1994 E320 Problem(s) - PeachParts Mercedes-Benz Forum

filon102 · #1 01-14-2012, 03:48 PM

Hi all. I have a benz which I replaced the head gasket on, but now i have idle issue. So i replaced: knock sensors (the wiring was stripped), MAF, IAT, fixed up the wiring hardness, checked the timing, plugged up purge solenoid valve since its stuck open (improved idle a bit), and now Im aiming at the ETA (Electronic Throttle Actuator).

Here is the problem:

the S1 (red box) has to have a short (zero ohms) when throttle closed, but when the switch opens it has to have infinite ohms (testing on 2k ohm scale). Which it did. So, S2 (green box) works the same way as S1 does, but when I was testing it I dint have the results that i was hopping for, I only got 1443 ohms either closed or fully open throttle.

So what do you guys think? I found a company that can rebuild my current throttle body for around 300 bux.

Btw, I bought a throttle body from ebay and the guy supposedly had it tested before it was removed from the car... but it turned out to be almost same value as i got from my own (~1200 ohms) but on S1, not on S2...

Kestas · #2 01-15-2012, 12:15 AM

Is the engine wiring harness original?

filon102 · #3 01-15-2012, 02:28 AM

I do not know, because the sticker was already peeled off, but the wires were bad and i had to solder new ones in. Funny enough, the only bad wires that were actually bad were for the ignition coils and for coolant temperature sensor, other ones were in great shape.

Of course after i solder them, I ohm tested each pin on the computer connector to make sure none were touching each other creating a short.

Kestas, do you have ASR on your 95'? If not, can you test out the pins on your throttle body? Im guessing that throttle bodies from 95' and from 94' w/o ASR are the same. Im only interested pins: #10 + # 6 and #10 + #8, I would like to compare my results to yours at (what happens after you WOT, and what happens when it is closed all the way).

I would really appreciated if you did that for me

porkface · #4 01-15-2012, 01:03 PM

i'd lay odds the eha harness is shot. replaced a few throttle bodies over the years for the same reason. it's not just the main engine harness, but every wire on the motor that degrades. you have to peel the insulation away to see it. any time those old harnesses get moved, wires start to touch things they aren't supposed to. good luck, chuck.

JimF · #5 01-15-2012, 01:34 PM

Quote:

Originally Posted by filon102

Hi all. I have a benz which I replaced the head gasket on, but now i have idle issue. So i replaced: knock sensors (the wiring was stripped), MAF, IAT, fixed up the wiring hardness, checked the timing, plugged up purge solenoid valve since its stuck open (improved idle a bit), and now I'm aiming at the ETA (Electronic Throttle Actuator).

Wow, you spent a lot of money and didn't get to the source of the problem . . that of the wiring harness.

As porkface and Kestas suggested, you must . . . . MUST replace it FIRST. . that in and of itself would have fixed your problems and saved you some $$$ b/c replacing the MAF, etc wouldn't have been needed.

The ETA's wiring harness (contained in the long pigtail) normally goes bad and needs to be re-wired and then, tested. Check Victor's web site for details on ETAs here including re-wiring and testing here

filon102 · #6 01-15-2012, 03:12 PM

Well, i replaced the MAF because when i was cleaning it, ive put in a q-tip to clean the surface of the sensor inside but I managed to break it (cotton ball got stuck, and my dumbass decided to pull on it instead of backing it up -_-, $180 mistake...

)

As for IAT, the car dint come with one, because the last owner managed to break the sensor itself when he was taking it off for some reason...

Quote:

Check Victor's web site for details on ETAs here including re-wiring and testing

I actually did see his videos on youtube and I went off to see if the wiring inside the ETA was bad... turn out to be good, then i tested the ETA. He posted up the video for SL500, which i believe has ASR because one of the switches has an open when throttle is closed, and other switch is closed when throttle closed... its not the same on my wiring schematic for non-ASR, because both switches appear to be closed when throttle is closed (as you see in my 1st post)

The only "bad" part of ETA is switch 1 (S1 on diagram). Im getting like ~14000 ohms when it is either WOT or closed. The other ETA that i bought used from internet has the same problem but less ohms ~1250 ohms or so... I would really like to verify good unit from someone that has a good ETA and compare my results to there's.

Thanks guys! I really am thankful for your replies!

Victor300E · #7 02-24-2012, 08:07 PM

JimF-thank you for recommending my site to other board members

And ASR and Non-ASR switches work the same- one opens and other closes. Reading are similar on both, just don't remember them out my head now.

