4th and 5th gear in my Z at 80-100% throttle seems to be putting so much load on the engine that the spark on at least one cylinder is being blown out.

 

The is apparent by a light vibration and tail off of power under heavy load in these gears :-(

 

Short term answer might be to reduce spark plug gap but this would produce a weaker spark and emissions wouldn't benefit.

 

Any views on a permanent fix for this problem? HKS ignition amplifier maybe?

 

Steve

I would try to fix it as a fault rather than thinking about adding extra equipment?

 

Which of your coil clips are loose or not quite as good?

 

Also, what happens when a coil starts to fail... maybe they require testing or something?

 

 

Jez, If I can't fix this then I might need those cliffs at Dover :-)

 

I'm going to lower my boost in 4th and 5th to a more sensible level and see what happens.

 

Must get the laser jammer / radar detector first though ;-)

 

Steve

Baically - mine doesn't have a problem at 1.3bar and all that air sucking... play with those cables!

 

If you want I have a set of used sparks you can try?

 

Steve,

I had a similar problem.

At 17psi and about 5500RPM the engine started missing.

I reduced the gap, replaced the fuel pressure regulator and the dampener, rerouted

the fuel lines to feed the fuel rails in parallel,

installed the HKS ignition amplifier....and so on.

 

It turned out to be the fuel pump!

I got a fresh one (´95) from a junk yard and no more misfire!

 

Yesterday things got even better when I had the bloody X-pipe thrown out from the exhaust.

It wasn't made as I was expecting it to be.

The exhaust pipes crossed each other, causing the total

exhaust diameter to be 3" instead of 2*3"!

Now the car pulls hard up to redline. The boost and the A/F-ratio are now stable as well.

 

After 2 years of tuning the Z is finally finished!

Now I just wonder how far I can raise the boost with stock pistons... ;-)

 

Maciej