Can I kick it? Missfire

Nissan 300ZX technical discussion forum: Maintenance, performance, installations, modifications, how-to's and troubleshooting.
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Ziggy1621
Posts: 1137
Joined: Sun Jun 10, 2012 5:57 pm
Car: '90 Z32 TT (Shibui)
'90 Z32 2+0 NA
'68 311 Roadster
2004 Rx330
2011 BMW 550i (TT)
Location: Cocoa, Florida
Contact:

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Ok, so I was on 4 cylinders (cylinder 4 and 5 missing) then I soldered in the PTU connector (old harness/new style PTU). Then I was up to 6 cylinders. Then an injector went bad (OHM'ing in the 30s) so I replaced it. Was running on all 6 until it got nice and warm, then Cylinder 5 was pretty much dead miss at idle (no change when I unplug the coil pack connector unless I was REV'd up to around 2500rpm, then you can tell the difference). Then I relocated the fuse box this weekend and now it is doing the same thing on cylinders 1 and 5.

I've cleaned all connections, swapped out the CAS, tested the PTU (haven't swapped it out) and pulled the coil packs to make sure they were firing (and they are), pulled the CAS and spun it by hand and all injectors are ticking and OHM'ing in spec) and ECU is code 55

I'm at a loss.... and getting very tired of this build :squint:


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Ace2cool
Posts: 11650
Joined: Sun Apr 20, 2008 5:21 pm
Car: 1991 Nissan 300ZX TT
1966 Datsun Fairlady 1600
2005 Suzuki GSX-R 600
1974 Honda CB550 Four
2009 Ford F150 Lariat
Location: Murfreesboro, TN

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Sounds like PTU to me still. Have you verified spark on that cylinder? If the spark is constant when warm, then it'll be the injector. It's one of the 2, pretty sure on that.

Actually, have you tried swapping coil packs?

User avatar
Ziggy1621
Posts: 1137
Joined: Sun Jun 10, 2012 5:57 pm
Car: '90 Z32 TT (Shibui)
'90 Z32 2+0 NA
'68 311 Roadster
2004 Rx330
2011 BMW 550i (TT)
Location: Cocoa, Florida
Contact:

Post

yeah, swapped coil packs and plugs. Guess I'll be pulling the plenum again and swapping injectors to see.


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