According to my diagram taken from Mitchells switch S1 is closed on idle and S2 is open on idle. And it's opposite when throttle is opened. There is something wrong with your ETA. I just fixed one customer ETA who had similar issue.
In Non-ASR ETA switch S1 is under linkage side cover, there is a microswitch there that you should hear clicking when you move linkage to park. There is a distinctive click.
Switch S2 is on the other side. There is no audible click and that switch is very hard to get to-gear, spring, clutch gear. Then there will be potentiometer block. S2 switch is incorporated into that block. To get inside one has to drill out small brass rivets and be extremely careful not to damage sliders.
I hope this helps.

filon102 · #8 02-24-2012, 08:32 PM

Thx victor, btw i've made a comment on one of ur videos and u never wrote me back... just saying lol

Well, a while ago, I got news from BBA-Reman, they said the clutch was bad on the ETA, and they had one is stock re-manufactured, so i said "Ok, Ill take that."

I also measured the S2 out of my own curiosity, and looks like it did stay between ~1400ohms WOT or not... which is stupid cause it makes no sense calling it a switch if it has resistance either open or closed but W/E

Needless to say after the install, the car still runs like **** on idle so im guessing i pissed 500 bux for nothing... AGAIN...

Im going to hunt down vacuum leaks, ive made my own smoke machine and ill see how that will work... also checked OVP see if the relay itself was bad or the wiring, everything was good.

If I can't find the problem, Ill guess ill just take it to benz specialists

Victor300E · #9 02-25-2012, 09:46 AM

Yeah, those switches work with tandem with each other-one opens and other closes. My understanding of system work is that when idle switch is sensed computer control ETA plate to adjust idle air supply based on O2 sensor reading and coolant temperature. When throttle is applied idle switch opens and throttle switch closes and computer starts sensing potentiometers values to know where ETA plate is and determine engine load, along with other sensors O2 etc.

I'm sorry for not replying on YouTube videos. I don't have much time to follow on comments. I reply to all emails though.

Good luck with vacuum leak.

filon102 · #10 03-20-2012, 08:41 PM

Little update:

I took her around the block, in order to some how "break-in" the new ETA, so when I punched the gas pedal, the car automatically went from 4 cylinder cavalier to 67 camaro with straight pipes

(keep in mind it was around 9pm sunday nite lol)

So I took it back to my garage, look underneath the car, and noticed my exhaust pipe was split in 2 pieces... in the next 45 minutes, I pulled the exhaust in order to bring it to my work to get it welded and I noticed that the o2 sensor had 3 wires hooked up...

I was confused by this because most of the time, it should have either 2 or 4 wires (2 wires = signal, and 4 wires = heater circuit and signal). Long story short, It idles better but yet still got hick ups, like I would be coming up on a stop sign, idles fine, next stop sign it will run rough...

As of right now, I'm busy (moving, school, work) so I can't really work on the car, Im still going to look for vacuum leak with my home made smoke machine... I'll give that a try and let you guys know how it works out

ryno365 · #11 03-22-2012, 08:40 PM

I've got a '94 E320 with some very very similar problems to yours (filon) it seems. How was your's running though? Was the idle just rough all round, high, missing or what? I've been CURSED with a high idle problem. (BTW you haven't spent nearly as much sniffing your bugs as my pour soul, OVP, MAF, IAT, O2 Sensor, Idle Air resonance valve, coolant temp sensor, reman ETA and a few other odds and ends... not counting the new wiring harness a few year ago)
I get the error code for "idle control inoperable", do you think that I may be suffering from similar ETA woes as yourself?
I haven't found any vacuum leaks, but seem to have an abnormally high vacuum in the crank case for idle (15-1800 rpm).
Any and all thoughts are appreciated.

filon102 · #12 04-14-2012, 10:59 PM

Sorry, been out a while.

Yes im guessing its got to do with ur:

1. ETA or
2. your wiring ETA itself
3. Engine wiring

can you give me a code number and ill try looking it up on all data.

So, here an update. I've decided to hook up fuel pressure gauges to the fuel rail and see what pressure its operating on. It turned out to be

Closed Throttle with Vacuum 3.2 - 3.6 bar Closed Throttle without Vacuum 3.7 - 4.2 bar
3.2bar (46psi) - 3.6bar (52psi)
3.7bar (53psi) - 4.2bar (60psi)

My pressure was at 53-54psi at idle with vacuum line hooked up from the regulator to the engine intake manifold. when i detached the vacuum line the pressure jumped to 60-61 psi.

So then i took hand held vacuum pump and put like 20 inches of vacuum on the regulator and it went to ~52-53 psi.

What do you guys think? Restriction in the line? bad FPR?

P.S. Plus my fuel pump started leaking out of nowhere... wtf?