hey guys, i really need your help on this one,
so.... iv been tuning cars successfully for about 10+ years mainly with crome, now i'm using neptune , so i can safely say that i know what i am doing when i comes to tuning,

i have a very bad misfires with all tuning platforms (hondata/crome/neptune) on the last several cars i tried to tune, i never had this issue before, and its driving me crazy,

first, i would like to mention that the problem is 100% NOT in the software's. and also 99% sure that the problem isn't in the hardware,

second, i am 100% sure that the problem is not in the cars that i tried to tune, (not a mechanical or a electrical problem)

here is what happened in order :
- while beginning a tune of a new car. i noticed a very bad idle misfire. tried to control it, adjusted the dizzy, set fuel pressure, the usual stuff, and when i noticed i cant tune the misfires (not with Afr and not with offsets) i tried my equipment (ostrich/hulog/s300) on a different car, and had the same resaults, bad missing.
-in the mean while i didn't know how to solve the issue, so i replaced all the capacitors in the ecu's,swapped ecu's, changed spark plugs and wires, cap and rotor, changed injectors dsm440cc pte550cc pte780cc pte1000cc and even with id 1000's, changed ignition coils. complete dizzys, map sensors, checked for electrical failures, and couldn't find any issues,
- i contacted moates and they replaced my ostrich/hulog/burn2.
- i purchased a new laptop along with the new moates equipment. i wanted a fresh start, my old laptop was... old...
- went back to the misfiring cars and still no change.
- tried my personal car DEMON in my p28 , still no change
- i borrowed a laptop and tuning equipment from a friend, because i assumed something was wrong with mine, and still no change (in several cars),

here are the symptoms:
-at idle the car misfire a constant misfire, its a very repeatable and not a your occasional lean pop.
-whatever afr i give it 12.5-15.5 i still get the same miss, although the pop is less noticeable at richer afr of course. but still not acceptable because some of these cars i tuned in the past and they didn't had these issues,
-with all accessories off (headlights off) the misfire feels really bad, 14.4-14.0v
-when turning on headlights/defroster the misfire feels a little better 14.0-13.8v , but its still there no matter what afr i set,
-the batt voltage is pretty much the same +-0.6v so i know i'm not falling on my face with the preset injector offsets, so is i see the problam is not with injector offsets,
-when lowering idle ignition timing from the map from 16 to about 4 the miss feels like its completely gone,

as for now i am lost on this,


tomorrow i will upload my maps and logs for neptune,crome and hondata, so it will be easier to the helpers if you are using a different platform,


here are some videos of the miss and some data.
you wont hear the misfire with laptop speakers, you need some bass yo

crome:


neptune:

 

Good post, good info. But, hey, you've been around. Lol.

Make sure the exhaust is not clogged. Too much backpressure? Conversely, make sure intake and filter is free.

Rule out the iacv. Tune it out, disable, block off.

I didn't see you specifically mention spark plugs. Checked?

I had a vinyl glove sucked onto my screen mesh intake of turbo. Did the same sorta thing. Restricted flow toooo much.

I'll check your vids later, on phone atm.

 

Idk what you have for a cam, but a glance at neptune's vid, and you're at almost 400mbar @ 900rpm. Thats high. I bet you have a clog somewhere. I'd expect like 300mbar. 290 even.

Just a quick glance.

 

no clogs,
i have this issue in several cars, the specific car in the video has a cam, a 59300, but i have this issue even on stock engines, with bigger injectors and stock map sensor,

tnx

 

is your ignition timing gun on the fritz giving you bad readings

 

yes, timing light is ok,
as for my experience no position on the distributor will cause such a bad miss,

tnx

 

Bad gas?

 

how's the engine compression? Might worth checking valve lash.

 

gas is good, engine is in perfect condition,
if i install stock injectors and a stock p28 the car works just fine,
thanks

 

I got the phantom misfire code p1399 and it was the o2 but your wideband so that cant be it. Strange that is multiple cars and ecus.

 

Static test the injectors maybe leaking

 

still sounds like a hardware issue to me. perhaps a bad USB or datalog cable you're using, or a short in your wideband.
I think your process of elimination has been a little sporadic, I'm just going to list what I would do and we'll see what you might be missing.

start with stock injectors and ecu as a safety, do not hook up any tuning devices or wideband.

a) change to known good chipped ecu (yours with the demon), and a known good stock rom on a chip.

if it runs good, try again with an ostrich (no DL connected). If it fails, probably one of the cables, most likely ribbon.
if it still runs good on the emulator, plug in your datalogger - if that fails, either J12 wasn't removed or one of your cables is bad.
If you're still good, replace injectors & adjust flow. If your problem starts here, it's either a vac leak or offset.

if still no misfire, install your wideband, monitor by digital serial without 0-5v wire connected. Still good, plug in that analog wideband wire. Try another car. If you're still good at this point, sounds like a rom issue.

b) if using a stock rom on a chip causes misfiring, then try a known good TUNED rom and change the injector flow to stock. change to a different port number, double check baud rate and parity. if it runs good, try again in a different rom editor. replace usb and datalog cables. NOW use a different computer, as bad cables may have damaged your USB ports. Uninstall your rom editors, reinstall. Check global settings for fuel type, base timing, dwell, input voltage tables. Disable all rom features, reenable one at a time.

Not exactly in order depending on what you find, but hopefully some of that might be useful.

 

Nice rundown thats great info your very knoledgable.