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SVTPerformance's Chain of Restaurants
Tuning À la carte
[help] Cold Tip-in Issue
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<blockquote data-quote="SnakeBoostE85" data-source="post: 14752071" data-attributes="member: 160175"><p>OK I have finally resolved this… not really using any of the above mentioned solutions, as none of them worked for me. My theory here is that ethanol's flashpoint is much higher than gas and it just needs a ton of freakin fuel when it cold to prevent tip-in issues. So here goes… in order for the startup cold fuel table to be effective until the car warms up I had to hold it open loop much longer than stock. Which we touched on above. So I started taking notes on how long it would take to reach 100 degrees from various start up temps and basically plugged round values into the time-delay for closed loop table. </p><p></p><p>[ATTACH]37707[/ATTACH]</p><p></p><p>so as you can see I might wait as long as 5 minutes to go closed loop based on startup temp down to about 20 seconds if its near 100 degrees. The problem is that I noticed my short term fuel trims were all over the place until the car was warmed up. (maybe I need to replace my front 02 sensors), but until the car was warmed up, the 02's were basically useless and short term trims were useless to help control fueling. </p><p></p><p>Knowing that my MAF transfer function was tuned to the TEE, I figured why can't I just use my MAF at startup instead of the closed loop crap. So holding it open loop allowed me to get the startup cold fuel table to work. </p><p></p><p>So I added a ton of start up cold fuel below 100 degrees ECT. </p><p></p><p>[ATTACH]37708[/ATTACH]</p><p></p><p>I think its richer than it needs to be, but the stock values were clearly not enough fuel to prevent the tip-in condition. I will probably pull some out on the lower end until I find the threshold of the tip-in condition. My wideband is reading about 12.x at part throttle, but at idle its 14.7 (running ethanol, but using gas afr's)… anyone see an issue running rich at cold start up? I wouldn't be hurting anything except being less emission friendly I presume. </p><p></p><p>Next I also lowered my manifold volume quite a bit until I had hot tip-in issues. I settled in at 6 liters. (keep in mind I am scaled) The BA3000 mvf file changes manifold volume from 10 to 4 and I am running a 2.9 Liter blower so 6 is probably about right with the scaling. </p><p></p><p>So all in all.. I'm only effecting things below 100 degrees ECT and I didn't have any hot tip-in conditions. </p><p></p><p>This might be a bit of hack-ish way to fix the problem, but I honestly could not get a reaction from the car unless I held it up open-loop. Again the 02 sensors just don't work until they are warmed up so closed loop fueling is basically useless. </p><p></p><p>Curious on folks thoughts and concerns with the solution here.</p></blockquote><p></p>
[QUOTE="SnakeBoostE85, post: 14752071, member: 160175"] OK I have finally resolved this… not really using any of the above mentioned solutions, as none of them worked for me. My theory here is that ethanol's flashpoint is much higher than gas and it just needs a ton of freakin fuel when it cold to prevent tip-in issues. So here goes… in order for the startup cold fuel table to be effective until the car warms up I had to hold it open loop much longer than stock. Which we touched on above. So I started taking notes on how long it would take to reach 100 degrees from various start up temps and basically plugged round values into the time-delay for closed loop table. [ATTACH]37707[/ATTACH] so as you can see I might wait as long as 5 minutes to go closed loop based on startup temp down to about 20 seconds if its near 100 degrees. The problem is that I noticed my short term fuel trims were all over the place until the car was warmed up. (maybe I need to replace my front 02 sensors), but until the car was warmed up, the 02's were basically useless and short term trims were useless to help control fueling. Knowing that my MAF transfer function was tuned to the TEE, I figured why can't I just use my MAF at startup instead of the closed loop crap. So holding it open loop allowed me to get the startup cold fuel table to work. So I added a ton of start up cold fuel below 100 degrees ECT. [ATTACH]37708[/ATTACH] I think its richer than it needs to be, but the stock values were clearly not enough fuel to prevent the tip-in condition. I will probably pull some out on the lower end until I find the threshold of the tip-in condition. My wideband is reading about 12.x at part throttle, but at idle its 14.7 (running ethanol, but using gas afr's)… anyone see an issue running rich at cold start up? I wouldn't be hurting anything except being less emission friendly I presume. Next I also lowered my manifold volume quite a bit until I had hot tip-in issues. I settled in at 6 liters. (keep in mind I am scaled) The BA3000 mvf file changes manifold volume from 10 to 4 and I am running a 2.9 Liter blower so 6 is probably about right with the scaling. So all in all.. I'm only effecting things below 100 degrees ECT and I didn't have any hot tip-in conditions. This might be a bit of hack-ish way to fix the problem, but I honestly could not get a reaction from the car unless I held it up open-loop. Again the 02 sensors just don't work until they are warmed up so closed loop fueling is basically useless. Curious on folks thoughts and concerns with the solution here. [/QUOTE]
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Tuning À la carte
[help] Cold Tip-in Issue
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