Hey all,

Got my neptune and wideband setup all working. Have begun to street tune my D16Z6 engine with bolt ons. I have started from the stock p28 map.

I have been dialing in the low cam map based on a copy of target A/F I found in the neptune help, not sure if I should be tweaking that at all? (been trying to find more information on developing a proper target A/F map, still researching). At any rate I am getting the fueling close to the target A/F, and my engine seems to be running much more smoothly now.

My plan for the high cam map is to set my VTEC crossover low (1500 rpm, or whatever makes sense) and ignore low load crossover. Then tune the vtec map to the same target A/Fs I did the low cam. Once it's tuned across the whole map to run within the proper A/Fs I will then experiment with different crossover points near the stock setting (4875 rpm), picking whichever crossover point feels most smooth.

Does this make sense/is it a safe way to go about tuning the high cam map? I figure even though I will never use to low rpm portions of the map, if I have the entire map tuned in, I don't have to worry when experimenting with crossover points?

The research I have done seems to imply this is a good way to do it, but hearing it first hand is always better. If anyone could let me know if I am thinking or going about this wrong, It would be greatly appreciated.

Thanks,
Matt

 

you're on the right track but taking it a bit extreme. you are correct in needing to set vtec lower than expected in order to get the maps dialed in correctly. but you're going waaaay too far with it. for starters, vtec won't even work that low because there's not enough oil pressure. 2nd, it'll run like total *** that low if it were to actually function that low, and make it a HUGE pain to dial in the maps. 3rd, for that instant that it actually tries to engage vtec, it'll starve the rest of the engine of oil and can damage any internals that rely on oil for lubrication.

I suggest setting it to 3800, definitely not any lower. if it throws a cel for oil pressure, try 4000 or 4200.

 

Agreed. If you're still running the stock cam and manifolding, the crossover point should be within +/- an couple hundred rpm of stock. I would honestly be surprised if you need to change it at all. Just worry about getting the afr's dialed in, log log log log log, and make small changes as needed.

The target AFR's are something that you'll figure out as you learn. The stock NepTune table is a good, conservative starting point.

If you want to start playing with timing, use something like Brad Barnhill's Virtual Dyno to do some full throttle pulls and see if you can make any changes. Don't get too crazy with advancing, especially if you don't have any knock monitoring.

 

^^^ These guys know what they are talking about. I tuned my own car with Neptune over the last few months. I have no prior tuning experience, and my method consisted of datalogging to and from work every day, making tiny changes at a time. Get the A/F's spot on like stated above between the two maps, but don't forget about adjusting your compensation tables like IAT and ECT.

IAT drove me NUTS for a while. I would wonder why I could get eveything perfect one tuning day, and then the next morning when the air was cooler and denser everything was going lean! Best thing you can do is get all of the fuel maps perfect at a certain temp, the SAME temp, then don't even touch the maps again. Just adjust the IAT corrections as you find yourself in varying air temps.

Remember: in the cool morning or night-time air, the car will want to lean out because the air is denser. The inverse will happen in the middle of the day when IAT's are high!! <- The car will want to richen up beyond your target A/F. ECT is actually easier since generally you will just want a tad richer condition when the engine is cold, tapering to a correction factor of "0" when warm, and these values are fairly linear.

If you haven't already, you need to read the Crome Tuning manual. The first few pages are helpful, but kinda technical. Closer to the end there is a section on dyno and street tuning. Read BOTH as they contain golden info on how to go about this. The inertia dyno tuning section applies directly to street tuning so don't skip that part.

Good luck, you can do it.

 

Oh dang, well good thing I only experimented with that once then. Drove part home with it going into VTEC at 1500, on the highway. Ran like ***, but the oil pressure CEL never came up, and appears to run fine after (Still audibly engages as well as switches map, and runs identical to before.) last time I will do that.

Thanks for the info, I will follow the advice you gave me. Starting to get the AFRs on the main map pretty dialed in, gonna disable vtec and the the main map real solid, then do what you suggested. I figure the vtec will be identical or nearly so to stock, but I want to tune the two maps without the added variable of the crossover interfering with AFRs, and also learn the technique.

Right now I am using the IAT corrections that came on the stock map. It seems to be fairly close, but I will definitely have to tweak them. Going to start reading up on that heavily.

