I'm not sure I'm making progress, ruling things out anyway.

Fuel pressure regulator, no fuel at vacuum connection (running).

Purge valve, pulled input hose, has vacuum at the purge valve, no difference in running. I will clean later when I replenish my WD-40 (never use the stuff except for starting big diesels).

Spark plug connectors, checked each, all look good/clean/shiny inside.

Coils, each had .8 ohm on primary, about 8.25k ohm on secondaries.

It's hard to narrow it down to which cylinder without a misfire code, so no point in moving the coils around. Since it appears to be one cylinder misfiring, and consistantly (every revolution), it doesn't seem like it could be fuel pressure or un-measured air / vacuum leaks, nor air purge, nor EGR. Has to be either the injector, coil, wiring, ECU, or valve. Valves seem like they're okay as it has good compression at cranking speeds.

Code cleared, driven a few blocks twice, and started/moved a couple of times. New codes are: 47 (again) and 49 on pin 8.
The 47 I don't really understand, is it coil related or does it have more to do with the 49 low voltage at engine module.
On to the 49 code, could be OVP relay? Seems it wouldn't run if the OVP relay were open, plus other things like the tachometer wouldn't work and an ABS warning light? Grounds are all good and clean.

I'll look in the shop, I have a few OVP relays, might have the correct one, could that be the problem or would it just not run?

Lots of questions, thanks.

__________________

Gone to the dark side

- Jeff

OVP would be suspect if it is the old orig part..they have been updated ti a new part#, bu most have been replaced by now.
Pull it and see what the part # is. That could be the 49 code and would be a cause for low voltage condition, along with possible battery voltage/alternator ..check those.
Archieves has the two OVP #s..

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A Dalton

I'll still have the single-cylinder miss, ... seems I'm fixing everything except the main problem.

I hate to spend another $300 on the coils and wires/connectors, plus an OVP, without knowing it is the problem. It's starting to look like it'll be a parts car soon, I'm losing interest fast.

__________________

Gone to the dark side

- Jeff

OVP is the newer 000 540 67 45. I will check voltage at output pins.

__________________

Gone to the dark side

- Jeff

<>

Then throw a Scope on it and you will know in 20 seconds.....

That is the problem with DIY diagnostics on Full Electronic Systems. You need the tools/equipment .
We just try and give you a possible cause with the limited info you give,
The reason I even mentioned moving the coil is b/c you stated you had isolated the misfore to a specific cylinder.
And an OVP is not just an On/Off power relay..it has limit circuitry with diode/zenier circuit for spikes that can and do cause low V to HFM/SFI..
You have a low voltage condition, which means anything in that feed , from a poor connection at the HFM fuse, to the OVP/Alt/ Battery / etc.
And the HFM Default injectors when misfore is detected, so that cuts fuel at the same time, compoiunding the miss

Good point. Without any misfire codes, there's no easy way to know what cylinder it is, and whether it's moving with the coil. I guess I'm at the limit without a scope.

__________________

Gone to the dark side

- Jeff

That is why we always change the plug connectors ..they are resistors and they break down and you can not see that w/o a scope.

But, a scope is a large investment for a DIYer , so an option in your case would be to buy ONE coil and go down the line with it at each position.
I see the on ebay for cheapo.........
That still does not address the low voltage condition of code 49.
Wire Harness been looked at??

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A Dalton

The coils are blue-tag ones, might need replacement anyway. I'll order a plug-wire & connector set, and the coil packs. If un-installed coils are returnable, I can do it this way and start with the connectors/wires and move on to the suspected coil position as needed. If non-returnable, I'll just order one coil and swap it one at a time.

The voltage outputs at the OVP are good, replaced the fuse also just for grins, it is a fairly new OVP, ... I'm wondering if the many times I've turned the key on to pull codes and etc. might have thrown the low-voltage code. I reset and will monitor it. Unfortunately, it's not really driveable as-is so the error codes aren't really going to reflect all problems.

Basically it appeared to be a good project for my teen daughter's car, she's been cleaning carpets and leather, getting ready to drive it, the colors are nice so I'd hate to pull it from her at this point just to harvest parts for other M-B projects, ... she's already fallen for it. I'm stuck. Thanks again for the help, I'll let you know how it turns out with the parts.

BTW, no dealer nearby, for the price of the parts mentioned above, probably couldn't get through the door from my experience, why not?

__________________

Gone to the dark side

- Jeff

I would change the battery over-night for the LV condition...and then I would Archieves the Wire Harness so you can see what you have there... all the coils and connector will not help a bad wire harness problem and they ALL had bad harnesses..

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A Dalton

Battery charged, and new.

I'm aware of the wire harness issue, don't know whether it has been replaced, but there are no wires with shrinking nor brittle insulation on the engine, so I am not considering that an issue.

I'll have the coils/wires/connectors overnighted, should be able to install them Friday.

__________________

Gone to the dark side

- Jeff

>


Wish I had a dime for everyone of the post that said that until they opened up the harness .........

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A Dalton

In opening the harness, what does this entail and where am I looking? I'm not looking for trouble, but if it needs a $1000 harness on top of needing tires and other items, it's an organ donor for my other 124 projects tomorrow. I should probably be checking.

__________________

Gone to the dark side

- Jeff

There are tons of pictures in the archieves..they pick a few spots that you can razor into and then re=wrap if it is OK [ which means it was changed, b/c all origs are bad, regardless of what anyone tells you.]

Here is a typical "Looks Good " until opened harness:

http://www.peachparts.com/shopforum/attachments/tech-help/60542d1225661857-how-screwed-am-i-e420-w-pictures-wiringharness1.jpg

And here is an Archieves post on Harness that will take an hour just to read thru.......

MB Wiring Harness Failure

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A Dalton

I cut it open, ... hate to do that, but it sounds like a "need to know" item.

Wires are shiny, pliable, and look great.

Fresh tag on part of the harness says: 124 440 5632

I guess I got the new harness.

On to coils and wires I guess, it escapes the organ-donor stall ... for now.

I forgot my evil laugh: Buwaa haa haa. (almost a Frankenbenz).

__________________

Gone to the dark side

- Jeff

I guess I got the new harness.
>

Harness verification is not part #, it is date code,
ZD is design date and FD is manufacture date..it is FD date that tells if you have a new harness.

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A Dalton