Error codes 5, 7 & 9 on '94 E320
 

After driving my new to me E320 back from Fl without a problem, yesterday the car had a rough idle and the check engine light came on. The error codes fashed 5, 7 & 9 although the car runs better but still doesn't feel smooth. Any help is appreciated, thanks.

1 No fault in system
2 Oxygen sensor inoperative
3 Lambda Control inoperative
4 Air injection inoperative
5 Exhaust Gas Recirculation (EGR) inoperative
6 Idle Speed Control inoperative
7 Ignition System failure
8 Coolant Temperature Sensor - Open or short circuit
9 Intake Air Temperature Sensor - Open or shor circuit
10 Voltage at Air Mass Sensor too high or low
11 TN (RPM) signal defective
12 Oxygen Sensor heater open or short circuit
13 Camshaft Position Sensor signal from - EZL/AKR Ignition Control Unit defective
14 Intake manifold pressure at start too low
15 Fuel throttle information defective
16 Idle speed information defective
17 Controller Area Network (CAN) data exchange - malfunction between units
18 Adjustable Camshaft Timing Solenoid - open or short circuit
19 Fuel injectors - open or short circuit, or Emission Control System Adaptation at limit
20 Speed signal missing
21 Purge switchover valve - open or shot circuit
22 Camshaft Position Sensor signal defective
23 Intake Manifold Pressure with engine running too low
24 Starter ring gear segments defective
25 Knock Sensor defective
26 Upshift Delay Switchover Valve - open or short circuit
27 Coolant Temperature Sensor deviation between circuit No. 1 and sensor circuit No. 2
28 Coolant Temperature Sensor (Coolant Temperature Change Monitor)

My guess is that you have a problem with your EGR valve or a blocked hot inlet pipe where it enters the intake manifold, and that this one fault is causing the other codes to pop up.

When did the car experience the rough idle? At start-up and when cold, or after it has warmed up?

First, the original EGR valves were defective and will stick. There is a TSB that addressed this issue, and the part was updated. I also believe the part number was changed.

There is a way to check if your EGR valve is not working due to a plugged up hot inlet pipe, or if the valve itself is sticking (sticking open or closed):

The ECU sends an electric signal to the switch-over valve which opens the EGR valve to engine vacum. The vacum pulls open the diaphragm on the EGR, allowing some of the exhaust gas to recirculate back to the intake manifold (thus the name, Exhaust Gas Recirculation). The purpose is to reduce smog emissions.

The ECU will not send this electric signal at idle or wide open throttle, or until the engine has warmed up. So, if you hand pull about 12" of vacum on the EGR at idle with a warm engine, you are creating a very lean condition (vacum leak) and the engine will attemp to stall and run very rough. This tells you not only that the EGR is opening, but also that the hot inlet pipe is not completely plugged up. If, when you pull vacum and nothing changes, then you know that either the valve is not opening up, or the hot inlet pipe is completely blocked.

Now, release the hand vacum and the EGR should snap shut. Engine should smooth out. If the EGR sticks in the open position, the engine will run rough at idle until the engine warms up.

There is another possibility that the diaphragm in the EGR itself may leak and cause an internal leak. The test for this is to see if the hand vacum will hold the EGR open for a period. It is common on vacum leaks to not be as noticeable with a cold engine as the engine is running rich and that helps off-set the added intake of air caused by the leak.

Steve Brotherton wrote an article and posted pictures on the blockage of the hot inlet pipe at the intake manifold. Here is alink to the article. It is posted on the DIY link at the top of the page:

http://www.peachparts.com/Wikka/EngineControls

Steve Brotherton and Benzmac have posted that they perform the cleaning of this pipe every 60,000 miles.

I have also read a post by Benzmac that he also installs a new pipe these days as it is cheaper to do so than to take the time to clean it out.

There is a lot in the archives on cleaning out this pipe if you try the search function.

<<When did the car experience the rough idle? At start-up and when cold, or after it has warmed up?>>

At start up when the engine was cold. After that instance, I have not had any rough starting however the engine does not feel completely smooth. Thanks for the tons of info, I 'll be checking the EGR this weekend.

Would the engine wiring harness have any effect on these error codes as I believe that that it is the original.

Doubt 7 and 9 are related to EGR fault
But 7 can be coil tower resistor connectors [ thus bad idle]and 9 can be IAT sensor unplugged at cross-over pipe or someone unplugged it while running and did not reset the code..
Also, on code 5, if you find egr valve does operate normal w/vac test, then look at the plastic vac line that feeds the SOV for EGR circuit...these are famous on 104s for breaking from heat fatique and will pop a 5 code
[ front of engine, under plastic cover]
I always eliminate the plastic tubes and go full rubber....

From Another thread, Arthur you said,

<<For the benefit of all, I have posted this Recall Campaign # 95-0131 for all the models w/sticking EGRs.
Please print out a copy as I can leave this posting for only 1 week. [ sorry, I just can't tie up my limited space]
Arthur
http://members.aol.com/ajdalton7/egr1.jpg>>

Does that mean that Mercedes Benz will replace this EGR valve free of charge?

