Tuning EHA etc. on M103 - verification of methods

1986-1995 : 200TD, 200CE, E200, 260E, 300E 2.6, 300E 2.8, 300E, E320, 400E, E420, 500E, E500, 300CE, E320, 230TE, 300TE, 300D 2.5 TURBO, E300 DIESEL, 300TD, 300E 4MATIC, 300TE 4MATIC, E36 AMG
Post Reply
CraigB
OZBENZ Admin
Posts: 5519
Joined: Thu 23 Jun, 2005 1:18 pm
Model you own: I own multiple different models
Location: Hawthorndene (Adelaide)

Tuning EHA etc. on M103 - verification of methods

Post by CraigB » Tue 07 May, 2019 8:29 pm

So updating progress on a petrol smelling, less than ideal fuel economy 1990 300TE (named Otto in honour of Joe's dog!). I've been researching the ins and outs by googling but knowing the amount of info and mis-info out there, I thought i would document what i found out, what i did and invite comment and verification from those that know more than me.

I moved the car when cold over the pit (to successfully finally fit the new sls hose) and noticed the smell of fuel a bit stronger than normal. Air cleaner off and noticed the EHA looked pretty wet. I had read that they normally leak from around the area of the wires, but after wiping with a rag you could see fuel leaking from the top join of the EHA and fuel distributor. So I thought maybe its just the o-rings. I had a spare 560 fuel distributor that looked pretty clean so i just swapped in the o-rings out of that and fired it up. Straight away i could see it was leaking all over the place and out of the small holes. So I researched how to test the duty cycle etc. with the aim of swapping in the 560 EHA and giving that a go (same part number) before shelling out for a new one.

So the consensus I could work out to test is that you need a multimeter able to test duty cycle (Hz on mine and a display that shows % when switched to it). As i understand, the EHA can vary pressure in the fuel distributor between top and bottom cells and that will richen or lean the mixture, or something like that. There is a screw in the back of it, that you need to remove the EHA to get to and needs a 2mm allen key and is behind a cover that looks like a flat blade screw - just unscrew the cover. The mixture adjusts on the go as part of the CIS system but you also need to adjust it with the static setting - not sure if that's the right word. In hindsight I wish I had measured the leaky one, but fuel was going everywhere and I was keen to replace it. So I fitted the 560 unit, connected the tester and fired it up to see what happened.

Following one guide I took the cover off the round plug/port on the LHS inner guard and i put the red lead in 3 and black in 2 and fired the car up and it showed 50.7% but wasn't moving. I pulled the black wire out of 2 and it started to fluctuate and raising revs moved to low 40%. So first question there is what is the right place to plug in and test that. Also, do those numbers sound right? The following link suggests it is.

https://www.500eboard.co/forums/index.p ... tion.2663/

Checked there was no leaks, refitted cleaner and took it for a drive. It feels much stronger and torquier and needing less pedal to make it move - so hoping this will lead to a corresponding fuel economy improvement. Wait and see.

Questions:
1. Does that sound right that I can just swap one off a 560 onto a 300 and it is calibrated just right? I'm thinking that if it is about balance of upper and lower chambers then maybe its ok.
2. by plugging in to the port, as I understand it I am measuring the health of the whole system including the O2 sensor. Is that right and if it is 50 and dropping to 40 that this indicates my O2 sensor is ok and not needing replacement?

And if you do need to adjust the EHA, as i understand it the lower % means richer and to make it richer you turn the screw right and leaner to the left.

Any discussion welcome and appreciated.
Craig Baulderstone
280s's
280SE3.5
280SL Ruby
300TE Otto
350SL Gloria
350SLC Lurch
450SEL Boris
500SEC's...including Syd
560SEL's Foufou and Zac

User avatar
AMG
OZBENZ Admin
Posts: 5913
Joined: Thu 01 Jan, 1970 10:00 am
Model you own: I own multiple different models
Region: New South Wales
Location: Dark side of the Moon
Contact:

Re: Tuning EHA etc. on M103 - verification of methods

Post by AMG » Wed 08 May, 2019 12:23 pm

haha Otto der Große w124 :king: :thumbup: :rr:
He's finding the garage too cold at the moment. Poor bugger has just had an op last week too.

Let me re-read your post and see if I can send you any info I may have laying around in WIS. :cheers:
Current:
1987 560SL 4sp. auto Signalrot "Stella"
1987 190E 2.3-16 5sp. man. Blauschwarz "Hermann"
1992 300CE-24 6sp. man. Perlblau / Iceblau "Gretel"
1992 Range Rover Classic 4sp auto Ardennes Green "Oswald"
2012 E63 AMG Speedshift MCT Diamantweiß "Klaus"
Previous:
1986 560SEL Anthracitgrau "Schultz" - In Mercedes Heaven
1987 190E 2.6 4sp. auto Signalrot "Sabine" - which now resides/owns Andrew M's Garage
1972 350SLC Astralsilber "Lurch" - now in the loving care of Craig B
1989 2.5-16 Blauschwarz 4sp. auto (parted) formerly owned by Derek/Hasan.
2012 Renault Sport Megane RS265 Trophy 8:08 6 sp. man. Liquid Yellow "Jean Rédélé"

Ivanerrol
Mercedes Demigod
Posts: 5966
Joined: Sat 12 May, 2007 2:21 pm
Model you own: w204
Location: Melbourne

Re: Tuning EHA etc. on M103 - verification of methods

Post by Ivanerrol » Sat 11 May, 2019 10:34 pm

You need to carefully check the old EHA to make sure there are no cracks.
If the EHA is bolted in too tightly it can crack and leak.

