348 Persistent Misfire

Whilst the car was on test, they checked the temperatures of the exhausts with a thermal camera. The left bank was running much hotter than the right suggesting a lean mixture rather than the rich mixture the fowled spark plugs suggested... I'm still not sure about this point but facts are facts...

Anyway, I have two new O2 sensors on order (best to fit in pairs). Once they are fitted, we can do some more tests and we'll know a little more...

As I said previously, I'm hoping to run the car without the thermocouple ECU's, but I'm looking for proof that the car doesn't run on a default map when this 'change' is made...

Hopefully another update coming soon!

Thanks again!

 

I am just taking a moment , I take em were I can

 

Two things I can think of offhand that could explain wet/fouled plugs combined with higher exhaust temps:

1) Significantly retarded ignition timing-- if the spark event is occurring late, combustion in the cylinders themselves may not be complete enough to keep the plugs clean and the remaining fuel may be burning in the exhaust, raising its temp.

2) Advanced exhaust cam timing. This should show up in a comparison of compression readings. I thought you'd already done one but scanning back through the thread I didn't notice mention of it. I'd suggest checking compression on all 8 cylinders forthwith if you have not done so already. You've beaten your head against the wall for a while now so it might be time to reconsider the basics.

 

She's not completely out of the woods yet, but your point is well made Jackie & Bill! Thanks

 

What was the problem and solution?!

 

Do you have a misfire?

Mine was 34 year old spark plug wires....

sjd

 

Yes- CYL 1-4 check engine light. Replaced ground wires, battery cables, relays, Oxygen sensors, etc...

Plugs, plug wires, etc... all two years old.

 

Did you check fuel pressure?

 

Yup. The following were also checked and were all fine:

- Coil Packs
- Fuel Pressure
- Fuel injectors / wiring
- Mass air flow sensors / wiring

 

What is the code your getting?

 

Crank sensor / wiring for that bank..???