Author Topic: Ford Zetec Rocam Blunder - BSFEEChannel #14  (Read 3581 times)

0 Members and 1 Guest are viewing this topic.

Offline bsfeechannelTopic starter

  • Super Contributor
  • ***
  • Posts: 1667
  • Country: 00
Ford Zetec Rocam Blunder - BSFEEChannel #14
« on: February 24, 2018, 09:07:16 pm »
Or how engineering is like walking on a razor edge.


 
The following users thanked this post: GeorgeOfTheJungle, AllTheGearNoIdea

Offline AllTheGearNoIdea

  • Supporter
  • ****
  • Posts: 269
  • Country: gb
    • AllTheGearNoIdea
Re: Ford Zetec Rocam Blunder - BSFEEChannel #14
« Reply #1 on: February 28, 2018, 08:45:28 pm »
 Had a look at your channel and you have some interesting stuff on the automotive electrical side of electronics. The robot voice thing just sounds horrible and most people wont even try to watch your channel. Drop the voice and you will do fine.

Thanks for sharing
AllTheGearNoIdea Where Its All About The Gear
 

Offline bsfeechannelTopic starter

  • Super Contributor
  • ***
  • Posts: 1667
  • Country: 00
Re: Ford Zetec Rocam Blunder - BSFEEChannel #14
« Reply #2 on: March 01, 2018, 05:35:14 am »
Thanks for watching. The approach on cars is purely incidental. Below I provide the script I fed to the computer. So you can turn the volume off and watch the video again.

Quote
Meet the Ford Zetec RoCam engine known elsewhere as Duratec. It is cheap, small, and has an impressive torque for its size and power. Everybody raves about it, but the owner complains that the engine loses power when this car is climbing up a hill.

So I volunteered to have a look. One thing I noticed is that when you rev up the engine it vibrates a lot. This can be an indication that the problem might have to do with a spark plug not firing properly.

But before I could check the spark plug wires, which is one of the first things you do in this case, I noticed a rhythmic snapping sound synchronized with the vibrations. Looking closely I could see a spark coming out of the ignition coil. So I decided to remove it and see what is going on.

And here we have it. It is made by Bosch in Germany. The date code apparently says 2010 june the 22nd. FoMoCo stands for Ford Motor Company. You can see it is encased in what appears to be a Bakelite can potted with epoxy. This close up photo shows discoloration marks left by the spark, and what appears to be a hole on the insulation.

This coil is not in fact one coil but two double ended coils. They are controlled by the E.C.U. (Electronic Control Unit). It is merely a high voltage step up transformer.

What caused this leakage? It turns out that near the coil goes a hose from the thermostat housing to the heater valve. To relieve the strain on the hose coupling they designed a steel support. But apparently the engine cooling system team do not talk with the ignition system team at Ford. They placed the support, that goes attached to the engine block, which happens to be electrically connected to the ground of the entire car, unbelievably close to one of the high voltage terminals.

They had to resort to a solution like that because of their decision to use plastic as the thermostat housing.  Their worries were not unjustified. The coupling of this same hose on the other end at the heater valve, which is also made of plastic, and for which they had not devised a strain relief, broke off a little later.

In solving one problem, they created a couple more.

This car has a variable spark voltage. When the E.C.U. detects that the engine has a demand for extra fuel intake, for instance when driving up a hill, it raises the voltage, which can get as high as 40kV. When a metallic object connected to the ground is placed at a distance beneath the appropriate clearance, this voltage is enough to produce a dielectric breakdown. With successive breakdowns the insulation is eventually destroyed, and even carbonized, providing a conductive path.

In these photos it is possible to see how close the support is from the coil terminal: less than 1 cm. You can see where the leaked spark strikes.

So, no wonder the engine was losing power. The spark, instead of taking place inside the combustion chamber, was firing the air.

After testing the ignition coil for continuity and unwanted short circuits, I realized it would be worthwhile to repair the insulation with epoxy and install it back again on the engine and see if it all works. Apparently, yes. it does. No leakage.

