cwhite951 Posted May 11, 2021 Report Share Posted May 11, 2021 My track car build was running perfectly at idle / no load. After I had the top end apart is now either wont start or runs very erratically. scope looks fine but when I can get it to briefly run (at idle speeds) the rpms are all over the place peaking way over 8k rpm on the data log. Rechecked the crank and cam sensors - looked fine and the scope trace looks prefect. any ideas? Quote Link to comment Share on other sites More sharing options...
Adamw Posted May 11, 2021 Report Share Posted May 11, 2021 Please attach the triggerscope and a copy of the tune. Quote Link to comment Share on other sites More sharing options...
cwhite951 Posted May 13, 2021 Author Report Share Posted May 13, 2021 I fixed the issue but that raises a question - it turns out that the cam sensor was picking up some background noise, I backed off on the gap and it works fine. I used to be an Electromotive dealer and their system only looked at the cam sensor on start up to determine the correct cycle and then ignored any further input. If noise on the cam sensor is disrupting the RPM readings then the Link must be continuously looking at the cam sensor and using that input for calculations. Can you fill me in on what the ECU is using the cam signal for once the engine is running ? Quote Link to comment Share on other sites More sharing options...
Adamw Posted May 13, 2021 Report Share Posted May 13, 2021 Depends what trigger mode and what sync mode you are using. You have given no info. In multittooh mode you will need the cam sesnor as that tells the ECU which tooth on the crank to work from. In missing tooth mode with "cam pulse 1X" sync mode the ecu just checks if a cam pulse occured in the last revolution or not. With nearly any of the modes you can unplug the cam sensor when the engine is running and the ecu can keep track of engine position, it is only when you have a bad signal on the crank as well that it needs the cam again to re sync. Quote Link to comment Share on other sites More sharing options...
cwhite951 Posted May 16, 2021 Author Report Share Posted May 16, 2021 OK - some info - 60-2 tooth crank trigger set to 11 teeth at TDC, Hall effect crank and cam sensors, single tooth cam trigger. Cam pulse 1x sync mode. I have a log bit its slightly larger than I can post (481k) and I cant figure out how to edit its length. program file attached Quote Link to comment Share on other sites More sharing options...
Adamw Posted May 16, 2021 Report Share Posted May 16, 2021 Multitooth/missing mode would be perfectly happy without the cam sensor so that wasnt your problem. I would say your issue is using level 4 filtering on trigger 1, at high RPM that will actually start filtering real teeth out, then it will lose position and would need a working cam sensor to resync. I would use no more than level 1 on a 60 tooth wheel. Quote Link to comment Share on other sites More sharing options...
cwhite951 Posted May 21, 2021 Author Report Share Posted May 21, 2021 its working now but I am still puzzled. the RPM readings were fluctuating during cranking enough so that the push button start would disengage because it though it was way over the 'stop cranking' rpm threshold. if it did fire I logged spikes of 22,000 rpm when it was barely running. I regapped the crank sensor several times and it made no difference. I looked closer at the scope and saw odd random signals from the cam sensor, regapped that and it runs fine. Doesn't make sense to me! whats with the 56.87 kb max attachment? thats pretty small.... OK, fixed the quota issue - so here is the data log and screen shot of the erratic behavior screen shot.pdf 944 link log.llg Quote Link to comment Share on other sites More sharing options...
Adamw Posted May 21, 2021 Report Share Posted May 21, 2021 On 5/12/2021 at 9:45 AM, Adamw said: Please attach the triggerscope and a copy of the tune. Quote Link to comment Share on other sites More sharing options...
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