190e rough idle setting fuel/air mix

[sebw2341]

Hi,
I have a 190e that currently has a rough idle and lack of power intermittently that I'm going through and getting everything sorted before using it as a daily.
So far I've:

-Changed most parts on the ignition system spark test showed all good.
-Compression test on all cylinders all tested good.
-Smoke test found leaks on idle air system and replaced brittle pipes
-Changed injectors
-Set up the mechanical IACV as best as I can

the next few things I want to do is
-Set the fuel-air mix
-pressure test on fuel distributor
-Rebuild fuel distributor

While I'm waiting for my pressure gauge to be delivered I'm looking to set my fuel-air mixture correctly. Looking at my new spark plugs after putting them in running the engine for a bit they were already getting pretty fouled. Does anyone know of any guides for setting the fuel-air on the 190E checking my car I do not have the lambda sensor on the exhaust (no pin 3 on x11 diag connector, no pin 23 on ECU connector, no wire under the carpet, and as far as I can see no sensor on the exhaust).

As far as I can see I need to use an exhaust gas analyser but I'm unsure of the best one to buy and what CO level I need for it to be at the correct level so far I have found this one which has some mixed reviews but might be down to people using it incorrectly.

Is there any information that might help?

 

[DREAMER NO2]

What type of spark plugs did you fit ?. anything with R in is a no no . . 80% of all problems on this type of engine is due to electric items . I tell everyone to replace ht leads , plugs, distributor top, and the rotor , Do this first and forget those ht parts for another 5 years . And above all use Bosch or Beru parts .And i will never ever use parts made by unouno down the back alley . I start by doing this with every problem car i have had .Then if i still have the problem i investigate the other items next . Then i follow up with a fuel pressure test and then a flow test . As for moving the air -fuel mixture i would leave that alone its set from new and should not need changing . Unless some ones has been operating on it, to muck up the settings of air to fuel mix .

 

[sebw2341]

What type of spark plugs did you fit ?. anything with R in is a no no . . 80% of all problems on this type of engine is due to electric items . I tell everyone to replace ht leads , plugs, distributor top, and the rotor , Do this first and forget those ht parts for another 5 years . And above all use Bosch or Beru parts .And i will never ever use parts made by unouno down the back alley . I start by doing this with every problem car i have had .Then if i still have the problem i investigate the other items next . Then View attachment 69870 i follow up with a fuel pressure test and then a flow test . As for moving the air -fuel mixture i would leave that alone its set from new and should not need changing . Unless some ones has been operating on it, to muck up the settings of air to fuel mix .

Ok I'll leave my air mix till the end

I've change all those parts on the ignition system. Spark plugs are Bosch H7DC if I remember correctly. Cap and rotor arm are also Bosch. It's only the leads that aren't from a brand called ci ignition. The only other non Bosch or mercedes parts I've fitted also was a cheaper OVP relay called VEMO that was the only one I could find on the site I ordered on and febi injector seals.

Currently waiting for my pressure gauge to get delivered did have one but it was incorrect and the fitting I bought to adapt it ended with me getting fuel everywhere. So I'll update on that when I get the kit and do the test.

As for that guide you attached is there the Bosch service guide to go with it? It says to refer to the guide I would be interested in reading through it while I wait.

 

[DREAMER NO2]

The IACV how did you set it up i know that its operated by vacuum from the engine and works by 12 volt power .Did the hoses going from it look good, no leaks ?.

 

[sebw2341]

The IACV how did you set it up i know that its operated by vacuum from the engine and works by 12 volt power .Did the hoses going from it look good, no leaks ?.

My valve is a mechanical one rather than electric part number 5 on this parts catalogue so far I've replaced all hoses and connectors connecting to it between breather hose (including it), aux air valve and AFM boot (including boot itself) the only one not done is part 110 which I ordered the wrong part and waiting for a new one from Mercedes.

To set it up I followed the guide in the Haynes manual to turn it left or right depending on idle speed. get the engine up to 3000 for 10 seconds then let it rest. With idle speed between 750-850.

 

[DREAMER NO2]

Yep i slipped up loking at w102 and right away i thought it was a 2.3 you have a 200 lost on those sorry. Not to many of those 2 litre around..You have points in that engine so are those good ? only problem i ever had with my W123 was electrical my spark plug lead to no 4 was breaking down . And once again on the W124 same problem plug lead faulty ..Every time i buy another car first thing i do is a ht tune up ,,all ht parts off for new ones . You know you have a filter in the fuel distributor dont you ? on the inlet pipe brass fitting remove it and see if its blocked up.

