I just recently started having a hot/warm restart issue where during cranking, I get what I assume a misfire, where it almost stops the starter once or twice, then the engine starts and runs fine on the same cranking cycle. This is on a S4 N/A engine, stock internals, no emissions, running an Adaptronic standalone. Starts fine when cold.

I first noticed this when I was tuning my acceleration enrichments, I accidentally stalled the engine with too much fuel on monday. I have a duplicate post in the adaptronic section, but I dont know if it is something in my tune or a bad CAS. I tried changing my startup fueling and timing from 9 BTDC to 0 BTDC, all made no difference, except when I didnt have enough fuel, it just cranked. I also recently changed my fuel injector settings a few days earlier, but I cant remember if I did any hot restarts, if I did, there was no issues.

I attached a log file, in CSV showing my ECU readings, you can see my rpm drop from 300RPM to 200RPM right before it starts, but the only other thing that changes is a slight increase in ignition dwell by 0.2ms or so. I do notice my MAP readings are high during crank, I am using the stock RX7 MAP sensor, wired like stock, maybe it looses power during cranking?

I am suspecting a CAS loosing signal or giving incorrect signal when warm at low RPM, due to the fact that changing my cranking timing to top dead center makes no difference in the kickback.

 

i've experienced this with too much cranking timing, the FSM says cranking timing is 5btdc. i have noticed that if the engine is cold, this can be too much, and if its hot you can run more.

if this is a new symptom, it could be something with the CAS signal, maybe the ecu doesn't sync it right right away

 

Thats the funny thing, at 9 BTDC, I have no problems starting a motor that is below freezing, no kickback, cranks for 2 seconds maybe at most, then fires right up no problem. Same timing with an engine at full operating temperature, and it kicks back, even with timing at TDC. The heat thing is what may be leading me to a failing CAS, as from past experiences, ignition components tend to start failing when they are hot.

 

Well this is wierd, warmed up the truck after work (-15C right now), started up fine cold, let it idle for 15 minutes, drove around the block, was at full operating temperature. Starts fine. I was going to put an older tune into the ECU, but wanted to get it to kick back first. Definately intermittant, might try tomorrow taking a long drive then seeing if it acts up, and if it does, put a tune in that I never had starting issues with and see if it goes away. If not, then it is not in my tune.