R34 25GT Engine Light 21

[CF.Panda]

12 hours ago, GTSBoy said:

Yeah - I mean, go the other way. Smaller range. Not larger.

AHHHH gotchaa, I'll do that once I am home again. I tried doing the harness with the multimeter but it seems the car needed a jump, there was no power when it was in the "ON" position. Not sure if I should use car battery jump starter or if its because the stuff that has been disconnect the car just does send power.

[joshuaho96]

20 hours ago, CF.Panda said:

I attached the image of the only thing I found, nothing to do with ohms in the manual only torque values etc. However, being they are so close to each other I am almost certain they are good. Tomorrow I will test the spark plugs while I am there. and look at the ECU connections.

Diagnostic flow for a code 21 says check signal at the ECU pins, on a voltmeter of some kind it should read 0.1V at idle, 0.12V cranking, 0.15-0.25V at 2000 rpm. Check each coil such that +1, -3 is infinite or very high resistance, -3, +2 should do the same. (-1, +3), (+3, -2), (+1, -2), and (-1, +2) should all be somewhere between 0 ohms and high resistance. If you trace the path from the coil pin all the way back to the ECU in the diagram the resistance you measure at the coil vs connected to the harness should be pretty much the same. 

[CF.Panda]

Update: tested my spark plugs that are supposed to be 5ohms with a 10% deviation and one gave me a 0 ohms reading and the rest were 3.9ohm<, so one bad and the others on their way out.

[GTSBoy]

1 hour ago, CF.Panda said:

3.9ohm<

Could be correct. Meter might be that far out. Compare against a known 5 ohm 1% resistor.

[CF.Panda]

1 hour ago, GTSBoy said:

Could be correct. Meter might be that far out. Compare against a known 5 ohm 1% resistor.

I bought 6 new spark plugs to compare readings. They will be here tomorrow and ill see if meter is far off if it all. I know one is at least reading 0 so its best replace all anyway if one is bad, from experience. I still have to test the harness just to be sure its not a double issue and I waste my time haha-the old plugs are iridium I always thought those lasted more than 50,000 km.

[CF.Panda]

1 hour ago, GTSBoy said:

Compare against a known 5 ohm 1% resistor.

I'll get one of these also just for giggles

[MBS206]

1 hour ago, CF.Panda said:

I bought 6 new spark plugs to compare readings. They will be here tomorrow and ill see if meter is far off if it all. I know one is at least reading 0 so its best replace all anyway if one is bad, from experience. I still have to test the harness just to be sure its not a double issue and I waste my time haha-the old plugs are iridium I always thought those lasted more than 50,000 km.

Ha, I stopped running Iridiums and fancy spark plugs in RBs as they last just as long as coppers, and coppers are way way cheaper.

RBs foul the plugs well before "they expire the plug"