 

the fun part comes when you try to differentiate iat compensations from ect compensations due to driving style and weather changes haha

 

I was using the canned IAT values also, turned out to be wrong for my car and took me forever to realize what was going on. Through much trial and error I ended up taking the "High Load" values on either side of 0 up a little bit. Now A/F stays flat as a pancake no matter the air temp.

If you have questions just ask. There are plenty of peeps who have paved the way. Everybody who has the patience and wants to, should be able to tune, not just a select few.

 

Thanks for the info man.

Does anyone have a general strategy for determining IAT trims that worked well? Right now I am fluctating a fair amount (.3-.5 AFR between a hot and cold day (maybe 20 degrees difference) that may not all be from IAT trims though, as I am still tweaking a lot of other stuff as well.

Also, does anyone have any input on a good AFR for highway cruising? (60mph, 75mph...ect) right now I am aiming for 15.1. Though it is currently in ~14.5 on level ground at 60mph in fifth gear, just enough throttle to maintain speed.

Thanks,
Matt

 

1) after you have all the maps tweaked as best you can, on another day with the car bone cold, start her up and go driving as soon as possible, normal driving style not aggressive. keep an eye on engine temp and datalog the whole thing up until it warms up. that'll give you an idea for ECT compensations below 160/170. iat will typically stay pretty cool during this time too, hopefully. make your ect adjustments.

2) then cruise on the highway for a bit, that'll get oil temps and iat's nice and hot while keeping ect nice and cool. then hop off the highway and proceed to some backroads, trying to maintain a decent speed to keep ect temps low. now pay attention to iat's and tweak iat comps as necessary, trying not to let ect's get too warm.

3) then on another day starting with a bone cold car, go out again and repeat number 1, and feel free to get a bit heavier with throttle after it's at operating temp to get ect's even hotter, but keep your speeds low (below 45mph if possible) so the radiator doesn't get too cold. basically do a bunch of stop and go driving being fairly heavy on throttle. this will increase ect's above thermostat rating, usually about 15-20 degrees above thermostat rating. and the faster you can get to this point the better, because iat's will hopefully stay cool and pretty consistent. now you can adjust ect comp for the next level above thermostat rating.

4) repeat number 1, 2, and/or 3 in a climate that is opposite what you did them in originally for touchups.

basically, things heatsoak and affect sensor readings and running characteristics. that's what the compensations are largely for, not just climate change.
ie:
-short term low speed not long after initial startup will typically cause low ect and low iat
-a bit more low speed after the above (especially at frequent higher load) will typically cause high ect and low iat
-prolonged high speed low load causes low ect and high iat
-prolonged low speed at any load will cause high ect and high iat
-getting the engine bay nice and hot, then parking the car for half hour or so, then driving again, will typically cause very high iat, and low ect for a short time period.

use these above characteristics when setting compensations, as using them can allow you to simulate exactly what you want during different climates to monitor changes to running conditions. like changing iat comps, you want to keep ect as consistent as possible while allowing iat to change a noticeable amount.

 

14.7
there is a good amount of strain (load) on the motor at highway speeds, low 15's for long periods of time will very slowly start overheating valves and eroding plug tips and piston tops. and for all you know, timing might be a slight amount too far advanced at that point too, and timing can be difficult to determine for part throttle. so you definitely don't want to run leaner than stoich if there's a chance the timing is a bit too advanced.

low load in lower gears is a totally different story though, especially when you're frequently moving the throttle and getting fuel cut during engine decel allowing internals to get frequent cool-off periods. I run my car at 15.1-15.2 at 18" vacuum and lower for gears 1-3, and 14.8-14.9 for 14-16" of vacuum in gears 1-3.
gears 4 and 5 at all loads below 11" vacuum, and from 11"-13" vacuum in gears 1-3, I keep it stoich 14.7.

 

usually I try to tell new tuners to keep it stoich, or a hair richer even, at ALL points in ALL gears below 11" vacuum, because the timing usually is not perfectly accurate and/or compensations are not perfectly accurate, and you need to leave some room for error. a lot of new tuners damage their engines because they try to copy an experienced tuner's personal setup, without having the actual knowledge or experience (or free time) to dial everything in so perfectly to actually allow for it to be safe.

hell, even on my own personal car I just finished 2 weeks ago, I'm still tweaking compensations and until I get them dialed in as perfect as possible I still currently am keeping afr around 14.4-14.5 on the highway

 

read the manual in my signature. it's for Crome, but it goes over the same parameters and tuning processes.