..solder connections, poor idle
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From: Del Monte Beach, Monterey, CA
..solder connections, poor idle
Guys i just pulled out my safc II harness last night. I had to hook up the AVC-R and wanted to double check the connections. The original hookups were made with wire connectors. I wanted these connections to be stronger and solder to the field harness so I wired everything up and resolder all the connections just as they were. The only thing i did was unhook my battery, reset the ecu and resolde the harness. This morning it was pretty wet and rainy out and the car is idling very low.. 750-800 rpm and it seems like its grinding at idle. It was definately not doing this before. Is this anything to worry about or the ecu just relearning fuel trims since i had it unhooked.
Thread Starter
Evolved Member
iTrader: (7)
Joined: Aug 2004
Posts: 1,252
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From: Del Monte Beach, Monterey, CA
nevermind jack has the answers
"Unfortunately after you reset the ECU, any time conditions change, air density, humidity, even running A/C will take a few "runs" of the engine (through a full warmup-drive-shutdown sequence) for it to adjust its long term fuel trims and your idle and part throttle drivability will get better.. it sucks, but it happens.
If your idle is real rich in open loop (when the car is cold) remove a little fuel using the S-AFC at 800-1500 rpm, if its lean, you'll have to add fuel.. It should be a little richer than the closed loop ratio (14.7:1) since when the car is cold, you want to "choke it" a bit.. so 13.9 or so is what you should target.. This is obviously only an idle recommendation in open loop..
with Piggyback fuel systems, you can figure out approx how much fuel to remove to scale for your injectors.. Figure out the % larger the injectors are, then remove basically that amount (less 1% from my experience.. so if its 10% larger, you can remove about 9%-10%, 680's would be around 20% larger, etc..) This is scaling for open loop to get you around where it would be *STOCK*.. then you need to tune for your modifications or idle characteristics due to cams, pipe upgrades.. and in open loop WOT which are the same things, plus boost and timing considerations.
So, if you removed your S-AFC, but the weather conditions have been fairly mild with low humidity, you may have found the car ran fine.. then the air density changed due to weather, humidity, etc.. and your idle got poorer.. Thats when you need to add a bit of fuel (as Rich described) and that is the need for the S-AFC. Remember, for part throttle highway driving, and idle after the engine is warmed up.. the S-AFC's settings do not have any influence on the ECU.. even if you set it up to alter mixture at TPS below 30%, the ECU would just tune it out..
Oh, also if you have bigger injectors, so at idle you could actually be dumping too much fuel without the S-AFC in open loop.. Idle would also suffer..
Ok.. I lost my train of thought.. If you want more insight, just PM me and I'll try to get you through it point by point..
"
"Unfortunately after you reset the ECU, any time conditions change, air density, humidity, even running A/C will take a few "runs" of the engine (through a full warmup-drive-shutdown sequence) for it to adjust its long term fuel trims and your idle and part throttle drivability will get better.. it sucks, but it happens.
If your idle is real rich in open loop (when the car is cold) remove a little fuel using the S-AFC at 800-1500 rpm, if its lean, you'll have to add fuel.. It should be a little richer than the closed loop ratio (14.7:1) since when the car is cold, you want to "choke it" a bit.. so 13.9 or so is what you should target.. This is obviously only an idle recommendation in open loop..
with Piggyback fuel systems, you can figure out approx how much fuel to remove to scale for your injectors.. Figure out the % larger the injectors are, then remove basically that amount (less 1% from my experience.. so if its 10% larger, you can remove about 9%-10%, 680's would be around 20% larger, etc..) This is scaling for open loop to get you around where it would be *STOCK*.. then you need to tune for your modifications or idle characteristics due to cams, pipe upgrades.. and in open loop WOT which are the same things, plus boost and timing considerations.
So, if you removed your S-AFC, but the weather conditions have been fairly mild with low humidity, you may have found the car ran fine.. then the air density changed due to weather, humidity, etc.. and your idle got poorer.. Thats when you need to add a bit of fuel (as Rich described) and that is the need for the S-AFC. Remember, for part throttle highway driving, and idle after the engine is warmed up.. the S-AFC's settings do not have any influence on the ECU.. even if you set it up to alter mixture at TPS below 30%, the ECU would just tune it out..
Oh, also if you have bigger injectors, so at idle you could actually be dumping too much fuel without the S-AFC in open loop.. Idle would also suffer..
Ok.. I lost my train of thought.. If you want more insight, just PM me and I'll try to get you through it point by point..
"
