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hovering between 14.0-15.0 doesnt seem like a huge cause for a backfire if you cruising and timing is steady.. where I was going with my statements above was if you are doing a WOT pull at (for example) 12.5 AFR then let off the throttle and it pegs the AFR sensor lean due to decel cutoff. I'd expect backfire in that circumstance if anywhere.
Also, what aidan said on the sensor situation. Where are you referencing you MAP signal from on the intake manifold?
It must be something with the map sensor, I know the throttle body's opening all the way and it's for sure reading the position right. I'll do some more reading on the different map sensors, I'm hoping it's just an issue of the wrong sensor being chosen in the program or something. Right now it's using the "LSx map sensor" but maybe I need to choose one of the specific part number options. The other option is to buy on of Holley's sensors, they're kinda on the expensive side but they're nice.
I'll see when I get done with the market today.
It's getting the map sensor data from the stock location right behind the throttle body, not my car but same thing:
Map sensor is the problem. The computer barometer says the pressure is 101.1kPa, the map sensor says it's 83kPa, 101.1 sounds closer to atmospheric.
Just got back from the parts store and I picked up a new map sensor for a 2010 corvette which corresponded to one of the PN already loaded into the computer, reads 98 while the barometer reads 101.1, closer for sure. One thing my buddy noticed was that the car was still really rich off throttle and I'm guessing that also had to do with the map sensor. I started the car for a second in the garage with the new sensor and gave it a couple real quick blips, went up to 80ish and then dropped to 30ish for half a second before returning to about 60 at idle.
I'll take the car out tomorrow and hopefully, the problem will be fixed.
Spark plugs looked good, got them under a magnifying glass and didn't see anything like what was on Aidan's, so that's good? I guess? Let's hope for no more knock.
Well the good news is my reducer actualy quiets it down a lot, I was able to do a back to back comparison today at WOT when it went shooting off the car and into the bushes as I was getting on an on ramp
Sounded like I had manly vtec when it came flying off lol
I also didn't realize how much more driveable it made the car, had to drive the car about 60 miles without it. My ears are ******* ringing and my head is pounding, not very fun haha
Downloading the datalogs now so I can see how the drive went
Bought a new reducer and 2 v-bands to attach stuff better. The v-bands won't get here until next week so it gives me some time to work on other stuff on the car, I need to add the flex sections as well.
Been focusing on the umbrella stand project but I did do a little work on the exhaust the last couple nights. Got the v-bands welded on the muffler, but then I was pretty much out of argon. Also made a new tip, I feel like a ricer. In my defense, I really hate the look of a cone sticking out the side of my car but I still needed to quiet it down for the street, still feels bad though. I tried just fusing the the two pieces together, ended up burning most of the weld, I think I was moving too fast. Doesn't matter though, that's kinda why I gave it a shot, it also kept the weld from having any ridge which is helpful for welding it to the v-band. Anyway, that's my small update for the week.
Could my sensitivity on my knock sensors be too high? It's set at 90 right now (that's what it comes at) but I seem to be getting knock at really weird times, like part throttle (30%) afr was like 14 and timing was 31. There were other spikes as well, but I seem to have 10-15% knock level at all times, even during cruise. I realize this is just noise but should it be that high?
@OGRacing I know you have the holley, any input on this? I noticed on your holley write up that your knock sensitivity was at 50.
I'm thinking if it's not the sensitivity I'm gonna try taking a bit of timing out of some of the areas and seeing if it knocks. If that doesn't work I'll throw in some 100 octane, we have 92 around here but in all honesty this engine isn't really being pushed at all, the gas shouldn't even be close to the problem. The static compression ratio is half a point lower than stock, it's got a sizeable cam, and besides a couple small changes, it's running a pretty much stock ls2 timing map.
Last thing, I'm seeing a max oil pressure of around mid 50's, even when bringing the engine up to around 6500. I've always heard 10 psi per 1000 rpm but is that something I should be worried about?
Here are some pictures of logs where knock occurred
This one the afr was at about 14, timing was around 30*, 15-20% throttle.
These two I tried messing with the colors some in the hopes of making it easier to read, but then the colors went away when I loaded the next data log so I said **** it.
