R33 Miss Firing

[phil33]

G'day guys,

i just serviced my r33 93 gtst. standard service plugs filter n oil.

put it back together and it sounds like its miss firing. iv tested the coil packs one by one and its seems they are ok cause every time i pull a plug off it miss fires worse. when under load it miss fires and spatters.?

is this a sign of a dying coil pack.?

any help would be much appreciated.

[Ben C34]

Could be a coil pack, more likely coil pack loom if problem only surfaced after you messed with it.

Unless you put some gumby plugs in there

[phil33]

well check the loom.

just checked the old plugs the last service i got done the dude has put BPR6E.. which are completely wrong. They are a lot thicker. could of those plugs stuffed the coil packs?

new plugs installed are BCPR6ES.

been trying to check the resistance on the coil packs but can't seem to find if Rb25DET S1 are the same as other RB coil packs and meant to be between 0.6 to 0.9?

[Ben C34]

wrong plugs won't damage the coils.

Not sure in resistance, it also doesn't seem to be a good way of diagnosing coils anyway as heat makes a big difference. clean the boots and apply silicon grease and see if that helps.

I think it's the loom though, they get heaps crusty due to the heat.

[GTRPSI]

If its idling fine but missfiring under boost, close your plug gap down to 0.8mm first as a test.....im guessing you used the factory plug gaps....maybe check your old plug gaps and see what they were at, most people close the gaps to help stop on boost missfires.

While there take a look around the coils for burn marks/arcing.

If you see arcing marks around coils try wraping them in electrical tape as a temp fix till you change them.

Also its good practice to use dielectric grease around the boot inner edge to help stop arcing through there too.

Edited February 9, 2014 by GTRPSI

[SkudR33]

When I first bought my car, I forgot to change the spark plug gap and it cause the biggest and most retarded misfire.

You sure you've gapped your plugs properly???

[phil33]

hey guys plug gap is 11mm same as the old plugs. the plug cap shouldn't matter on a fully standard car only running standard boost. should it?

also its coughing and farting on idle now then miss fires on free rev. i check coil packs n coil loom all wires are good. couldn't see any burn marks or arcing.

man this is doing my head in.

[GTRPSI]

Close the gap for a test, see what happens.

If it works you might have a weak spark due to coils on their way out.

[intercpt]

Get 0.8mm gapped plugs.

I accidently bought the 1.1mm and car misfired bad in high rpms!

Check all coil packs, connectors and the loom and spray with wd40.

Reconnect everything and you should be good.

[phil33]

got 0.8 mm plugs, tapped up the coil packs, cleaned the connectors n loom. still running rough on idle a missing under load.

i got a new fuel filter and noticed when i turn the key to acc the fuel pump stay on a lot longer then normal. even after i have tried to prime the lines 20 times.. :-/

any chance the pump is shitting itself. or is that the kind of thing that "it works or it doesn't."

[Ben C34]

see if the ecu has any error codes.

[phil33]

just checked the ecu's led has a solid red light all the time. no flashing. tried to find some info about but seems that it should flash if there is an error.