New leads and plugs cause problems

[Dannal]

Hey there. I just changed spark plugs and ignition leads on my VS V6 Commodore. I took it for a drive and it ran beautifully until about the 10th time I used the accelerator. It has developed a serious miss and only seems to be running on about 4-5 cylinders. I don't have the old parts to put back on so I am stuck with what I have for now. I have rechecked all the leads which seem to be connected to the plugs and the coil properly but it is still stuffed!

Please, if anyone had an idea on what has gone wrong please let me know.

Cheers!

[dufus]

Double check the leads and plugs and check that you haven't broken anything such as the coil etc.

[Dannal]

Double check the leads and plugs and check that you haven't broken anything such as the coil etc.

I have had a good look and can't see anything obvious. The leads all look ok and feel firm on the plugs. The leads on the coil are firm and the coil itself "looks" ok.

[Eliminator]

It wouldnt be the first time ive been given a set of plugs where some of them were faulty, if the car was running fine now it plays up all the time perhaps it could be a plug.

[commsirac]

The miss is permanently there now? if its only while driving, it could be an incorrectly gapped plug.
If it is at idle, chances are one plug or lead is a dud.
You can check all the leads easily enough with a multimeter.

One little tool Ive got that is great is a spark sensor, its a little triangle shaped thingo that you touch on to a lead and will sense the changing magnetic/electric field around a lead. If there is spark happening through the lead it will pulse with that spark. If the lead is dead or the plug is dead and no spark gets through then it will show nothing. Great little tool for finding the offending item quickly, given the problem happens all the time.
If you find a lead that isnt pulsing, it is the lead or the plug that is the problem, (or perhaps even the coil pack). To test which, swap one of the leads around(change at the coil pack end too) if the problem still exists on that cylinder its the plug, if the problem goes to another cylinder, it is the lead. Having one extra lead that is long enough to reach every plug that can be tried and substituted can speed up the process too.
Of course your mechanic can find it by connecting it up to an engine scope, but will have to also figure out whether it is the plug or lead.

[Morton]

It's possible that you cracked a spark plug when you installed it. It's also possible that you have a faulty lead.

If you kept the old stuff, it would have been perfect for double-checking. remember that in future

I'd suggest if it's idling badly full time, unplug each injector one by one while the car is running, to find out which cylinder is fouled. The one you unplug that doesn't cause any issues is the one that's screwed. Then work from there

[accentstencil]

Over tightening a spark plug can cause damage to the plug.

[Eliminator]

dont you hate it when people do up sprak plugs as tight as they can then in 6 months when they need to be removed there near seized due to the motor warming up and cooling off which tightens them even more lol

[hako]

One little tool Ive got that is great is a spark sensor, its a little triangle shaped thingo that you touch on to a lead and will sense the changing magnetic/electric field around a lead.

I had one of those and figured it would be great to check out my electric fence around the vege garden (to keep possums out) - anyways I put it next to the electric fence and next thing KABOOM! flat on my back.

[Cheap6]

It's possible that you cracked a spark plug when you installed it.

I'd say that Morton is correct here. It's easy to do. You might be able to see a thin line of 'Carbon' on the porcelain of the plug along the line of the crack.

[Bitemylip]

Mine did this, ended up being a faulty NGK spark plug that i had bought. it happens apparently.

[vs_wagon]

You might have pulled the EGR exhaust gas recirculation hose out. It's the little black hose that goes into the bottom of the throttle body. mine comes off all the time, and the car chugs like a biggest loser walking up the stairs. It's fiddly to put back... but a long screw driver and maybe needle pliers will help.
Just a thought.

[greenacc]

It's not the answer to everything, but in this case there's a good chance you will be able to see where the problem is by looking for sparks in the dark. Wait till night time, pop the bonnet and start it up. look around the coils leads and plugs. If nothing try revving it while you watch. If you see sparks somewhere, you have found the problem.

[delcowizzid]

NGK plugs have been bad of late i know of at least 5 people that changed plugs and had issues one v8 wouldnt even start after swapping the plugs the others just ran rough as .

[vxcalais_01]

I usually change plugs and leads on different days purely cause they a niggly lil bastards, and if faulty dont need to check everything at once.

[Dannal]

It turned out to be a dodgy connection on one of the injectors. The mechanic pulled one off at a time and by the time he got to the 4th one he had found it. Not only has the problem been solved cheaply but now the car runs like a dream.

[EREXON]

Dont know if this has been mentioned however this happned to me also the other day. Number 2 coil wasnt sparking.
Changed the 5 and 2 coil and everything is fine.

Just check for spark at the lead end if 1 isnt sparking check at the coil side.

At the coil side:
remove each plug 1 at a time from the coil step back get someone to start the car and you'll see if it arcs if not there is no spark from the coils.

Hope that helps

[RX25SE]

Heres a couple of tips.
If your sus on new leads or plugs, find out which cylinder is missing then swap leads first then plugs and see if the miss follows. If not, its something other than leads or plugs.
I always use a SMALL amount of "never sieze" type grease (Wurth CU800) on the plug threads when I install them. Never had a sticky plug.
Never had any dramas with NGK plugs or leads. IMO the quality of the leads is as good as OEM. Generally I use genuine leads as the price is good as well as the quality.
Cheers
J

[kz1000a]

Another czar for Morton


Dannal - just changed spark plugs and ignition leads. It has developed a serious miss

Morton - unplug each injector one by one

Dannal - turned out to be a dodgy connection on one of the injectors. The mechanic pulled one off at a time


mechaaaaanic?