1996 C280 sport missfire and alarm problems

Tim82

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Hello ,

This is my first post so bear with me.

My sisters 280 developed a miss fire , having dealt with a similar issue on this car before i replaced the coil pack controlling the cylinders that were missing.
Long story short it turns out that the 12 vault supply wires to the coils were shorting out inside as all the insulation had cracked and degraded.
During this time i had disconnected the battery as a friend had suggested this would reset the ECU.
Now i cant test to see weather my quick fix on the wires has worked because on reconnecting the battery , the alarm wont dissarm.The remote central locking works fine but i dont get the usual beep and indicator flash to indicate the alarm has shut off.
Battery is currently charging as i think my many hours of testing and engine cranking have drained it some what.

Please if anyone can help me here i would appreciate it as my sister has my car while i fix hers.
also is it possible to replace this section of the wiring loom that connects to the coils or is it time to get busy with the black tape.

Thanks in advance
 
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Tim82

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Any one?

Nearly 200 views and not one of you has an idea?
 

MissyD

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sorry, you've not had a response Tim, hopefully one of the technical guys will be along soon.
 
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Tim82

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I hope so sarah im coming to the end of my patience with it.

It seem the battery is at fault causing the alarm to remain armed but im still having problems curing the miss fire.After solving the insulation problem it is still running on only 4-5 cylinders.
 

Cole@MBS

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Hi Tim.
Do you have the red and green lights in the mirror?? when you un-lock the car, what do the lights do???

I found a good repair for the wiring is to slip the plugs apart and use heat shrink, this makes for a nicer repair........

Just trying to remember the re-set method for the key, I am sure Malc will have it to hand..
 
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Tim82

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Hi cole@MBS

I did have the lights yes , but i discovered the cause of my problem with the alarm was a faulty battery , with a charger connected i could arm and disarm the alarm all i wanted but as soon as i disconnected the charger it wouldnt work at all.
With that solved i was able to continue testing and looking for the cause of the missfire.
Still not solved it though , good strong switching signal on all 3 coil packs , all coil packs work , new plugs installed , head being scratched alot.
 

kth286

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is that the straight 6 (104 engine) ?
 

television

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This must be the 111 engine for 96 I think , its possible that the ecu is fried if the wires were shorting
 

bigasotonuk

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I would suggest that its the straight six engine as the O/P mentions 3 coil packs also a 1996 202 was prefacelift, and the 112 V6 engine was,nt fitted till the facelift
 
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Tim82

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yes it is a straight six engine , im afraid i dont know alot about the car.
What sort of cost is a new or replacement ECU
 
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Tim82

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also i cannot be exact with the age of the car as it had a personalized number plate , its been re registered since
 

kth286

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ok Tim

It has got to be worth trying the following:

Under each coil you have the extension pieces down to the plug.

they do fail.

inside each one is a 2k ohm resistor wire, which gets brittle due to the heat, and
makes a bad connection.

I would replace all three of those connection pieces - well I would be reading
the fault codes first to determine which cylinders are not firing, but you
may not have that facility - they cost approx £10 each from dealer (last time).

Give full VIN to dealer parts person, or order online via Inchcape web site.
 
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Tim82

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Alarm problems are back and they brought along a faulty immobiliser with it.alarm has gone dead , wont arm or disarm and immobiliser wont turn off.
Checked the coil extensions and they all are fine , good healthy spark from all three(tested on same feed)
Entire wiring loom from coils replaced.
Feel like im just going backwards with it now
 


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