Coil pack melting

[StephenG]

Hi Abscate, all the ground points are clean, if that was the problem it would probably affect more than one coil, also I have replaced the loom. Don’t give up yet, it’s still not fixed.

[RickHaleParker]

if that was the problem it would probably affect more than one coil,

Each bolt is a ground for one and only one coil.

[StephenG]

Yes Rick I know, they’re all clean and tight, I was thinking more of the crimp lugs on the loom. Either way it all looks as it should.I’m still wondering where I’m getting a 7ohm reading between ground and the primary coil even when the loom is disconnected from the coils and the fuse is out

[RickHaleParker]

Yes Rick I know, they’re all clean and tight, I was thinking more of the crimp lugs on the loom. Either way it all looks as it should.I’m still wondering where I’m getting a 7ohm reading between ground and the primary coil even when the loom is disconnected from the coils and the fuse is out

There is no direct pathway between pin #4 (Green-White +12V primary input) and ground. The primary is grounding is controlled by a MOSFET ( Metal Oxide Silicon Field Effect Transistor ) in series with the primary.

If a ground pathway on the primary (pin #3 or the spark plug) is poor. The bulk of the energy from the collapsing magnetic field with be converted into heat rather then transferred to the Spark plug and then to the Air/fuel mixture.

[abscate]

Make sure is the correct ones and a good brand.

Which coils ( make and part number ) did you buy ? The cheap ones are known to fail out of box with staggeringly high probability.most of us here run. Volvo ( new or junkyard) or Bosch , purchased from a reputable source eBay.

There is no direct pathway between pin #4 (Green-White +12V primary input) and ground. The primary is grounding is controlled by a MOSFET ( Metal Oxide Silicon Field Effect Transistor ) in series with the primary.

I love the way Rick uses tags to light up acronyms like this, +1000 points to start the year.



Here’s what the code to do that looks like.

Code: Select all

There is no direct pathway between pin #4 (Green-White +12V primary input) and ground.  The primary is grounding is controlled by a MOSFET ( [b]M[/b]etal [b]O[/b]xide [b]S[/b]ilicon [b]F[/b]ield [b]E[/b]ffect [b]T[/b]ransistor ) in series with the primary.

[RickHaleParker]

I love the way Rick uses tags to light up acronyms like this, +1000 points to start the year.

Boy if my English instructors could see me now.
They taught: "The first time you use an abbreviation, present both the spelled-out version and the short form" .

Perhaps i should of said my American language instructors. Nobody speaks English today not even the British. What passes for English today is a blend of many different languages.

[abscate]

I love the way Rick uses tags to light up acronyms like this, +1000 points to start the year.

Boy if my English instructors could see me now.
They taught: "The first time you use an abbreviation, present both the spelled-out version and the short form" .

Perhaps i should of said my American language instructors. Nobody speaks English today not even the British. What passes for English today is a blend of many different languages.

I’ve been better about doing this, and was taught the same , e.g, “ check your Electronic Climate Control ( ECC) control unit” but you have gone next level with those bold tags. Appreciated !

[StephenG]

Have left the car for a couple of days whilst being busy, however I have carried out a compression test (160ish on all cylinders) and put in a new set of plugs, which made no difference. Still no4 coil pack overheating, I have noticed the heat spreads from the end nearest the connector plug, but still no idea why. Next thing to check must be the ecu.

[StephenG]

A bit more thinking, if the ecu does not switch down to ground as it should then the flux in the primary is not able to discharge so will quickly overheat the coil and the mosfet and the built in connections in the coil pack thus exasperating the problem. Because the problem is induction based the fuse won’t blow unless or until an electrical fault occurs. So problem is most likely to be the ecu or no4 trigger wire open circuit.

[abscate]

The power dissipated in the coil is negligible. You are a long way from an ECM diagnosis on the tree.

Wiring faults
Cracked head
Bad parts
Ground fault on the A:51 wire