Robboo Posted December 28, 2013 Share Posted December 28, 2013 (edited) Hi guys, just replaced sparkplugs to fix a misfire which has worked nicely but I noticed in one of the spark plug holes (one directly underneath throttle body) there was a fair amount of oil round the spark plug which has then gone onto the coilpack edges. This was obviously the cause of the misfire but whats causing the oil to leak onto the plug and coil? My guess is something expensive to repair! Google tells me valve gasket? Thanks, Rob Edited December 30, 2013 by Robboo Quote Link to comment Share on other sites More sharing options...
350 Russ Posted December 28, 2013 Share Posted December 28, 2013 its a cam cover that leaks into the plug tube. I've got exactly the same leak on mine at the moment. The fix is to replace the cam cover as the seal for the plug tube is make into the cover and isn't removable so can't just change the washer I'm afraid. Quote Link to comment Share on other sites More sharing options...
ZMANALEX Posted December 28, 2013 Share Posted December 28, 2013 As what Russ has said, however I doubt if this was the cause of your missfire. Alex. Quote Link to comment Share on other sites More sharing options...
Ewen@Clark Motorsport Posted December 28, 2013 Share Posted December 28, 2013 Its a common issue on the 350, we have the genuine covers in stock for £195 each http://www.clarkmotorsport.co.uk/website/webshop/productsSearch.asp?searchPartType=Panel&searchCategory=Engine+Part Its also advisable to change the rocker cover gasket, they are £11.99 each Quote Link to comment Share on other sites More sharing options...
Robboo Posted December 28, 2013 Author Share Posted December 28, 2013 (edited) Awesome great help guys Could be alot worse! Edited December 30, 2013 by Robboo Quote Link to comment Share on other sites More sharing options...
Robboo Posted December 29, 2013 Author Share Posted December 29, 2013 Update, still misfiring in the freezing cold this morning Could it be down to the oil getting into that plug? Or should I look at replacing coils etc Quote Link to comment Share on other sites More sharing options...
ZMANALEX Posted December 29, 2013 Share Posted December 29, 2013 The oil from the failed seal on the rocker cover can not get on to the tip of the plug. Trace the missfire to what cyl it is, and swop over the coil pack to see if the missfire follows. Plenty preowned coil packs in stock if required. Alex. Quote Link to comment Share on other sites More sharing options...
Robboo Posted December 29, 2013 Author Share Posted December 29, 2013 Cheers pal il give it a try Quote Link to comment Share on other sites More sharing options...
Robboo Posted December 30, 2013 Author Share Posted December 30, 2013 (edited) Okay so swapped coil pack over, no difference same p0300 code. Also it was fuel on the tip of the plug not oil, only oil around the plug and coil side. Fuel is obviously from where its misfiring? Even tried a trick I found to unplug the coil while it's running/misfiring to see if the revs drop like they should and all coilpacks are dropping in revs so could the problem be elsewhere? Injectors etc? Or does the trick not work and should I still be looking at coilpacks? Getting confused now! Edited December 30, 2013 by Robboo Quote Link to comment Share on other sites More sharing options...
ZMANALEX Posted December 30, 2013 Share Posted December 30, 2013 Is the missfire evident on tick over ? If so what cyl was missfiring initially ? What cyl is now missfiring since you swopped over the coil pack ? Alex. Quote Link to comment Share on other sites More sharing options...
Robboo Posted December 30, 2013 Author Share Posted December 30, 2013 Yup its noticeable on tickover, worse when driving though. And I think its the cylinder directly under the throttle body (no.4? 6?). And i couldnt tell, I just got code p0300 again! Ive purchased a coilpack anyway, and if that doesnt work il have to swap the rest out then look at injectors I guess Quote Link to comment Share on other sites More sharing options...
ZMANALEX Posted December 30, 2013 Share Posted December 30, 2013 If noticable on tick over the missfire should be very easy to trace without guesswork as that can be expensive. Did the original missfire follow the coil pack swop ? Alex. Quote Link to comment Share on other sites More sharing options...
Robboo Posted December 30, 2013 Author Share Posted December 30, 2013 How can I trace the misfire mate? Just using my eyes and ears isn't working! Quote Link to comment Share on other sites More sharing options...
ZMANALEX Posted December 30, 2013 Share Posted December 30, 2013 If the missfire is evident on tick over, then all you have to do is unplug the coil packs one by one till you find the demon. You would have to have done this to establish which coil pack to move in the first place to check if the missfire followed the coil pack. Then it is a simple case of eliminating the coil pack, plug, compression issue, injector, in that order. However code po300 is a random missfire and could be related to numerous other things, but the above is a simple starting point. Alex. Quote Link to comment Share on other sites More sharing options...
Jay M1988 Posted December 30, 2013 Share Posted December 30, 2013 After reading this its good to know I'm not the only one with this issue. On tickover my 350z has a misfire, no rev change just feel a judder through the car randomly. Only seems to happen when up to operating temperature and in neutral. I haven't begun tracing it as yet but I will soon using the information above. I've noticed quite a bit oil around the oil dip stick area but this could be due to the crap design as I've checked oil recently. Ill keep an eye on this thread as I'm thinking trace the plug or coil and replace whichever Quote Link to comment Share on other sites More sharing options...
Robboo Posted January 1, 2014 Author Share Posted January 1, 2014 (edited) Just an update, one new coilpack fitted and just needs one more after doing the coilpack test trick again (properly this time!). This would explain the p0300 code - random/multiple cylinder misfire. Soon as the second coilpack gets here & fitted I'll see if ive finally got rid of the misfire! Edited January 1, 2014 by Robboo Quote Link to comment Share on other sites More sharing options...
Robboo Posted January 1, 2014 Author Share Posted January 1, 2014 (edited) After reading this its good to know I'm not the only one with this issue. On tickover my 350z has a misfire, no rev change just feel a judder through the car randomly. Only seems to happen when up to operating temperature and in neutral. I haven't begun tracing it as yet but I will soon using the information above. I've noticed quite a bit oil around the oil dip stick area but this could be due to the crap design as I've checked oil recently. Ill keep an eye on this thread as I'm thinking trace the plug or coil and replace whichever You can test the coilpacks (as long as youre sure its not sparkplugs causing the trouble, replace them first) by unplugging the coilpacks one by one with the engine running (make sure the misfire is there aswell, not sure if it works if the engines running normally) to test for a drop in revs. If a coilpack is faulty and you unplug it there wont be any drop in revs. Replace that one Remember do this one by one and dont keep them unplugged for that long with the engine running. You can test the ones under the air intake by removing the intake and unplugging the MAF so the engine still runs, you will need to get the fault codes cleared afterwards obviously. This is how I did mine and found the 2 faulty coilpacks Edited January 1, 2014 by Robboo Quote Link to comment Share on other sites More sharing options...
Jay M1988 Posted January 2, 2014 Share Posted January 2, 2014 Thank you dude that is really appreciated. Ill get the plugs changed first then go from there. Quote Link to comment Share on other sites More sharing options...
Robboo Posted January 3, 2014 Author Share Posted January 3, 2014 Other coilpack replaced and tested and all is running nice and smooth again, big thanks guys 1 Quote Link to comment Share on other sites More sharing options...
GMballistic Posted January 3, 2014 Share Posted January 3, 2014 Other coilpack replaced and tested and all is running nice and smooth again, big thanks guys Great stuff. Happy motoring. Quote Link to comment Share on other sites More sharing options...
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