Cold start AFR error
05-06-2010, 07:18 AM
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Cold start AFR error I've been tuning my car since I installed my cam (230/232, 110LSA), and I have it idling great, driving great, no surging, etc. I still have a little ways to go (try CL, tune in the MAF, WOT AFR/spark on a dyno, etc), but thanks to all the advice here I believe my drivability is 90% there. My only issue is that during cold starts I have a huge AFR error which closes pretty quickly as the car begins to warm up. By ~150-160°F ECT the AFR error is pretty much gone, but at a ~60°F start I can be off by as much as 12-15%. My VE tables are all tuned to operating temp, so I've basically raped the OL EQ table to give me a "good" AFR per the wideband as it warms up. The car fires right up and finds idle no matter the temp, but I feel like I'm missing a table somewhere to add extra fuel during a cold start besides the OL table. I'm still OL right now but once I figure this out I plan to see how it does CL before I switch gears to tune the MAF. Any ideas on how I can close this hole, or is this a normal thing? Thanks!
05-06-2010, 10:16 AM
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Yeah, my stock OLEQ table went all the way up to 1.72 I believe. I can't imagine even a stock engine requiring 8.5:1. I don't have a problem hacking the table since this is a small deal, but it just seems wrong in general. I know I can set CL to activate around 140° and not have any fuel trim problems, so I may just do that for now. I did find searching the HP tuners forum that you can alter the Short Pulse Adder (vs. ECT I presume) to help this out. I may try playing with that as well as the ECT/IAT ratio to see if I can get it any more leveled out.
