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Registered
1989 300e,SLS...412k Stock Standard
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85 Posts
Discussion Starter #1
hi i have a no start on my 300e,seems to be weak spark.cos i have fuel and air.new cap,wires,plugs.when testing my coil i got 1.7ohms on terminal 1 and 15,and the manual says 0.3-0.6,does this mean my coil done?i went to a junkyard,tested one and it gave same resuls as mine.had my meter set at 200 ohms.pls help with ur coil restance of healthy coil
 

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Registered
1989 300e,SLS...412k Stock Standard
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85 Posts
Discussion Starter #3
no one?anyone?i think my coil is kaput,can a use any 12v ignition coil for my merch,i heard that VW uses alomost the same even thouhg its round.
is this true
 

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Registered
1989 300e,SLS...412k Stock Standard
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85 Posts
Discussion Starter #5 (Edited)
The plot thickens...again

Hi Jayare and others....Help needed

sysmptoms that lead to no start are.....car drove fine to work one morning,in the afternoon when i was getting lunch....while idling on the drive through of mcdonalds,car just died,restarted,got my order and drove away....about 1 mile,car lost power when climbing a hill,was driving like 20km/p,there was a black smoke,got to a red light,died again,restarted,got to work,parked and went in.

later,drove about 15kmls,car started again,black smoke,stooped at a garage,and indeed,the car was running rich,plugs were covered in black carbon,all six of them,put my oldish plugs i replaced a 2 months ago,drove another 5kms and same thing happened,only this time,car died on its own,and has not restated since,got towed home at 01.37a.m,car now just cranks over and over,and if it catches,its only for 2 seconds and dies.

i got a brand new electronic 12v ignition coil,i got a orangeish spark that lead me to think the coil is weak,put the new one in and now i still get a blueshish
snap that doesnt snap loudly when tested(spark needs to be white and loud)

i tested the rotor arm and i got 1.1 ohms and its stamped 1.2ohms,can that be my culprit....?the car cranks strong but doesnt fire....i have gas,i got air....but spark seems to be evading me....ive done all tests that i could according to the manual....car has been sitting for 3weeks now.
 

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W124 Moderator
86 190E 2.3L 16V, 2 95 320TE's, 02 S500
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12,746 Posts
Fish,

Have you pulled a plug, grounded it and tested the spark at the plug?
 

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Registered
300TE 24V
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27 Posts
Could be an earth (ground) fault, clip a jump cable to the - (Neg) on the battery terminal and the other to the engine block... just it's quick n easy to try before looking any further, then try the car ? :thumbsup:
 

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Outstanding Contributor Always Remembered RIP
216 with everything. 2002 SL500 with everything. 2009 SL500 with everything.
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6,543 Posts
I presume its the EZL on a 89 car.

With a coil it is impossible to get any meaningful resistance check with an ohm meter as the battery in the meter can a pose the reading, plus with just one short circuit turn in 15.000 this cannot be measured.

The effects of a short circuit turn are that it will be OK from cold, but it will rapidly heat up, as it heats up the output will fall.

A coil works like this, for simplicity I will use points. with the points closed and a plus voltage on the plus terminal there is a magnetic field around the coil, when the points are opened the magnetic field collapses back into the coil in term of a voltage to produce the spark from the secondary. Now we have to put a gate across the points to stop energy/voltage escaping over the points so a condenser is used.


On the EZL versions the coil is wired the other way round with the plus going to the points set up and the - all time grounded. The gate is built into the EZL

The biggest fault with EZL is the contact heat sink paste dries out, the allows the power transistor to heat up to the thermal runaway point and switch off.

If it has not been damaged by overheating then re applying some paste could fix it.

This is the circuit for a 1990 300TE

http://www.autolib.diakom.ru/CAR/Mercedes-Benz/1990/300TE/SYSTEM WIRING DIAGRAMS/3613.pdf
 

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Registered
1987 300E, 1955 Plymouth Belvedere, 2005 Silverado 4x4
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963 Posts
FIFW, I checked the resistance on two used good coils I have in my spares box, both one reads 0.4 ohms the other reads 0.5 ohms.
 

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W124 Moderator
86 190E 2.3L 16V, 2 95 320TE's, 02 S500
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12,746 Posts
Now that I've thought about it and read back over all your post on this problem, it seems that your car will run (poorly) for a few minutes, belching black smoke etc. When you pull the plugs, you find they are black and damp. The assumption is that you aren't getting sufficient spark to allow a clean burn.

I am starting to think your problem lies with the fuel distributor. Several years ago I snatched up a 92 300E for chump change. It had sat for an extended period and needed a number of items addressed. One thing that occured was just like your problem. It would run well for a few minutes, began to bog down and finally cease to run. Pull the plugs and they'd be black and damp. Let it sit for a long period and the game would resume with the same end result. I swapped out the FD with another I had and the car ran (and continues to, 3 yrs later) perfectly.

Worth investigating if you have access to a spare FD to swap out and see if the problem goes away.

