190E 2.3 mixture adjustment
 

Hello.
I have just bought a 190E 2.3 8valve (1992). The previous owner had the fuel system readjusted as the idle was low and sometimes it stalled. Then the idle went up to 1000rpm and the car run much better. However, it didn't pass the emissions check and had to lower it again, so now it stalls sometime and doesn't run as it should.
I want to increase it a bit. He told me about a kind of adjustment with several positions, although the fuel distributor hex. screw sound more likely to me.

Can I do it myself (I have an oscilloscope and can check the duty cycle signal or whatever in the diagnosis conector if you explain me how to do it).

Is there any other adjustment in this car?

Best regards.

Print out the following web pages for your reference, and let us know if you have any questions or problems. Also search for discussions on mixture adjustment. There was one within the last couple of days.

www.landiss.com/mixture.htm

Duke

Thanks, I had that sheet already.
Then I should measure that waveform and then adjust the mixture with the screw so I get a 50% duty cycle at idle and at, say, 2500 rpm, is that correct?
If I manage to do so, can I be sure that it will pass the COx emission test? (it does now)?
Should that improve throotle response?

A lot of thanks. That forum seems very useful.

Sergio

Look at the following thread:

http://www.peachparts.com/shopforum/showthread.php?threadid=90225&perpage=15&pagenumber=2

second page, my last response, which is the third from last post.

It should start well and pass emissions. As far as "throttle response" is concerned, there will likely be no change. There's nothing wrong with the throttle response of these engines - it is essentially instantaneous, but the relatively soggy low end torque and lazy automatic transmission response can sometimes be misconstrued as "poor throttle response".

Duke

Does the 190 come with a cat. converter?

Thanks for the info.
Now I have found some threads in this forum (very active and helpful, by the way).
My 190e 2.3 8 valve (1992) does come with catalytic converter.
That's what I will do. Please correct me if something is wront or bad interpreted:

- Leave the car warm up to, say, 90 deg or so.
- Check the pin-3 signal of the diagnostic connector with an oscilloscope for duty-cycle.
- If it is not around 50%, I will touch the 3mm hex screw until it is: now a doubt: should I do this with or without the lambda probe connected (02 sensor)?
- The idle should stabilize. Should it change the number of rpms? What is the good number? Now it is about 700, but I think that's a bit low, what about 850-900?

Any help will be very appreciated.

Best regards,
Sergio

One more doubt about the procedure you have pointed to:

"3) Detach the purge line at the electric switchover valve and seal. On my car, this valve is mounted on the inner wall of the left fender, adjacent to the ABS controller. The subject line is black tubing with white stripes."

What is that? Is it related to automatic transmission? If so, do I have to remove something if I have manual transmission?

Best regards and sorry for so many questions.

I really like the EHA current for this mixture correction. The reason is that whatever happens, happens at the EHA.

I am pretty certain your above steps are about to screw with you. I'm a little fuzzy here but certain cars and I think yours might be one of them require the pin#3 diagnostic to be turned on from the other diagnostic connection by the battery.

If you have one of those models you will get a zero reading I think till its turned on. The EHA is still working during these situations so it is always useable.

A lot of thanks.
How can I activate that duty-cycle reading?
Best regards,
Sergio

Ooops. Another question. I have read somewhere that the idle speed is adjusted in some CIS systems with a 7mm separate screw. Is this correct or touching the 3mm hex will affect my idle rpms?

Thanks

Only the first 190s had adjustable idle speed. The amount of air entering the engine is what controls engine speed. The allen adjustment at the fuel distributor does mixture.

To start the diagnostic at the passenger side connector use the code retrieval initiation of a two second grounding impulse to hole number 3. Go to the DIY article about evaluating engine controls for more precise discussion of the diagnostic trigger.

Mmmmm.
Thanks. Sorry for asking too much. You mean that I can't adjust the idle to be faster? Or that adjusting the mixture will affect it?

Besides, where exactly is located the "passenger side connector"? Is it inside the cabin?

Sorry, I would be very happy if I could have a Service CD, I wouldn't bother you so much ;-)

Best regards

The other connector is in front of the battery on the back side of the engine bulkhead.

