[Miltec]

Hi all,
I have a 92 Gtr, runs fine until on boost, it then misfires intermittently
I have replaced plugs with ngk iridium gapped to .8mm and changed coilpacks to split fires,
I have removed and cleaned/checked all ignition and injector electrical plugs,
I still have the same problem.
Any help and advice would be greatly appreciated

 

[DazGTR]

Could be MAF or lambda sensors but do check the earth to the igniter pack mine was frayed and corroded causing intermittent misfire

 

[Miltec]

Could be MAF or lambda sensors but do check the earth to the igniter pack mine was frayed and corroded causing intermittent misfire

I have checked the electrical plugs on mafs and cleaned them with brake cleaner
The earth is intact on the igniter, I am thinking its likely to be an ignition problem.
It seems fine off boost but misfires when on boost, it is worse with load ie as you go through the gears.
Sometimes (rarely) it has a tendency to misfire properly ie off boost once engine gets hot I can solve this by pushing the plug on the igniter and it cures that instantly
But does not cure the on boost miss. I think two separate problems?
I have cleaned the pins on the igniter just wondering if the connectors in the plug are a bit loose creating a bad electrical connection?
Thanks in advance for any help

 

[DazGTR]

I had similar issue and I also changed plugs, cas, coil packs, and afm and it would fix it each time then it would misfire on boost up the road. In the end as the car is idling try wiggling any plugs/wires near plug and see if you can hear anything which is what I did and narrowed it down to what I thought was the plug at the back of the igniter until I looked closely and found the earth wire to only have one of the 7 wires actually connected cut it back crimped a new fitting on and sorted

 

[Miltec]

I had similar issue and I also changed plugs, cas, coil packs, and afm and it would fix it each time then it would misfire on boost up the road. In the end as the car is idling try wiggling any plugs/wires near plug and see if you can hear anything which is what I did and narrowed it down to what I thought was the plug at the back of the igniter until I looked closely and found the earth wire to only have one of the 7 wires actually connected cut it back crimped a new fitting on and sorted

I have just checked the earth again an seems fine, I have had the igniter plug completely apart to check each individual connector and they all grip the pins on the igniter tightly, I am not sure where to look next?

 

[DazGTR]

Check the fault codes on the ecu

 

[DazGTR]

Was the car running when you checked the earth

 

[Miltec]

Was the car running when you checked the earth

Yes car was running when I checked earth, it seems to run exactly the same if I disconnect it aswell.
How do I check the fault codes in the ecu in one of these?

 

[DazGTR]

Try this
http://www.skylineowners.com/forum/showthread.php?p=1472557

 

[DazGTR]

The plug is under the steering wheel column get your head under and you'll see it

 

[Miltec]

The plug is under the steering wheel column get your head under and you'll see it

Found the plug, got a nice shiny piece of copper wire, turned on ignition, shorted the correct two pins and nothing flashed?
I guess this means no fault codes?

 

[DazGTR]

It flashes in the clocks it's the engine check light it lights up red

 

[DazGTR]

Make sure it goes in to the pins properly I struggled at first

 

[Miltec]

It flashes in the clocks it's the engine check light it lights up red

Yes the one that looks like a cat with lines rising from it.
It just stays illuminated?

 

[Miltec]

Make sure it goes in to the pins properly I struggled at first

Right, I have finally got it to work.
2 long flashes and 1 short flash, so code 21 meaning ignition circuit?
Where do I go from here, does code 21 refer to a specific part of the ignition circuit?

 

[DazGTR]

Not sure its trial and error really if you can swap a good one to try the amplifier other than that test the circuit

 

[MS33]

Try this.
I did, and it fixed my misfire.

Fixing Your Rb26 Afm's - Tutorials / DIY / FAQ - Skylines Australia