Problem with VY acceleration??

[Brett_jjj]

When testing these carbon core type plug leads, you need to move the lead around as you measure the resistance, and if the resistance readings change excessively whilst the lead is being moved around, the lead is stuffed.A lot of people just lay them out on a table or whatever and measure them without moving them around.
Ive found over the last few years that plug leads these days, even the more expensive 8,9 or 10mm ones, start to loose their "edge" after around 12 months or so. Its probably because of the higher voltages these EFI systems run at. This starts to effect how the car starts and runs, it also starts to effect the fuel economy. If you want to keep your car running at its absolute best, then its best to replace the plug leads every 12 months or so with standard replacement leads. Dont bother with the more expensive leads as the ones Ive tried, like top gun and eagle, just go the same way as the standard leads, in around the same time period.

 

[wortus]

Unless the lead resistance is too high (close to or above the max.) and/or the insulation including the boots is damaged in any way changing them is not going to achieve anything the average driver will notice. The leads on my VY are genuine and well within the maximum resistance, I have checked them twice in the 4.5 years I've had the car and their resistance has not changed by more than what you'd expect in normal variance in a multimeter and they show no signs of overheating or any other damage. I've got no reason to doubt these leads are the original leads and the car runs fine.
The cores are usually nylon or kevlar coated with carbon. I had a lead go open circuit on my last Commodore a VN and it was sometimes hard to start and missed under load. If the resistance changes while moving the lead around there's probably a mechanical failure/open circuit and the multimeter is fluctuating as the material (carbon) would have a resistance per unit length that would not change by movement.
By all means if you want to spend money for no reason do it, my advice is if they check out OK leave them and it sounds like the miss was more to do with a loose lead anyway.

 

[Brett_jjj]

Ive seen quite a few silicon type leads change resistance as they are moved around, so I thought Id post it up as this doesnt get a mention very often. Its actually breaks or cracks in the carbon core that cause the resistance readings to flunctuate, and when a lead does this, it is considered stuffed.
Ive found time and time again that even after just 12 months or so, fitting a new set of leads will make the car start and run better and get better economy, even if the resistances on the old leads show to be ok still. As I said, they only just "start" to loose their edge after 12 months or so, they dont actually fail and need to be replaced after 12 months, they will probably last for 4 or 5 years, but the car wont be running at its absolute best for a lot of that time.
Theres a hell of a lot of people who have dramas with plug leads these days. Nearly every person who writes in asking about an engine thats running crook will be asked if the plugs and leads are ok etc etc. Plug leads carry a bloody big charge these days with EFI systems and it wears them out fairly quickly, a lot quicker than the old points and coil setups did..

 

[tothezenith]

Mine was doing the same a couple of weeks ago. plugs and leads had only been done like 10K prior. Turned out the O2's were faulty, sending bad signals and dumping in too much fuel, but got normal power when stomping the loud peddle as O2 signal isn't used in those high rev instances.