High Idle On E320
 

I would like to start off by thanking everyone who has helped me with all the problems that have suddenly overcome my 94 E320.
Thanks!
Now i just have two more things to fix. I replaced the fuel pressure regulator and the car now starts up fine and there is no more check engine light. The problem is high idle, about 1400 rpm and no kickdown under 40 mph. I have tried adjusting the bowden cable and the throttle cable with no success. This one is really stumping me. Should i adjust the idle screw? the problem started after i cleaned the throttle body with sea foam. Any help is welcome.
Thanks!
Adam

Well, first I would suggest seeing if there are any codes in CC/ISC (I am presuming that you don't have EA) (electronic accelerator, cruise control, idle speed control).

With a scanner I would like to see how far the throttle is opening and I sure would be sure of those linkages. The throttle assy goes to a fixed openning under some "limp home" conditions (limp home is a term for the default "basic" condition the system is designed to use when it can't trust itself).

I am pretty sure that the codes can be gotten by the impulse method, seems like pin 14 but thats from memory, definitely verify.

Pin 14 will get to it.
E320-124 chassis do have AE/CC/ISC module.

I have the codes , if needed.....

Okay, so what do i do, Do i need to jump pin 14 to retrieve any codes or do i need to have it hooked to a scanner for further diagnosis?
Thanks,
Adam

BTW: Im not sure what you mean by electronic accelerator. It does have a mechanical linkage to the throttle body. Does this change things od does the "electronic accelerator" have a different function?

A scanner would be nice (bg). That car will have actual values and maybe some activation available through a scanner.

But, As I replied I think it can be checked for fault codes by the impulse counting method. There have been many posts on making impulse testers. If you have a scope or voltmeter it can be done using the technique I describe in the DIY article "Evaluating engine controls".

Steve,
I have been checking the codes with that switch/LED box next to my battery. so far i have had all of them dissappear. Are these the same codes you are talking about or are they different codes?
Thanks for your Help!
Adam

Did you read the article?

The push button arrangement was constructed to facilitate reading the DM (diagnostic module - a totally US device installed to track US mandated emissions failures). You ONLY can read the DM with this technique.

Your car should have the 16 pin diagnostic socket and if you look in the holes, everyone that has a metal connector represents a system that can be evaluated by a simialr technique. Only problem is one must set up the light ones self for each system. One must also know what each system represents and eventually have a code list for the read out.

Steve,
Oh okay, I have read the article before but i must have not understood that part. I will go back and read the article and then test pin 14 for fault codes.
Thanks again!

Make the tester and as Steve says - test every hole that has the metal connector down in it then come back with the reading on each hole.

After i ground a pin for 3 seconds, what do i hook the test light to? pin and ground?

Here is the tool you can make to get to the other codes.
It shows what pins to plug into your diagnostic socket. [ pin #14 for your AE/CC/ISC module]
This is just a copy of the circuit Benz uses to get to the emmissions module with there built-in led, so the code retrival procedure is the same as the built-in one , except you can now move to the different modules....

http://members.aol.com/ajdalton7/e320led.jpg

Arthur,
Thanks for the schematic! I'll put one togather tonight if i can find myself a good momentary pushbutton.
Thanks Again!
Adam

If you can't find a momentary one, a regular on/off will work just to get you your codes . You will just have to switch it on/off for the required 2-3 secs.

A clear plastic film can makes a good chassis/container for the tool. You can run the leads out a hole in the bottom and mount the sw. in the cover. Can still see the led through the clear plastic and it keeps everything contained nicely.....
Have also used a plastic test tube and even a small plastic flashlight case with the led behind the lens.....
Spend a little time on making it a permanent tool , as you will use it many times....

I have an assortment of project boxes and and LED's from Radio shack. I plan on making it a premanent tool. Definately worthy of the tool box! :D

I have made several for some friends and a few members. We have found that it is best to keep the leads SHORT [ 4-5"s] so
it can be thrown back into the Tool Boxy without the wrapping up leads hassle,,,
Good Luck .
If you need the codes , get back to one of us...

Thanks for the tips! I would love to have a list of codes. Maybe someone could post them in the DIY section for all to have. :cool:
Adam

Maybe someday the DIY section can start accumulating code info. There is a real problem with such. The code book from MB for model years to 1993 is 260 pages and those were the simple models with fewer control units and less internal diagnostics.

The ability to know which chart to use for each system/model is a skill all to its self.

Send me your email and I'll send a pdf doc on EA/CC/ISC.

