AlexLSX7 Posted September 3, 2022 Report Share Posted September 3, 2022 I have a twin turbo ls3 in an RX7. I've had it running before with no issues and tuned it. I'm about done rebuilding the turbo kit. I moved the car yesterday and it started instantly like it always did. I span it round and put it back in the garage then let it idle for a bit (have let it idle multiple times before this) Went to start the car today and it's just popping and banging occasionally when cranking. Usually it does that when the front can sensor isn't plugged in. Ive checked the wiring and plug on that sensor and it's fine and getting voltage (3 pin) I can't reach down to the crank signal but was able to feel the wiring and it's not touching anything. When cranking the rpm signal on the ECU seems to come on and off like a pulse (not sure if that's normal as never paid any attention to it before). It is giving errors on the trigger 1 counter. I can't see trigger 2 turning on, but again I'm not sure if it did before as not paid attention to it I've tried loading an older map which made no difference. Other than trying to get to the plug for the crank sensor, I don't know what else to look at. Ive also tested the coils individually and I can smell fuel so I know the injectors are working as well as some pops when testing the coils. Fuel pressure is fine. I have a log of cranking if it helps but can't post till I get home. Any help greatly appreciated Quote Link to comment Share on other sites More sharing options...
Adamw Posted September 3, 2022 Report Share Posted September 3, 2022 Can you do a trigger scope while cranking. And attach your tune. Quote Link to comment Share on other sites More sharing options...
AlexLSX7 Posted September 3, 2022 Author Report Share Posted September 3, 2022 I did try that but nothing was showing. Messed about with the voltage settings on the side but still didn't get anything. I won't be at the car until Monday now if there is anything I need to change to get it working? Quote Link to comment Share on other sites More sharing options...
Adamw Posted September 4, 2022 Report Share Posted September 4, 2022 A scope will still give us clues even if there is no waveform displayed. Make sure you only click the capture button when you are cranking (not before) Quote Link to comment Share on other sites More sharing options...
AlexLSX7 Posted September 4, 2022 Author Report Share Posted September 4, 2022 Ahh I clicked it before I was cranking. I'll give it a try Monday and post the log. Quote Link to comment Share on other sites More sharing options...
AlexLSX7 Posted October 1, 2022 Author Report Share Posted October 1, 2022 Hi Adam, Apologies for the very late reply, the car is over an hour from me and I've not been able to get to it. So I had a spare cam and crank sensor so I replaced them both. Car started straight away. I tried turning it back on after letting it run for a bit and it wouldn't start again. I put an extra earth on from the engine to chassis and the car started straight away. Thinking it was resolved I carried on doing some other bits to try and finish the car. Gone to work on it today, started straight away everything seems fine. I turn it off and try turning it on again to see if it will start, of course it doesn't. I tried adding a thick earth from battery to engine as well as the other one I did and it just cranks over. I did a trigger scope, and trigger 1 (assuming crank signal?) Is just flat lining. Trigger 2 gets a line up then straight then down again when the capture finishes. I checked the wiring on both the plugs when I changed the sensors and they were both fine. I've checked the cam sensor wiring again and it's fine. The crank plug I can't get to as the headers in the way and I can't get under the car when I'm on my own as I can't get it over the pit without trapping myself. Does this sound like the wiring for the crank sensor to be the issue? Quote Link to comment Share on other sites More sharing options...
AlexLSX7 Posted October 1, 2022 Author Report Share Posted October 1, 2022 I've also just let it cool down for a few hours, tried starting it and it started straight away. It ran for a few minutes then turned off again and, again I can't start it, just cranks over Quote Link to comment Share on other sites More sharing options...
Adamw Posted October 1, 2022 Report Share Posted October 1, 2022 Attach the tune , log, and scope of it cranking. Quote Link to comment Share on other sites More sharing options...
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