OK, have got the plenum back on, coolant system is holding pressure, and I can get it to turn over and even run, but it's not firing on one cylinder. THe injector connector is getting good contact. My first thought was teh coilpack is stuffed, but I swapped it with one of the cylinders that was firing, and the coilpack is fine. I should note that before I pulled the plenum, it was firing on all 6, so I don't think it's something terminal like low cylinder pressure or something. What else could it be? Could one spark plug decide to crap itself fairly quickly? THey are NGK iridiums or some such, about 9, 000 k's old. Also, No0b question - what size socket do the sparkplugs take... (gotta go and buy a long flexi extension if I'm gonna check...)
It could be spark plug... Which number cylinder isn't firing? If you've swapped over coil packs and still no difference, then do the same with spark plugs. I changed my sparkies two days ago and I've already forgot what size the socket is Don't quote me, but I think it's 16mm. Give me two secs and I'll quickly check EDIT: Yeah, you need a 16mm socket
Make sure you put the injector and coilpack plugs back on the correct cylinders. - Actually that's probably pretty hard to stuff up but you never know... ?
Had a similar problem, It turned out to be either the PTU or the dodgy wiring to the PTU, Dont know which is was as I replaced both and now its all fine..
Awesome, thanks guys. WIll start with basic stuff first and go from there. It was actually hinting at rough idle before I took it apart, so maybe a temporal connection and not a causal connnection. How do I diagnose a faulty PTU - with datascan? Also, is the PTU the thing that has a series 1 and series 2 (the series 2 being the better of teh two?)
Thats it, drivers side, front of the engine block, unless it has been moved, see the following link.. http://www.aus300zx.com/tech/moveptu/movingptu.htm http://www.aus300zx.com/tech/ptu2/S2-PTU.html
NOw this is random - swapped sparkplugs, then BOTH cylinders fired up Like, WTF? I pulled the suspect sparkplug, had a look, and a bit of carbon but nothing terminal looking. Gently roughed it up with some sandpaper and tried again - nothing. Then I swapped it with one from another cylinder, thinking if the sparkplug is the issue, then that one will work. But then both cylinders fired up! Now, obviously I'm not complaining - my next move was datascan, possible series II put ($300...) but how can this happen? Surely either a sparkplug is working or it's not, how can swapping them make a difference? In any case, now I have a cooling system that holds pressure (and no under-plenum hoses) and spark on all 6 cylinders, so it's on to boost pressure testing....
Perhaps the spark plug wasn't seated properly... Maybe it wasn't tight enough, and the washer wasn't crashed. Anyhow, good to see it's sorted. A series II PTU is always a wise idea in my books