As for the support, one of the solutions is do away with it by using an aluminium replacement for the thermostat housing which happens to be available in the aftermarket, you don't need to be Einstein to deduce why. Or design a new support with the appropriate clearance.

I will leave that for the owner to decide.

Thanks for watching. Have a good night and stay beautiful.
 
The following users thanked this post: AllTheGearNoIdea

Offline AllTheGearNoIdea

  • Supporter
  • ****
  • Posts: 269
  • Country: gb
    • AllTheGearNoIdea
Re: Ford Zetec Rocam Blunder - BSFEEChannel #14
« Reply #3 on: March 01, 2018, 08:03:18 am »
Im just suggesting that you use your own voice because absolutely no one likes to listen to the robot voice woman it sounds just awful. Unless of course your some kind of mafia guy on a witness projection program in which case I’m saying nothing and anything you do is fine with me. 
AllTheGearNoIdea Where Its All About The Gear
 

Offline GeorgeOfTheJungle

  • Super Contributor
  • ***
  • !
  • Posts: 2699
  • Country: tr
Re: Ford Zetec Rocam Blunder - BSFEEChannel #14
« Reply #4 on: March 01, 2018, 08:28:42 am »
Interesting stuff indeed!  :-+

IIRC some Hondas had a similar issue in the '90s, they issued a recall to replace the HV/ignition/spark plug coils.
« Last Edit: March 01, 2018, 08:32:51 am by GeorgeOfTheJungle »
The further a society drifts from truth, the more it will hate those who speak it.
 
The following users thanked this post: bsfeechannel

Offline bsfeechannelTopic starter

  • Super Contributor
  • ***
  • Posts: 1667
  • Country: 00
Re: Ford Zetec Rocam Blunder - BSFEEChannel #14
« Reply #5 on: March 01, 2018, 03:54:35 pm »
Unless of course your some kind of mafia guy on a witness projection program

More of a fan of Kraftwerk and Daft Punk.
 

Offline AllTheGearNoIdea

  • Supporter
  • ****
  • Posts: 269
  • Country: gb
    • AllTheGearNoIdea
Re: Ford Zetec Rocam Blunder - BSFEEChannel #14
« Reply #6 on: March 02, 2018, 08:14:10 am »
Kraftwerk whats not to love.
AllTheGearNoIdea Where Its All About The Gear
 

Offline mikerj

  • Super Contributor
  • ***
  • Posts: 3231
  • Country: gb
Re: Ford Zetec Rocam Blunder - BSFEEChannel #14
« Reply #7 on: April 24, 2018, 03:58:14 pm »
Note that all throttled spark engines have a variable spark voltage, but it's the pressure in the cylinder that determines this voltage, not the ECU.

When the ECU decides it's time for a spark it cuts off current to the coil primary (for an inductive ignition system), and the voltage on the secondary of the coil naturally rises until the gas between the spark plug electrodes is ionised.  The voltage required to achieve ionisation is roughly proportional to the pressure in the cylinder (Paschen's Law), and this pressure increases with engine load, i.e. when you open the throttle, more air is allowed into the cylinder and the coil voltage has to rise higher for the spark to form.
 

Offline bsfeechannelTopic starter

  • Super Contributor
  • ***
  • Posts: 1667
  • Country: 00
Re: Ford Zetec Rocam Blunder - BSFEEChannel #14
« Reply #8 on: April 24, 2018, 08:15:14 pm »
Note that all throttled spark engines have a variable spark voltage, but it's the pressure in the cylinder that determines this voltage, not the ECU.

I thought that because this is a naturally aspirated engine with fixed compression ratio, the absolute cylinder pressure (for a given constant atmospheric pressure) would be the same regardless of load and speed. But obviously I was wrong.This made me conclude that the ECU's control over the amount of energy that the coil stores accounted for the variable spark peak voltage. In any case, it is good to know that this is a problem that can happen with any engine of this kind if not enough attention to detail is given in the design.

Thanks for the input.
 


Share me

Digg  Facebook  SlashDot  Delicious  Technorati  Twitter  Google  Yahoo
Smf