W124 E220 Harsh idle, not a thread about the loom, please see!

[MB094]

Hello Everyone,

I am a fairly new member here, and believe it or not since my last post i have been still "fixing" my E220 and its not funny anymore, i think its something small but cannot guess anymore, which i will say why.

The problems started with the loom yes, and that has been rebuilt properly actually since the rebuild i opened it up again to check every connection and soldering and i re-checked my notes when doing it and every wire is in place which it should be because when we did it we went one by one one in one out so that is good for sure, then i replaced the following : MAF, O2 Sens., Throttle body, OVP rel., Eng. Temp. Sensor, Intake manifold gasket, Air Temp sensor, Ignition leads, Spark plugs, and the following circuts were re-wired ; MAF to ECU & OVP, Sensors on front of motor, Injectors, Coils.

Here comes the issue, i still have an irratic idle, it surges between 600-850rpm, and it feels like its missing being rough, and it doesnt matter if its in P,D or R although when the engine is cold it wants to stall sometimes it does sometimes it doesnt, but also sometimes as it happened a few days ago, and last week all of a sudden its smooth as new, and i got home while it was nice and i switched the motor off then back on again and bang when back to stupid idle again when..so i when to a local Merc specialist, the guys are German and fellow Mercedes Club members, and he plugged it onto a computer and done a live test and he said he could not see the MAF getting power, and for everything else he said works good, thats when i re-opened the MAF wiring but its all good there are no bad connections no open circuts, so i plugged everything back on and i tested the socket for power and there is, but i dont know what it means, i have no figures to go by no diagrams nothing, on the MAF pins/or socket #1. there is 2.5V, #2. there is 12V, #4. there is 8-9V, #5. is ground. so really my question is any of these figures are wrong?

I have the new MAF and the old one and the motor runs the same with it, is this problem now an ECU problem ? i have a spare ECU which is out of a year older E220 but no difference runs the same.

Please anyone with any advice would be appriciated, and im also getting wiring diagrams next week but any more info to help would be appriciated.

Thanks eveyone

regards, Les

 

[bolide]

You've changed so many things that it's difficult to pin this down. My instinct says it's the throttle body or the loom

AFAIK the ECU controls idle via the throttle body. If the TB has a fault, or a bad potentiometer track, that could cause the intermittent problems. Did you ft a new TB or a secondhand one? If secondhand, just because the vendor says it works doesn't mean it does...

Nick Froome

 

[MB094]

You've changed so many things that it's difficult to pin this down. My instinct says it's the throttle body or the loom

AFAIK the ECU controls idle via the throttle body. If the TB has a fault, or a bad potentiometer track, that could cause the intermittent problems. Did you ft a new TB or a secondhand one? If secondhand, just because the vendor says it works doesn't mean it does...

Nick Froome

Hi Nick,
The loom and TB looks good and as mentioned i had the car put on live data analysis and i specifially asked that is it good because i didnt just want to relay on just yes its good, anyway i also asked about the loom and because i have thw wires soldered from the pins it works good because they saw it through the computer test, only what codes that they got was for the MAF and the O2 sensor but the O2 sensor because of the MAF but it actually gets power so this is were im stuck, because of all this i went through one by one again and checked the wires but they are good i would put my neck on it and sometimes its ok sometimes it isnt if the loom was not in order it would not be on and off it would be just crap...

 

[grober]

Thinking outside the box for a minute---- is it possible your voltage supply is fluctuating. This could be from worn alternator brushes, poor earthing - [first check the engine to chassis earth strap and the battery earth strap ] or some sort of intermittent parasitic drain from a wiring short to earth--- which could literally be anywhere in the car but might be made worse by water or movement. Other possibility is a jamming inlet camshaft adjuster leaving the cam advanced sometimes at idle.

 

[MB094]

Thinking outside the box for a minute---- is it possible your voltage supply is fluctuating. This could be from worn alternator brushes, poor earthing - [first check the engine to chassis earth strap and the battery earth strap ] or some sort of intermittent parasitic drain from a wiring short to earth--- which could literally be anywhere in the car but might be made worse by water or movement. Other possibility is a jamming inlet camshaft adjuster leaving the cam advanced sometimes at idle.

I was thinking it too, i checked the charge and its stable and good, so regulator is good and charges with i think 13.4V Tomorrow i will be checking all the earth cable even the main one. Although there is one loose but i connected it in with no success,..how could i check the inlet cam? at a certain RPM i have a little noise coming from them cam area where the oil cap is, its a little bit like a grind and its been like that since i had it and it goes away i think its like from 1800-2000RPM but only if you quickly rev it up there from idle, and was good like that before my main cable burnt down thats when all problems started...

as a side note, i had to put a new earth cable on the numplate lights as they didnt work, but everything else works on the car.

 

[kth286]

what about the EVAP system ?

Is the valve on inner wing pulsing when engine up to temp - you should be
able to hear it and feel it pulse with your hand.

It has MOT written on top of it.

They can get sticky and be open when they should be closed.

The engine then sucks fumes when it should not, and gets partially strangled.

 

[MB094]

what about the EVAP system ?

Is the valve on inner wing pulsing when engine up to temp - you should be
able to hear it and feel it pulse with your hand.

It has MOT written on top of it.

They can get sticky and be open when they should be closed.

