M103 EHA/Lambda Adjustment HELP - PeachParts Mercedes-Benz Forum

TCCBass · #1 10-10-2002, 12:57 AM

I think I've narrowed down the problem to either the EHA or Lambda adjustment (or both). I unplugged the EHA and the car ran GREAT...no hesitation, power, exhaust didn't smell so strong. Friend helped me test the Voltage to the #3 pin. With the EHA unplugged the reading was 1.7. With the EHA plugged it read 6.9. I tried adjusting the lambda both ways (push down, turn) and it didn't change the reading at all.

The 02 sensor is new, and I've replaced every sensor I can tell MIGHT have something to do with this. In the next couple of days I'm getting a meter that does duty cycle.

Does this sound like the EHA out? I'm more than willing to replace it if this hesitation will STOP...

Thanks for ANY ideas!!!

#2 10-10-2002, 07:00 AM

Robert,

I remembered to put the meter in the car last night. Measuring the DC voltage at pin #3 will not give you a meaningful indication. It needs to be set for 50% duty cycle.

You need to read the Steve Brotherton article about this in the DIY and maybe do a search on lambda adjustment. There was a good thread about this by Donnie a couple of years ago.

I have a customer in house today and will probably be out to lunch with her, but let me know when you would like to pick up the meter and I will try to have it ready for you.

Good luck,

pmizell · #3 10-10-2002, 08:00 AM

TCCBass:

Sears sells a very affordable and competent digital multimeter for $30 WITH duty cycle. You need to measure the mA coming from the EHA if you find that your duty cycle is fluctuating wildly (beyond the allowable 10-15%).
If after you check your duty cycle and it fluctuates wildly you'll then need to check the mA coming from the EHA using a MB harness tool -- which I have and you're welcome to borrow it. (please email me and I'll be happy to mail it out to you)

If the EHA is not giving out the proper mA, this still doesn't mean your EHA is bad .... it could be due to improper lower chamber pressure in the fuel regulator, or a short circuit somewhere between the ECU and your EHA.

Good luck with your diagnosis...

#4 10-10-2002, 08:21 AM

I have one of the $30 duty cycle DMM's from Sears. Actually it was $27 because I accidentally bought it on a 10% off Craftsmen Tools day.

I understand, though, that they no longer offer that meter. This is the one that TCCBass is borrowing from me.

As for the EHA harness, where did you get it? Would it be difficult to make?

Have a great day,

#5 10-10-2002, 08:32 AM

Here it is. I found it at Sears.com under: Craftsmen Tools/Electrical Items/Other

Sears Item #03482040000
Mfr. Model #53338

Inflation has hit, however, it is $39.99 on that site. That is still a great bargain. It wasn't long ago when the lowest price you could find for ANY DMM was over $100. This is a very good little meter.

Have a great day,

pmizell · #6 10-10-2002, 08:46 AM

Larry,

I bought the harness from a MB dealer. Cost was $15. It would be tough for me to make, for others more electronically inclined, I doubt it. It's on loan if anyone needs it.

#7 10-10-2002, 08:50 AM

Paul,

Sorry to be a pest about this. Do you have a part number?

Thanks and have a great day,

pmizell · #8 10-10-2002, 09:00 AM

Not a problem Larry. p/n is 102 589 04 63 00 07. On how to use it, here's a blurb from a previous post.

Quote:

Once you have the amp meter and harness Part #102589046300ks you can remove the air filter housing to locate the eha which is located on the back side of the fuel distributor. It is a small black box with a two pole wire connector on it. Your harness will plug into the vehicles harness and the eha. There will still be a third connector this is were the amp meter leads go. Make sure the positive lead of your meter goes to the solid black wire on the test harness. Turn the ignition on engine off and you should have a reading of around 19 mili amps. If this reading is ok start the engine and let it warm up to operating temp. You should see the amp meter moving back and forth across 0 amps. 0 amps is your mid point so you should have even movement on the negative and positive side of 0. If you do not have this reading you will need to adjust the lamda. This is done buy moving the screw down inside of the lamda tower, which is located on the left side of the fuel distributor. I believe it takes a 3mm allen to adjust it. If there is a metal ball in place on the top of the tower you will need to get a new lambda tower and break the old one off. Install the new one and make your adjustments. The new tower will come with another steel ball its up to you if you want to reinstall it. Once you have the lamda set correctly at idle you need to bring the rpms up to 2500 and the lamda readings shouldnt change within 15% of your idle readings. If it does you have further problems. Also while your doing this make sure the eha isnt leaking fuel they prone to do this after some years and mileage.

Good luck..

Cap'n Carageous · #9 10-10-2002, 09:40 AM

Paul, what was the verdict on your EHA. Did you ever figure out what the problem was?

pmizell · #10 10-10-2002, 09:48 AM

Not yet Stephen

I really haven't had time, and the engine runs flawlessly with only a minor drop in MPG it seems, so for now, until I get more time I'll let it be.

I do have 2 new screw seals that I forgot about. Think I'll put those on and see if that solves the problem. I also need to connect that vacuum line at the base of regulator

.

TCCBass · #11 10-10-2002, 10:43 AM

I guess one advantage of having this fuel problem and not driving the car is that it is getting to be a LOW mileage car. It's been sitting a lot. 1K miles in about 3-4 months.

I will get the meter from Larry hopefully today. I have to be up in that part of the city this afternoon.

Thanks for all the instructions...I may go to the dealer and buy one of those harnesses this afternoon. I REALLY appreciate the instructions on checking the EHA and the lambda. I drove it this morning with the EHA powered. It is driving better than it did before I started all this, but it's apparant that it's running quite rich.

Paul, you spoke of the vehicle's harness. I know where the plug is for the EHA, but where is the other harness? Will it be apparant when I start fishing around under there? Also, I assume I use the extra plug shown for testing?

I'll post results this evening. I'm ready to put some miles on this car (and get more than 10-12 MPG)!

#12 10-10-2002, 11:48 AM

Robert,

While I'm thinking about it, make sure you change the oil and filter as soon as you correct the rich condition. Your oil is being dilluted with fuel in this situation, not a good thing.

Have a great day,

TCCBass · #13 10-10-2002, 12:06 PM

Larry,

I'm due for an oil change...so it will get one as SOON as this issue is resolved.

Thanks for your help!

pmizell · #14 10-10-2002, 01:30 PM

Unplug the connector from the EHA. The harness then plugs into the EHA, second connector plugs into the wire you just disconnected from EHA, and third is for testing.

You'll figure it out, none of the 3 connectors are the same.

Also this part (tool) normally isn't stocked at MB dealers. They probably will have to order it for you.

Good luck..

TCCBass · #15 10-10-2002, 07:58 PM

SUCCESS I think! I got the meter from Larry Bible. Tested it when I got home. Was registering at 82-84%. Got it calmed down to around 45, drove it for a bit, and adjusted it to where it ranges from 49-55% A/C off and 45-51 A/C on. I'm pleased with that for right now. It seems to fluctuate and not stay at all steady, but if it averages those I'm pleased. It perhaps could be time for a new idle valve (it's been cleaned thoroughly) but overall...after I removed the resistor for timing and with this adjustment the car runs like it did before I bought it. Needless to say I'm VERY pleased. I'll knock on some Zebrano that it stays that way!

Thanks for ALL the help...I'm once again a satisfied 124 owner!