My EF Falcon always runs fine never missed a beat but yesterday i put a 2ton trailer on and it kept loosing all power and missing really bad for a few seconds and then it would go fine. It did this about 10 times over 80km, but as soon as i took the car off the transporter and drove home (50km) it was fine and has been since then. I was thinking it was time for a new coil pack, but it seems strange it's only doing it when pulling a big load, or is this common?

Thanks

Hi,

I would think of leads first, then maybe it is starving for fuel. The engine is under a lot more load, so it has to work harder and will need more fuel. Leads and filter would be a good starting point. This is just a suggestion, but what I would try first. Are the plugs and gap good ?

Regards 96ELGli

My eb used to miss under load (mates in the back) it turned out to be my timing, if you have a timing gun handy check it.

Hope it works out for ya!

Sorry I just realised how stupid I sounded!

Last edited by fullyforded on Sun Dec 09, 2012 2:29 am, edited 1 time in total.

Every time I hear of engines occasionally misfiring, I think of how mine did that. It was the coils.
I figure if it were having problems only when under load, it would do it all the time when it was under load, like dragging a heavy trailer?
While I'm here....and apologies if the answer is bleeding obvious, I've always been somewhat confused to what exactly 'under load' actually means.
Yes, I know when an engine's under load....but does it just mean that an engine uses more rpm than normal for any given task, as it has more mass to move, or it has to move that mass quicker?
If that's the case, it's just means the piston/valve speed is higher, and it wears quicker?

Hi,

"Underload" means the engine is moving the vehicle. If you rev the engine in Neutral or with the clutch in it's not under load. When the vehicle is moving the engine is underload. In this instance I meant the engine was under a lot of load as I was towing a trailer.

EF's have a Cam angle sensor so no timing adjustment.

ignition sounds likes its too weak and breaking down under load. Done leads or plugs lately?

If not, the coils on EF are a common problem

Another (maybe remote) possibility is engine knock. I understand that the EF ECU is very agressive and pulls out heaps of ignition advance if it detects knock. This will show up as a sudden loss of power under peak load. If you fill up with higher octane fuel and the problem disappears, you have your culprit. The fact that it happens only under maximum load at moderate RPM sounds like knock to me. Weak ignition can do something similar though. Knock is often triggered by build up of carbon in the combustion chamber, creating hot spots. There are various chemicals that can remove or reduce carbon without taking the head off.

What he said.
If it's missing under load 99% it's ignition. I've had this same problem myself, it was the coilpack. Happened up steep hills and more when it was cold/damp,
Yes knock pulls 6* timing out every time it hears a knock but that won't feel like a miss, just a bit of a power drop. Factory fuel/spark maps are very conservative and I've never heard a knock with my knock-box on any factory tune.

If the leads aren't too bad, it's probably the coilpack. Could also be a dirty plug.
Pull the plugs (use some oil on the threads when replacing!), give them a good stiff wire brushing with some strong solvent. Or just replace them.
Replace the leads if you can, the Bosch Motorsport or "Top Gun" set are good.

Get some silicone dielectric grease (any speed shop should stock it, also known as "tune-up grease".
-Pull each lead, using a bit of solvent on a clean cloth clean the plug ceramics, coilpack towers and the insides of the boots
-Coat the insides of the boots, plug ceramics and coilpack towers with a thin layer of dielectric grease

If it's still missing, chances are the coilpack has developed a HV soft-spot in the insulation. Time for a new one.

Tips:
-Number the leads before pulling anything, draw a quick sketch of the coilpack's output numbering
-Pulling leads - use a twisting motion and pull the lead from halfway down the boot, NOT the lead itself