The engine then sucks fumes when it should not, and gets partially strangled.

I dont know to be honest as today i pulled it off and when i shaked it charcoal was falling out from not the Motor but other end, i dont think i hear it pulse i will check it out tomorrow again so if i touch it i should feel something? i sprayed contact cleaner in it to see if any difference but nothing..id like to hear something about this though? any suggestions?

 

[grober]

what about the EVAP system ?

Is the valve on inner wing pulsing when engine up to temp - you should be
able to hear it and feel it pulse with your hand.

It has MOT written on top of it.

They can get sticky and be open when they should be closed.

The engine then sucks fumes when it should not, and gets partially strangled.

Good call!

 

[bolide]

Have you tried watching fuel pressure in the rail at idle?

Nick Froome

 

[MB094]

Have you tried watching fuel pressure in the rail at idle?

Nick Froome

Yes i have, because i also put new fuel filter as well and i had to put a new fuel pressure regulator as well.., i will go under the bonnet again soon and will post what i have done..

 

[w124nut]

Hi MB094, I have just been reading May's edition of Mercedes Enthusiast in which there is an article on W124 rough idling. The article mentioned that a new throttle return spring may fix this problem cheaply. Just a thought.

 

[MB094]

Hi MB094, I have just been reading May's edition of Mercedes Enthusiast in which there is an article on W124 rough idling. The article mentioned that a new throttle return spring may fix this problem cheaply. Just a thought.

Yes it could be a point, but sometimes it idles so smoothly really, when its good its so smooth, with even bad engine mounts you cant feel or hear a thing, i said il change the engine mounts when this is sorted..

 

[MB094]

FIXED!! well i can say yes i am certain its fixed!, i was so happy but also very ****** as well!, as mentioned before when i was at the workshop the guys live tested it, and it showed that the MAF is not getting or showing power, so i thought oh maybe a connection or soldering problem,..well no!,..i re-opened only the MAF cables and was good, i tested the ends and everything looked good and fine, so i re-opened the plug that goes on the MAF and tested the power and it had power, so then what else?...well i visited my friend nearby and he has a convertable E220 1995 with shot loom but original Bosch MAF and still running good well he is going to do the wiring this winter anyway i put it on my car and Yes!, bloody aftermarket $hit that i have bought my car ran so nice, he took it for a drive he said it runs much much more smoother then even his so it proves my point the wiring is good damn good and i ordered an original Bosch MAF of Ebay from Germany and waiting for it to arrive, my Coupe has bad engine mounts, but it ran so smooth that you could not feel the engine from inside at all! So here we are it is true that
other then Bosch all other stuff is **** that goes on Merc`s!!


I would like to thank everyone though for their input and help!

regards, Les

 

[MB094]

..and guys!, DO NOT BUY products from this company :

BBT Automotive Components GmbH

 

[Deleted member 26392]

How much was the new bosh item then?

 

[MB094]

How much was the new bosh item then?

I found it by accident on Ebay, il paste the link over here for you :

Bosch MAF Mercedes 0280217100 0000940048 W202 S202 C124 W124 W210 A124 S124 S210 | eBay

it comes with 2 year warranty, its made by Bosch and its original it is listed that way if it isnt il send it back easy but the seller also has 100% feedback so it looks good

 

[Lxb3]

what about the EVAP system ?

Is the valve on inner wing pulsing when engine up to temp - you should be
able to hear it and feel it pulse with your hand.

It has MOT written on top of it.

They can get sticky and be open when they should be closed.

The engine then sucks fumes when it should not, and gets partially strangled.

I was poking under the bonnet of my T124 E220 yesterday (having finally got the cheap catalytic converter to fit...! Much like the Threadstarter says, sod cheap parts... it's always a false economy), and noticed the little module with MOT written on top and a pressure-type hose heading to God knows where through the bulkhead, ticking away quite happily to itself... What the hell is the EVAP system, where does this go?! Just out of idle ('scuse the pun) curiosity.
Many thanks!

 

[grober]

I was poking under the bonnet of my T124 E220 yesterday (having finally got the cheap catalytic converter to fit...! Much like the Threadstarter says, sod cheap parts... it's always a false economy), and noticed the little module with MOT written on top and a pressure-type hose heading to God knows where through the bulkhead, ticking away quite happily to itself... What the hell is the EVAP system, where does this go?! Just out of idle ('scuse the pun) curiosity.
Many thanks!

GOES TO THE CHARCOAL FILTER UNDER THE WING WHICH IS PART OF THE PETROL TANK EVAPORATION CONTROL SYSTEM.
http://www.mbclub.co.uk/forums/bodywork/119085-can-anyone-identify.html

 

[kth286]

Whilst it was not answered on that thread, it seems that if the charcoal filter gets clogged up, it can cause the petrol tank to gradually collapse due to vacuum being created in it.

In the service book it is a 72,000 mile service item on my 124.

 

[haggis2768]

Whilst it was not answered on that thread, it seems that if the charcoal filter gets clogged up, it can cause the petrol tank to gradually collapse due to vacuum being created in it.

In the service book it is a 72,000 mile service item on my 124.

Yup.in the paperwork for mine it had new tank, filler neck, all pipework and finally the charcoal canister replaced.
Kinda funny that all this was done by M.B. Glasgow..who also did all the services. Someone obviously forgot to do the canister when they should have!!!