The idle is automatically controlled. If it is wrong it is broke. Mixture doesn't change rpm untill it is so bad the engine runs poorly and thus slower.

Question for the knowlegables out there
 

OK, so I have a European version of the 190e, first one to come out or something like that and it never had an O2 sensor. This should explain why pin number 3 on the X11 connector is missing (hole there but no metal connector).

So I brought it over here and they (US garage) "converted it" to US specs. They drilled a hole in my exhaust pipe and welded an O2 sensor in there (perminantly - try to replace that one easily) and connected it somewhere, not sure. I can follow the wire to see where it goes if that will help... Is it really working for me or was it some sort of a kludge job since the car probably doesn't have all the systems necessary for everything to work right? Also, maybe this O2 sensor is bad. Can I tell and God forbid it is I can't just unscrew it out, does it hurt anything if I just ignore it?

BUT, if I have no pin 3 in X11 then I have no Lambda on/off ration that you guys are talking about. I also have no "cigarette" box on the battery side with the OVRelay in there, mine I found on the left side of the fender with only 1 fuse on top. WELL, that aside, HOW do I adjust my mixture on my car besides running it at idle, turning the adjustment until it runs rough, then turning it until it runs smooth and fast, and then picking somewhere in between? The has to be a better way...

Stevebfl, can you please comment and help! Detail would be most appreciated as sometimes its like a puzzle trying to understand what people are talking about on this board and having to search and read other posts for more details on individual terms.

Thanks!!!

-=>Raja.

I would suggest following the wire from the sensor and see where it goes. There were a multitude of ways people created lambda control. Before you try and understand lambda control you might as well figure out if and how they do it.

One way that was done was to take the coolant temp sensor and cut the wire. They would feed both ends into a new box that would read the O2 sensor and change the effective resistance of the temp sensor to alter mixture. It was a terrible method and never stayed in adjustment for any length of time. Some cars would actually just need to have the O2 sensor hooked to the original computer and some people changed the controllers and added the O2 sensor. You should determine what you have and go from there.

Tracked the wire down
 

Hi Steve:

I tracked the wire from the O2 sensor and it goes to the big computer style connector (its taped into it with electrical tape so they spliced it in there I suppose) that plugs into what I presume is the computer of the car behind the battery on the wall. Its a big rectangular black box with the printer cable style connector plugged in the top of it.

In front of the battery, on the back of the firewall, I only have one connector which goes to the brake pad sensor to light when the pads are gone. So, no diagnostic connector at the passenger side.

I guess I really have one of the first versions of the 190e and it seems to be alot simpler than the others here. I have that screw to adjust the idle speed, the mixture adjustment screw, the added O2 sensor spliced into the computer, and no pin 3 connector in the X11 hole #3.

What would be the best course of action now? That O2 sensor was installed in 1986 by the way so could it still work or is it faulty by now? Its only seen about 90k miles since it was installed (I have 120k miles on the car) but many years of living in that exhaust pipe...

Thanks for your help, as always, it is much appreciated!

-=>Raja.

I presume the car has KE with an EHA. As with all KE cars the easiest image of what is happening is to monitor EHA current.

One can see all the forms of electronic correction at work cause that is how they work: by changing the EHA current. The early KE cars were all positive current and lambda had correction in the range 0-16ma. The car was adjusted to 8ma in closed loop. Monitoring EHA will tell you if you have closed loop.

If you can open the circuit to the O2 sensor the range of lambda correction can be determined by the "through the Captain" method (search the archives).

The figures from my EHA
 

Hey Steve:

Here is another post that I wrote when I checked the figures from my EHA:

"Hey guys:

I've read around on the posts here and learned a few things thanks to all, but I am a little bewildered on how to set my mixture right on my car.

From what I read, people say I have to put an amp meter between the EHA and it should read 7 to 8ma current draw at idle if the mixture is set right. Someone also said I could check this also from pin #3 on the diagnostics port. Well, I went under the hood this evening and here is what I found:

a) I don't have a pin #3, its missing in the hole. #1 has about 8 volts or so, #2 0.0, #4 is 13.7, #5 is 13.6, #6 is 12.6 and #7 through #9 are 0 volts to ground when engine is running at idle.

