95 E320: Rough idle above 4000RPM - Page 3 - PeachParts Mercedes-Benz Forum

EricSilver · #31 08-19-2006, 11:37 AM

Quote:

Originally Posted by Arthur Dalton

Why don't you just press the code button and see what code is stored that tripped ther CE
Search Code tool

While waxing the car I tried that.

Pushed button, LED illuminated, then went off when I let go of the button. No flashes returned. Held button down for several seconds and let go. No flashes returned.

I have not restarted or driven the car yet, but will see if the CEL is still on when I do.

Arthur Dalton · #32 08-19-2006, 11:41 AM

There is a specific retrieve LED/SW procedure.. check the archieves.
The trick is to hold the button for 2-3 secs for code ECU initiation.
If you have a CEL, you HAVE a CODE.

EricSilver · #33 08-19-2006, 10:55 PM

Quote:

Originally Posted by Arthur Dalton

If you have a CEL, you HAVE a CODE.

Not any more. The CEL is off.

Evidently, when I was trying to test it earlier, I held the button long enough to clear the code. Went for a drive a while ago, and the light was off. (I hope it is permanent.)

I am surprised that the previous owner, and his repair shop, were unable to clear it over the course of three years. Is the "holding the DM button" some obscure method that few people are aware of?

Arthur Dalton · #34 08-20-2006, 06:36 AM

< >>

I don't know anybody who doesn't know about it..

..but don't assume the only way to get rid of a CE is with that procedure. ...it will also clear itself after the fault has been rectified. Clearing it with the button procedure usually results in re-occurence b/c you have not fixed the fault.
CE lamp is there to TELL YOU that a problem/fault exist and the Engine Management System wants it FIXED because the problem is interferring with the ECUs capacity to control the systems mapping parameters. ...in other words, the car is not going to run as effeciently as the design is capable of doing and it is also not going to pass an emmissions test b/c something is broken or out of spec.........the codes just help you get an idea of what part of the complex system the ECU thinks you should be looking at...or , at least , which part of the system has detected a fault and reported that back to the ECU for further evaluation.. It DOES NOT mean to change that part
mentioned in that code.

EricSilver · #35 08-20-2006, 09:00 AM

Because the CEL was on so long, and a number of things were done since it appeared (new 02 sensor, new wire harness) and because the DM does not flash back any fault codes at all, I am hoping it was a quirk.

My last emissions test scores were
** HC ppm: 10 (Limit 125)
** CO%: 0.00 (Limit 1.00)
so am not concerned about that as a problem.

If the CEL returns I will prepare to do some further testing (using your code reader) if that happens.

Speaking of quirks, the oil pressure sender issue is another. On cold start, the oil pressure needle pegs just at the lower edge of the 3.0 line. Once the coolant temperature crosses 80 there is a tap/click from the dash, like a tiny hammer hitting plastic, and the gauge then pegs well above the 3.0 bar line.

tvpierce · #36 08-20-2006, 09:21 AM

Did your car pass the emissions test with a CE light illuminated?

I thought that was an automatic failure?

(I'm not in a state that requires emissions testing. But my understanding was that all systems had to be functioning properly -- and that checking for trouble codes is part of the emissions test.)

jp

EricSilver · #37 08-20-2006, 09:42 AM

Quote:

Originally Posted by tvpierce

Did your car pass the emissions test with a CE light illuminated?

I thought that was an automatic failure?

(I'm not in a state that requires emissions testing. But my understanding was that all systems had to be functioning properly -- and that checking for trouble codes is part of the emissions test.)

jp

Yes it did, and when codes are checked no faults are found. The service tech says that the codes sometimes will not reset. Also, given the odd behavior of my oil gauge, I would not be surprised if there is an electrical/ground fault in the instrument cluster itself, which may have contributed to that.

