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  #1  
Old 06-01-2003, 07:03 PM
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Here's a toughie....(long story)...and the answer is......

'93 600sel, 200,000km on clock. A few weeks ago I had an issue where the car in the middle of a trip started to flood, I got the car to the clients, shut down, went back out later in the day, no start. Replaced sparks, car ran fine for a couple of weeks. Then on the Monday am trip to the client, in approx the same area, car did the same...surge, bog, surge, run rich. I got to a service area, shut down, the vapours in the exhaust caught fire out the tailpipe, rear bumper damage. Floated the car to the dealership, diagnosis... MAF on the right side (replaced). Got car back, headed back to the client, not quite as far this time, same issue... surge, bog, surge... float the car back to the dealer...diagnosis MAF on the left side (replaced). Got car back, worked around town, car does same again...float to dealer...diagnosis left ECU, replaced, Got car back, put about 500 highway miles on, same issue last night (Saturday). Fortunately I was close to dealer, car is now at dealer, no float this time.

Gentlemen....What could possibly cause the car to go to such a rich condition without tripping the MIL light? What would cause such a condition even after the 2 MAFs and 1 ECU were replaced?

The issue has typically manifested itself after at least an hour on the road at freeway speeds..( I do very little city driving)

I know that the service manager will be pulling his hair out on this one when he sees my car in the morning. Any suggestions will help, thanx in advance,
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A mercedes is an inanimate object and therefore must respond to logic and reason.

Last edited by mithra; 06-24-2003 at 09:09 AM.
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  #2  
Old 06-01-2003, 07:46 PM
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Hopefully one of the more knowedgable pros will repsond.

For sure, the dealer you've used is incompetent. Three trips and it's still hosed??

You mentioned mileage in kilometers, so I suspect you are not in the U. S. If you were, I'd call MB North America. Wherever you are, you will likely need to get the Mercedes dist. rep involved.
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  #3  
Old 06-01-2003, 08:09 PM
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I'm no expert in MB, nor do I know your car very well, but I would check the fuel delivery and return, perhaps something is getting stuck closed and results in all the fuel which should be returned getting dumped into the cylinders, this popped into my head after you mentined that the car works fine on the highway and starts acting like this when you get off the highway.

xp
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  #4  
Old 06-01-2003, 08:17 PM
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Dealer is following diagnostic results

Unfortunately, the diagnostic computer, ( i believe it is the STAR system), had indicated by the fault codes that these components were defective. The techs and the service advisor will be as perplexed as I, considering that on Friday at 4:30 pm, the diagnostic machine had indicated no faults after 5 days and 400 miles. By Saturday evening...the gremlins had reappeared!!!??!!!
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A mercedes is an inanimate object and therefore must respond to logic and reason.
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  #5  
Old 06-01-2003, 08:35 PM
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Fuel pressure won'y set a code right away.

I don't know what the diagnostic computer was telling them, but I take what they say with a grain of salt anyway. There is no such thing as a diagnostic answer from a diagnostic computer. It is only guidance.

Without a problem when the diagnostic is run, all one has is a few hints from the records of failure. No fault code is taken for certain. It is the basis for testing. If the problem is gone, substitution becomes the diagnostic test plan. They have so far eliminated 3 items from the possible problem causes. When they get the problem fixed I would suggest they replace the old parts that obviously don't contribute to the problem.
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  #6  
Old 06-01-2003, 08:48 PM
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Steve, Thanx

Steve, is there anything that you might suggest, the symptoms are ALWAYS: surge
settle down
surge
settle down
run rich
The economy meter will always fluctuate with the surging, then following the surging pattern will indicate a "full fuel " condition. When this happens the economy meter stays pegged even under a trailing throttle condition. When the issue manifests itself, the car will start, if shut off without any trouble. THe exhaust will be extremely rich smelling (blue smoke).

THe issue typically happens when I am on cruise at about 120kmh (70 mph) after about an hour or more of driving.

At any other time the car performs flawlessly, with no hint of anything untoward.

Thanx in advance
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A mercedes is an inanimate object and therefore must respond to logic and reason.
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  #7  
Old 06-02-2003, 12:38 PM
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Codes....

