1995 Maxima Ignition Problem

BOBBY.J.HATFIELD

MEMBER
1995 NISSAN MAXIMA

With all plugs removed from engine and using only the starter to rotate the engine, I am getting no spark on three plugs. Two plugs (No. 1 and 5) appear to be sparking faster than should be and the no. 6 plug appears to be sparking normal. I swapped coils around and it does not appear to be either spark plug or coil related. Put O-Scope on ECU signal to no. 2 and no pulse was present. The No. One was pulsing more than it should have (which represented why it appeared to be sparking more than normal). No trouble codes are indicated by the ECU. This is a 1997 engine that I installed (replacing a 1995. Both engines are 30DE engines. The only code on the ECU prior to engine swap was the air intake temperature sensor (which was disconnected). After reconnecting and resetting ECU codes, there are now no diagnistic codes. Any help would be appreciated.

Monday, October 1st, 2007 AT 12:37 PM

1 Reply

92 MAX

MEMBER
36 POSTS

Gidday Bobby

Your half way there! Connect your O-scope up to the input side (wiring side of plug) of the ignition module/multiple power transistor assy mounted on the end of the cylinder head opposite the fan belt end. A gray plastic package 2 mounting screws.
7 wires one side a to g(6 inputs from engine ecu and 1 ground) and 6 the other 1 to 6 (all grounding or pulling low each ignition coill)
You ought to be getting similar pulses on each input and similar on the outputs, if in's are ok and out's not then I'd suspect the module or it's connectors. It's a fault I've seen a few times exactly as you describe with some firing some not. Sometimes it will get worse when heating for 10 minutes with a hot air gun
'not too hot though'
If all the in's are not ok I'd be checking if the connectors are clean or back at the ecu connections, I havn't had a ecu cause the fault you describe, although you may be first !
When replacing the moduleClean off the module mounting surface with meths or similar then use a thermal conductivity paste sparingly and do not overtorque otherwise you'll distort the replacecment module and it'll have a hard time transfering the heat.

Do your tests with a fully charged battery so your results are consistant

Good luck !

Regards
Don
New Zealand

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Thursday, November 1st, 2007 AT 3:14 AM