misfire or pinging?

[-==L=a=N=c=E==-]

While i've been road tuning my car in preparation for mini-jam. I've come across a situation.

Anyways, i have a Techedge 2A0 wideband, and a knocklink knock detector.

At 16psi, im running 11.5:1 (rich for safety) and timing has been adjusted to appropriate levels via the knocklink. I get the occasional 'miss' i think....

I've moved the boost up to 17-18psi, and it seems to break up once i get up into the rev range.

When ever it has this 'miss' the knocklink goes right off the scale.

I just want to check, the actual miss im hearing isn't pinging, but rather the ignition breaking down?

and if it is ignition breaking down (ill remove the plugs and check there condition for knocking/lean) would i solve this by closing up the gaps?

[RobertoX]

Does the lambda read high when you get your 'miss'? If the engine is missing then the unburnt fuel/oxygen will go past the sensor and it will read the extra oxygen giving a lean reading.

[CrUZida]

What are you plugs gapped at?

If its still the stock 0.8mm, I'd reduce it to 0.7 or 0.6 and see if that makes a difference.

[-==L=a=N=c=E==-]

My Wideband isn't quick enough to read LEAN in the event of a miss, but the AFR does get a bit leaner when it does 'miss'.

And removing timing advance doesn't appear to help at all, which makes me think it is missing.

[-==L=a=N=c=E==-]

Plugs i havn't checked in a while, but i believe they were the factory set gap for the plugs. I have another set here which ill throw in and test this afternoon and check the gaps.

[chris davey]

I thought that the o2 sensor could only read burnt mixture so if there was a miss (and no ignition) then the mixture that is sent through the exhaust wasn't read. ???

If it is missing then yeah first thing to do is check plug gaps. If you are using x4 and decent coils you shouldn't have an issue with spark strength.

I would be pulling the plugs for a look though. The only thing is that to read the plugs correctly you are actually supposed to turn the engine off as soon as your miss/ping happens and pull them out then. I can't see how this can be done easily especially not on the road.

[oldcorollas]

nah, oxygen sensors read.. oxygen so if it doesn't fire, then you have a shitload of oxygen and it reads lean..

the datalogging isn't fast enough to see a change when you get a lot of this "missing" ?

[-==L=a=N=c=E==-]

nah, oxygen sensors read.. oxygen so if it doesn't fire, then you have a shitload of oxygen and it reads lean..

the datalogging isn't fast enough to see a change when you get a lot of this "missing" ?

I'm not datalogging, im watching the display on my wideband gauge. Ill data log it on the weekend, and see what happens.

[chris davey]

crazy mofo. Datalog everything! just in case.

I would check the plugs before going out again though just in case.

[Ribfeast]

Sounds a bit like crook coilpacks to me...

[-==L=a=N=c=E==-]

ill try reducing the plug gap first, and if it is crook coil packs, then ill just upgrade to an MSD and GM coils.

[-==L=a=N=c=E==-]

I pulled the old plugs out on the weekend and had a look, i found the culprit, being that the plugs were just plain worn out.

Changed the plugs to the spares i had, for slightly hotter ones (6's compared to 5's) and the misfire has gone away, and picked up a fair bit of torque in the process.

So for now, plugs was the issues. Thanks all rep to those who suggested something.

[chris davey]

Jeez you confused me. Don't you mean colder plugs (as in for hotter combustion that don't preignite so they are actually colder).

I have 7's in my car BTW.

[-==L=a=N=c=E==-]

i went one grade hotter plugs, cause thats all i had.

I'm fairly sure i had 5's initially, and gone to 6's now.... or it could be 6's, and gone to 7's....

BTW: Chris if you have a look at your rep, it might look kinda weirdo.... that was just a copy and paste typo....

[CrUZida]

Jeez you confused me. Don't you mean colder plugs (as in for hotter combustion that don't preignite so they are actually colder).

I have 7's in my car BTW.

FYI NGK and BOSCH go in opposite directions with numbers vs temp.