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So part of the problem that I didn't realize is that the closed loop was turning on too early and trying to learn which was ******* up the idle. It was trying to learn at 900 rpm so it was throwing weird amounts of fuel at it, by the end of yesterday it couldn't even idle when it was just started. I turned the learning feature to about 1400 rpm and also turned down the learning amount. I'm gonna reset the fuel table around idle to what it was when my buddy was messing with the timing.
My timing table is based off map but it looks to be more conservative than that one, the section around where it idles is a little weird and not super smooth since he was just trying to get it to stay the rpm to stay in one area. Another thing I noticed is that at idle the target afr is sitting at 13.5. That could be higher right? Like 14:1?
It still seems like my datalogger is giving weird values for rpm and tps. Looking at the logs yesterday it looked like I only hit around 5000 rpm, but I could swear I went higher than that under an underpass with my girlfriend. Looking at the map in the data log, the values seem to be accurate. I really need to have someone watching the laptop and tell me how high the tps goes up and what the rpms hit so I can be sure.
Here's my fuel (lb/hr), target, and timing tables. Green dot on fuel table means ecu has modified it
I really need somewhere to test this car, my city is having a "crackdown" on "streetracing" because some dumb bitch complained about subaru's revving their engines and said when one passed her on the road. She said was shaking so bad she had to pull over to the side of the road. Bitch, if you're shaking cause a car passed you going over the speed limit, you need to get the **** off the road to start with lol. It was all posted on FB, I wish I could have gotten some screenshots, it turned into a **** storm lol. My city is full of a bunch of people who need hobbies other than sticking their nose in other's business.
Which leads to part of the reason I got a ticket for sound the other day, the other reason is cause, well, it's kinda loud so and I knew I was bound to get one eventually. The cop was kinda a dick at first but I think he realized I wasn't just some douche with a giant exhaust after talking to me a tiny bit. He asked me if it was a corksport exhaust before I told him it was a v8 Anyway, they're throwing tickets at cars that look modified now apparently. I can't really mess with the idle in my driveway too much and I'm kinda starting to enjoy driving it on the street less, mostly cause it's so stressful to drive on the street (getting a ticket didn't help, at least it's a non-moving violation).
I'm thinking I just need to start taking the car to the track already. Kinda pointless to drive it on the street, especially around my city. The only thing I'm worried about is break in, think it'd be fine to track the car at like 300 miles if I get the tune more dialed in?
I was thinking about trying one of the scca track nights, but I've also heard about them being kinda disorganized? At the same time, I really wanna get the car on the track and I'm kinda low on money so the lower cost is kinda helpful. What do you guys think? Oh I also think I found my main oil leak! The oil pressure sensor wasn't loose, but it wasn't tight and the copper washer wasn't sealed well. So I'm hoping that's it for oil leaks. Almost done with the coolant over flow, I've been slacking.
Also been putting in some decent work on the blue car this week. Got an intake made, it came out pretty decent. It's a bit shorter than stock, IIRC it's something like 18-23" long is best for the bp, not sure what it is for the 1.6 but I figured it'd be closish to that number? Anyway, it's shorter and has an AEM dry flow, makes nice induction noises, hopefully makes more power? Who knows, it's a 1.6 anyway. I mostly did it because I didn't have an extra stock intake and the one the other dude made literally sat the filter two inches from the header. Nice hot air intake buddy! Car sounds good between the exhaust and the intake though!
Also got the new tires and wheels mounted, need to roll the front fenders just a touch. I welded the spot welds back in the the PO decided to drill out...with a drill bit. C'mon man, they sell spot weld drills are harbor freight for basically nothing. Not even sure why he drilled them, maybe the thought he was gonna take the gas tank out the top Gonna try to get the soft top done today and paint the spot welds I did yesterday. Also finish up putting down the sound damping. Then it's just finish re-upholstering the seats and my parents have a super nice miata.
Edit: Ignore some of the stray wires and lines in the engine bay shot, some of that **** is left over from the PO, pulled another hunk of wires out of the car the other day haha
My timing table is based off map but it looks to be more conservative than that one, the section around where it idles is a little weird and not super smooth since he was just trying to get it to stay the rpm to stay in one area. Another thing I noticed is that at idle the target afr is sitting at 13.5. That could be higher right? Like 14:1?
