Smith

I'm with you in that I've never really come across head gasket issues on a VQ, and I've had a few myself with higher mileage. Definitely not losing coolant, but I agree that it might be worth doing a leakdown at some point. I don't remember specifics on when I pulled that plug but I do remember thinking that it was an unburnt fuel situation. I'm finding very strong spark every time I test, which is frustrating. Figured that could also indicate that the injector was dumping too much fuel into that hole, which led to the pulling and cleaning of those. I did not swap that injector to a different location when putting them back in, and now I'm rather regretting that decision. Also no flow test, but from what I saw the flow shouldn't have been TOO far off from the rest. If I go back in that deep, I'm probably just going to end up replacing all 6 injectors this time around. Speaking of which, how much trust should I put into aftermarket injectors? It's hard to stomach spending OEM money on something that may not even be needed, ya know? What I'm seeing come out of the exhaust is definitely fuel and not oil. I'm all too familiar with the sights and smells of both. As far as the power valves go, I'd like to believe I would have spotted an issue there when I had the intake apart but I didn't check those specifically and I'm far from perfect. I'm thinking at this point my next steps might need to be leakdown, then pull the intake back off to check those and swap out injectors just to eliminate some of the more pain-in-the-ass possibilities. Thanks for the help!

Thanks for the response! I also somehow completely forgot that I tested out swapping the MAF a while back and that didn't fix the issue either. For good measure, I checked on my scan tool and am getting reads of around 3.6gs so should be good there. Haven't had a chance to give the video a watch but will do so after work, so thank you for linking that.

Ok the title may be a bit dramatic, but I definitely need help. I've been around here for years since I got my first R50, but I honestly don't remember if I have ever posted. I have mostly just read and absorbed until I've come across an issue that I can't seem to figure out. Thought I might see if anyone has an ideas for me that I haven't tried already. I'm on my second R50 now, which is a 2003 with the VQ35 and about 135k miles. A while back I started feeling a little roughness in the idle but only once the engine was fully up to temp and at its lowest idle (in gear). At the time there were no codes aside from one regarding the key chip not being recognized some of the time (I forget the acronym) because I'm using some cheap aftermarket key. Regardless, I figured that shouldn't have any effect on anything once the engine is running. Time goes on, the roughness in the idle gets a bit worse and I finally pull a Cylinder 1 Misfire code (probably P0301 but I'll have to confirm later). Started with replacing plugs then swapping coils around to see if it followed, it didn't. Compression test showed within a few percent of the other 5 cylinders' PSI. Injectors were all pulled, tested, and cleaned on a little homemade rig I made out of a 12v battery, some spare hose, and a can of carb clean. Fresh o-rings and those went back in. Aside from maybe running slightly better overall, the same idle issue and Cyl 1 Misfire code remains. No apparent vacuum leaks, and the one leak I did find with the "spray carb cleaner around the engine bay while running" test was a huge crack in the underside of the intake hose/pipe which has since been replaced and apparently wasn't the problem, despite my excitement in thinking I had found the issue. One other likely important detail that I forgot about until this point in the post is that sometimes I'll have to crank the starter for 3-5 seconds to get it to start, and when that happens it seems to dump quite a bit of fuel out the exhaust immediately after start. I'm assuming this is fuel that is being passed through Cyl 1 without being ignited while cranking. This hard start also seems to only happen if the engine is warm but has been shut off for greater than a couple minutes. If it's cold or was just shut off, it usually starts just fine. Any tips or help would be massively appreciated, as this has been keeping me up at night quite a bit. I'm usually fairly decent at diagnosing things like this but apparently I'm missing something. I know there is a ton of experience rolling around in these forums, so I'm hoping one of you knows exactly what's going on so I can feel dumb and have a smooth idle again.