W124 230E duty cycle question

[damiangt3]

Hello,

I've recently taken ownership of a UK 1992 230E and have a few questions regarding the duty cycle reading I'm getting.

So far I've checked the plugs and they are fine, a little carbon but overall brownish-white and in good condition. I've changed plug leads for new Bosch ones and the replaced thermostat. The distributor and rotor arm are new, I've also replaced the Intake Air Temperature sensor as it was literally in pieces and dirty as hell. The OVP has been replaced too.

I've been running 98-99RON fuel with injector cleaner in it for the last 3 tankfuls and I've got the EZL-KAT set to S. I've averaging 350 miles until the fuel warning light comes on.

I have quite poor warm and cold starting, takes 3 attempts before it fires and does require a little accelerator before firing. Idling at hot, warm or cold is steady.

Right, on to the duty cycle. checked the conditions whilst cold and ignition on where the duty cycle reads 70% and 20% when moving the accelerator. On starting the car and running whilst cold it reads around the 50% mark. All this seems to be correct from what I have read, however when the car reaches operating temperature it still reads 50% and this does fluctuate too much on throttle. I was expecting to at least have to adjust the mixture a little, what worries me is that the car possibly never starts in open-loop hence the poor starting. Is this a sign of a faulty Coolant Temp. Sensor? Is the mixture setting only 'enabled' on open loop?

Any advice would be welcomed!

 

[grober]

I take it you have read this article ? PeachPartsWiki: Mercedes-Benz Driveability

 

[chriss428]

Hello,

I've recently taken ownership of a UK 1992 230E and have a few questions regarding the duty cycle reading I'm getting.

So far I've checked the plugs and they are fine, a little carbon but overall brownish-white and in good condition. I've changed plug leads for new Bosch ones and the replaced thermostat. The distributor and rotor arm are new, I've also replaced the Intake Air Temperature sensor as it was literally in pieces and dirty as hell. The OVP has been replaced too.

I've been running 98-99RON fuel with injector cleaner in it for the last 3 tankfuls and I've got the EZL-KAT set to S. I've averaging 350 miles until the fuel warning light comes on.

I have quite poor warm and cold starting, takes 3 attempts before it fires and does require a little accelerator before firing. Idling at hot, warm or cold is steady.

Right, on to the duty cycle. checked the conditions whilst cold and ignition on where the duty cycle reads 70% and 20% when moving the accelerator. On starting the car and running whilst cold it reads around the 50% mark. All this seems to be correct from what I have read, however when the car reaches operating temperature it still reads 50% and this does fluctuate too much on throttle. I was expecting to at least have to adjust the mixture a little, what worries me is that the car possibly never starts in open-loop hence the poor starting. Is this a sign of a faulty Coolant Temp. Sensor? Is the mixture setting only 'enabled' on open loop?

Any advice would be welcomed!

you seem to know alot of technical stuff when i had this problem it was a snapped spring on the throttle boddy pully/accelorator cable also check the rubber section on the underneath of the throttle body as leaks cld also be an issue as i say my spring was gone and corsed this my w124 200 te runs fine with no spring saprisingly lol but the 230 need'd 1 hope this helps myfellow 230 owner

 

[stuu]

Have you tried adjusting the eha valve?

 

[damiangt3]

you seem to know alot of technical stuff when i had this problem it was a snapped spring on the throttle boddy pully/accelorator cable also check the rubber section on the underneath of the throttle body as leaks cld also be an issue as i say my spring was gone and corsed this my w124 200 te runs fine with no spring saprisingly lol but the 230 need'd 1 hope this helps myfellow 230 owner

Thanks Chris, what sort of MPG do you get? I can deal with the poor starting if the car seems to running fine once started.

Have you tried adjusting the eha valve?

Hi Stuu, any suggestions on how to do this?

I take it you have read this article ? PeachPartsWiki: Mercedes-Benz Driveability

I've read this, it was this article that started me thinking, although how much of that article is 500E and/or US/California related is what slightly confuses me


Thanks guys

 

[chriss428]

well depending on how i drive and traffic from 18mpg -38mpg ruffly i have a manual 8v mind so may differ from what u may have and the dodgy start will only get more anoying trust me

 

[damiangt3]

well depending on how i drive and traffic from 18mpg -38mpg ruffly i have a manual 8v mind so may differ from what u may have and the dodgy start will only get more anoying trust me

Thanks Chris, that's the primary reason for trying to diagnose the problem. I think I'll spend some time over the weekend looking for vacuum leaks, when I was reseating the crankcase breather tube I did notice how easy some of the vacuum leads slipped in and out (oooooeeerrrr!).

