Lean Detonation Thoughts?
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From: Texarkana, Texas
Lean Detonation Thoughts? Just bought my first Ls1 last week. I noticed on the way home it had a detonation at wot about 5k rpm. Filled with premium (93), changed plugs to Tr6's, changed fuel filter, checked for vacuum leaks, cleaned the maf, and reset pcm. I still have the ping.
I Atap'd the car today and found both front o2 voltages under wot at 5k rpm at .835. I know they are not real acurate, but this seems pretty lean, and would explain the detonation. Getting up to 4* knock retard when the o2's go lean. Also the ltft's are about -7%. Looks like the pcm is actaully leaning the engine too much.
The car was owned by an older getleman, and is completely stock. No lid or anything. Has 54k on it.
Any thoughts on what to look for?
I Atap'd the car today and found both front o2 voltages under wot at 5k rpm at .835. I know they are not real acurate, but this seems pretty lean, and would explain the detonation. Getting up to 4* knock retard when the o2's go lean. Also the ltft's are about -7%. Looks like the pcm is actaully leaning the engine too much.
The car was owned by an older getleman, and is completely stock. No lid or anything. Has 54k on it.
Any thoughts on what to look for?
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From: Birmingham, AL
If it's stock, why'd you use TR6s just out of curiosity? These cars are notorious for running rich when stock so it's odd yours does seem lean at WOT. That really makes no sense to me. When you replaced the plugs and put the plug wires back on, did you go one click for the plug, and 2 clicks for the coil pack? Believe it or not, if its not clicked twice on the coil pack that will cause KR. I didn't believe it until I tried it myself. 
If we could see your atap logs in a text format somebody could probably be of a little more help to ya though.
If we could see your atap logs in a text format somebody could probably be of a little more help to ya though. Thread Starter
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From: Texarkana, Texas
I did get em on right. I have a friend who is very familiar with these cars, who helped me. It's been pretty hot here, and seemed when the engine was cool it didn't ping as bad, so I thought the one step colder plug might help with the detonation. That was before I got access to Atap. Also was considering n20 in the future.
My friend has my log on his laptop, so I don't have access to it right now to post it.
I feel like I covered my bases pretty well, but I must be missing something. I even pulled the y pipe to make sure the cats weren't clogged or gutted, and checked fuel pressure. I did find that my factory installed slp muffler has a broken baffle inside. Doesn't seem like this would cause the lean condition though.
Unless I don't understand how it works, I don't think knock retard is my problem. It is retarding because of the knock caused by the lean condition. If it's lean and causing knock, I should get knock retard right? I have been focusing on the lean condition.
My friend has my log on his laptop, so I don't have access to it right now to post it.
I feel like I covered my bases pretty well, but I must be missing something. I even pulled the y pipe to make sure the cats weren't clogged or gutted, and checked fuel pressure. I did find that my factory installed slp muffler has a broken baffle inside. Doesn't seem like this would cause the lean condition though.
Unless I don't understand how it works, I don't think knock retard is my problem. It is retarding because of the knock caused by the lean condition. If it's lean and causing knock, I should get knock retard right? I have been focusing on the lean condition.
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From: Birmingham, AL
Yes, it does look like you covered all the bases before posting on here. Can you tell if the car is really pinging or if it is just false knock? You are correct. If it is indeed a lean condition, then that would more than likely be the cause of the KR. Something important to check is at what RPM it begins to show knock retard on the logs.
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From: Texarkana, Texas
It is definately ping. I can hear it pretty loud, especially after the car warms up. I just got my Hp tuners today. So I will do some more checking. As far as I can remember it showed 0 knock retard until about 5200 or 5400 rpm's. Then it showed up to 4*.
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I decided to try what everyone says not to do. I changed the stoich to 13.1. No other changes. My wot o2's were .890 to .900. All cells showed 0 knock retard and the car ran great. No detonation. I know this is a little rich, but it's a lot better than the lean mixture I had before. Needs more fine tuning.