I'm not super well versed in LS tuning yet, so take this with a grain of salt, most of it is generally applicable though. As long as the ECU and injectors can handle idling leaner (which they should be) you can definitely be leaner than 13.5. "Normal" idling and cruising is 14.7 AFR, which is stoichiometric. Do you have a cat? Do you have emissions? If not, you can idle and cruise in the ~16-16.5 region if you want to maximize efficiency. If you do have a cat, then tune for 14.7 in idle and cruise. The spark map looks pretty good, it seems on par with what I've seen before for LS motors. If you lean it out, you may want to add some timing in the cruise areas. A leaner mixture burns slower so the flame front needs to start earlier. The engine is not knock limited in this region, so you won't hurt the motor doing this, but it's hard to know if you go too far since you don't have a dyno to know if you've hit MBT. For the Miata motor, I basically used the Megasquirt basemap, and advanced timing by 2 or 3 degrees for every 1 AFR I leaned out.
Alright, first thing I'll try is bumping cruise up to 15:1 since I don't have emissions/cat. I'll try idling at 14.5-14.7? That alone should help some of the fuel efficiency. I guess I'll try adding a few degrees at cruise as well.
It's supposed to be wet until Tuesday so that's the first day I'll get to test stuff. Gonna see if maybe I can drive somewhere kinda out of the way of stuff and maybe do some playing around with the idle to see if I can get it to idle better, especially coming back down from high rpms. If I can go somewhere where people won't get pissed off maybe I'll have some more luck.
I'm not super well versed in LS tuning yet, so take this with a grain of salt, most of it is generally applicable though. As long as the ECU and injectors can handle idling leaner (which they should be) you can definitely be leaner than 13.5. "Normal" idling and cruising is 14.7 AFR, which is stoichiometric. Do you have a cat? Do you have emissions? If not, you can idle and cruise in the ~16-16.5 region if you want to maximize efficiency. If you do have a cat, then tune for 14.7 in idle and cruise. The spark map looks pretty good, it seems on par with what I've seen before for LS motors. If you lean it out, you may want to add some timing in the cruise areas. A leaner mixture burns slower so the flame front needs to start earlier. The engine is not knock limited in this region, so you won't hurt the motor doing this, but it's hard to know if you go too far since you don't have a dyno to know if you've hit MBT. For the Miata motor, I basically used the Megasquirt basemap, and advanced timing by 2 or 3 degrees for every 1 AFR I leaned out.
Going off of what Ace said... Idle should be a 14.7 target. It's typical that you'll have it hover between 14.5-15.0 (especially with a cam) at lower idle RPM but engine's don't like to idle much leaner than 15.2 or so usually based on my experience. You don't really have a need to go leaner than that at idle anyways, as you want to ramp it down to stoich once you get into some throttle anyways. Spark map doesn't look bad, but I think most of your gains can be seen there. Cruising around 15.5 should treat you fine, and you can ramp the timing up a few degrees in those zones for reasons Ace stated. I've always found most of my MPG increases didn't come from AFR, but more-so from my timing map. More timing = more torque at any given throttle % = less throttle required in cruise range = less air = less fuel = more MPG is the logic on that one. You have knock sensors to be able to view. I don't recommend knock-based tuning, but its handy. If you do knock in the cruise range you know you're pretty far past MBT, so you can use that as a tool at minimum
Going off of what Ace said... Idle should be a 14.7 target. It's typical that you'll have it hover between 14.5-15.0 (especially with a cam) at lower idle RPM but engine's don't like to idle much leaner than 15.2 or so usually based on my experience. You don't really have a need to go leaner than that at idle anyways, as you want to ramp it down to stoich once you get into some throttle anyways. Spark map doesn't look bad, but I think most of your gains can be seen there. Cruising around 15.5 should treat you fine, and you can ramp the timing up a few degrees in those zones for reasons Ace stated. I've always found most of my MPG increases didn't come from AFR, but more-so from my timing map. More timing = more torque at any given throttle % = less throttle required in cruise range = less air = less fuel = more MPG is the logic on that one. You have knock sensors to be able to view. I don't recommend knock-based tuning, but its handy. If you do knock in the cruise range you know you're pretty far past MBT, so you can use that as a tool at minimum
Ok, that makes sense about the timing gas mileage. Kinda like trying to power our old impala with a 283, I always told my dad we'd probably get better gas mileage if we threw a 350 in it since you wouldn't have to full throttle it all the time, doesn't matter now since it's gone thankfully. I know theo had also mentioned something similar about knock being a ways past MBT with ls engines so I guess I can think about that in the future. I've also got a buddy who works at a porsche shop and he had mentioned I may be able to get some dyno time for cheap at some point so that may be an option down the line as well. Gonna go hang out with him on sunday since he's back from school so I'll ask him about it again.