The following codes were identified this morning

LH2SFI 010 CTP (idle) recognition from EA, CC, ISC
constantly grounded

These were the codes that came up on the last attempt at repair.
On the last repair attempt, the tech also swapped the ECUs side to side to try and isolate the fault. When the tech swapped the ECU, the 010 fault followed to the other side of the engine, leading the tech to believe the ECU was faulty. Now the new ECU is exhibiting this fault.
As I indicated earlier in the thread, there were no codes after a week of driving, but there is now.
THe car acted up on Saturday night at about 1130pm. The shop cleaner moved the car Sunday morning at 6 am and the car ran fine....the car ran fine this morning when it was moved into the shop.
ANy suggestions/directions/hints would be greatly appreciated, thanx in advance
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A mercedes is an inanimate object and therefore must respond to logic and reason.
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  #8  
Old 06-02-2003, 03:28 PM
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Ask dealer to install fuel pressure transducer so you can monitor fuel pressure with a regular DMM during the event. I don't know if they would have it available. Fluke makes a good one, but it is about $300.
http://fluke.com/products/home.asp?PID=10101
The regular pressure gauge would require a hose in to the car, not safe!
Reg. Mike

Last edited by myarmar; 07-12-2003 at 10:05 PM.
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  #9  
Old 06-02-2003, 03:46 PM
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Would a damaged CAT cause this?
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  #10  
Old 06-02-2003, 04:49 PM
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What about this?

Hi there,
I'm no mercedes injection specialist, but on many other systems, the temperature sensor has the largest effect on the fuel mixture. A cold engine indication would be a high resistance, which an open connection would give you. I have seen this problem (open connection or defective sensor) on both throttle body and Bosch k injection systems. Possibly something to check would be the integrity of the wiring from the temperature sensor to the ECU. Both of these conditions should eventually cause an error code, however. Just something to think about...

Good luck!
Richard Wooldridge
'82 300D/4.3L V6
Etc...
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  #11  
Old 06-02-2003, 06:53 PM
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Thanx for replies

Mike, Yal, Richard, thanx for suggestions, last that I talked to dealership, the tech was checking the wiring harness to verify its integrity. The service advisor also indicated that he would also make things right for the unnecessary parts. I will post news as it comes available. Thanx guys.
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A mercedes is an inanimate object and therefore must respond to logic and reason.
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  #12  
Old 06-02-2003, 09:45 PM
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has this always happened in the same place on the autobahn?

if so, do you notice any microwave towers nearby. or any military antenna farms.

i used to experience a similar problem when driving near an antenna array. some strong radio frequencies were infiltrating the computer and glitching it.

if you suspect this could be your problem, you have a rfi/emi infiltration problem that can only be solved by better shielding your engine management computer.

alternatively, what are the weather conditions when you experience this problem. rain, perhaps. anyway, you might have a problem with a circuit board.

if either of these are your problems, you will need to grab the dist rep and take him for a ride into the area where you experience these problems. otherwise, it will never be soluble.

good luck.
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  #13  
Old 06-02-2003, 10:05 PM
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Albert,

It is funny you stated the question regarding micorwaves .... I was thinking of that also. Long shot of course.

Haasman
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  #14  
Old 06-03-2003, 01:17 AM
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Back in the early 80's I worked in a mainframe computer environment. Among others, we had an NCR system whose DASD was being damaged by an Air Force radar unit about 15 miles away. The bit patterns on disk were being modified by the AF radar sweep.

Who knows?
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  #15  
Old 06-03-2003, 02:34 AM
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not a long shot.

you would be astonished at what is out there.

i have been mapping this stuff in my area for many years.

unbeknownst to most, there are a lot of secret antenna arrays and if you drive near them, with an unshielded engine management computer, you might find your engine shutting down. inexplicably.

this is one of the reasons that i refrained from acquiring more computer-oriented vehicles. needless to say, after i acquired my 1997 w140c i began to get a picture of rfi/emi sources in the texas countryside.

there is a lot of secret stuff out there. and the power of them is such that they can glitch a vehicle's computer. and unless you are driving that route routinely, and experiencing that problem routinely, you might never guess what is the source of your problem.

but if it happens all the time, in the same area only, the vehicle is not to blame. go complain to the mod.
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