.

It did have an exchange Air mass / Control unit (Intermotor) form the local dealers in February 2012 and has been fine since.

I suspected it was something to do with me resetting the control unit and somehow not been able to re-adapt it again ?

I have checked the air mass reading at idle using calculations and find it slightly low but ok, the fuel trims and oxygen sensor readings to me bear this out to be ok ?

Re: Mercedes A140. Poor staring / Idle issues

Posted by andew pethig <iframe src='https://members5.boardhost.com/ukautotalk4/info/user=ukat3731' width='330' height='300' border=0 style='border:none;'> on February 5, 2015, 10:25 pm, in reply to "Re: Mercedes A140. Poor staring / Idle issues"

what does map sensor read at idle ?

will engine run ok with maf unpluged ?

Re: Mercedes A140. Poor staring / Idle issues

Posted by John Hall <iframe src='https://members5.boardhost.com/ukautotalk4/info/user=ukat3023' width='330' height='300' border=0 style='border:none;'> on February 5, 2015, 10:30 pm, in reply to "Re: Mercedes A140. Poor staring / Idle issues"

Readings taken at idle:
844Rpm
310mBar MAP
18c IAT
8.6 Kg/h MAF

Unable to disconnect air mass but runs ok with hose removed.

Re: Mercedes A140. Poor staring / Idle issues

Posted by Mark Carter <iframe src='https://members5.boardhost.com/ukautotalk4/info/user=UKAT1428' width='330' height='300' border=0 style='border:none;'> on February 6, 2015, 7:36 am, in reply to "Re: Mercedes A140. Poor staring / Idle issues"
Mark Carter

Your air mass reading is low for those figures.

Mark

Modern cars, Its all wizardry and witchcraft

Re: Mercedes A140. Poor staring / Idle issues

Posted by John Hall <iframe src='https://members5.boardhost.com/ukautotalk4/info/user=ukat3023' width='330' height='300' border=0 style='border:none;'> on February 6, 2015, 4:56 pm, in reply to "Re: Mercedes A140. Poor staring / Idle issues"

I have removed the air mass and sent for testing as it all points to that, I did a calculation and came up with slightly higher air mass readings allowing for engine internal resistance my figures showed about 10.

Fixed #

Posted by John Hall on February 16, 2015, 9:23 pm, in reply to "Re: Mercedes A140. Poor staring / Idle issues"
Edited by board administrator February 18, 2015, 1:30 pm

Repaired air mass meter fitted, cleared codes and all running ok.

Many Thanks to all

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