Hot start issue in SD mode

[ramjudd]

The solution is likely simple, but I keep missing the mark by **this** much.

the symptom: upon start-up, engine RPM initially runs up to 1500rpm (normal) then drops down very low, almost (or does) stall. Rich AFR for the first 60-90 seconds of idle time, then smoothes out to Open Loop FA setting (if in SD mode with O2s off) or to stoic (if O2s on).

All the vehicle's Ive tuned in SD (6) have varying degree's of this hard start issue when warm. The bigger the cam and/or TB, the worse it is. My wideband does show a very rich condition upon start up and on through about the first 60 sec of idle time of about 11:1. I have tried many things to include RAF, IAC Park, StartUpInitial, BAse timing tables, Cranking VE, Main VE down low, etc. The only thing that seems to affect this AFR is adjusting the main VE down low around the idle rpms and MAP. The RAF seems to help a little with the start-up idle dropping too low. But I am still not happy or convinced I am tuning the right tables for this condition. Help me out, gang!!

Robert

[405HP_Z06]

The solution is likely simple, but I keep missing the mark but **this** much.

the symptom: upon start-up, engine RPM initially runs up to 1500rpm (normal) then drops down very low, almost (or does) stall. Rich AFR for the first 60-90 seconds of idle time, then smoothes out to Open Loop FA setting (if in SD mode with O2s off) or to stoic (if O2s on).

All the vehicle's Ive tuned in SD (6) have varying degree's of this hard start issue when warm. The bigger the cam and/or TB, the worse it is. My wideband does show a very rich condition upon start up and on through about the first 60 sec of idle time of about 11:1. I have tried many things to include RAF, IAC Park, StartUpInitial, BAse timing tables, Cranking VE, Main VE down low, etc. The only thing that seems to affect this AFR is adjusting the main VE down low around the idle rpms and MAP. The RAF seems to help a little with the start-up idle dropping too low. But I am still not happy or convinced I am tuning the right tables for this condition. Help me out, gang!!

Robert

Your at least the second person to report this problem. There has to be some other start-up tables that affect this.

HP Tuners - Are there any other tables in the code that we don't have access to that would affect this?

[Chris@HPTuners]

The solution is likely simple, but I keep missing the mark but **this** much.

the symptom: upon start-up, engine RPM initially runs up to 1500rpm (normal) then drops down very low, almost (or does) stall. Rich AFR for the first 60-90 seconds of idle time, then smoothes out to Open Loop FA setting (if in SD mode with O2s off) or to stoic (if O2s on).

All the vehicle's Ive tuned in SD (6) have varying degree's of this hard start issue when warm. The bigger the cam and/or TB, the worse it is. My wideband does show a very rich condition upon start up and on through about the first 60 sec of idle time of about 11:1. I have tried many things to include RAF, IAC Park, StartUpInitial, BAse timing tables, Cranking VE, Main VE down low, etc. The only thing that seems to affect this AFR is adjusting the main VE down low around the idle rpms and MAP. The RAF seems to help a little with the start-up idle dropping too low. But I am still not happy or convinced I am tuning the right tables for this condition. Help me out, gang!!

Robert

email us a logfile. what is the commanded AFR showing during this problem? the afterstart enrichment tables control the transition from cranking to normal fueling.

The IAC tables do not control fueling at all, they just control the IAC.

Generally with larger cams you need to reduce the VE around idle by as much as 20-30% depending on the overlap.

are your injectors scaled correctly or are they stock?

I run a 245/242@106 and starts fine in all weather.

Chris...

[ramjudd]

Afterstart enrichment tables? which are these?

I will get another log here soon to you if I dont figure it out in mean time. Thanks Chris!!

Robert
www.gen3motorsports.com