Jim
 

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Registered
1989 300e,SLS...412k Stock Standard
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85 Posts
Discussion Starter #11 (Edited)
thanks for all the replies,JAYARE i did test the spark from the coil lead itself to ground,from the spark plug to ground,and i got a blueish spark,i swapped the ignition coil with a new universal coil and still got the same blueish spark,so that ment even tho my coil seemed out of spec it still fired good.

as per JAYARE's suggestion with the fuel distributor,i opended all injector lines on the FD,with my old coil hooked up,had a friend crank the engine,fuel started spraying all over the engine bay,way too much pressure i thot,but funny enuf the car fired, i closed all lines individually while revving the motor by hand,as i closed the last line on the FD,it started bogging down,backfire,and stumble,mind u im still revving by hand,black smoke belching out the exhaust like a tractor at this stage.

i opened the last line,motor freely revved,black smoke was at a minimal but still there,crack opned the second injector line,balck smoke reduced again...motor was now peppy,i cud feel all the power of my 300e....

closed the lines again and same scenario again,black smoke came back,stumbles,and as i reduced the revving it died.
at one stage i took off the fuel mixture thinking mabe the plunger is stuck an its causing the overfuelling,what i noticed is that the plunger pin in the distributor had free play even though the plunger was at resting position,dont think it shud but not sure,since there is no pressure.

can the FD cause an overfuelling?

now i suspect three things

1.my pressure regulator is no longer supplying enough pressure to direct extra fuel back to the tank,even thoogh it sprays good when line opned.

2.my eha is no longer regulating the lower pressure in that the upper is too high(not sure about this one.

3.My fd:mad::eek::eek: is Overfuelling....thereforeengine is flooding.

i can only get a FD at a junkyard,will that be fine testing it on mine with the donor cars eha attached to it
 

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Registered
1989 300e,SLS...412k Stock Standard
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85 Posts
Discussion Starter #12
Could be an earth (ground) fault, clip a jump cable to the - (Neg) on the battery terminal and the other to the engine block... just it's quick n easy to try before looking any further, then try the car ? :thumbsup:
now that u meantion this....i cleaned all grounds with fine sand paper,even the one the main groung unfer the car,it had oil spilled on it,so i took it off and sprayed with carb cleaner,since it dries and put back on...

but ill try that other suggestion and report back
 

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W124 Moderator
86 190E 2.3L 16V, 2 95 320TE's, 02 S500
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12,746 Posts
Yes, the fuel distributor can "over fuel". If you can, snag one from the junkyard and see what happens. Should be a no loss deal for you. Here, there is a 30 day money back policy on pulled parts.

The EHA could be the problem, but if it isn't leaking, then it is most likely good. Fuel pressure regulator "could" be the problem, but not as likely as the FD.

Jayare
 

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Registered
1989 300e,SLS...412k Stock Standard
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85 Posts
Discussion Starter #14 (Edited)
Yes, the fuel distributor can "over fuel". If you can, snag one from the junkyard and see what happens. Should be a no loss deal for you. Here, there is a 30 day money back policy on pulled parts.

The EHA could be the problem, but if it isn't leaking, then it is most likely good. Fuel pressure regulator "could" be the problem, but not as likely as the FD.

Jayare
im starting to believe my fuel distributor is gone,while i was busy packing my tools,i smelled fuel under the car,and when i opened the oil cap it was strong,put a small wire in a rag in the dipstick tube and sure enuf,my oil has fuel in it,:confused:i cant farthom how fuel got in there but the manual does mention it so i guess its a possiblity....funny they dont mention the FD,only to check pressures....
 

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Premium Member
'92 300TE 4matic 280,000miles, '92 300TE 4Matic 'Ice Blue Metalic' 101,000miles
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10,394 Posts
Fish,
You can test fuel pressures on the upper and lower ports of your FD-compare to factory specs and also the pressure difference @the two ports. I think Jim's idea to substitute a junker FD is sound, because you're trying to see if you can replicate the problem with an identical part.....same thing happens, look elsewhere. EHA going bad will most probably leak fuel out of its body.

Too much pressure at the FD and it's your fuel regulator.

Kevin
 

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W124 Moderator
86 190E 2.3L 16V, 2 95 320TE's, 02 S500
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12,746 Posts
Fuel in the oil is a result of the cylinders being washed down from excessive over fueling. You really don't want that to continue. Change the oil/filter as soon as you get the fueling problem corrected. Get the FD changed out.

Jim
 

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Premium Member
'92 300TE 4matic 280,000miles, '92 300TE 4Matic 'Ice Blue Metalic' 101,000miles
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10,394 Posts
Fuel in the oil is intuitive; if it's not firing in the combustion chamber, then the excess gas is washing down past your rings into the sump.

Kevin
 

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E500(1993) E220cdi(2004) SL500(1994)
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282 Posts
Hi.
can someone please tell me if a primary coil resistance of 0.9 ohm (for a r129 SL500 at) is normal or does it mean that the coil is dead??
For info the secondary resistance is at 11000 ohm.
Please guys answer...
Thnxxx
 

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Registered
'95 E300 DIESEL, '91 600SEL, '92 600SEL
Joined
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17,388 Posts
Hi.
can someone please tell me if a primary coil resistance of 0.9 ohm (for a r129 SL500 at) is normal or does it mean that the coil is dead??
For info the secondary resistance is at 11000 ohm.
Please guys answer...
Thnxxx
That's a question you need to ask in the R129 forum vs. resurrecting a 6 year old thread.. This is the W124 forum.

Where in Belgium are you? You're probably not that far from me.
 
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