UGHHHHHHHHHHH... fixed my header leak yesterday and now the car is running crappy at WOT and anything more than 10psi, whats weird is that its only sometimes...

If its a boost leak, would the car go rich?

 

stupid suggestion, but when doing the header fix did you make sure all the plug wires got pushed on all the way?

 

Maybe spark blow out ?? How old are the plugs ??
Check plug gap..

 

Funny you mention that... because when I took them off to fix the header leak they WERENT too tight, when I put them on I made sure they were tight. Plugs should be fine... I mean why would they crap out when I took them out for a header gasket replacement? you know?

Could it be a boost leak? If this were the case though wouldn't it read rich on the WB?

 

ok so... apparently one of the spark plugs was loose? Was using a cheesy socket so maybe that was the cause... Still missing at higher rpm and higher boost though, but only sometimes... and nowhere near as bad.
Plugs are gapped at .035... digital 6, msd wires, msd coil etc etc.

 

I don't think I'm the only one thatll tell u to close the plugs to 030". Its free. You asked if a leak would cause a rich condition. Are u going rich when its sputtering?

 

na i thought it was a boost leak...
WTH though... its full msd ignition, i doubt its the plug gap?

 

You maybe right but it is free to do. What heat range?

 

I would change the plugs.....those are so delicate that it is possible that the porcelin may have cracked causing a miss.

 

I changed them already... these are brand new.
they are 1 heat range colder, bkr6e which is the equivelent of a 3923

 

so at 10psi it runs pretty darn good.. just misfires at the VERY top of fourth.
13 psi and in third its missing all over.

 

Do you have any way to monitor fuel pressure during your runs? Also, try closing that gap down on the plugs to .028-030...

 

0.035" is too large of a gap, Even for a 6 series MSD.

Plug gap is one of the most common FAILS.

 

If FP was dropping wouldn't it go lean? AFR stays at a steady 11.8 at its leanest point.

Going to try regapping today. Will have updates later.

 

I never undersand why people ask what FP is at when the AFRs are good.

 

.028 and the misfires gone...
Weird though because before at the same boost level it wouldn't miss at all at .035. I did have a header leak though?

 

awesome I'd like to see how many people have fixed misfires with a plug gap change.

 

I did. On my GTP many years ago. I changed SEVERAL sets of plug wires, two sets of plugs, all three coil packs and the module before I figured it out. I spent a lot of $$$ chasing a fricken ghost...

I know its not a turbo car but I figured I'd respond...

 

Glad to hear that the plug gap solved your ignition problems. The reason I asked about fuel pressure is because losing fuel pressure can cause lean misfires. It would be hard to see on your wideband but you would notice it on your FP gauge.

 

Finally, I don't understand why guys don't try this first. It is a free fix, just gap em!

Dude glad you found the issue. Remember run as much gap as you can or as tight as you need to prevent issues.
Last, high energy ignitions will erode the plugs over time and the gaps will grow.

Or how many shops have been paid for high dollar tune to only re-gap some plug and return it to the customer........

My local turbo shop ask the customer to come in and gap his plugs and sent him on his way.... Problem Fixed! No Charge!