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Thread: Engine Knock - help with logs - adjusting SAFC

  1. #1
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    Angry Engine Knock - help with logs - adjusting SAFC

    I have been trying to get this knock issue figured out for a couple weeks now without any luck. I just got the car running and it idles and I can free rev the engine just fine. no issues!

    So I take the car on a quick drive and I ease into the throttle a little. Once the throttle gets past 40% the car starts to buckle likes it's missing and I am getting 1-9 counts of knock.

    Right now I have the SAFC zeroed out as the car is pretty much all stock. "Mods listed in sig". I swapped out the MAF with another one I have and still the same issues.

    Looking at my logs it looks to be that when I start to get on the throttle the car is running to lean when I get the 9 counts of knock, 15 AFR at 1800 RPM's!!! Looking at the rest of the log when the throttle is in the same and the AFR is the same I get no knock. Why is there no consistency in the logs?

    Log File http://3s.gonzoinc.com/albums/userpi...02-17_Pull.xls

    So here are my questions:

    1: SAFC Lo/Hi throttle settings: What the hell do these mean? Is it the percent the throttle is open? I need a plain answer here as all of the other description I have found don't make any sense! I think mine are currently set at 30/60

    2: With no corrections on the SAFC and the engine solely running off the TT ECU why is it running so damn bad! I have checked all sensors and everything looks good. I am going to change out the front O2 as I think it needs it as I had to change out the rear as it was DOA.

    3: Why is my Accerlerator enrichment "ACLE" all over the place even though I am not giving it any gas? Is it due to the IAC counts being so high? Having with high idle after decel, Might be related. Thread here for idle issues Idle issue IAC steps - 3000GT/Stealth International Message Center

    4: I also lowered the plug gap to 29 as I though it might be blowout due to the higher compression of the 10:1 pistons. Could the lower gap be making the problem worse?

    Any advise as to what the problem could be or how to adjust the SAFC to compensate?

    I'm really stuck here guys and any help would be appreciated. I am trying to get the car ready for BRG in two months and this is really holding me back from finishing off a bunch of other projects due to the engine not stable at this moment.

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  2. #2
    Banned Feedback Score 11 (100%) J. Fast's Avatar
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    Quote Originally Posted by DrGonzo View Post
    I have been trying to get this knock issue figured out for a couple weeks now without any luck. I just got the car running and it idles and I can free rev the engine just fine. no issues!

    So I take the car on a quick drive and I ease into the throttle a little. Once the throttle gets past 40% the car starts to buckle likes it's missing and I am getting 1-9 counts of knock.

    Right now I have the SAFC zeroed out as the car is pretty much all stock. "Mods listed in sig". I swapped out the MAF with another one I have and still the same issues.

    Looking at my logs it looks to be that when I start to get on the throttle the car is running to lean when I get the 9 counts of knock, 15 AFR at 1800 RPM's!!! Looking at the rest of the log when the throttle is in the same and the AFR is the same I get no knock. Why is there no consistency in the logs?

    Log File http://3s.gonzoinc.com/albums/userpi...02-17_Pull.xls

    So here are my questions:

    1: SAFC Lo/Hi throttle settings: What the hell do these mean? Is it the percent the throttle is open? I need a plain answer here as all of the other description I have found don't make any sense! I think mine are currently set at 30/60
    SAFC Hi/Low settings is all airflow signal, it's based on Hz. That's all your compensating. Low is 0-125 Hz, Mid is 125-175 Hz and High is 175 and everything above.

    Quote Originally Posted by DrGonzo View Post
    2: With no corrections on the SAFC and the engine solely running off the TT ECU why is it running so damn bad! I have checked all sensors and everything looks good. I am going to change out the front O2 as I think it needs it as I had to change out the rear as it was DOA.
    Have you tried clearing the old Timing and Fuel trim maps off the ECU? What happens when you try adding fuel to the rev range it starts breaking up at? Is the ecu responding to your input and giving you back timing and lowering knock when you add fuel in High Thrttle Settings?

    Quote Originally Posted by DrGonzo View Post
    3: Why is my Accerlerator enrichment "ACLE" all over the place even though I am not giving it any gas? Is it due to the IAC counts being so high? Having with high idle after decel, Might be related. Thread here for idle issues Idle issue IAC steps - 3000GT/Stealth International Message Center
    I can only tell you that incomplete combustion, unmetered air disturbance, saturation or starvation of air or fuel, and or electrical signal, wiring can lead to problems aswell.

