LS1 Misifiring help!!

[adamc11]

Hi guys,
Got some new spark plugs today and i changed them over. Plugged it all back in and 1 or more of my cylinders is misfiring.
Got 2 replacement leads from supercheap auto and shuffled them around too see if if leads were faulty, but still no luck.
Had RACV come out and he tested all the coil packs and they are all sparking to the leads.
Any ideas on what the problem is or how i can diagnose it? I will take it to the mechanic tomorrow but if i can figure it out tonight it will be better.
Maybe i should start putting in my old plugs and see if that fixes it, assuming all leads are okay?

Thanks.

[Not_An_Abba_Fan]

You either have a dodgy plug or you have got the leads in the wrong order.

Pull each lead off and determine which cylinder isn't firing. Swap that plug with an old one and see what happens.

[adamc11]

You either have a dodgy plug or you have got the leads in the wrong order.

Pull each lead off and determine which cylinder isn't firing. Swap that plug with an old one and see what happens.

Ok will try, might be hard to diagnose which one isn't working.. hopefully it will misfire worse. What do you mean leads int he wrong order.. as in wrong coil pack to wrong plug?

[adamc11]

Any way to test leads?

[adamc11]

Also it's safe to unplug the injectors one at a time and try and diagnose yeah?

[burnz]

have i missed somthing, they are coil on plug with 2" leed's.
how can you have the fireing order wrong??

[a vpaero to please]

it is cool to unplug inj. but will lodge codes but you prob broke the new plug or if you took the plugs out hot u may have pulled the thread out of the head and the plug isnt in correct now and you cant get the leads on wrong (abba fag)
see what you get!!

[adamc11]

Guys also i didn't put any grease or anti cease on the new plugs before putting them in.. should i have?

[adamc11]

it is cool to unplug inj. but will lodge codes but you prob broke the new plug or if you took the plugs out hot u may have pulled the thread out of the head and the plug isnt in correct now and you cant get the leads on wrong (abba fag)
see what you get!!

Plugs went in fine, thread was still there and i didn't force them in.

[adamc11]

Tested all the leads with my mates voltmeter and they all work. Must be the plugs. I am pulling them all out, have noticed the first one i pulled one is sort of burnt at the end.. which means its probably firing.. right?

[CANYONERO]

i changed the plugs and leads and my ls1 was playin up at higher revs, i had a check and the mate that was helpin my didnt quite push two of the leads onto the plugs properly. cleaned them up shoved them in properly and no more probs...... have you checked to see that all your leads are on snug to the plugs and coil packs?

lol at mixing leads. there is no way you can. practically idiot proof.

[andyman]

is the ceramic damaged on the plug from when you tightened them up, some times if the socket is angled a bit tightening, it can crack them

[adamc11]

is the ceramic damaged on the plug from when you tightened them up, some times if the socket is angled a bit tightening, it can crack them

Checking that now. One was cracked but fking i cracked it when pulling it out i think argghhh!!!!!!

[adamc11]

Guys... am pulling plugs out now. IF THEY ARE BURNT AT THE ENDS, does it mean they were firing?

[andyman]

if they are going a light greyish/brown to black on the tips of the electrodes then yes its firing, if the whole plug is black its a good possibility its not firing

[adamc11]

Well i pulled all plugs out, put 4 old ones in the front 4 cylinders and 4 new ones in the rear and it is doing it. Will remove new ones one by one.

[Not_An_Abba_Fan]

When it is idling, pull each lead off the plug one at a time. If the idle changes put it back on. If the idle doesn't change, that is the dodgy plug. Or you could take the injector plug off, if the cylinder isn't firing it will have the same effect.

Leads on in the wrong order, was thinking V6....my bad.

[adamc11]

When it is idling, pull each lead off the plug one at a time. If the idle changes put it back on. If the idle doesn't change, that is the dodgy plug. Or you could take the injector plug off, if the cylinder isn't firing it will have the same effect.

Leads on in the wrong order, was thinking V6....my bad.

Is that safe? I know it's not safe to unplug from the coil packs, will get a HUGE shock.

Anyway i removed one of the new ones and put an old one in, and now it's smooth... so possibly a dodgy spark plug.

[adamc11]

Hey guys... it is safe to run 7 cyl on new plugs and 1 cyl on the old plug yeah?

[CANYONERO]

if you dont have a choice yeah, not desireable, but if your buyin a new one when you can i cant see no harm in it mate. gotta be better than only runnin on 7!

[cpbait]

whats the plug gaps like? did you check them before you put the new plugs in? are they all even, are one or more at different plug hight(bent slightly or opened more than the rest) seen this before where people haven't checked as they should be ok from factory or the supplier and one or two are slightly out causeing it to misfire and run rough a bit.

i check plug gaps every plug change i do weather its a customers car or my own, takes an extra 2 mins, but can save alot of heart ache. i have heaps of mechanics say to me y bother checking gaps, they'll be fine from the manufacturer, nothing to worry about, but i do it for peace of mind and iv seen brand new plugs do it to people, even in the workshop, one plug gets dropped or opened too much from the manufacturer and they get put in the box or u drop them ur self not relising, u put it in and it runs like ****, and u chase everything except for the plug gaps, check them just to make sure, i may be wrong may not be it, but will take 2 mins to check, hope that may help abit.

[andyman]

When it is idling, pull each lead off the plug one at a time. If the idle changes put it back on. If the idle doesn't change, that is the dodgy plug. Or you could take the injector plug off, if the cylinder isn't firing it will have the same effect.

Leads on in the wrong order, was thinking V6....my bad.

everyone dont do this, NEVER pull a ht lead off while an engine is running, they need to be earthed at all times, if a lead is pulled off while an engine is running the thousands of volts will travel back through the coil and most likely kill it as its trying to find an earth,

unclipping the injector lead is a much safer operation to perform, but is still not desirable

[adamc11]

Thanks for the help guys.

Cpbait, i have Brad from Enhanced gap them for me, so that was ok.

After hours of stuffing around, it turns out one of the plugs wasn't working (i'd say from the start). I tested it in a second cylinder that worked with the new plugs and still no luck. It is not cracked and seems fine (seems gapped ok), so i guess it's a dud. Unfortunately in the process of changing plugs around i broke a new one, so two arn't working =(

[cpbait]

oh ok, cool, cool. yeh that can happen 2. atleast you know what it is now, good work.

[minux]

wtf, how do you break a plug from changing them?