Arthur Dalton · #38 08-20-2006, 10:48 AM

<>

Be aware that the tool is used to get codes from the Other systems of the car.
The built-in LED/SW combo only gets codes from the Emmissions Diagnostic Module [ DM] and these codes are ONLY codes that effect emmissions. You use the tool when looking for other operating codes [ such as ignition and fuel related system]..which can be stored without you knowing they are there b/c they do not trip a CE lamp. [ which is why we make the tool] The tool is nothing more than a copy of the actual built-in one, which lets you expand the cababilities of owner code access [ unfortunately, these late 24 chassis are the last with this feature and anything later requires an 0BD2 scanner].
Many codes [but not all]that finally result in CE activation are actually faults that originate in other systems that are finally recognized by the DM as effecting emmissions , so access to these other modules is a recommended technique in tracing down other faults..a perfect example would be a code 23 from pin 8 [ ignition module].. this would indicate a mis-fire code on a particular cylinder that the driver may notice well before the mis-fire finally got bad enough to filter the info back to the DM b/c it was effecting emmission specs. The tool would immediately pick up this type fault if the HFM/SFI module was checked for codes ..way before the DM would trip the CE............
The main culprit for late 124 false codes stored in any of the modules is usually a bad wire harness... once that has been replaced , these systems work fairly well, but no where as well as later 0BD2 systems.

EricSilver · #39 08-21-2006, 10:22 AM

Got some results:

CEL came back on today. Did the LED test and it flashed 5: EGR.

Time to clean the EGR pipe, one of the "most likely To Do" tasks on the list I made when I got the car.

I know of the drill & speedo cable, and the bicycle brake cable methods, and will give one of those a go -- unless I find an easier method.

gmercoleza · #40 08-21-2006, 10:37 AM

Quote:

Originally Posted by EricSilver

While revving the engine in idle this morning, it became rough just after 4000rpm.

I just noticed this. A little OT, but you should know that revving an unsprung engine to high RPMs can cause damage. RPMs of 4K, 5K, 6K, etc. should only be reached while the engine is under load. Again, sorry if off-topic.

Arthur Dalton · #41 08-21-2006, 11:06 AM

<
Time to clean the EGR pipe, one of the "most likely To Do" tasks on the list I made when I got the car.
>>

Don't assume EGR tube blockage until you have tested it. There are several other EGR faults on 104s that will bring u a code 5. Along with a Factory TSB part up-grade for EGR code. I will post a basic EGR flow test , if you are interested in diagnosing the fault before you go for a tube blockage repair.
Or go for the possible blockage and see if that solves it ..and if not, then repost you have the CE/code 5 again ant then you can do the flow test.

EricSilver · #42 08-21-2006, 11:34 AM

Quote:

Originally Posted by Arthur Dalton

Don't assume EGR tube blockage until you have tested it. There are several other EGR faults on 104s that will bring u a code 5. Along with a Factory TSB part up-grade for EGR code. I will post a basic EGR flow test , if you are interested in diagnosing the fault before you go for a tube blockage repair.
Or go for the possible blockage and see if that solves it ..and if not, then repost you have the CE/code 5 again ant then you can do the flow test.

I'll wait for your flow test.

My "clogged pipe" assumption is based on the "most likely" scenarios I've read in various EGR threads. If that turns out to be the problem, I'd probably prefer a tube replacement over a cleanout, since both seem to be equally tedious DIY jobs.

EricSilver · #43 08-21-2006, 11:35 AM

Quote:

Originally Posted by gmercoleza

A little OT, but you should know that revving an unsprung engine to high RPMs can cause damage. RPMs of 4K, 5K, 6K, etc. should only be reached while the engine is under load. Again, sorry if off-topic.

As soon as I got to 4000 rpm I stopped -- because of the misfire. Only attempted it twice, so I suppose I am OK.

Arthur Dalton · #44 08-21-2006, 11:41 AM

Quote:

Originally Posted by EricSilver

I'll wait for your flow test.

My "clogged pipe" assumption is based on the "most likely" scenarios I've read in various EGR threads. If that turns out to be the problem, I'd probably prefer a tube replacement over a cleanout, since both seem to be equally tedious DIY jobs.

I will post the procedure as soon as I find it in the Archieves .. I did a complete DIYer article on it a couple of years ago..hold on, it's comin'..

.... and , Yes, If you do find you have to get into the blockage, you do want to go with the new tube as that eliminates the problem rather than just cleaning it every time...

EricSilver · #45 08-21-2006, 05:45 PM

Quote:

Originally Posted by Arthur Dalton

I will post the procedure as soon as I find it in the Archieves .. I did a complete DIYer article on it a couple of years ago..hold on, it's comin'..

Is this the procedure? (From a 2004 post of yours):

Although there is a reasonable chance that the egr tube is blocked,[common 104 prob], an easy test for vac. flow is to simply apply some vac [ hand pump or vac source] to the egr while at idle. This opens the egr and will cause the engine to stumble..[ go lean]...if it does ,the tube is not blocked and other parts of the egr system are suspect...