This one I was on the throttle a bit, around 70%. The afr was on target of around 13:1. Should have had the timing displayed but then it just starts knocking, kinda confusing. It also starts again with basically no throttle input, or at least it has a couple decent spikes.
Throttle input here is pretty low, afr is lower than the target and timing is high twenties but it knocks a bit.
This last one is the one that really confuses me, it starts knocking a when I'm back off the throttle?
Overall, I'm really starting to wonder if it's false knock, maybe from some valvetrain noise or something? For instance I know when I start the car it picks up knock (pretty sure this is from my partially chewed up flywheel). I don't know, do you guys have any ideas?
31* of timing is a TON!! this ain't a big block. I have mine around 22* at idle. in the low RPM (say 1500-2000) & high load area, it gets dropped down to 18* . I was getting a really bad knock at parking lot speeds. it sounded like a diesel. WOT most guys run around +-26* but let your tuner work out WOT numbers.
if you have forged pistons those will cause false knock @ idle. with forged pistons on my car, i turned the knock sensor timing spark-cut for anything under 2200rpm.
About oil.
LS motors last forever if and only if you keep them oiled. 10psi x 1000rpm is a must. if your seeing 10psi and the motor is fresh we need to change the oil or start doing some tricks to get it up. first off never use FRAM Extra Guard. that alone kills 3psi. Purolator or K&N oil filters only. on my car, i run 5-w40. i was in the 10-w30 camp for a while. I had 60psi at cold idle and 80 psi at cold wot. seeing that it blew the oil filter off at LS fest last year I dropped it back down to 5 weight. That and at WOT@6500 rpm I was getting 57psi. just shy of the desired 65PSI. so we bumped the w30 to a w40. Keep an eye on oil temps. big headers close to oil pans like to heat up oil. if you're having an issue a heat shield will do wonders.
__________________ OG Racing
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800.934.9112
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Originally Posted by Mobius
Hopefully so, but let's hope it's never necessary. Experiencing your safety gear in action is ... not optimal.
31* is at partial load medium low rpms, I have about 25* at WOT over 3000 which is pretty consistent with what I've seen from ls3's, may drop it down to 24*, some people say anything after that is pretty much wasted.
Yeah for oil I was seeing a max of about 56psi. I'll look at trying out some different oil, maybe filter too. Not sure how wix ranks. I do have ceramic coating on the headers but maybe this winter I'll try making some heat shields for the oil pan when I have the engine out.
Did you have a reason for choosing 50 as your knock sensitivity?
31* is at partial load medium low rpms, I have about 25* at WOT over 3000 which is pretty consistent with what I've seen from ls3's, may drop it down to 24*, some people say anything after that is pretty much wasted.
Yeah for oil I was seeing a max of about 56psi. I'll look at trying out some different oil, maybe filter too. Not sure how wix ranks. I do have ceramic coating on the headers but maybe this winter I'll try making some heat shields for the oil pan when I have the engine out.
Did you have a reason for choosing 50 as your knock sensitivity?
not relly, i turned my down significantly to try and quiet them at idle.
__________________ OG Racing
Your Source For Motorsports Safety Equipment WWW.OGRACING.COM
800.934.9112
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Originally Posted by Mobius
Hopefully so, but let's hope it's never necessary. Experiencing your safety gear in action is ... not optimal.
That's one of the things I'm gonna try, from what I've read people said you shouldn't have any noise at cruise but may have a little at idle. I have a decent bit at cruise and like 20% at idle.
Hopefully gonna drive the car this weekend, just need to finish up the flex sections in the exhaust. I may take some timing out of the part throttle areas as well, hopefully I won't see any more knock.
That's one of the things I'm gonna try, from what I've read people said you shouldn't have any noise at cruise but may have a little at idle. I have a decent bit at cruise and like 20% at idle.
Hopefully gonna drive the car this weekend, just need to finish up the flex sections in the exhaust. I may take some timing out of the part throttle areas as well, hopefully, I won't see any more knock.
stock pistons? or forged?
if you have stock they should be dead quiet.
__________________ OG Racing
Your Source For Motorsports Safety Equipment WWW.OGRACING.COM
800.934.9112
703.430.3303 info@ogracing.com
Originally Posted by Mobius
Hopefully so, but let's hope it's never necessary. Experiencing your safety gear in action is ... not optimal.
