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I've recently decided to poke at my car again, hoping to address what appears to be a lack of power before 4000rpm. Previously I guess I wouldn't have noticed it as I could break traction if I floored it before ~30mph, but last summer I upgraded to some 285 Michelin pilot 4s in hopes of fixing my traction issues. At the same time I started messing with my maf scaling to run a 3.5" intake. My car felt slower, I assumed it had to do with running super rich and ruining another set of cats. Car still drove fine so I just put off looking into my cats. I started logging some things and at this point I don't think my cats are my problem. After 4k, car seems ok so I thought it might be an issue with the cam timing, but I don't have a way to check the cam position and I don't have a cel for it. Thinking I might have messed up something with the tune I went back to a 3" intake and switched back to the tune that was on my car before I messed with anything.
Here is an example of what my car is doing. I launched from ~1600rpm, full throttle, no spinning. It feels like the car bogs down and just doesn't wake up until ~4000rpm. I am suspecting that my power loss is timing related, but I don't know what normal would be. Timing up top seems fine where I'd assume any problems would show so I'm really not sure where I should start looking.
Kclv doesn't really mean much. The value isn't fixed and varies based on load and RPM. The posted log has 15-20 minutes of driving since flashing a different tune so the kclv has been reset. My kclv at idle ends up somewhere in the low 20s after a couple trips to work and back.
Datalog a WOT 3rd thru 4th gear pull if you get the chance and only monitor cylinder 1-6 misfires,engine rpm, fuel pressure and bank 1-2 lambda. Also check if your port injection fuel rail dampers and your HPFP fuel damper is leaking.
Kclv doesn't really mean much. The value isn't fixed and varies based on load and RPM. The posted log has 15-20 minutes of driving since flashing a different tune so the kclv has been reset. My kclv at idle ends up somewhere in the low 20s after a couple trips to work and back.
Lol you say that, but every time I see a Lexus having acceleration issues they have a low KCLV... You should be at 25 minimum, even after a couple trips. I'm able to reset mine in about 50 miles and its in the high 20s.
Lol you say that, but every time I see a Lexus having acceleration issues they have a low KCLV... You should be at 25 minimum, even after a couple trips. I'm able to reset mine in about 50 miles and its in the high 20s.
Hope you figure it out.
What he said is actually true. I was having horrible acceleration issues, whilst my kclv was at 26. Kclv is a good general indicator of vehicle health, but doesn't pinpoint small issues like the one he's having
Kclv is a good general indicator of vehicle health, but doesn't pinpoint small issues like the one he's having
KCLV also correlates to timing which he suspects might be an issue. I don't know how serious the issue is, what is the before/ better 0-60 time? 2k DA doesn't help acceleration. Were the previous runs done in better DA?
I've had better than a 5.5second 0-60, that just happened to be the pull that goes with the posted log. I went in and edited the timing in the tune to see what would happen and the timing doesn't look as weak. I'm ~15-20 miles in since the last flash and my kclv is at 23.5 at idle. I'm skeptical about the kclv doing anything as the first posted log was within 10miles after flashing a different tune and my timing up top was 30+ degrees. I'm wondering if maybe my timing tables in the tune were my problem. I wish I had another example outside of mine to look at and compare with as some things don't make sense still. Example is that I set the max timing under load at 30 degrees but I have 30+ in the last couple logs.
I had a different intake that I had messed with the maf scaling for and had adjusted fuel so my afr at wot would be ~12.5:1. I just recently went back to my original aftermarket tune to eliminate any issues that I may have accidentally caused by messing around with the tune.
With the cats, I have suspected that I may not have done them any favors by running super rich while messing with maf scaling last year. I can't compare maf values after messing with the maf scaling to see if I'm flowing but my 0-60 times have since been a little slower. Since switching back my peak maf values are less than I had in the past, but I'm willing to assume the weather may do be a bulk of the difference. I have some stuff laying around to replace my cats with resonators, but I'm super hesitant as I'm pretty sure the car will sound terrible. I'm sitting on that option until I have to address the cats as these will be the third pair I've had to replace.
I had a different intake that I had messed with the maf scaling for and had adjusted fuel so my afr at wot would be ~12.5:1. I just recently went back to my original aftermarket tune to eliminate any issues that I may have accidentally caused by messing around with the tune.
With the cats, I have suspected that I may not have done them any favors by running super rich while messing with maf scaling last year. I can't compare maf values after messing with the maf scaling to see if I'm flowing but my 0-60 times have since been a little slower. Since switching back my peak maf values are less than I had in the past, but I'm willing to assume the weather may do be a bulk of the difference. I have some stuff laying around to replace my cats with resonators, but I'm super hesitant as I'm pretty sure the car will sound terrible. I'm sitting on that option until I have to address the cats as these will be the third pair I've had to replace.