Thanks for the help guys, I really appreciate it, I'm such a noob at this lol
Starting out with baby steps. I increased idle afr to 14.5, but didn't touch the timing there. I increased the cruising target afr to 15:1 and added two degrees of timing there.
I was doing some reading and it looks like most guys are hitting MBT at about 23-24* with ls3s. From what they said, past that there's nothing really to gain. Still holding off on WOT for a little bit though so that doesn't apply to my driving right now. My table is pretty similar to some of the ones I saw, I may change it some when I get closer to opening it up. I'm gonna take it out for a drive Wednesday with one of my buddies and hopefully log some decent miles. I still haven't seen any oil under the car since the last time I drove it so I'm hoping that oil leak is finally fixed.
Also, I was looking at the fuel map and since I haven't been giving it 100%, there's a pretty steep drop in my fuel map from where the computer's been learning and adding fuel. I was thinking of trying to at least add a bit so that it kinda plateau's out from the tip right now? That way the computer can do what it needs but it won't be a sudden drop in fuel when it's starting to learn that area? Or should I kinda continue it at a linear slope, or just leave it? Maybe I'm just overthinking things but that seems like it could be kinda bad with the way it's sitting right now?
You can see what I mean below, the second picture is just the graph from the side.
I did some more digging around for ya. Sorry I dont have much to go off of from the ECU you are using in specific, but hopefully this helps answer your questions. You're definitely going the right direction with your initial fuel targets and mild timing change in cruise.
So the long story is that the LS3 ECU has the capability to be reflashed to run on speed density. I forgot about this in my previous post about HPTuners as I haven't used this capability yet as I prefer to keep MAF for a DD unless its prohibitive for big power applications. That said, there are some VE maps out there for LS3's that I can view. At the very least you can get an idea of what your VE map may look like and how you want to taper off your fuel map for a good baseline. LS3 heads are known to flow air very well, so its not surprising to me to see that peak in your VE peaking in that zone depending what your cam specs are.
The VE map you see below is from a stock cam LS3 with bolt on's.
This one is from an LS3 with a 224/230 114 cam in it
Thanks man! Mine will probably be closest to the last one so that's helpful to have something to look at!
I drove the car 100 miles today! Did abut 10 without the reducer and threw the reducer on to see how it would react. Definitely quiets it down some, it's still loud but it's less so and it's noticeably quieter on the freeway. It idles a lot better now that the learn function isn't turning on when it's trying to idle and messing with the fuel. Cruising hung at 15:1 and it idled between 14.5 and 14.7. Went through about 6-7 gallons of gas today which isn't great but there was a bit of hard acceleration for the first 10-15 miles before we got on the freeway and headed north.
I also finally got my coolant overflow done so that I don't have to keep stealing them from my other cars. Still need to make one more mount on the side to hold it a little steadier but it works well for right now. I found my fuel tank cover as well which is really nice since I've been searching for that!
It may look stupid as **** poking out the side of the car but it works decently!
This was my mothers day present, I thought it was kinda cool so I figured I'd post it. My mom's a runner, she's done 19 marathons I think. It was my first time doing something like this but I think it came out alright.
Just got back from a 160-mile drive. Car was backfiring for the first hour or so, really weird since nothing's changed since yesterday, gonna take a look at the logs between yesterday and today and see if there's a difference. Other than that the drive went well, I changed the oil this morning to regular old non-synthetic but no more break in oil. It's nice to not buy $60 worth of oil anymore. Just 90 more miles and everything should be broken in which is sweet. I'm gonna try to go get an alignment next week.
is it backfiring off the throttle when you are coasting down to a stop? if so, not super uncommon on a LS setup with full exhaust. My CTSV backfired quite a bit with just cat deletes and it sounded glorious. Usually that occurs when the car goes lean while off throttle, but you would be under no load in that coasting condition so its perfectly fine. Lean is ok in this case. When you are off the throttle, you can basically turn injectors off by decreasing VE in that area. Most OEM's do this now for MPG increases. In HPTuners this is called Deceleration Fuel Cut Off (DFCO) if you want to dig into it a bit and read up.
