Saturday, January 15, 2011 - 08:58 pm, by: Michael Toet(Myke31)
Help please...
I got all the plugs out, and plugs 3, 4, 5 & 6 were black. 1, 2, 7 & 8 were good.
The only thing I can see that is common with 3, 4, 5 & 6, is they are the longest leads. They are all driven by the dizzy/coil pack that sits in front of the opposite bank. Could a bad earth reduce spark to these plugs due to the longer lead?
I also found the firing order is 1, 8, 4, 3, 6, 5, 7, 2. The bad plugs all fire right after one another 4, 3, 6, 5. No idea if that means anything or if it is just a coincidence.
What else do they have in common? Does anyone know what can cause these centre 4 cylinders to have black plugs?
Monday, January 17, 2011 - 02:13 pm, by: Michael Toet(Myke31)
Nope, Jol. On each bank of cylinders the middle two are clagged. These are driven off the dizzy located on the opposite bank. So the two on the left are off the right dizzy, and the two on the right are off the left dizzy. However the remaining two cylinders driven off either dizzy are all good. So not consistent, and I was left wondering why only two out of 4 on each dizzy are black, and why is it only the middle two cylinders?
Thats why I figured it probably wasn't the dizzy or the coil packs (all of which are new).
Monday, January 17, 2011 - 02:43 pm, by: Daniel Arndt(Darndt)
Must be the ECU then Mike. Either it is the problem or is causing the problem. Meaning if the caps or drivers are bad in the ECU it could be over fueling these cylinders. OR the ECU could be fine and is purposely over fueling these cylinders. EG faulty sensor telling the ecu it needs more fuel.
Your replacement ECU shouldn't be too far away anyway. I'd also do the O2 sensors just for the hell of it. Ive read somewhere you can get universal ones which work fine.
Monday, January 17, 2011 - 05:20 pm, by: Tom Richards(Tomr)
have you measured the resistance of the leads?
if you do a search, resistance has been posted previously. looking outside the square, if they are low quality leads, they could all be "failing" to some degree, but the effect will be more noticeable on the long ones
Tuesday, January 18, 2011 - 11:22 am, by: Michael Toet(Myke31)
No, I haven't measured the leads. They are NGK, and the plugs are NGK platinum.
I pulled the plugs out again after a short trip and they were nice and grey. The trip would not have allowed the engine to heat up to operational temp (plus ECU would have still been in open mode - Or is it closed?). I am wondering if heat is an issue.
Dan, still waiting on the ECU. Hopefully I get it today.