Benz recall campaigns are a little tricky
They don't send out a recall, but rather , they tell the dealers that if a car is in for service, to check the date numbers on the egr and if it is in that production, to change it.
The car can be there on an EGR complaint or just routine service...
They do this on a few issues, rather than owner notification as one sees w/other manufactures..
The part # was not changed, just a production date coded ones were either defective from the manufacturer or there had to be a tolerence change during production [ my assumption], as the complaint was 'STICKING'..
If the dealer found any, they were to RED paint dot them so other dealers knew the new part was installed....
So, I guess it is up to them, sort of..
Gilly might be able to help on that info...
As you can see, I no longer list that jpg [ I have no space]
But , if you would like a copy, email me and I will send one out in jpg for ya..

<<Doubt 7 and 9 are related to EGR fault
But 7 can be coil tower resistor connectors [ thus bad idle]and 9 can be IAT sensor unplugged at cross-over pipe or someone unplugged it while running and did not reset the code..>>

This car is new to me, could someone tell me where is the tower resitor connectors are and where the IAT sensor is? I will be roto-rooting the pipe connecting the EGR to the intake manifold this weekend. Thanks.

Resistor connectors are under each coil . They connect the coil to the plug [ there are 3 of them] They are routinely changed when channging plugs due to their high fail rate and low cost..
The IAT sensor is in the cross pipe , between the MAF and the intake.
If it is open, disconnected , etc, that is your problem..
If not , post findings and I will give you the temp/resistance chart for checking the values for spec.

Are these the coil resistor connectors?

NO
They are under each coil...
the coils pull up and the resistor connects the coil to the plug..

Are these the ones, I'm having trouble finding the part to order...I just ordered a Mercedes W124 owners' workshop manual (Brooklands) to get a an overview of the 94 E320, thanks.

No

They are called "Spark Plug Connector "
There are 3 of them and they are under the coils..

FastLane -- under- engine electrical

the latest...
 

There's 3 different types under that heading, all without pictures, of course, one says:

Spark Plug Connector
for Direct Coil Ignition
As used on M 104 motors,for cylinders 2,4 and 6. Fits directly on to coil . As used on M 111 motors,for cylinders 2 and 4. Fits directly on to coil .

The other says:

Spark Plug Connector
3 per car
Optional with 000 156 75 10.

these WorldPac inventory programs that everyone uses are horrible...they're ambiguous and never tell you what you need to know.

I just got my VMI from the local dealer. I just bought the car with 69K miles. The pneumatic actuator was done at 31,709 miles, the water pump at 32,535 miles along with temp sensor element, the engine harness was replaced at 42,877 miles (goodwill!) and cylinder head gasket was done at 66,203 miles (goodwill!). The orinial owner must have have a good relationship with his dealer. The local MB dealer just told me they would replace the EGR on the recall! Hopefully they won't charge me $400 to clean out the hot inlet pipe! I better clean it out myself because the CE light is triggered and I want to clean up everything BEFORE they combine it the EGR replacement and I get a whopping $500 bill, you know how service cost can esculate at a dealership. Thank you so much Arthur. Now I have to get a speedometer cable.

<<There's 3 different types under that heading, all without pictures, of course, one says:

Spark Plug Connector
for Direct Coil Ignition
As used on M 104 motors,for cylinders 2,4 and 6. Fits directly on to coil . As used on M 111 motors,for cylinders 2 and 4. Fits directly on to coil .
>>

Yeah, very confusing

But , that is the part I was referring to..

And they used to be $8 , too
I would call Phil at fast- lane .. I am sure he will have the correct #s..

hot inlet tube...damn!
 

Paul, now I can't wrench the tube off because there is no access so I take off the EGR valve and I can't seem to extricate it off the bolt studs. Now how do I access the hot inlet pipe? Is the entry on the underneath side of the EGR valve? Is there a small entry? As I cannot flip it over to see it, is there a small opening to insert my cable to roto-root the hot inlet pipe? Thanks, guys.

Ok, I finally got around to swapping the plug connectors and the spark plugs while I was at it...and I NOTICED that the middle ignition coil is DIFFERENT from the other two?! This doesn't seem right...I guess I have to order an ignition coil to swap out the suspect "wrong" one. I can't believe some Mecedes dealer put in the wrong part, and the spark plug is black?! Please advise guys, thanks...

All's well...
 

OK, I swapped out the resistor plug connectors and reset the codes. The engine runs well and the CE light has not come back. Thanks suginami and Arthur for your help. Now the damn Becker cassette player won't accept the theft code as I can't punch a "7" when I diconnected the neg battery cable to work on the engine! Oh well, it give me an excuse to buy a CD/MP3 player for the car. The Mnroney Label for the car listed a high performance sound system as an upgrade option.