Looks like the clutch fluid may be boiling which is cool lol. I drove the car a couple days ago and towards the end of the drive if I left the car in gear and held the clutch in it would start making some noise and then letting the clutch out. If I popped it out of gear it would go away, it was only if I held the clutch in. Gonna try wrapping my line in reflective tape but I know that's gonna just be a band-aid. Going to need to find a permanent solution at some point, maybe run the line inside of a heat shield or something?
Changed the oil to 10w-40, I'm seeing just below 70psi at 6000 rpm now which is good. Unfortunately, the one datalog that I wanted to look at got corrupted or something because every time I try to open it the program crashes. I tried re-downloading it but that didn't help either. Also didn't get a chance to change the tune at all since we left kinda in a hurry. I changed it that evening and we'll see how it reacts when I drive the car next. I dropped a degree of timing out of the part throttle areas above 2000 rpm. I added 3kpa of offset to the map sensor since it was reading 98kpa while the barometer was reading 101.1. Also changed the top two rows of my target afr so that it's at 12.5 instead of 12.8 and I took a degree of timing out of the top row of above 3000rpm. From what I've read MBT is pretty consistently at 24* for an ls3 so that's what I changed it too. I also reduced the knock sensitivity from 90 to 70. I made sure to save that all to a new tune so I can go back since it was quite a few changes at a time.
I confirmed my bias of car meets are stupid for the most part, went to a small one with my buddy with the 240 and it was mostly just a bunch of idiots. They asked him if his 1j was a twin turbo, while his hood was open. I mean maybe they just can't count? But 1 is pretty easy to count to lol. I got asked a bunch of times what shop built my car, which was kinda cool, mostly annoying. Mostly stance bullshit, just really not my scene. Not a big fan of just sitting in a parking lot and circle jerking with a bunch of dudes.
The reducer makes a noticeable difference on driveability. Low end is much better, it's a lot easier to let the clutch out but there's a noticeable power loss with it. Either way, it makes it bearable to drive on the street. Oh instead of shooting the reducer out at WOT it just shifted the exhaust about a quarter of an inch to the left lol. I guess there's some pressure in there
car shows... Ill admit that Its fun to show off your stuff, but it gets rediculous saying the same **** over and over. and then there is that thing where you are showing the neighborhood what car has a **** ton of cash into it. To me, that just puts a bulls eye on your car.
when my exhaust ran past the clutch it would boil too. I switched to the pfc665 fluid and the issues went away.
also if you ever get a feeling like the clutch won't disengage at high rpm's. aka the clutch isn't working. it's not the fluid. ALL of the ls1 forums point to a hydraulic issue. after replacing all of that stuff twice over I found out it was the pressure plate. the OEM plate fingers are really cheap and they need to get beefed up.
__________________ OG Racing
Your Source For Motorsports Safety Equipment WWW.OGRACING.COM
800.934.9112
703.430.3303 info@ogracing.com
Originally Posted by Mobius
Hopefully so, but let's hope it's never necessary. Experiencing your safety gear in action is ... not optimal.
I have some of the sleeve stuff in the second link sitting around that I can use, I'm gonna try ordering some of the sleeve from the first link, hopefully I can get it to go over the banjo fitting. Gonna do a layer of that, then the other sleeve, and then some reflective wrap, hopefully that'll do the trick. I have some motul600 that I just flushed my brakes with so I'll put some of that in there as well. Maybe I'll try the pfc stuff down the line if this doesn't work.
I haven't had any high rpm clutch problems so far, I'm hoping the spec won't pull any bullshit and make it a couple years. Probably gonna replace my clutch setup the winter after this one, my flywheel got pretty chewed up when I had that starter problem. I'm just hoping it is only clutch fluid boiling, the last thing I want to do is pull the transmission. I hate that damn t56.
05-19-2017, 11:56 PM
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In my defense, I really hate the look of a cone sticking out the side of my car but I still needed to quiet it down for the street, still feels bad though. I tried just fusing the the two pieces together, ended up burning most of the weld, I think I was moving too fast. Doesn't matter though, that's kinda why I gave it a shot, it also kept the weld from having any ridge which is helpful for welding it to the v-band. Anyway, that's my small update for the week.
