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I had a tune that seemed to be very reliable until I changed to sequential injection. I got the VE table adjusted for the change as it made the car run a little more rich. Now my main problem is when the car warms up enough for EGO to kick in the idle can hunt up to 900 RPM. Turning on idle advance seemed to help it smooth out a bit but it can still hunt pretty bad and also upon releasing the brake at idle the hunt will get even worse and sometimes even kill the car.
Attached are my tune and a log of the issue. Spots where the hunt gets really bad is after releasing the brake and the end of the log is it actually dying from releasing the brake.
Idle is fine as the car is warming up until EGO turns on.
I also have an issue at cold start of the engine wanting to die when giving throttle. Super light throttle input is ok but any more and it stumbles hard before reving up. Revs fine after it warms up a bit. I can get a log of that tomorrow after it cools.
Never had any of these issues until I went sequential. Let me know if you need anymore info!
You should probably change your idle advance to 10 degrees across the board so the idle advance numbers and the timing correction don't fight each other. Your MAT Air density table needs to pull less fuel when hot, your log is at 121 MAT which will pull 12% fuel, getting worse as the sensor heatsoaks. This probably causes the EGO to try to add fuel and get into a loop. Your Idle VE Table is barely tuned, lots of the value are exactly the same and that won't help. Your Idle Timing correction curve could be way more aggressive on the -RPM End.
For your stumble issue,
Change your cold accel multiplier in your TPS Enrichment from 100% to 110% or something, and consider more WUE if that doesn't do it
Idle hunt still there but a little better. Does it look like I am on the right track?
This log I caught a kind of worst case scenario. Car was already hot. Let it sit on my lunch break and when I started it up the MAT was heat soaked even worse. Car would actually only run for a few seconds until I took more fuel cut out of the top end of the MAT Air Density Table. It was dying even before EGO kicked in. I can give a log of that as well if needed.
also as a side note. Stumble on cold start is much better now.
I can't open your log for some reason but your ASE is doing almost nothing. Only adds 5% more fuel for barely any time, I would recommend making your ASE graph duration look like a U so heat soaked starts are rich, and make the extra amount of fuel like 4x the current amount, maybe 20 instead of 5% more fuel. That will keep fueling in check before EGO kicks in.
Yeah as it got better you are definitely on the right track. Look at the spark values/VE Values that it is hunting and see if there is a large difference in the spark values and VE values its hitting.
If your car is stumbling on throttle tip in cold starts it wants more fuel. Tune based on feel, make sure your WUE table is giving enough enrichment. Yours is at 100% from 100 clt to fully warmed up, reference my table on the left and try something more like it.
I see what you mean with the log. I can't open it either. I cropped and exported that one something must have gone wrong. I'll just attach the full one. It has the car dying on hot starts (which isn't a problem now) and the idle I tried to crop at the very end.
As far as WUE goes. I'll get it sorted. I was kind of in the middle of playing with it to see what it liked.
I can see the spark and VE values osculating but not sure how to use that info to fix it.
You can try turning off EGO during idle till the hunting issue is solved. Some cars don't like EGO at idle ever, or the PID settings are too aggressive for it to work at idle and require adjustment. Keep closed loop idle on, no reason to turn it off, the alternative is open loop which isn't very good.
On that log EGO isn't doing anything until 30 seconds of the motor running, so it goes super lean after start and dies not due to EGO, just due to ASE taper being super short and adding almost no fuel, and WUE doing nothing after 100 CLT. Change your ASE to be long and add much more fuel and it shouldn't stall.
Look at your Idle VE Table when the idle is hunting, when the idle hunts the AFRs go from 14.7 to 13.0 and back and forth. Your issue probably lies in the Idle VE Table, one cell being way more rich than the other. EGO doesn't change during the hunt.
You could also make your RPM Timing Correction curve more aggressive on the -RPM Side, better to have it higher than your target so it settles slowly. Running this on a 93 NA Running 640CC Injectors in sequential and it works great.
EDIT - Missed another thing, change your closed loop idle PID delay from 1 to 2, when I had it set to 1 it would fail to perform the crank to run taper and immediately closed the idle valve too much (referencing the 850 rpm value on my closed loop idle initial value table) causing my car to stall sometimes on hot starts.
So I got the car hot to start the idle hunt. I shut off EGO at idle so it only runs above 1500RPM. Hunt immediately stopped. I saw that the AFR was like mid to low 12's so started to pull fuel in the Idle VE table. As it got to about 13 it started hunting again. Added fuel till it was under 13 and it was stable. Took fuel back out and it hunted real bad and died. So it's unstable above 13, that explains why it wouldn't idle smooth with EGO as it was trying to hit like 13.7.
Isn't mid 12's a little fat though? Is that something I need to look at or does sequential injection just need to be a bit fatter at idle? I have sequential on, 640 injectors, and COPs just so you know my setup.
Only other problem I have left is at start the car cranks, fires, hits decent RPM, then almost dies, and hunts up and down and then settles. I notice that the timing spikes up to 24 and as it does it leans out and then almost dies but eventually settles. Not sure why the timing spikes like that. Still an issue of not enough fuel? That seems to be my cause for everything so far.
Your dead time voltage % curve isn't right if you are using FF640CC injectors, check the dead time voltage curve and compare with the chart here and change the curve 3 table and it should help fueling stability at idle.
Should easily be able to idle at 14.7 especially with sequential injection, pretty sure the botched dead time table may have something to do with it. Should match the linked curve exactly.
The uploaded tune looks like its running semi sequential injection?
Last edited by HowPrayGame; 10-07-2020 at 04:48 PM.
****. semi sequential was the issue. Set to full sequential, started, and it was at 15.6 AFR and holding steady. Dialed it back to mid 14's. Didn't realize I had the wrong one selected!! Thanks for catching that.
Found a new issue though. Now when I start at a hot temp after ASE turns of the car slowly goes up to a super high AFR and dies. If I rev it a bit it will stay alive but when it gets back to idle it will still be a high AFR but low enough it will run. The AFR will slowly go back down to the mid 14's after about a minute of letting it sit and idle after that. This was at 180 or more CLT.
10-05-2020, 07:47 PM
Idle Hunt after going sequential injection
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