 

[sebw2341]

What type of spark plugs did you fit ?. anything with R in is a no no . . 80% of all problems on this type of engine is due to electric items . I tell everyone to replace ht leads , plugs, distributor top, and the rotor , Do this first and forget those ht parts for another 5 years . And above all use Bosch or Beru parts .And i will never ever use parts made by unouno down the back alley . I start by doing this with every problem car i have had .Then if i still have the problem i investigate the other items next . Then i follow up with a fuel pressure test and then a flow test . As for moving the air -fuel mixture i would leave that alone its set from new and should not need changing . Unless some ones has been operating on it, to muck up the settings of air to fuel mix .

So I got my gauge and tested the fuel pressure.

For testing, I mostly went off the instructions that came with the gauge (attached below). First EHA connector off gauge connected between cold start valve and test port marked.

Here I got a bit mixed up with instructions but I'm adding it anyway in case it helps. Just turning the fuel pump on not starting the engine and valve closed I got 3 bar pressure with fuel cap off and 2 bar with it on.

At this point, I started the engine ( this took a bit with the valve open) immediate pressure was 5.5 bar with the valve open when I closed it the pressure was between 5 - 5.05 bar.

Next, I let the engine warm-up (80C) this didn't seem to change much valve open ~5.5bar when closed 5 - 5.05 bar.

Therefore, If I'm correct I have a system pressure of 5.5 bar and dif pressure of 0.45 - 0.5bar.

Next, I did holding pressure starting from 5.5 bar before turning it off.
Straight after switch off, I got 3.05 bar.
After 10 minutes 2.6 bar
After 20 minutes 2.5 bar
After 30 minutes 2.5 bar
After 40 minutes 2.45 bar

The instructions I got for my gauge say 2.6bar after 20 minutes so seems to be within spec.

Next, I did the flow test approx 30 seconds of cranking I got ~1.6 litres of fuel in the bucket.

Does all this seem to be in spec I'll try and find the exact spec for my engine if I can but I would think there would be too much difference?

The only other thing I noticed was when the engine was warming up it got a lot more stable at around 50-60c.

If these are all within spec what would be the next step?

 

[DREAMER NO2]

So it looks like the fuel pressure is in specs . And that the problem you have is some place else ...Do you have the economy gauge on the left hand dials in your console ? if so where is the needle pointing on tickover ? i still think its vacuum related . How do you go about test for vacuum leaks .

 

[sebw2341]

So it looks like the fuel pressure is in specs . And that the problem you have is some place else ...Do you have the economy gauge on the left hand dials in your console ? if so where is the needle pointing on tickover ? i still think its vacuum related . How do you go about test for vacuum leaks .

Don't have an economy gauge. To test for vacuum leaks I smoke tested it ( homemade tester with large jar some pipes, some smoke tablets, and a battery-operated pump). I went in from the brake vacuum boost line wherever I looked online this seemed to be the port to go in through. Covered up the AFM plate and crankcase breather line. When smoke testing it I found smoke coming out the AFM boot and have since replaced that. I have also since replaced the hose 110 as previously mentioned.

 

[DREAMER NO2]

With the airbox off just press down very gently on the flap to see what free play thats there . you will see it will only move about 1/16 aprox and then you should feel a risistance .

 

[sebw2341]

With the airbox off just press down very gently on the flap to see what free play thats there . you will see it will only move about 1/16 aprox and then you should feel a risistance .

Just tried it.

With the engine off a small amount of free play no more than 1-2mm. When engine on no free play at all,

 

[DREAMER NO2]

That would be right i would think . What i did on my engine was i pushed the trottle plate down and my engine stalled . try it

 

[DREAMER NO2]

Did you try to push down on the flap when its running ?> you have distributor with points in it on your engine yes? i read about the Hall Sensor being faulty . And check the coil out put along with ht centre king lead ... go out in the dark lift up the hood and look for sparks on the top of ther coil /

 

[sebw2341]

Did you try to push down on the flap when its running ?> you have distributor with points in it on your engine yes? i read about the Hall Sensor being faulty . And check the coil out put along with ht centre king lead ... go out in the dark lift up the hood and look for sparks on the top of ther coil /

I didn't push the flap down this time but when I did it before the engine stalled.

Which hall sensor for ignition and how do I test it?

I have previously tested for spark with this including the main ht lead between ignition coil and distributor spark and all of them appeared to be consistent including the main lead but 4 times faster for obvious reasons.

 

[DREAMER NO2]

Yes they are good i have one the same . Do that check in the dark for us . I dont know how to check the hall but i will find out if possible for you . And you can have spark but is it a strong spark . Do you have point in the distributor . The hall is on the distributor , i am just grabing straws it is only what i find out doing a search . I still think it is ht problem . have look in the dark for tracking on the coil mainly . I must pop out now so pick you up Sunday

 

[DREAMER NO2]

Did you check in the dark for flashing shorts along the top of the coil and all electrical parts /.