JunkEvo9 Posted November 5, 2023 Report Share Posted November 5, 2023 Afternoon Everyone, Attempting to figure out a misfire/breaking up issue on my fully built Evo 9 Car was running perfect and then one day sounded like it had rolling anti lag, figured it was fouled plugs as they had dyno time and roughly 300 miles on them including some drag racing. (Brand new build) Swapped 4 new plugs IKH24's gapped to 0.018" - Same issue. Started tracing the ignition system for obvious issues per Raif's recommendation & found the OHM racing relay box had water in it which corroded a pin on the relay & the relay itself. Replaced the pin & relay with exact parts, same issue. Figured it burned the coils so I replaced all 4 AEM smart coils, same issue. It's tuned by Raif at RRT, one of the best really at a loss here. My friend has an almost identical build and I compared his logs to mine I'm not seeing anything out of the normal. Compression is mint across the board, Leak down is all under 15% cold. Swapped cam sensors, no change triggers look normal under the scope to my eyes. Fuel pressure is good. Fuel quality is good, E75. Had the injectors flow tested, all within 10% of one another. Boost leak test yielded no leaks tested to 60PSI running all alphalock clamps. Checked all my grounds, nothing weird found. Quick run down on the setup: RRT Aluminum Rod Shortblock, Headgames cylinder head, Precision 6875, ID2600's, JMF billet manifold, Morrison Fab Forward Facing Setup, PPG Gearbox just a drag build/weekend car. Link G4X, EGT's/Coolant Pressure/Fuel Pressure/Oil Pressure failsafe's. Running an OHM Racing Smart Coil setup still on wasted spark. log 1.llgx Quote Link to comment Share on other sites More sharing options...
Adamw Posted November 6, 2023 Report Share Posted November 6, 2023 There are no obvious misfire causes in the log. Can you explain the misfire in more detail - does it happen at any specific RPM? Does it happen with just a "free rev" or only under higher load? Was it misfiring in the log? If so, where? Note your fuel pressure is reading zero in the log and doesnt appear to be set up correctly so I think this is probably making your injector deadtimes shorter than they should be, cant tell if that is causing any other effects without the tune. Quote Link to comment Share on other sites More sharing options...
remski2 Posted November 6, 2023 Report Share Posted November 6, 2023 Could it be that you are running 14.7AFR and targetting 11.79 ??? all while on boost ... Quote Link to comment Share on other sites More sharing options...
Vaughan Posted November 6, 2023 Report Share Posted November 6, 2023 11 minutes ago, remski2 said: Could it be that you are running 14.7AFR and targetting 11.79 ??? all while on boost ... Misfires read as leaner mixtures as the air was not burnt meaning oxygen is entering the exhaust Quote Link to comment Share on other sites More sharing options...
remski2 Posted November 6, 2023 Report Share Posted November 6, 2023 2 minutes ago, Vaughan said: Misfires read as leaner mixtures as the air was not burnt meaning oxygen is entering the exhaust I see what you saying.. Quote Link to comment Share on other sites More sharing options...
JunkEvo9 Posted November 6, 2023 Author Report Share Posted November 6, 2023 17 hours ago, Adamw said: There are no obvious misfire causes in the log. Can you explain the misfire in more detail - does it happen at any specific RPM? Does it happen with just a "free rev" or only under higher load? Was it misfiring in the log? If so, where? Note your fuel pressure is reading zero in the log and doesnt appear to be set up correctly so I think this is probably making your injector deadtimes shorter than they should be, cant tell if that is causing any other effects without the tune. The only time it misfires is when entering higher load (WOT). In the log I've attached I did a pull in 3rd and 4th. In 3rd 4500-4650RPMS is where its breaking up. Later in the log is 4th, it's breaking up 4200-4350RPM. I haven't logged it much more than this due to the fear of hurting something. The Fuel pressure has since been repaired I noted it on the log & I have a new sensor installed base pressure is 60PSI & doesn't drop when the vehicle is misfiring. 2nd fuel pump isn't turning on as the ECU is not seeing enough boost to command it on. I'm really starting to think its something with this OHM racing ignition system as everything else seems to check out 1 hour ago, remski2 said: I see what you saying.. This was one of the first things I checked when I saw the AFR Quote Link to comment Share on other sites More sharing options...
koracing Posted November 8, 2023 Report Share Posted November 8, 2023 Misfiring under higher load is typically a sign of weak ignition. Plug gap, plug type, dwell, etc. can all have an affect. Quote Link to comment Share on other sites More sharing options...
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