HELP! lean on hot starts
 

so ive been running ms3 pnp for 3 months and have had hot start issues from install of my ecu, my Intake Air Temp sensor is installed right after my intercooler away from heat. ive played with my after start enrichment settings but still no luck. after a few minutes or so my AFRs well richen up and runs fine. cold starts fine but just cant seem to figure out my hot start issues. any help or advice would be greatly appreciated!!

https://cimg9.ibsrv.net/gimg/www.mia...96c5cfcd4a.png
https://cimg1.ibsrv.net/gimg/www.mia...d08bff389c.png
https://cimg2.ibsrv.net/gimg/www.mia...092eff1644.png
https://cimg4.ibsrv.net/gimg/www.mia...7f289cd377.png

I am actually playing with the cold end now, but the hot end is old and works well. Actually, cold end is working well also, but is not mature.

ASE Taper is in Tenths of Seconds, not Cycles, for these tables. Inj are FF 640's, but this was similar on Yellow Top 425's.


https://cimg4.ibsrv.net/gimg/www.mia...815948f61d.png

MAT Correction looks like this: I am not using it to fix hot restarts, but to keep fueling constant at 70 kPa and up vs MAT temps.

https://cimg1.ibsrv.net/gimg/www.mia...f9aab5fa9b.png

I suggest you go to Meet and Greet section and introduce yourself. Tell us about your car, your mods, your goals.

DNM

David would you be willing to share your warmup enrichment curve also?

Thanks

Sure.
This is with the advice of Curly to enable some extra richness at low CLT for drivability. To preserve that, EGO is not active below 120*F.
https://cimg5.ibsrv.net/gimg/www.mia...2f6deacd69.png

thanks david! ive installed the FF 640 injectors as well ill try those setting out and see how she does!

You may or may not be happy with exactly those. I posted so you would have a feel for the shape needed. To overcome heat soak of injector coils that results in lean hot restart, one must add ASE and ASE Taper time.

alright cool I will keep that in mind for sure, do you think I should be using seconds rather than cycles? or is that just what you prefer?

I usually use cycles and get it to hot restart OK before running out of adjustment (you can only go so high). So I’d start tuning in seconds so you have room for adjustment when you’re done.

I'm also running the FF640 inj and have hot start issues. What has helped the most has been increasing the ASE taper at higher temps. I noticed this on the DIY MSM base. Also increasing the EGO correction and reducing the activate temp.




https://cimg6.ibsrv.net/gimg/www.mia...cc789aee37.jpg
https://cimg7.ibsrv.net/gimg/www.mia...a379caa7cf.jpg
https://cimg8.ibsrv.net/gimg/www.mia...3393000013.jpg

Ted75zcar recommended time over cycles. I agree that it yields more consistent results.

How does the factory tune compensate for hot fuel on restarts with the stock table on the NB2 returnless system?

I would think it could be done with an MS? Anyone crack it?

Factory tune does it with a much more capable ecu with endless hours of developed entertainment into it.

Returnless is not the issue.

so I made my settings close to David's settings and its made a deference. i've drove all over today with my lap top and kept making adjustment and its considerable better!! still need to do some work on it but its starting and idling ok now when hot, for sure on the right track. I really appreciate the input!!

this is what I ended up with today
https://cimg7.ibsrv.net/gimg/www.mia...53d8b4064f.png

LeoNA have fixed your issue running you taper time that high or are you still having issues sometimes?

I’m still having issues but it is substantially improved. I’m going to do a little testing today and will follow up later.

Increasing the EGO control authority to 20% in the idle area has helped.

Good point. I am running +20, -17%, after judicious tweaking of idle VE table. Off idle it can be substantially less.