Brb199 Posted February 19 Report Share Posted February 19 Hi, having an absolute battle with a vk56 not revving past 5500rpm under load. This use to run fine not a new setup. I’ve been through everything. Today I noticed the cam trigger scope is changing from when cranking, the flat line where there is no teeth runs across the top of scope and once it’s running it runs across the bottom. It’s like the pattern is switching upside down once it starts. is this normal or am I on to something? thanks Quote Link to comment Share on other sites More sharing options...
Vaughan Posted February 19 Report Share Posted February 19 Not uncommon for trigger signals to swap like that, attach a PC Log of when you are running into this 5500rpm limit under load Quote Link to comment Share on other sites More sharing options...
Brb199 Posted February 19 Author Report Share Posted February 19 The AFR's have gone lean but at the same time tail pipes have gone black and new plugs are black after the very lean run in the log Log 2024-02-19 9;26;56 pm vk56 flat 5000-5500 (32-39 seconds WOT).llg Trigger Scope Log 2024-02-18 4;05;09 pm.llg Quote Link to comment Share on other sites More sharing options...
Vaughan Posted February 19 Report Share Posted February 19 Misfires will show up as lean, your log isn't showing any trigger errors or cuts. Is it lethargic and does it run any different than it used to below 5000rpm? Can you hear a misfire? Have you done a compression test? Are any of the injectors leaking? Can you confirm ignition timing with a timing light? Quote Link to comment Share on other sites More sharing options...
Brb199 Posted February 19 Author Report Share Posted February 19 It feels normal up to 4500rpm and after 5000rpm it falls over feels real lazy to about 5500rpm but not really missing and popping much just lazy all plugs are the same swamped. Revs up like normal on lite load. I’ve done fuel flow tests injectors hold pressure and are about 3 hours old. I’ve moved trigger wheel to line up with factory phasing better had timing light on multiple times, swapped in new cam and crank sensors coils and plugs tested map sensor tested spark through to 7000rpm checked all the cam timing, compression tested. about to swap in different ecu. Quote Link to comment Share on other sites More sharing options...
Vaughan Posted February 19 Report Share Posted February 19 Do you have any old logs to compare against? VVT or non VVT motor? Quote Link to comment Share on other sites More sharing options...
Brb199 Posted February 19 Author Report Share Posted February 19 It’s a vvt engine. No pc logs to compare against. Was just thinking about vvt it could be going fully advanced but not sure if that would rob so much power off it. only making about 400hp at 5500rpm and at that boost pressure I’d normally be heading towards 650+ Quote Link to comment Share on other sites More sharing options...
Vaughan Posted February 19 Report Share Posted February 19 The right hand cam is reporting errors in your log but it also looks like you aren't trying to use them as targets are always at 0. Quote Link to comment Share on other sites More sharing options...
Brb199 Posted February 19 Author Report Share Posted February 19 I’ve been meaning to get back into that area as that was years ago when it was set up and always went good but not setup 100%. Also wondering if Iv got some broken valve springs as it would still compression test ok. Last night in the dark at around 10-20% load at 6500rpm all were glowing but feels a lot like 6 cylinder at 100% load. It’s turning into a real head scratcher Quote Link to comment Share on other sites More sharing options...
Vaughan Posted February 19 Report Share Posted February 19 Given the ECU isn't cutting or hitting trigger errors and the timing comes back fine and there is no audible miss I would definitely be leaning towards it being something mechanical. Quote Link to comment Share on other sites More sharing options...
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