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Discussion Starter #1
Hello all.... C124/M119/1993/No ASR

In the past six months of driving, I have had the occasional EA idle surge in park. When this happens, the idle in drive goes up to about 750RPM (it usually idles at about 550 when at operating temp) It seems that this never happens at night when its cold out, only in the day, when its hot out. So usually when all this shit starts acting up, it all goes away within one key cycle, and I chalk it up to an 'electronic hiccup' (silly me)

Then, a few weeks ago I had the idle surge, followed by a C.E.L. upon next startup. Codes in the DM and in the EA/CC/ISC popped up for Faulty signal to EA from fuel control unit. Cleared codes and all was well.

Then a few weeks later, the idle surge came back, and it got worse. Not only did it surge in park, but the idle would climb in drive, and as the car got warmer, the idle got higher (over 1100 RPM). It did not go away with key cycles. The next day, I checked all my vacuum connections and linkage pivot points, and then retrieved codes again for faulty signal from fuel control unit. Car ran fine after erasing codes.

So today, I was in the valley, it was a bit warmer over the hill than it is here on the coast. About 83 degrees outside. Stopped for gas, and noticed the in drive idle a bit high. Raced when I went into park, but was gone when I restarted two minutes later. Car drove great on the way back home, went back to the shop, and just because I was curious, I decided to plug in and see if the code had reappeared (no check engine light). No fault codes anywhere. So I says to myself... self... thats some pretty weird stuff.

Leaving the shop, car runs fine. Get to the house (less than 5 minutes away), and as I shift into reverse.. WHAM, theres that strange idle again. Shift to park... idles all over the place.
I will go back to the shop tomorrow and expose some EA harness to inspect. Engine harness good.


So... what I'd like to know is...

Do you guys think it possible for the EZL to be the issue. I know they can get hot and act up, and temperature seems to be a factor.

What about the EA module? What if the CPU box is overheating? Would that account for the temperature playing a role in this mess?

Or do I just bite the bullet and buy an actuator... Like I said, Ill go in and check the harness on the EA for insulation issues tomorrow. I just have a hard time thinking that if the wire insulation is bad, that I wouldn't be experiencing this problem all the time. And that clearing codes shouldn't have an effect if the wires were actually touching inside. If that were the case, I would think that I'd have a hard fault that would re-register right away, or not be clearable at all.


Sorry for the lengthy essay, but the more info I can give you the better.

Thanks in advance for any responses.

BRIAN
 

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Well... I cant help much, but here is my personal experience:

After buying the 220E, I experienced some cruising speed problems. The engine would COMPLETLY cut out if I maintained speed and when reaching the idle speed it would hold it perfectly. This problem was intermitent.

Say the engine is on, tranny in Park and idling perfect... If I accelerate and try to keep it at 2k rpms, the engine would cut off until reaching idle and then it would climb rpms again, reaching 2K and cutting again... this would go on forever.

As I said, this happened a lot of times, but not always.

I researched the net and found that early Benzs had also problems with the wiring INSIDE the Throttle Actuator... Found a used unit on eBay.de and replaced, returning the 220E to perfect functioning.

To sum up, eventhough the problem is intermiten, you can have the refered "hard fault" there messing w/ your head.

I hope you find the damn graemlin :D
 

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And you're sure your diagnostic system survived the conversion intact - that you couldn't be losing a mass air flow sensor fault code, for example.
 

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Discussion Starter #4
And you're sure your diagnostic system survived the conversion intact - that you couldn't be losing a mass air flow sensor fault code, for example.
As with any project of this magnitude, you can never be 100% sure. But I am 99.9% sure that the diagnostic system is completely functional. I am questioning the integrity of the donor car parts waaaay before I think about our work. Mainly because of the limited amount of splicing we did. The majority of the wiring in the conversion was just plug and play. Thats why we used the entire dash harness as well. We really only brought power to the harness from a different location, no wire cutting or splicing to any sensors, switches or components.

I really want to know if an EZL hypothetically could produce these symptoms, and why does the problem increase with engine temp.


Thanks for your responses so far.

B.
 

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Discussion Starter #6
Dont really want to go used, because Ill never be sure of the condition of the used one. Thats what I have now.

I did get a different code today... in the DM, it said fault from EA/CC/ISC. As opposed to the one previously that said EA/CC/ISC fault from fuel control system

Does anyone have the description and operation for the potentiometer inside the EA. What is the theory, what EXACTLY does it do. Im leaning towards buying a new unit, but I still would like to know the theory. I browsed threads in the 140 and 129 forums too, but not alot of info

BRIAN
 

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Discussion Starter #8
What's the year of your 119 motor? Some of the early 400Es had a replaceable potentiometer, see below, which is apparently now out of production, but coincidentally I happen to have one.

SG-Motorsports Air Flow Meter Potentiometer Replacement

Uhhhhhh.... wait a minute.

I am familiar with that airflow sensor on a 4 or a 6 cyl, but not on an 8.

Am I to understand that the potentiometer INSIDE the EA looks like the one in the sensor in that picture.

I can dig one of those up if thats the case. Ive never disassembled an EA, but I think Ive seen pics, that show gears from the actuator to the flap, with the potentiometer in the middle.

Thanks for spending ur time with me..... BRIAN

Oh, and its a '93. The kind with the big round connector, not the barrel plug
 

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Discussion Starter #9
The only thing I can think of is that SUUUUPER early 119's still had CIS, with a fuel distributor way in the back. Ive only seen one or two of those and I think only on an SL that I can remember. Maybe thats what you were referring to?
 
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