dolucasi

I was a member on BimmerWorld and did not realize there is a sister Benz Forum here. So here it goes, my first post.
Final version of the EHA current and Battery Voltmeter installed.
I tried 2 faceplates (pre-90 style zebrano, and glove compartment black faceplate cut-up). I prefer 2 black one.
Now that these cars are 30+ years old it would help to have gauges like these installed in case of CSIE-Jetronic trouble. The vacuum gauge on the cluster helps too of course.
Car is a '89 (with a '90 console) factory ​​​​​​​5-speed, 200+ Kmiles. Original owner.
- Cheers!



5-speed, 200+ Kmiles. Original owner.
- Cheers!

jzchen

Cool!

Got a DIY you don't mind sharing???

From the same guy on the dark side...

dolucasi

Hey JZ! Good to see you here. I will do a DIY post on this some day if there is enough interest.
The gauges in there are custom designed for this application and I must say they are not cheap as they are custom hand made.
I wanted to have a close to factory look with old technology.

Just having that EHA meter there is worth 10,000 words of explanation on how the CIS-E works. And it is a great diagnostic tool as well.

If there is enough interest, I can order more of course and a bigger order may make it more economical.
But the installation is rather simple and with the correct harness it is plug and play.

For the post '89 W201's it starts with buying a factory storage bin from the dealer before they stop making them. I believe the cost is <$50 and replaces the cassette holders which are worthless now. The pre '90 consoles are easy since the wood is there, you just need to drill 2" holes in the zebrano wood (first picture)

- Cheers!

Dave Kost

What's your thoughts on adding a air fuel ratio gauge ?

dolucasi

Hi Dave, I'm not sure if a signal like that is available. I suppose the oxygen sensor signal is available in the neighborhood next to the console but that is not exactly a ratio of the air fuel mixture.
As far as I know it shows the difference in the oxygen content between ambient and exhaust gasses.

What do you have in mind as the source for the air/fuel ratio? I suppose the AFM pot signal can be displayed as the air flow quantity but there is not a direct measurement of fuel flow.

Good to see you here Dave.

Dave Kost

I would want to put a wideband sensor in the exhaust before the Catalytic Converter to monitor the actual Air fuel Ratio right after combustion.

Thoughts?

190Efan

To echo dolucassi, these cars aren't real sophisticated and they lack the computer electronics so common in new cars today so your odds of coming up with the sensor you seek may not be that great.

jzchen

I think that's a great idea for non-machinists like me. Regarding the factory storage bin I have one, but it does not have a zebrano wood face???

I've had it for years but my radio has a cassette deck (and CD changer in the trunk) so I just kept the cassette storage there....

dolucasi

The Zebrano is from my original '89 console (above the ashtray). The 16V's put their battery voltage/oil temp/lap counter there.
For the post '89 consoles the glove compartment plastic (in 3nd picture) is the exact height needed. One just cuts the 2 ends and pop it in. The gauges are also an exact snug fit to the storage bin. Once inserted, they do no move.

I would recommend chucking the cassette holder and putting in the storage bin. I had that set-up for a couple of years before deciding on putting gauges and phone holder there.
These days good place to store the masks and the hand sanitizer!

dolucasi

Can a wideband sensor in the exhaust actually output the air/fuel mixture in the intake? I feel the EHA current is sort of telling how much extra or less fuel needs to be put in the mixture to minimize the O2 content for optimum combustion. I'm not too familiar with the wideband tailpipe sensors to be honest. It would be cool to have one in the car but a digital display maybe distracting in the console and take away from the original look . Maybe one can put one in the ashtray bin.

Dave Kost

A wideband sensor reads the exhaust gas and converts it to AFR number. I used them in setting up carbs and Porsche Mechanical Fuel Injection MFI. The sensor must be before the CAT. You can see the AFR at all the running conditions. Very easy to read and interpret. My thoughts here are, someone says my car is running rough, hard cold start etc. My first question is Is it rich or lean? Yea, you can read the EHA voltage but what if the adjustment needed is out of the range of the ECU/EHA ?