Just did a rough calculation after filling her up this morning, 345 miles on 56.5 litres of fuel, so not too bad considering the 80-90 on the M40 and stop/start into Oxford

I have to say not a bad place to spend 500-600 miles a week and having no clutch pedal is a godsend!

 

[chriss428]

Thanks Chris, that's the primary reason for trying to diagnose the problem. I think I'll spend some time over the weekend looking for vacuum leaks, when I was reseating the crankcase breather tube I did notice how easy some of the vacuum leads slipped in and out (oooooeeerrrr!).

Just did a rough calculation after filling her up this morning, 345 miles on 56.5 litres of fuel, so not too bad considering the 80-90 on the M40 and stop/start into Oxford

I have to say not a bad place to spend 500-600 miles a week and having no clutch pedal is a godsend!

so you are an auto my friend well have you looked at the economical and sports mode switch next to the gearstick check there is a differance when you switch from 1 to the other as that may have gone which could effect ur mpg in a bigway and also the vaccum pipe under the throttlebody is 1 of the loosest i have come across on both my w124's

 

[chriss428]

any progress my friend? also any pics?

 

[damiangt3]

any progress my friend? also any pics?

Will spend some time having a play today, did a bit of remedial rust removal (sandpaper, Kurust, primer, just need to sand and spray) on the rear arch and sunroof. Hopefully this will help!

Had a bit of a play with some carb cleaner and removed some of the carbon deposits on the throttle body and butterfly. Still hasn't improved the starting however but makes me feel better doing it

When I swapped the stereo I did notice the battery voltage was lower than expected, somewhere between 50-75% charged, perhaps a recharge might improve matters, just a pity my CTEK trickle charger is in my other car (away being fettled). I've got a set of new Champion S9YCC plugs to replace the NGKs.

I'm actually enjoying doing all of this, new cars with all-fangled electronics are just not this much fun!

Pictures? Hmmm, I'll see, the 230e is Smoke Silver (silver! more like gold) with it's original wheeltrims......now do I get a set of 8 hole alloys?

 

[chriss428]

Will spend some time having a play today, did a bit of remedial rust removal (sandpaper, Kurust, primer, just need to sand and spray) on the rear arch and sunroof. Hopefully this will help!

Had a bit of a play with some carb cleaner and removed some of the carbon deposits on the throttle body and butterfly. Still hasn't improved the starting however but makes me feel better doing it

When I swapped the stereo I did notice the battery voltage was lower than expected, somewhere between 50-75% charged, perhaps a recharge might improve matters, just a pity my CTEK trickle charger is in my other car (away being fettled). I've got a set of new Champion S9YCC plugs to replace the NGKs.

I'm actually enjoying doing all of this, new cars with all-fangled electronics are just not this much fun!

Pictures? Hmmm, I'll see, the 230e is Smoke Silver (silver! more like gold) with it's original wheeltrims......now do I get a set of 8 hole alloys?

yeh picture just being nosey as havent come across another 230 owner onhere yet lol and up2 you on the 8hole not my cup of t lol i have pepper pots on my estate and c-class 15" amg areo's on the 230 rolling on a drag look of tyres 195 70 r15 on the rear and 185 55 r15 on the front lol

 

[damiangt3]

Have you tried adjusting the eha valve?

Didn't adjust it but gave it a good clean together with the idle control valve. Did notice how loose....ish the hoses were underneath the throttle.

Interestingly, when I changed the plugs it started first time for the first 3 starts (cold, warm and hot) now it's reverted back to 2-3 attempts before starting.

After a little further research it seems that the duty cycle values I receiving ie. 50% when idling isn't an indicator of a correctly 'tuned' engine but a sign that the lambda isn't working (or connected), so my next task is to check the down pipe end for the sensor as the wires are still there under the carpet by the front drivers seat.

A new exhaust was fitted by the previous owner so need to check whether the cat is still there and if sensor is fitted or blocked off and the cables snipped.

So when I get chance in the next few days I'll connect a multimeter to the 3rd wire and check the voltage.

Does this all sound valid or am I adding two and two and coming up with the wrong answer?

Still this isn't the reason for the poor starting, does the lambda provide correct mixture information during open loop so perhaps a rich mixture is affecting the starting?

 

[chriss428]

i was told yesterday that our older mercs ( the cheek ) have high idal coldstarts so perhaps this has gone and such messed up the whole starting process i found that if i turn the demister and fans on str8 away from start that my idal goes all funny and can cut out so now i let the car set the engine then turn everything on lol to test thepower drain try putting ur fans on full power then hitting the demister lol