I put the amp meter between the EHA, and it shows -0.14ma when engine is at idle. If I step on the gas, it jumps up to 4, 5, or even 7ma, but then quickly returns to -0.14 or so.

I found out that you have to push down in the aircleaner hole with a 2.5mm wrench and just before the engine dies it engauges and you can rotate the mixture setting. Makes the engine run slow and rough or smooth and fast. I played with it a bit but the amps remain at -0.14 at idle. I did readjust idle speed with adjustment screw when I played with mixture settings, but no luck with getting EHA voltage to 8ma. What gives and where do I go from here?

I want to get the mixture set right as my car is hard to start hot and I want to eliminate this as an issue. Dialing it in by ear seems to work, but I'd rather do it scientifically with a voltmeter if someone will be kind enough to tell me how to!

Thanks!

-=>Raja."

I will go search for "through the Captain" as you suggest to see what those words might mean. I drove the car today to work and it seems to hesitate slightly with part throttle (it feels like its missing or something) and I think now that I read some of the DIY information its hesitating around the 2k to 2500 rpms range. If I am on the highway I don't feel any hesitations - they only appear from 40mph to 60mph or so. If I throttle the engine up by hand while I'm under the hood, I can feel the engine "pulse" a little bit as its running say 2k rpms (no tach while I am under the hood). Idle is smooth, fast idle is smooth, 3000 rpms and beyond is smooth, just the midrange is not good. I'm thinking maybe its the mixture screw to fix that hesitation at part throttle?

Closed loop?
 

Mind my ignorance, but what is closed loop mean?

Dumbo mechanic but at least with the desire to become knowlegable about cars!

-=>Raja.

There are a lot of terms that I trow out and most have extensive discussion in those phrases in the archives. I have writen detailed descriptions of "closed loop" and "EHA monitoring criteria" on these forums more than once; and so have others.

The term closed loop is not just an automotive term. It refers to a method of control. Basically it means that in order to do overall control one designs a system to do a function with measurable output. One then monitors the output and changes the input to keep output exactly within bounds. In an auto engine management system the O2 sensor is used to do the measurement of output (exhaust oxygen content to be exact).

From your EHA readings it sounds like there is no feedback control (another variation of the closed loop concept). That is the purpose of the "through the Captain" test. It will give you your controllers capabilities.

I think I will finally go for it: However, I have some doubts after reading the "Bosch KE3-Jetronic Mixture Adjustment" document:

Do all of the cars have the tamperproof tower/ball? If I remover the filter cover, can I check that?

When testing the duty-cycle measurement before turning on the engine, it says that you must deflect the air flow sensor plate to test the idle contact: does that mean that I should remove the filter cover and press the plate down a few mm or what?

Thanks for your help.

I have done some measurements at pin-3 of X11 connector, as commented in other post, although repeated here for reference:

When idling, I see about 50% duty cycle, fixed there until the car warms up or, if hot, for several seconds. Then it starts fluctuating around 40-45% or so.
If I accelerate , the average duty cycle decreases to about 25% at 2000-3000 rpm, fluctuating +/-5% approx.

What does this mean? Shouldn't both readings be very similar and around 45-50%?
My car doesn't have an idle mixture adjustment, so how can I correct this, if something is not correct?

Please share your experience. Thanks in advance,

Sergio
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1992 MB 190E 2.3 (8 valves)
1995 Renault Clio 1.9D
1993 Citroen Xantia 1.8i (sold)
1980 Renault 12-TS (gave away)

Yes, the duty-cycle represents the correction necessary to achieve the mixture required. When it is different it means the effective mixture is different.

In your case the mixture is richer at higher speed. That actually translates (usually) to the mixture being leaner at idle. This is the most common way it will be off and usually represents small airleaks or injector flows that are poor at small flow rates. One must remember that the mixture required is barely that which is necessary for good running.

Thanks.
Can this affect performance or only idling?
How should you correct this, altering the mixture setting?
Thanks!