Just a thought, if you have an interest in the state of your engine.

dolucasi

The beauty of the EHA current gauge is that it is telling you what the ECU "thinks". Meaning if something is railed one way or the other (to max enrichment or max leaning) you will see it right on the gauge. For the W201 it will be either +20 (max enrichment limit) or -20 (max leaning limit). Unfortunately without the EHA current monitoring you can not see this from the Duty cycle readings as it will just send a code. You will also see if the ECU is performing proper enrichment during warm-up etc. It will even hint at fueling issues because the ECU will start to react to pressure drops, etc by enriching. You will also see misbehavior as the system transitions from open loop to closed loop. Because when this transition happens the EHA current in a properly working engine will not see an abrupt jump. If it does it may cause a stall or other discontinuities. So once you have this gauge in, it is a tremendous diagnostic tool, coupled with the other OBD-1 diagnostics.

You will also notice if your fuel cut-off is not working properly as the EHA current will rail to ~ -60mA during fuel cut off. In this gauge that is near the last tick mark (the gauge is not linear after +/-20mA by design but rather exponential)

This is why I was saying to properly maintain a 30+ year old KE-jetronic system, this gauge may just turn out to be invaluable. Only time will tell.....

dolucasi

BTW, Dave do you have a spec for the wideband sensor output as AFR number. Is it a digital output?, analog output?
Does a wideband sensor have unlimited life or would it need to be replaced frequently?

Dave Kost

Dolucasi

You can get either a digital or analog. I prefer digital. I don't know how long it would last without replacing but if if you are dumping raw fuel in the exhaust I'm sure that will shorten the sensors life. But then, you will be able to diagnose this condition and hopefully remedy it before it causes any damage. I wonder how many catalytic converters have been damaged with raw fuel.

Neither of my 190e's have economy gauges and I am thinking of adding a vacuum gauge too.

Here is you tube video that talks about the AFR gauge.

190Efan

Nice to see the old BW gang making the move to MB World.

dolucasi

My bigger issue would be the soot with my oil burning. Would be nice to see a DIY on this but it will be more involved since one has install the sensor.
Something to consider "After" my bottom engine rebuild.

190Efan

Look on the bright side, at least you'll know what you'll be up to in the near future thanks to your W201's oil burning, lol. I can't wait to find out what the culprit for the oil burning turns out to be. It's likely you can measure the oil burning but unfortunately it's less likely the measuring will identify the actual culprit for the oil burning without an engine teardown. Oh the joys of W201 ownership, lol. I'm already bracing for what my W201 has in store for my finances in the near future and despite the over the top pampering it gets.

Dave Kost

have ever checked your pre cats for blockage?

dolucasi

Strangely, the pre-cats looked super clean inside when I removed the head 2-3 years ago. I was pleasantly shocked. Maybe most of it burns up in there since they get so hot.
The manifolds had quite a bit of soot though.

190Efan

You might really go back to basics and get some engine dye from your local parts store, put that in and see if it leaks out anywhere. That might shed some light on where the problem might be?

dolucasi

No leaks whatsoever 190Efan. Car has an under belly cover and a pad between it and the engine. Squeaky clean for years. You would think it is a new engine down there (at 200K miles).
As I mentioned it is from the repeat of cold starts daily for 32 years. I'm pretty sure of it, but that will be covered in a separate post some day when I remove the engine form the car.

dolucasi

I happened to have a very convenient location to add that, if the 1-2-3 exhaust manifold is good enough for it. Easy to tap that EGR cover plate .

190Efan

That's good to know. My engineer father always taught me to rule out the easy and obvious first when diagnosing an issue. It's sounding more and more like it's 32 years of wear and tear that I agree won't be found until the engine is taken apart. Can't wait to see the video.

355190e26

What's up Dolucasi, I finally made it here too!
Having seen the gauge setup in person, I can say that it has a nice factory look and provides a nice way to monitor the what the CIS is doing in real time.

As for the mystery oil burning question, we discussed this issue extensively last week. I suspect it's piston rings, but it's strange how his car is the only M103 I've seen that burns oil on the bottom end.
My green 2.6 w/ 232K miles doesn't burn a drop of oil, even though it has been run pretty hard it's whole life. Both of us also have rebuilt cylinder heads from the same shop too, so we know it's not top end.

Regarding the possibility of wideband sensor, I would just have a bung welded in before the 02 sensor, past the pre-cats.

dolucasi

Good to see you are here 355. My only explanation is the piston rings from cold starts. And specifically oil rings, as the compression and leakdown is fine. Car was used <5 miles each way for 30+ years. So 40K starts. I wonder what that equates to as in wear and tear compared to highway miles driven with 10K starts.
- Cheers!