Weather can be a huge factor when intake air temps go up. Your ignition advance numbers in op seem low at 11, I'm wondering if that captured the launch and the brake was on as it moves up after that and seems more like mine. My 350 doesn't hold KCLV values in one place for long, they seem to always change but are generally low 20s to 25.
I've still have oe cats (4x) and oe resonator and pull 255 through the MAF.
So I have read into some details with KCLV and knock feedback and I can now get my KCLV to move up real quick. I got mine up past 22 degrees within a few minutes of flashing the ECU by understanding that the ECU adjusts KCLV based on the knock feedback value. There is no need to do full length WOT pulls through multiple gears, just need to keep the car under load and watch the knock feedback value, adding more load every time it settles at -3 degrees. I went from a KCLV of 15 up to 19 within a red light by power braking, then added a few more degrees accelerating with partial throttle between 15-50mph. A knock feedback value of -3 degrees means the timing for that rpm/load has settled and is good, more than that and there is more timing to be had, less means the ECU will back down some on the timing. I went back to a previous tune and ran through the KCLV thing and the timing looks better, however I had more immediate results with timing after changing some values. I am curious as to why my mid/upper RPM timing is good right after flashing but the lower RPM is "slower" and has to learn. I wish I had a different, known good timing table or tune to compare against as I am wondering if my original OVT tune is just too aggressive down in the lower RPMs.
As for the car, it still seems like its down on low end power. I did a couple launches this morning and with gaining ~5 degrees of timing through 3500rpm I seemed to have dropped ~.1 second compared to what I logged a few days ago. I reviewed the logs with the OEM maf curve and I am definitely down from where I was a couple years ago. Mechanically the only things different with the car now is I have a full 3.5" intake, slightly wider rear tires, and I have added a couple 18" vibrant resonators. I have also discovered a slight valve cover gasket leak on the drivers side with my overall oil consumption between oil changes going from full to low on the dipstick. I replaced my plugs last year and did a compression test on all cylinders while I was at it. I was ~140k on the car with the cylinders testing in the 185-195psi range. I feel that the engine is in pretty good shape and shouldn't struggle to get a sub 5 second 0-60 again with the tires and modifications I have made. I really really want to get this figured out without having to touch my cats, but I am starting think that the only way to know for sure that it isn't the cats is to ditch the cats. I am now 20something dollars into ordering some cat cleaning fuel additive snake oil off of amazon just in case. I will give it a couple weeks to see if it does anything then ditch the cats for a pair of smaller resonators and hope the car doesn't become too obnoxious.
So I have read into some details with KCLV and knock feedback and I can now get my KCLV to move up real quick. I got mine up past 22 degrees within a few minutes of flashing the ECU by understanding that the ECU adjusts KCLV based on the knock feedback value. There is no need to do full length WOT pulls through multiple gears, just need to keep the car under load and watch the knock feedback value, adding more load every time it settles at -3 degrees. I went from a KCLV of 15 up to 19 within a red light by power braking, then added a few more degrees accelerating with partial throttle between 15-50mph. A knock feedback value of -3 degrees means the timing for that rpm/load has settled and is good, more than that and there is more timing to be had, less means the ECU will back down some on the timing. I went back to a previous tune and ran through the KCLV thing and the timing looks better, however I had more immediate results with timing after changing some values. I am curious as to why my mid/upper RPM timing is good right after flashing but the lower RPM is "slower" and has to learn. I wish I had a different, known good timing table or tune to compare against as I am wondering if my original OVT tune is just too aggressive down in the lower RPMs.
As for the car, it still seems like its down on low end power. I did a couple launches this morning and with gaining ~5 degrees of timing through 3500rpm I seemed to have dropped ~.1 second compared to what I logged a few days ago. I reviewed the logs with the OEM maf curve and I am definitely down from where I was a couple years ago. Mechanically the only things different with the car now is I have a full 3.5" intake, slightly wider rear tires, and I have added a couple 18" vibrant resonators. I have also discovered a slight valve cover gasket leak on the drivers side with my overall oil consumption between oil changes going from full to low on the dipstick. I replaced my plugs last year and did a compression test on all cylinders while I was at it. I was ~140k on the car with the cylinders testing in the 185-195psi range. I feel that the engine is in pretty good shape and shouldn't struggle to get a sub 5 second 0-60 again with the tires and modifications I have made. I really really want to get this figured out without having to touch my cats, but I am starting think that the only way to know for sure that it isn't the cats is to ditch the cats. I am now 20something dollars into ordering some cat cleaning fuel additive snake oil off of amazon just in case. I will give it a couple weeks to see if it does anything then ditch the cats for a pair of smaller resonators and hope the car doesn't become too obnoxious.
incorrect exhaust back pressure sometimes is the culprit for power dip/loss or torque loss in the 1-3k rpm range.
08-06-23, 11:41 PM
Missing power.