    Quote Originally Posted by DrGonzo View Post
    4: I also lowered the plug gap to 29 as I though it might be blowout due to the higher compression of the 10:1 pistons. Could the lower gap be making the problem worse?
    Have you pulled the plugs to see if they're fouled or to see what color they are?

    Any advise as to what the problem could be or how to adjust the SAFC to compensate?

    Start all over again with the base AFC.

    Set Low first het the car to settle around 100% while watching your logger. Do the same for midrange. And then for High as log as it keeps giving you timing and not knocking keep giving it fuel.

    Check the basic stuff, and start off with 0 correction and low throttle point at 20% and high at 80% start all over again with the low and STFT, do midrange, and go back to high and see where that gets you. You should be able to dump mounds of fuel in there, enough to flood it and kill it, so maybe it's your logger or 02's are on the fritz. Tuning can be frustrating, you have to stay with it though.

    Beer's on me Greg

    Cheers
    Last edited by J. Fast; 02-18-2011 at 02:41 AM.

  3. #3
    Never finishes any verified
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    Quote Originally Posted by steve68 View Post
    Pulling back the base timing would be a good start. What's it set to anyway?

    Low fuel trim should be 100%, it's pegged out low which means it's too rich at idle, maybe the FPR is over running/ pressure too high. Medium & high trims don't look good either.

    If you reset your ECU the trims will go back to 100% and the car willl run worse until it relearns, if everything is set up correctly the trims will stay at 100%.
    There's no point in even driving the car until you get that part of it sorted.

    Steve

    Base timing is set to 7deg. FPR is a FuelLab and set to 43psi, it's not getting overrun. The bcars not running rich at idle the AFR is in the range of 14-18 range which is a hair little on the lean side at certin points.

    Quote Originally Posted by J. Fast View Post
    SAFC Hi/Low settings is all airflow signal, it's based on Hz. That's all your compensating. Low is 0-125 Hz, Mid is 125-175 Hz and High is 175 and everything above.

    Have you tried clearing the old Timing and Fuel trim maps off the ECU? What happens when you try adding fuel to the rev range it starts breaking up at? Is the ecu responding to your input and giving you back timing and lowering knock when you add fuel in High Thrttle Settings?

    I can only tell you that incomplete combustion, unmetered air disturbance, saturation or starvation of air or fuel, and or electrical signal, wiring can lead to problems aswell.

    Have you pulled the plugs to see if they're fouled or to see what color they are?

    Any advise as to what the problem could be or how to adjust the SAFC to compensate?

    Start all over again with the base AFC.

    Set Low first het the car to settle around 100% while watching your logger. Do the same for midrange. And then for High as log as it keeps giving you timing and not knocking keep giving it fuel.

    Check the basic stuff, and start off with 0 correction and low throttle point at 20% and high at 80% start all over again with the low and STFT, do midrange, and go back to high and see where that gets you. You should be able to dump mounds of fuel in there, enough to flood it and kill it, so maybe it's your logger or 02's are on the fritz. Tuning can be frustrating, you have to stay with it though.

    Beer's on me Greg

    Cheers
    I'll start by dumping the maps and clearing the ECU. I haven't done that yet so it will be a good start and might help to clear up and crap siting in there.

    Plugs are great. I just pulled them the other day to check to see if they were fouled.

    The car is reacting to adjustments made on the SAFC so I don't think it's a wiring issue.

    The problem is that if I set the hi/low to 20/80 then I am unable to make adjustments in the ranges I need to. When I am getting knock it is always within the mid range which is a calculation based off of the hi/low and I cannot make adjustments to that range.

    I really don't think it's a SAFC issue, I think the problems lye elsewhere. In theory I should be able to run the car without the SAFC since the engine is pretty much stock just 10: pistons. Many other have done it when doing FWD/TT conversions.

  4. #4
    Never finishes any verified
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    Any other ideas!

    Trying to get a couple of options here so I can knock out all the testing at once.

  5. #5
    seize the carpe! Feedback Score 0 Lithium's Avatar
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    Did you properly set up the Hi/low throttle points on the SAFC?

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