Lean Hot Starts..
#1
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Hello all,
I've been reading a lot about this issue ever since I've been getting horrible hot starts after getting tuned. Tuner was great, but I would just like to learn myself too.
Apparently the NB's returnless fuel system seems to be a big factor, but I've seen some NB1s not have this issue at all, or somehow tuned it out. I've seen some threads about adding more ASE taper when it's hot, I forgot who but someone set 180* to 1100 in ASE taper. Decided to try it with no luck. Added more ASE because IIRC from another post fuel cools down the injectors, no luck. Moved my IAT to my coldside IC, no luck. I read messing with the MAT Density table could fix it, but it shouldnt be used to combat heatsoaked sensors or injectors. I want to do this as right as possible and not seem like a hack.
Could this be a IACV problem sticking? ._.
Cold starts are good, RPMs taper from 1800 or so down to 1000 smoothly with a tiny bit of afr hunt. VE tables seem, to me, decent. WOT pulls are always 11.8 cruising is always hitting target afr etc.
Hot restarts get weird (or I've just got poopy brains) after driving around maybe about 8 miles, turn it off, sit for 5 mins, it wont start without a little bit of throttle manipulation. AFRs hunt for a bit, pegs full lean and stalls. I can drive off right away but as soon as I come to a stop it struggles for a bit then stalls unless i keep my big toe on the throttle a little bit.
FlowForce 720 injectors
AEM 30-0300 WB02
MSPNP2 3.4.3
GT2560r
DW255 FP
school me, sh-t on me etc, I just want to learn and fix my car.
I've been reading a lot about this issue ever since I've been getting horrible hot starts after getting tuned. Tuner was great, but I would just like to learn myself too.
Apparently the NB's returnless fuel system seems to be a big factor, but I've seen some NB1s not have this issue at all, or somehow tuned it out. I've seen some threads about adding more ASE taper when it's hot, I forgot who but someone set 180* to 1100 in ASE taper. Decided to try it with no luck. Added more ASE because IIRC from another post fuel cools down the injectors, no luck. Moved my IAT to my coldside IC, no luck. I read messing with the MAT Density table could fix it, but it shouldnt be used to combat heatsoaked sensors or injectors. I want to do this as right as possible and not seem like a hack.
Could this be a IACV problem sticking? ._.
Cold starts are good, RPMs taper from 1800 or so down to 1000 smoothly with a tiny bit of afr hunt. VE tables seem, to me, decent. WOT pulls are always 11.8 cruising is always hitting target afr etc.
Hot restarts get weird (or I've just got poopy brains) after driving around maybe about 8 miles, turn it off, sit for 5 mins, it wont start without a little bit of throttle manipulation. AFRs hunt for a bit, pegs full lean and stalls. I can drive off right away but as soon as I come to a stop it struggles for a bit then stalls unless i keep my big toe on the throttle a little bit.
FlowForce 720 injectors
AEM 30-0300 WB02
MSPNP2 3.4.3
GT2560r
DW255 FP
school me, sh-t on me etc, I just want to learn and fix my car.
#4
Retired Mech Design Engr
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I'm not sure when I'll get a chance to look at your log, but it sounds like your EGO is either not taking over as ASE tapers out, or your VE table is too lean.
I run +/-17% EGO authority in the idle area and, between winter idle and summer hot restart / idle, use that full 34% range. If your EGO is pegged at your 15% limit when the car goes lean and stalls; then add more VE in the needed cells.
I don't have a feel for EGO control set to Simple, vs PID regarding response time.
I would put reasonable MAT correction back in. Else you will run lean when it gets cold. (depending on the temp at which your tune was done).
I detected no change in hot restart issues after I converted to return-style fueling.
DNM
I run +/-17% EGO authority in the idle area and, between winter idle and summer hot restart / idle, use that full 34% range. If your EGO is pegged at your 15% limit when the car goes lean and stalls; then add more VE in the needed cells.
I don't have a feel for EGO control set to Simple, vs PID regarding response time.
I would put reasonable MAT correction back in. Else you will run lean when it gets cold. (depending on the temp at which your tune was done).
I detected no change in hot restart issues after I converted to return-style fueling.
DNM
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