spoiled@21

As the title states I am running the appropriate copper NGK plugs one heat range colder that stock. I am getting an occasional hiccup when I accelerate. Usually at part throttle but sometimes at WOT. It just feels like one cylinder doesn't spark. you can hear it in the exhaust it is just an instant momentary sound change and can feel the power leave for a split second. I thought it might be an injector not firing but there is not even a slight minute change in my AF when it happens. (I logged it) unfortunatly the EMS doesn't log misfire but everything else that I can read, monitor, or log is within operating conditions. There is no knock voltage out of the ordinary (it never goes above .8v until the vtec spike). I have 02 feedback on which is working really well so far. I run about a 12:1 through 6k and then 11.5-11.8:1 all the way to red line. (at wot). I am going to pull the plugs tonight and see what they look like as they have about 700miles on them. The last set I changed were really brown on the tips from running way to rich before I got tuned and oddly enough had some burning or turning brown of the white part (where the part number is before the threads) indicating it is getting kind of hot in there. Like I said knock is under control and there is no sign of detonation or preignition. I am pretty sure my 255lph fuel pump is keeping enough pressure in the rail or I would get funny AF readings. I am at a lose as to the cause of this. I still am leaning towards the spark blowing out theory.

is making 325hp enough to warrant going down another step in heat range?

btw the plugs are gapped at .035

anybody have any ideas.


9lbs pulley, 550cc injectors, aem ems, aem adjust fpr, 255lph fuel pump,


the other thing i was thinking was that it might be my bov. it is set kind of hard and does not vent the 2lbs of boost I am making at 4800prm on the highway while under part throttle conditions. it only vents at 0% thottle.


thanks,
alex

stitos2k

Gap it down between .033 to .030 and see if that helps. Going a step colder won't stop the spark from being blown out. You go a step colder to lower the chance of detonation.

You might want to check your wiring too and make sure there is no corrusion, worn spots, and you have good contact with the plug. It could also just be a bad plug. Replace the plugs and try again, copper plugs are so cheap it's worth a try. You can always hold on to the current set as backup/emergency plugs if they are in good shape. Of course if replacing the plugs fixes your problem I'd just throw them out.

spoiled@21

well the last set of plugs did it to. so I don't think it is the plugs. I will change the gap when I pull them out tonight. I didn't mean for the heat range to sound like a solution to this problem but rather the burning of the middle of the last ones sounds like I should because they shouldn't turn brown like that.

There is only 45k miles on the car so I hope there is no corrosion in the insulator or connector.

spoiled@21

Pulled the plugs tonight and they are already beginning to turn brown on the mid part. I think I need to go 1 step colder.

I still got a little hestiation at 7500 at wot on my first run. It didn't do it on the way home from the bar but well see about tomorrow. I changed the gap from .035 to .032

I am gonna give the densos a little while to reclaim to reliablitly and then switch. anybody else with a suggestion?

Partshelper

I use the NGK 4554 8 heat range. gapped at .025 they run great

spoiled@21

iridium?

stitos2k

Iridium's have been proving unreliable in FI for a growing number of people. The copper plugs are a better choice at this point.

If your plug is turning brown and looking burnt you're probably running lean. When did you have your tune done? Some aftermarket ECU/piggyback ECU's don't correctly compensate for dramatic air temperature changes, and with the colder weather you may have gone into lean condition since summer.

You can have detonation from running lean, but you can't run lean from detonation... IE if you're not getting detonation now changing to a colder plug won't stop you from frying the spark plug if your running lean.

I'd say your not blowing out the spark so much as cooking your plugs.

spoiled@21

according to Xviper plus that run lean turn white and plugs that are in a rich environment turn brown. I am not detonating according to my knock sensor logs. The EMS was tuned 10 days ago. I never go above 12:1 under more than 25% throttle. Sure it runs stoich 13-14 under no load cruising down the hwy but that it is supposed to do that. I assure you there is no lean mixture happening. I will post some logs from this week tonight.

If it was detonation wouldn't it be more predictable? I mean detonation and 4k under no load no boost and like 20-30% throttle? I have a hard time with that theory with out some more evidence.

stitos2k

I never said you were detonating, just that there's no reason to go to a colder plug if your not.

And your right, brown is rich. I got it mixed up. If your running to rich you may be fowling the plugs and not getting a good spark. Lowering the gap MAY help... Might not. You may have to head to the tunner and have him lean it out a bit.

You can't light gasoline if there is no oxygen present. If you run rich enough its like trying to light a match under water.

Actually you may want to try a step hotter plug...

spoiled@21

thanks, Sorry I missed understood you. I am gonna try those 4554 plugs they are the same copper racing plugs as my 7173 but they are not projected tip. so the tip wouldn't be down in liquid gas.