I'm trying to get to the bottom of why my Z struggles on the dyno but is ok on the road. Can someone please check my current theory.

 

Let's assume an electrical problem somewhere on the left bank. This only shows up under severe load, not simply going up hill for example. This could also account for occasional black smoke out of the left exhaust which would be unburnt fuel. The coils/connectors/ptu/loom could all be culprits with bad connections or corrosion.

 

Main question is does an increased load create more stress on the ignition system such that it only shows up on, for example, a dyno?

 

Cheers guys.

Yes !

 

A dyno run is about the heaviest single load you will put on an engine. (Unless you tow caravans up Portland Hill etc )

You're right. My concern is how long before the problem begins to manifest itself on the road. This could be my early warning...

Could be plugs, when were they last changed.

Although handbook says 54k (tips ok) but ceramic insulator can start to breakdown long before causing shorts. Check plug and look for small blisters/white deposits or even cracks at interface of metal body and ceramic shield.

 

------------------

ray

IIRC he had greddy plugs put in on the dyno.

 

------------------

airflow meter,poor fuel,exhaust gas sensors,wiring harness(extra heat),temp sensor,too thin grade of oil(getting past rings and lowering octane+fouling plug(S))poor intercooling,fuel temp sender,fuel filter(slight blockage)weak vacuum lines,bad chip?slightly blocked injectors(when did you last have them cleaned)turbo seals leaking?these could all cause something of a misfire,Yes the dyno is the hardest single test you can do to an engine

p.s try spraying a fire extinguisher(co2)on the intercoolers (ilminates heat soak)suprised your garage didn't do that as a matter of course(high hp turbos+dyno's don't mix)hope this helps!!