Almost left me stranded - PeachParts Mercedes-Benz Forum

wbrian63 · #1 04-23-2007, 09:02 AM

'92 300SE

Road trip from Houston to Dallas last weekend. Ran like a top all the way up (except for the usual climate-control shenanigans). Ran fine Saturday & Sunday morning around Dallas.

Returning home on Sunday, noticed a slight miss on occasion at speed (75-80mph). Initially thought it was just my imagination, but went to accelerate hard to move around a dummy in the left lane and definitely noticed the miss. Worse the higher the RPMS.

Made it back to Houston OK, but there were times I was wondering if it would or not.

Car idles like a dream - in gear or in park. Open the throttle while in park and the missing starts at about 1800-2000 RPM and gets worse from there.

Pulled codes from all the systems I could think - here's what I found:
Pin 4 - LH-SFI - no codes (1 blink only)
Pin 7 - Electronic Accelerator (6 & 11)
Pin 8 - Base Module (6)
Pin 13 - TNA (11)
Pin 17 - Distributor - no codes

From AllDataDIY, the numbers mean:
Electronic Accelerator
Code 6 for the EA points to Starter Lockout/Backup Switch
Code 11 indicates a problem with the Fuel Safety cut-off signal to the LH-SFI module.

Base Module
6 indicates a jammed A/C compressor or broken poly belt. This is an old stored code I failed to clear.

Pin 13 - I'm not able to find out what code 11 means here.

I searched this forum for the TNA-Signal (pin 13) and several posts indicated problems relating to a failing/failed crankshaft position sensor.

I'm hoping this is something simple like one of the fuel pumps has quit, or the filters are clogged. I did purchase gasoline just before I left, but it was from a Shell station on 35 @ Mockingbird, so hopefully bad fuel isn't the issue.

I've just found a TSB article on AllData that indicates code 11 for the EA indicates "Engine Hesitation During Acceleration/Misfire Under Load" with code 11 ties to a failed Electronic Accelerator actuator. I have noticed on occasion that the car bogs somewhat coming off the line under hard acceleration, and other times it just goes like stink. Hopefully the EA isn't the problem, because that's $$$, but at least I don't have a car payment.... The only "good" thing about that part is it's like 10 minutes to R&R, so at least I don't have to pay huge labor dollars to swap it.

I dropped the car at my local indie this AM since the DTC's didn't point me in any particular direction.

Any ideas, or others willing to offer sympathy?

Falsapartenza85 · #2 04-23-2007, 04:15 PM

Well, I had one of these beasts, until it was stolen. But thats another issue....

Personally, i would check the Engine wiring harness, if you haven't already replaced. As well, check the Air Sensor on the intake cleaner. Check all wires for arking and brittle insulation.

Let me tell you, if it was a throttle problem, it would not accelerate. Mine would just die, would not accellerate. I would re-start, then she would go fine for a bit, then cut off, it would run, but no matter how i pushed on the pedal, i couldn't get her to go forward- the engine wouldnt rev.

Keep me posted, this looks like an interesting problem...

How many miles do you have on her????

wbrian63 · #3 04-24-2007, 12:36 AM

Indie mechanic got it fixed in a jiffy. Cap and Rotor were all but toast.

Worst part about this whole mess is that I had already purchased a Cap & Rotor, just didn't have time to install them.

The mechanic is one of those that won't install customer-supplied parts, so I had to pay 1.5 hours work (1 hour diagnosis + .5 hour install) on the cap/rotor, plus part cost at full list price.

I could have fixed this problem in my driveway last night for only the cost of the cap and rotor at wholesale.....

grrrrr.

Anyway - running like a top now - even better than before.

Texholdem · #4 04-24-2007, 02:47 PM

Quote:

Originally Posted by wbrian63

Indie mechanic got it fixed in a jiffy. Cap and Rotor were all but toast.
...
I could have fixed this problem in my driveway last night for only the cost of the cap and rotor at wholesale.....

grrrrr.

Anyway - running like a top now - even better than before.

What is the function of cap and rotor?

Thanks!

Falsapartenza85 · #5 04-24-2007, 06:58 PM

The Cap and Rotor distribute the electrical charge to each of the 6 spark plug wires, which then send the charge to the spark plug, thus making a spark that ignites the gasoline. It is ignition and firing related. Very common to find a greenish residue when you remove the cap and rotor. It is caused by oxidation on the internal copper parts.