Here are the codes i pulled of all the pins!
Pin#3: 6 and 12
Pin#7: 1
Pin#8: 8
Pin#14: 2 and 11
Could someone please turn this into english for me.
Thanks A Lot!
Adam

TTT
I'm anxious!

AS for pin 14 which is for cc,isc,ea. Code 2 is for the e/a unit N41. Most early models had the harness problem inside the e/a , baiscally the harness falls apart and you have to replace the ea,cc,isc unit. Dont remember code 11 . This is off a 16 pole connector I take it and not a 38. I have replaced alot of these units as well as engine and starter harness' on the e-320s. :D

I think i understand,,, I need a new wiring harness right? I heard there was some sort of recall/warranty on these wiring harnesses correct?
Thanks Again!
Adam

I got about six items into the 14 item description of code 2 and erased it last night when I realized that repeats were included and the the difference was in the testing; to voluminous too possibly write.

Code 2 via the impulse counting method can be further deliniated to six separate codes if one uses a scanner. Erik is right the problem is likely in the throttle assy EA/CC/ISC, but a number of the items under code two refer to the closed throttle switch.

The code 11 is again 4 possible codes with HHT. They all revolve around : fuel safety shut-off and closed throttle recognition.

I would say the problem is that the controller is having a hard time deciding where closed throttle is.

I doubt that this is covered by MB, but consider the throttle assy an investment as if yours is original its basically a failure in waiting.

<<
300E EXPERT

Registered: Apr 2000
Location: Lake Geneva, WI
Posts: 626
Here are the codes i pulled of all the pins!

Pin#3: 6 and 12 >>

PIn 3 is the emmisiions module and the same codes you can get with the built-in sw/led.
6-idle speed control inoperative
12- O2 sens heater open/shorted.

Pin#7: 1 >>

Pin 7 is a/c module and 1 flash is "No codes stored"

Pin#8: 8 >>

Pin 8 is HFM-SFI module .
8-ISC system

Pin#14: 2 and 11 >>

Pin 14 is ea/cc/isc module
2-cc/isc control module
11-closed throttle recognition sig- fuel shut off

As you have cleaned the throttle , it is possible to trip some of these codes if you hand lift the throttle cable. This will trip a
"Limp home Code " and must be cleared.
If you have unplugged the o2 sens, the same can apply..
So, write down your existing codes and erase them.
Now start from scratch to obtain the correct codes.
From there , a HHT scanner will give you a better, more detailed diagnoses...

As said, check wire harness closely....

And you may want to take SB up on the pdf file for future reference....

I see you made the tool ????

I hate to interject, but the "ea/cc/isc" unit and the wiring harness issue.

Is the ea/cc/isc unit another name for the throttle actuator?

Does the actuator go bad or just the wiring harness?

Can the wiring harness be replaced, or do you replace the whole throttle actuator?

It's just about $1,000 to replace the throttle actuator.

Yes the ea,cc,isc is the throttle actuator and you replace the assy. I have about 10 old ones still laying aruond here that I show customers.:D

Hmmm, Well, Is it safe to say that replacing the throttle actuator will solve the problem for sure or should i have a technician dig a little deeper? I did get code 11 to clear but code 2 is still there. From what i am seeing the idle is just high. Is this going to cause any adverse affects if i don't repair it? Is there any further diagnostics i can do myself? A grand for a throttle actuator is a little hard to stomach!
Thanks!
Adam

You can have a tech read the live data and then advise you of what to do.:D

So basically, the throttle actuator on early M104's (93-95??) need to be replaced often because the wiring harnesses on the actuator's go bad?

Is it because the insulation on the wiring degrades just like the frequently discussed engine wiring harnesses?

Is there any other part of the throttle actuator that fails, or is it just the wiring harness portion?

Based on Steveb's comments, is it something that will go bad eventually, even if it hasn't yet?

I bought a throttle actuator (from Fastlane) to cure my idle problem (idle was hunting up and down). Didn't install it because I was unsure of my diagnosis from reading the archives. It turned out to be a vacuum leak at the intake manifold.

I still have the actuator at home and was going to sell it or return it. I wonder if I should keep it and install it now, or wait until the part actually goes bad.

Or, I could sell it to Adam Bourassa. Wanna buy it from me? We have the same engine.

It is my opinion that the original throttle assy's were less durable than what is being sold now. I did a number check and there is two possible throttle assy's. One for cars with ASR and one for cars without.

Because this device is a complicated mechanical device with many moving/wearing parts and potentiometers, I suspect that they will generally give problems. I can verify that this similar part is having problems on BMWs, VWs, Volvo's, and Saabs, having fixed and read about fixes in all these marques.

If Paul's unit was the right unit, seems that you two ought to get together and fix a car.