The logic behind that backfire happening (if its happening under coast down scenarios) is when you are under load your exhaust stream has a rich condition (excess fuel), when you let off the throttle it goes lean in the exhaust stream which is excess oxygen. Those streams reach a wonderful meeting point and KA-BOOM, GURGLE, POP, POW POW PEW happens! If you are on a base tune where you're richer than stoich in the cruise range and leaning out fuel during coast downs I'm not surprised to hear the car is backfiring a bit. The closer you get cruising to stoich AFR or higher (14.7+) the less I would expect the car to have the tendency to backfire.
The lean condition also makes the combustion happen slower, which is why your high RPM, low load portions of your spark map have high timing. This is to keep the slow(ed) combustion happening in your cylinder as much as possible during these perfectly ok lean(er) conditions. My other suggestion if you are having backfiring is to increase your timing in those zones and see if that helps some.
This is hard to help diagnose without a log to actually look at and I'm really just pulling at straws based on experience, but I hope this helps you make sense of what could be going on
It honestly didn't seem to happen for any reason, it was kinda random. I'd totally understand off throttle, in fact it does give a nice off throttle pop after I get on it but it just kinda happened for an hour and then stopped. Maybe something with an exhaust leak? All my joints are slip joints so they're bound to leak a little. I'll try to find the log where they happened, I wish I didn't have to download the logs to view them, they take forever to download haha
If it happens again tomorrow maybe I'll see if throwing another degree or two at cruise helps at all? That was the weird part, it would just happen randomly while cruising and I was in the 15:1 range the whole time.
There was a time when I opened it up a bit in 5th since there was a guy merging onto the freeway at about 40 (******* love that) and I wanted to get past him so I wouldn't have to slow down. Anyway, it was backfiring constantly, like maybe 3-4 times a second while I was on the throttle (imagine shooting a .22 kinda rapid fire like). I had my foot down so it was probably like 2000-2500 and 70% throttle. I know that's not too helpful if you can't see what was going on haha, I'll plug the laptop in and download everything for the next hour or so and see if I can't find the log where it happened. Maybe I can post some pictures in the morning.
Also I think I have a decel cut off in the holley computer, I was gonna dig into it some down the road when other stuff is buttoned up.
Found what I think to be the problem with backfiring during just normal cruising, it was dipping between a target of 14.0 and 15.0 depending on throttle position, so basically it'd dip into a bit richer for a second and then go back to lean. I'm guessing that's what was causing it. I can't seem to find where the 5th gear short pull was which is weird, it should have been pretty obvious. I'll try to simulate the same thing today. I need to keep track of what time it happens in the drive, I'm gonna take a stopwatch today so that I can see the exact time and then go to that in the logs.
If I'm understanding correctly though, basically not enough fuel is getting combusted, so I should increase timing in that area?
Any reason why my MAP would be at like 80kPa at WOT? Hit 500 miles and did some WOT pulls today but it was only getting up to like 80-84 kPa which meant the timing was higher than it should have been and the fuel ratio was as well. Looks like I was seeing some knock from the data log, luckily I didn't do too many pulls, only a few and for pretty short time periods.
I'll pull the plugs tomorrow and see how they look, hopefully, it wasn't too bad.
Couldn't get it to duplicate the 5th gear pull rapid backfiring today.
05-11-2017, 02:28 PM
Anyway, they're throwing tickets at cars that look modified now apparently. I can't really mess with the idle in my driveway too much and I'm kinda starting to enjoy driving it on the street less, mostly cause it's so stressful to drive on the street (getting a ticket didn't help, at least it's a non-moving violation).
Gonna try to get the soft top done today and paint the spot welds I did yesterday. Also finish up putting down the sound damping. Then it's just finish re-upholstering the seats and my parents have a super nice miata.
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