Weird hesitation while starting, 1996 E320 M104, should I worry? - PeachParts Mercedes-Benz Forum

aTOMic · #1 03-02-2011, 01:32 PM

275K miles, haven't changed the (Bosch Copper) plugs in a while, could that be it? It's like the engine encounters a strong resistance (for about 0.5 seconds) while the starter is turning it, but it does start on the same turn of the key . Not every time, warm/cold doesn't matter, but getting more frequent

. (new, not rebuilt) Bosch starter in 2008. Idle hunts a bit when cold, not much over 1500 RPM . No reverse, doubt that matters but you never know.

Ferdman · #2 03-02-2011, 04:30 PM

Spark plugs should be changed every 30,000 miles. If it's been well past that point it would be a good idea to replace them ASAP, then go from there.

aTOMic · #3 03-02-2011, 07:18 PM

I don't think it's been that long, but close, thanks for the reply. I have new plugs but I keep waiting for them to install themselves to no avail.

I forgot to mention the red herring... I have BYPASSED the NSS (Neutral Safety Switch) by jumping the gray/rose wires under the hood, that could affect the engine management I assume, though not while starting because the bypass makes the car think it's in P or N.

If this was an old car I'd check the timing. Sounds like an engine with too much advance. No knocking on mid-grade gas though.

Ferdman · #4 03-03-2011, 05:56 AM

That engine requires premium grade gas to perform properly. Recommend installing new spark plugs and switching to premium grade gas. The Owner's Manual and the fuel filler cap door advise using premium gas only.

Texholdem · #5 03-03-2011, 10:03 AM

May I ask why you bypassed the NSS?

Quote:

Originally Posted by aTOMic

...
I forgot to mention the red herring... I have BYPASSED the NSS (Neutral Safety Switch) by jumping the gray/rose wires under the hood, that could affect the engine management I assume, though not while starting because the bypass makes the car think it's in P or N.
...

aTOMic · #6 03-03-2011, 11:27 AM

Quote:

May I ask why you bypassed the NSS?

Yes you may.
Because it froze rendering the car stranded every time the temps went below freezing; the cowl drain drips off the transmission and onto/into the switch, a common problem if I recall from my extensive searching and yet another thing I plan to fix when I get the trans out to fix reverse. RE the drains, I vacuum each drain with an appropriately sized hose monthly, since the indestructible leaves from our trees clog them; they all (1 ea fender and the upper and lower cowls) seem to be open. My NSS jump (which is temporary) is more fully described here, on page two. http://www.peachparts.com/shopforum/showthread.php?t=256907

Quote:

That engine requires premium grade gas to perform properly.

Could that cause the symptom I described?
You have a valid point, however it happens with both grades; I put mid-grade in last time because 93 was $3.60 and 89 was $3.18, up 60 cents almost overnight. Also, it was only 3/4 tank, but I agree these cars "get mad" with any deviation from the norm. Moment of weakness, please forgive me. Normally use Premium only.

Thanks for the replies gentlemen!
-Tom

Texholdem · #7 03-03-2011, 02:40 PM

Quote:

Originally Posted by aTOMic

Yes you may.
Because it froze rendering the car stranded every time the temps went below freezing; the cowl drain drips off the transmission and onto/into the switch, a common problem if I recall from my extensive searching and yet another thing I plan to fix when I get the trans out to fix reverse. RE the drains, I vacuum each drain with an appropriately sized hose monthly, since the indestructible leaves from our trees clog them; they all (1 ea fender and the upper and lower cowls) seem to be open. My NSS jump (which is temporary) is more fully described here, on page two. http://www.peachparts.com/shopforum/showthread.php?t=256907
...
-Tom

Hi Tom,

in your post http://www.peachparts.com/shopforum/showthread.php?t=256907 you "jumped from #2 to #4 with a 1 inch long piece of 22 ga wire" of the X22/1 connector whereas Jeremy, who gave you the tip, said "To bypass the NSS, cross the violet and violet/white wires."

that seems unclear to me, crossing #2 to #4 could mean exchanging the two wires while jumping could mean leaving the wires alone and additionally connecting #2 with #4.

Thanks!

aTOMic · #8 03-03-2011, 07:55 PM

May I ask why you ask, Tex?? Have you a similar problem, or do you just hunger for information??

He meant jumping. To answer your question, I left them alone and removed the top of the connector, exposing the top of the pins, then, after testing to be sure I wasn't crossing + & - or drawing 20Amps, I did the jump in the female side of the connector with the aforementioned wire "U" upside down in the holes, replaced the plug and viola, I can start in any gear I guess, i only start it in P myself.
Regarding my post, I may have the color(S) wrong, I was (and am) working from memory

and the cars are slightly different (his is a diesel); but the location of the plug is clear in the picture and identical to my M104's, the plug however is different than in his other picture. IIRC the wires that get jumped are the same color (gray/violet stripe?) one each to/from the NSS. the others are the reverse lights(?) most likely.

If you need me to I'll take a pic when the ol' ball&chain gets home tonight.
HTH, Tom

Texholdem · #9 03-03-2011, 10:32 PM

Tom, I had similar problem when the temperature plunged to subzero in Texas few weeks ago. Had to let my MB in the garage and took my wife's Acura TL. Now as it got warmer it does not happen again. I'll try your fix next time when it re-occurs. Thanks for being patient and taking the time to elaborately explain it to me. I appreciate it and look forward to your pic. Good job DIY-ing.