You really need an automotive multimeter with duty cycle % scale.
I bought mine for $50 at dickless smith but Jaycar has them.

The whole system needs to be calibrated to get this right.
Throttle position potentiometer,
Air plate in the plenum chamber
Make sure no air leaks in the rubber seals
Etc etc

In reality to get all these right you need to take it to a Bosch KE injection specialist who know what they are doing.
W211 - E240
W204 - C280
Departed
W202 - C200, C180, C180
W126 - 380SE , 380SE (Ex SA Import), 560SEL
W124 - 300e, 260e (ex Japan)
W111 220s (Indonesia) 4 speed manual column shift
W123 230
W116 450SEL
W140 420SEL
W210 E240, E240
W209 CLK 240
W201 190e 2.6 (ex U.K.)

CraigB
OZBENZ Admin
Posts: 5519
Joined: Thu 23 Jun, 2005 1:18 pm
Model you own: I own multiple different models
Location: Hawthorndene (Adelaide)

Re: Tuning EHA etc. on M103 - verification of methods

Post by CraigB » Sat 11 May, 2019 11:17 pm

Yep - old EHA leaking - I could look for cracks, but its leaking so just chucking it. And I have and used an automotive multimeter with duty cycle % scale. Apologies if that wasn't clear in the original post.

The only change was to bolt on a good not leaking EHA off a M117 560 engine and check to find multimeter showing 50.7 on the % scale, which from research seems to be correct and that research (in that link) also suggests that this duty cycle measurement (taken from pins in the round plug on guard) takes into account the signals the system is getting from other sensors - so if you can't get the right adjustment and operation (like how it drops to 40 at say around 2500revs) then there could be other sensors wrong.

So if the duty cycle is measuring bang on and the car is driving like an absolute dream now, would you still take it to a KE specialist? If those items were out of adjustment or air leaks would it run so perfectly?

Since i wrote that original post I have been driving the car more and whereas at first I was a bit disappointed the car seemed so sluggish compared to the 560 and so thirsty, it is now so much closer and has that same sort of 'magic' feel - so smooth and quiet, just gently pressing throttle has it responding, pulls effortlessly up the steep hills around home and the trans is seamlessly changing back at just the right time whereas before i was having to pull the lever back, rather than planting the foot to have it harshly change back. Its quite a transformation for such a small amount of work and also at the same point in time i have changed that sls hose that used the wrong type of hose and was noisy - absolute dream to drive now and i am so impressed. Given how gently i am pressing the accelerator now and the lack of petrol smell from under the bonnet, I would be very surprised if I don't also see a drop in fuel usage to the sort of numbers others have quoted.
Craig Baulderstone
280s's
280SE3.5
280SL Ruby
300TE Otto
350SL Gloria
350SLC Lurch
450SEL Boris
500SEC's...including Syd
560SEL's Foufou and Zac

User avatar
AMG
OZBENZ Admin
Posts: 5913
Joined: Thu 01 Jan, 1970 10:00 am
Model you own: I own multiple different models
Region: New South Wales
Location: Dark side of the Moon
Contact:

Re: Tuning EHA etc. on M103 - verification of methods

Post by AMG » Sat 11 May, 2019 11:32 pm

I'm of the opinion Let sleeping Otto lie :coffee2: :evilgrin:

He sleeps a lot, as you're aware.
Current:
1987 560SL 4sp. auto Signalrot "Stella"
1987 190E 2.3-16 5sp. man. Blauschwarz "Hermann"
1992 300CE-24 6sp. man. Perlblau / Iceblau "Gretel"
1992 Range Rover Classic 4sp auto Ardennes Green "Oswald"
2012 E63 AMG Speedshift MCT Diamantweiß "Klaus"
Previous:
1986 560SEL Anthracitgrau "Schultz" - In Mercedes Heaven
1987 190E 2.6 4sp. auto Signalrot "Sabine" - which now resides/owns Andrew M's Garage
1972 350SLC Astralsilber "Lurch" - now in the loving care of Craig B
1989 2.5-16 Blauschwarz 4sp. auto (parted) formerly owned by Derek/Hasan.
2012 Renault Sport Megane RS265 Trophy 8:08 6 sp. man. Liquid Yellow "Jean Rédélé"

Post Reply

Return to “W124”