This creates some questions. Why would you want the stoich at 14.6? My ltft constantly showed -7, trying to achieve 14.6 I assume. Thats great for part throttle, but crap for wot. If I edited the ltft to be near 0 then I would basically just be subtracting fuel correct? I need to add fuel to get a richer condition. I logged some .815 earlier today which tells me the car is way too lean, so why is the pcm still pulling fuel? I may be missing something, but it seems that my whole lean detonation problem is being caused by the pcm trying to achieve 14.6 afr.
This creates some questions. Why would you want the stoich at 14.6? My ltft constantly showed -7, trying to achieve 14.6 I assume. Thats great for part throttle, but crap for wot. If I edited the ltft to be near 0 then I would basically just be subtracting fuel correct? I need to add fuel to get a richer condition. I logged some .815 earlier today which tells me the car is way too lean, so why is the pcm still pulling fuel? I may be missing something, but it seems that my whole lean detonation problem is being caused by the pcm trying to achieve 14.6 afr.
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From: Texarkana, Texas
Do you think it's possible I have a map problem? Pe enable Map is set to 15. If the map never shows over 15 Pe would not be enabled. Does anyone know what it is supposed to be set to?
I will run it again today and see what the map is showing under wot.
I will run it again today and see what the map is showing under wot.
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From: Birmingham, AL
You want stoich at 14.6 because that's where you get the best gas mileage not at WOT. As far as MAP, mine sits at 37-40 while cruising. My PE Enable MAP is also set to 15. Have you gotten a chance to log some to see if it does show over 15?
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Verdad Gallardo TECH Enthusiast
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From: Birmingham, AL
Yes, that's in kPa. Nope, it wouldn't be n PE all the time because there are other tables it references also, mainly the PE Enable vs. TPS%. All these conditions have to be met in order to go into PE. Post up those logs as soon as you get them.
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Once you've logged some data, you need to export your log. This creates a .CSV file you can import into Excel or Access and manipulate from there. Once you've got this file, you hit the Manage Attachments button below the message box, and you can upload your file you created as long as it's not too big.
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From: Texarkana, Texas
Thanks! I just made another log and now I'm really stumped. Tps was 4.5v, map was 27-28kPa, cannister purge was 0, and it stayed in open loop the whole time. Everything seems exactly the way it should be, except it is pulling 7% fuel to try to achieve stoich as opposed to going to pe. I don't understand what would make it go to open loop, but still not go to pe.
I would post the logs, but they are on a friends laptop, and I don't have Excel or Access.
I would post the logs, but they are on a friends laptop, and I don't have Excel or Access.
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If you just made a log, does that mean you have a laptop? I'm a bit confused as to why your log would be on your friend's laptop unless you're logging with it now. lol What fuel trim cell is being used at WOT and >95% tps?
I'm a bit confused as to why your log would be on your friend's laptop unless you're logging with it now. lol What fuel trim cell is being used at WOT and >95% tps? Thread Starter
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My friend lives about 6 blocks from here, and we have been using his autotap on his laptop. I just got my hp tuners yesterday, and he is a lot more familiar with his auto tap than I am with my Hp tuners scanner, so I have been picking him up before I make a log, and then dropping him off at home after. Every time I want to look at something else I just run by his house on the way to my test area.
The fuel trim cell being used is 22.
The fuel trim cell being used is 22.
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Ah, I understand now! Is the fuel trim cell ALWAYS 22? or just at WOT? Could you get your friend to email you the log file? He'd have to export it too tho in order for people w/o atap to see it.
Is the fuel trim cell ALWAYS 22? or just at WOT? Could you get your friend to email you the log file? He'd have to export it too tho in order for people w/o atap to see it. Thread Starter
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Only at wot. We have done several logs with different monitors. What would you want to see? The last one we did just showed loop status, tps v, map, and canister purge. Keep in mind that I'm now doing my wot runs with the stoich set to 13.1 to keep from tearing it up. .815 volts on the o2 yesterday scared the you no what outta me!
Would I be able to post the exported file without having Excel or something on my computer?
Would I be able to post the exported file without having Excel or something on my computer?
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From: Texarkana, Texas
I did get a little info. The pcm is commanding pe mode and targeting 11.7 a/f. I didn't know how to check that before. Now I just need to know why it's running so lean, when the pcm should be adding fuel.
