Dick Posted March 10, 2022 Report Share Posted March 10, 2022 After getting my Link G4+ installed in my WRX I've been getting very loud engine knock for about a second or two on a cold start, so was wondering if there's something I can configure to delay the engine starting and crank over for a couple of seconds before the engine starts? I've tried setting up a timer that activates when RPM is > 0 (cranking over reaches about 200rpm on the starter motor) with GP RPM Limit but the engine still tries to start even though I set the RPM limit to 0 or 100rpm until after 2 seconds and just sounds really awful. Is there a config I can adjust to completely prevent the engine starting at all and just have the starter motor crank over for x seconds that doesn't involve GP RPM Limits? Cheers Quote Link to comment Share on other sites More sharing options...
Vaughan Posted March 10, 2022 Report Share Posted March 10, 2022 Couldn't think of a way top do it purely in software without using a gp rpm limit on G4+ but something like this should just be full cut for the first 4 seconds, obviously change DI 1 to whatever your start pos input is. Note I haven't tested this so it might need tweaking. As a side note do you know if the knocking is lifters, vvt or something else? Quote Link to comment Share on other sites More sharing options...
Dick Posted March 11, 2022 Author Report Share Posted March 11, 2022 Hmm, yeah that's similar to what I had done, which still tries to start the engine (I'm assuming GP RPM limits only take into effect when the engine is actually running? Maybe my fuel pump needs to be rewired cause it's currently on as long as the key is turned to on regardless if the car is running or not, rather than only being on when the cars running). As for the knocking, I'm not too sure. I'm still learning about cars (had the link installed at my local mechanic). Everyone I've asked about the knocking on a cold start says it's fine but I really don't like it (flashbacks to the two engines I've already lost due to spun bearings). I'm currently half way through just tapping into the crank sensor wires so that I can turn the crank sensor off either with the link or an external switch, haven't decided what's going to be better yet! Quote Link to comment Share on other sites More sharing options...
Vaughan Posted March 11, 2022 Report Share Posted March 11, 2022 8 minutes ago, Dick said: I'm assuming GP RPM limits only take into effect when the engine is actually running Did you have the startup lockout set to 0s? I also set that up to cut fuel and spark as cutting fuel after it has injected pre start fuel won't stop that from burning and cutting just ignition might make it flood. I wouldn't recommend screwing with the crank wires as that leaves a lot of room for trigger errors, you could instead either switch the ecu off, crank, switch ecu on, start or you could wire up a push button to one of the ECU DIs and set it up as the stop switch. Quote Link to comment Share on other sites More sharing options...
Dick Posted March 11, 2022 Author Report Share Posted March 11, 2022 6 minutes ago, Vaughan said: Did you have the startup lockout set to 0s? I also set that up to cut fuel and spark as cutting fuel after it has injected pre start fuel won't stop that from burning and cutting just ignition might make it flood. I wouldn't recommend screwing with the crank wires as that leaves a lot of room for trigger errors, you could instead either switch the ecu off, crank, switch ecu on, start or you could wire up a push button to one of the ECU DIs and set it up as the stop switch. Yep matched your settings, still had it trying to start and then the limit kicks it back off. I'm wondering if it trying to start might be if there's unburnt fuel? What do you mean by "switch the ecu off, crank, switch ecu on, start"? Open to any options that allow me to just let the engine turn over with the starter but not start at all (which is why I thought tapping into the crank sensor would work, cause if you unplug it, it replicates exactly what I want to happen, turn over without starting the engine). Not sure if I'm making much sense since this is all new to me and I might not be explaining the desired effect too well Quote Link to comment Share on other sites More sharing options...
Adamw Posted March 11, 2022 Report Share Posted March 11, 2022 The set up that vaughan gave should do exactly what you want. Will need a copy of your tune and a cranking log if it is still attempting to run with those settings. Do not mess with the crank sensor wiring, they need to remain shielded as much as possible to prevent interference. What model wrx & engine is it? Quote Link to comment Share on other sites More sharing options...
Vaughan Posted March 11, 2022 Report Share Posted March 11, 2022 22 minutes ago, Dick said: Yep matched your settings, still had it trying to start and then the limit kicks it back off. I'm wondering if it trying to start might be if there's unburnt fuel? Shouldn't be any ignition but I would have to test it on the desk to be sure. 22 minutes ago, Dick said: What do you mean by "switch the ecu off, crank, switch ecu on, start" crank the engine with the ecu off for a little bit to build oil pressure and then once oil pressure has built up turn the ecu on and start the engine. Quote Link to comment Share on other sites More sharing options...
Dick Posted March 11, 2022 Author Report Share Posted March 11, 2022 4 minutes ago, Vaughan said: crank the engine with the ecu off for a little bit to build oil pressure and then once oil pressure has built up turn the ecu on and start the engine. Is that very easy to do? I can't think how I would start with turning just the ECU off with the key in the ign.. 5 minutes ago, Adamw said: The set up that vaughan gave should do exactly what you want. Will need a copy of your tune and a cranking log if it is still attempting to run with those settings. What model wrx & engine is it? Yeah it seems like it should, so I'm starting to think it's my fuel pump being on before the car is (my mechanic said it's a bit odd that the fuel pump is on when the car is off with just the key in the ign), so I might investigate what's going on with that. The engine and engine/body loom is from an 04 WRX, the engine is either an EJ205 or 207, we're not too sure as the markings on the block just say "S20" (no, not S20C), so there's a lot of questioning we're doing with that too lol. I'll grab logs shortly, anything I need to do for logging the data you'd need or just enable logging, start the car (with the settings above), and upload the log file here? Quote Link to comment Share on other sites More sharing options...
Vaughan Posted March 11, 2022 Report Share Posted March 11, 2022 5 minutes ago, Dick said: Is that very easy to do? I can't think how I would start with turning just the ECU off with the key in the ign.. Add a push button that is wired to the starter so that you can crank it with key off or add a switch in the wire which turns the ecu power relay on Quote Link to comment Share on other sites More sharing options...
Dick Posted March 11, 2022 Author Report Share Posted March 11, 2022 3 minutes ago, Vaughan said: Add a push button that is wired to the starter so that you can crank it with key off or add a switch in the wire which turns the ecu power relay on Oh good idea! I'll add a switch for the starter! I have an immobilizer so hopefully it won't interfere with that Quote Link to comment Share on other sites More sharing options...
Adamw Posted March 11, 2022 Report Share Posted March 11, 2022 2 hours ago, Dick said: Yeah it seems like it should, so I'm starting to think it's my fuel pump being on before the car is (my mechanic said it's a bit odd that the fuel pump is on when the car is off with just the key in the ign), so I might investigate what's going on with that. Even with the pump running, the injectors arent squirting so there should be no fuel or spark. There will be a tiny bit of fuel injected from the pre-crank prime but should still be no spark. 2 hours ago, Dick said: anything I need to do for logging the data you'd need or just enable logging, start the car (with the settings above), and upload the log file here? Correct, just start log, crank, then stop log & save. Quote Link to comment Share on other sites More sharing options...
Dick Posted March 11, 2022 Author Report Share Posted March 11, 2022 Alright so for now I've just rigged up a switch to the starter, and just gonna use that to prime the engine on cold starts. Comfortably happy with that result, may come back to this attempt to automate it in the future but for now it'll do! Vaughan 1 Quote Link to comment Share on other sites More sharing options...
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