RB JET

Hey everybody I'm new to this forum and have just recently bought a evo8 with 60,000kms completely standard apart from cat back blitz exhaust, over the last 2 weeks the car has been starting and running completely fine but when I take off with light load it has had a light what seems to me to be ignition breakdown or misfire but after it has warmed up say 2-3 mins later its completely gone, thing is its only done it 3 times in the 4 weeks I have had it. So my question is why could be causing this random intermittent problem? I quickly pulled the plugs out and all coils,leads, and spark plugs visibly looked fine, the plugs were NGK IGR7A-G, I was thinking maybe I may need to try a different heat range? But otherwise I'm not really sure as its only done it a few times for a short period then completely goes away once a bit if temp is there, if you have had a similar problem or no of what could be causing it please post it up to help me out as I would like to sort it, all help is greatly appreciated

llDemonll

iTrader: (21)

Check the plug gap. Should be .020-.024

RB JET

Ok will do should I run a 8 heat range instead of a 7?

egis

I use on my 8 heat range

RB JET

.020-.024 is a real small gap! Considering the plugs that are in were put straight in out of the box at 0.7

llDemonll

iTrader: (21)

sorry, my measurement are in inches, yours are millimeters. .7-.8mm i believe is correct

edit: checked my math, .5-.6mm is .020"-.024"

your gap is about .03" which is huge for stock plugs / coils, that's likely your issue. tighten that gap down to .5-.6mm and see if that helps your issues!

Ricoswave

iTrader: (5)

I have been battling this very same issue for a long time. My car never did it, and then started to do what you describe every morning, without exception. Been through plugs, wires, coils, maf, timing is dialed in and new walbro fuel filter. If you have any luck let me know. I have heard alot of people say that this is normal and the car needs to just warm up, but I drove my car for two years without a hint of a misfire at low rpm when it is cold.

RB JET

oh really so yours does it every Morning?Mine didn't do it this morning when I went to work and drove it again at lunch time and was fine but when I went to leave work it did it only for a very short period then was fine, I'm still yet to re gap the plugs and will do tomorrow night then see how it goes and then ill look into replacing the coils

RB JET

was also just thinking i had an alarm fitted to to the car a week after i bought it and then a few days after that was the first sign of this problem, and just looking at where the installer had mounted the alarm sieren in the engine bay it seems he has unbolted the earth strap off the guard and mounted the sieren there and put the earth strap back on but its on the painted side of the alarm sieren bracket perhaps causing a bad earth??? will rectify this tomorrow also i hope im on a winner

chu

iTrader: (72)

How old are the plugs?

IMO, for the mods you say you have, sticking with the 7 heat range is probably the best. If the plugs are old, replace with OEM plugs, or got with copper BPR7ES or BR7ES. Coppers are cheap to buy and test and see if you can repeat the issues. THe gap everyone is recommending is good; I prefer to stay around .24-.27. Closer if running higher boost.

RB JET

I'm not 100% sure on how old the plugs are although they look reasonably new but who knows

chu

iTrader: (72)

If you don't know, it's probaby time to change it.

RB JET

Ok so I have replaced the spark plugs with BPR8EIX and gapped down to .5mm fixed the earth that my alarm installer messed up so now it's a matter of playing the waiting game to see if it plays up! Fingers crossed! Otherwise next step is coils and leads

PS car didn't skip a beat all day today anyway but we will see what's happens from here ill keep everyone posted

RB JET

Update: the past 2 afternoons when leaving work the car has started fine but when I go to accelerate or drive out the car park it has hesitated or missed but only with very light throttle and by the time I'm out of the car park it's gone,

I'm going to replace coils and leads tomorrow and have a quick check over for loose vacuum lines, then go from there

Worst part about it is It never turns the CEL on making diagnosis that bit more tricky but ill keep an update as to how it goes once I have replaced the coils

llDemonll

iTrader: (21)

sounds more like the car runs like **** when it's cold (which they do). they pull hard as **** (because everything is cold) but they dont want to nor do they like it. turbo cars need to warm up