longan Posted July 31, 2021 Report Share Posted July 31, 2021 Hi everyone, I have a G4X for an evo 8. Car is running flex tune and has cams. Car has been tuned but there are some minor issues around idle dip but the start need alot more work. Car is currently running e85. Currently have the following 2 issues that I have been trying to iron out. Cold start, requires a really long crank for it to start. I have attached log and file. How do I work out if it needs more/less fuel or more/less air. Pretty much I have maxed out both. Warm start, it is a 50/50 chance it will start on first crank or it needs 2 cranks. I have attached log too. You can see in the log. First crank was fine but the two proceeding start required two cranks. I can see the crank enrichment value uses 0 percent ethanol value when it should be at 75 like the first crank. Does this mean the sensor is faulty or misconfiguration on the ecu? During drives and the cold start, the ethanol percentage is correct. warm start.llgx longan31-07-21v2.pclx cold start.llgx Quote Link to comment Share on other sites More sharing options...
Adamw Posted July 31, 2021 Report Share Posted July 31, 2021 For the Ethanol value at start up, change the sensor lockout time to 0s, it will then read as soon as powered up, this lockout time is used to mask the erroneous sensor readings at start up in systems with no check valve. The next firmware release has a new feature where it will "remember" the last value from when the engine last stopped for the next start up. Cold start on E85 is never easy, you need vapor for combustion, but ethanol has a low vapor pressure so there is very little vapor in the port when the port walls are cold. Thats why you need to dump so much fuel in to get a tiny bit of vapor. The problem is it becomes a fine balance between getting enough vapor in without large pools of liquid fuel fouling the plugs. In the crank enrichment settings you still have a lot of room to move with the "first crank prime". This value is how much extra fuel is added to the first revolution so usually is a good one to adjust. You are only at 40% now so try shifting it in big chunks to see if it gets better or worse. Say try around 200 & 400%. You can also try moving the injector timing later so it injects when there is air moving in the port. Try around 200BTDC to see if that helps. If it does you can change it to a table based value later. Warm start I suspect will probably improve with fixing that start up lockout time. Also, not related to any of your issues at all, but I suggest in your idle ignition settings, change proportional to 1.0 and derivative to 0, I can see in the log it is way too active and not idling happy at those values you have in there. Change idle actuator integral to 0.5. Update to latest firmware also. Quote Link to comment Share on other sites More sharing options...
longan Posted July 31, 2021 Author Report Share Posted July 31, 2021 HI Adam Thanks for your help! Make sense. I will update the sensor setting and play with the cold start and retest warm start tomorrow. Strange in the configuration help blurb for that sensor setting it says the ECU should use last known value during that lock out time. Must be a bug on this version. I will try the new values you suggested for idles as well. I will talk to the tuner about upgrading the firmware as his ultimately responsible for the tune/ecu. Quote Link to comment Share on other sites More sharing options...
longan Posted August 1, 2021 Author Report Share Posted August 1, 2021 Hi Adam, The warm start is perfect now when it 90 and above (operating temp). Below that, it start on first crank but kind of struggle with low revs for abit then bounce back up and is fine. Do you know which setting i should concentrate to fix that? I have attached a log with cranking at 60/70/80/90. You can see the rev dip beside at 90. Regarding cold start I am still need to play with the first prime crank. I tried with 200 today but not sure if it helped or not. I will try 400 tomorrow and see. longan-01-08-21v3.pclx warm start at different temp.llgx Quote Link to comment Share on other sites More sharing options...
Adamw Posted August 1, 2021 Report Share Posted August 1, 2021 The idle valve position is stable the whole time so it appears to be fuel related. I think it may want more crank enrichment (CR table). You can see below when the Inj PW was initially up around 5ms (due to first crank enrich + higher MAP), the RPM shot up quickly, but when inj PW dropped back to 3ms the RPM started to fall. Quote Link to comment Share on other sites More sharing options...
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