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Dry fouling on cyl 5 and 6 plugs; going nuts. Help?
supernova_6969 posted a topic in Nissan L6 Forum
hi guys! I have this L28 turbo, megarsquirt 2 car that i bought already built (engine rebuilt 1000kms before I bought it). the guy told me all i had to do was tune the tables and it'd be great (last time I buy an already modified car). It ran really rough, idled poorly, and did weird things under boost (boost, drop boost, reboost, etc). the AFR was all over the place (both too rich and too lean). I changed the plug wires (which leaked current everywhere), played a lot with the tune a lot with somewhat better AFRS overall (still very rich though, with intermittent issues) Long story short, i decided to change the plugs (yeah yeah, should have right away, screw me, I'm on a tight budget) and I tested and cleaned the injectors, which function well. first run after that, I let it idle till it was warm, then took it out for a 5 minute spirited drive (with 3-4 times running full boost for 2-3 seconds), then back home. I checked the plugs right away and I found this: the plugs are in the following order: 6-5-4-3. essentially, the plug 6 is very dry-fouled, plug fire dry-fouled, and plug 1-2-3-4 are super clean, like new still. looking into the matter, I tested compression, and I have 170+ in all cylinders. neither 5 or 6 are the lowest of the bunch. I thought maybe the injectors (which are batch fired 1-2-3 and 4-5-6) had a problem even if I had tested them, so tonight I switched the plugs and the injectors around so the 5-6 got the clean plugs and the injectors from cyl 3-4. I did the same run and got the exact same results: plug 6 is very dry-fouled, plug fire dry-fouled, and plug 1-2-3-4 are super clean, like new still. I'm thinking it could be one of the three following issues: -somehow cyl 5-6's inj. are not getting proper current and might be staying open for too long or something (which I think is unlikely, since it's batched with 4 as well and that guy's cool). -maybe something is wrong with the spark. either the distr. is faulty, or the wires (even if the wires are are new) and 5 and 6 aren't getting good spark. (i'm thinking the coil is fine, since 1-4 have no issues) -maybe my valves are poorly adjusted and creating issues (they are a little noisy, although the high compression suggest they should be mostly fine. I'm going to look into these issues, but does anyone have other suggestions? one thing to mention is the engine runs REALLY rich right now (betwen 9:1 under boost and 12:1) i know it's an issue and i plan on working on this, but that's not the problem for the fouling or else ALL my plugs would be similarly fouled (I guess). any suggestions is more than appreciated. I'll post as i test things..
