Hey guys, Recently I had a leaking injector causing cyl 1 to misfire alot! I have since pulled the plenum and replaced the injector and seals. No more misfiring when driving normally. I also discovered that my timing was retarded by 10 degrees. I had originally set the timing off the little loop of wire on the ptu - however i have since read that you should do it directly off the coil for cyl 1. I found that the timing was only 5 degreees BTDC. So i changed it back to the proper 15. However since then I have noticed that upon hard acceleration the engine will make a funny stumbling kinda noise at around 2000-2500rpm. Its not like a whole cylinder is missing --> its more like the whole engine lags for a second. At higher revs it works fine. I didn't replace the upper plenum gasket as it was only a couple of months old. Could this be the problem? Or have I set the timing wrong or something? Any input much appreciated.
Also I am running new spark plugs (copper ones). With 1.1mm gap. Should I re-gap them to 0.8 or something?
Not running any tune. Just stock ecu. Running stock boost also. Although today I just installed an EBC (however it has had this problem for a week or so since i fixed the injector). Still running 9psi anyway. I might try another boost leak test tomorrow incase unmetered air is coming in causing lean out. Just a q - with the boost leak test - how long should i keep pumping air into the system? I'm scared that i'll put too much. SHould I have the compressor on for like 10 secs or something? My tyre gauge doesn't seem to really register low psi levels so its hard to tell. Btw i tried unplugging both o2 sensors but it made no difference.
Just an update: Pretty much fixed now. I was running BKR6E-11 copper NGK plugs. I've switched to the iridium 0.8mm ones from Caz. Seems to have fixed the issue. I now have timing back on the proper 15 degrees and no misfire/stumble. I find this strange seeing that I was using the right type of plug - just a copper thats all. So for anyone with similar problems - run the iridium 0.8mm plugs from Caz.
