tuning issue afrs sweeping

[cadet18]

i have ordered the stock maf and injectors and 2 ecus hopefully i can get it to run on the stock map then ill go into tuning

[float_6969]

Sounds like a good plan to start with. Make sure and keep us in the loop!

[cadet18]

ok so new wiring specialties harness is in. that made a huge difference in just how it runs. unfortunately my wideband died right after. im using a buddies external tailpipe wideband now and the car is close to stoich at idle but rich as crap(in the 9's) under load and cruise. ive been looking into tuning and i need to learn how to covert my vq tables for the n62 maf in nistune. anyone know a calculation or where to find a calculation so i can do this. i believe that is what is causing me to run so rich. i am tuning with the narrowband feedback cut off. i still havent gotten the new ecu in so the o2 signal still reads 0 volts. i know the vq map for CA is 52 point and the z32 is 64 point or something like that but no one says how to convert.

[cadet18]

so crazy update i was trying to go through louiswuns tuning guide and i noticed the ecu's o2 signal coming on and off. im assuming the wiring was my whole issue along with a bad o2 sensor im currently waiting for the car to cool down and change out the o2 sensor

[cadet18]

got the car idling good and cruise is close but not quite there (13.4) at cruise (14.4) at idle. problem is when i accelerate it goes crazy lean even under the lightest of throttle. what should i change to make that better?

[Buddyworm]

If you're not using the proper VQ table then that's your problem as far as lean AFR's go under load. The VQ table basically allows the ECU to translate MAF voltage into air flow.

You don't need to do any calculations for Injector or MAF changes in Nistune, it does that for you. Including scaling VQ tables of differing lengths.

The O2 sensor voltage isn't your problem. The cars run fine with them unplugged, just a tad rich. They cause none of the symptoms you're seeing under load because in most cases you'll be running in open loop.


**Edit: What do you mean by "crazy lean"? It's normal for the AFR's to spike to 16 or so when applying more throttle because there's a split second after you open the throttle that the engine is ingesting more air than it has measured. It should quickly bounce back to the appropriate range though. If it's staying super lean then I would recommend making sure you're using the proper VQ table, like I stated above.

[cadet18]

i mean its going to 18 + constant under acceleration

[Buddyworm]

Yeah that's waaaaaay too lean, lol.

What's the status of your tune as far as your VQ table goes?

[cadet18]

well i had a guy tune the car awhile back but it had issues. so i just got the fuel maps changed from that one and kept the vq tables but i think ill try just changing afm and injectors in nistune then see how it runs. i can email you my .bin if youd be willing to take a look at it.

[Buddyworm]

PM'd you my email!

At this point I suspect you need the appropriate VQ map in there. An engine modded with different Injectors and MAF should run fine on stock maps with tweaks to just K, Latency, and the VQ table. It's only once you get in to map expansions for more boost that you need to really pay attention to your fuel and ignition tables.

[cadet18]

ive got it all sorted just need some tweaking for more boost and bigger turbo. i just reset to the nistune map and resized injectors and changed maf. the car runs great now but its a little lean in boost i suspect bc of the bigger turbo. its in the high 13's low 14's in boost but idle, cruise all that is good now. i suspect my problems stemmed from a bad o2 sensor and a bad engine wiring harness.

[Buddyworm]

Did you tell nistune to rescale your TP scales for you when you made the adjustments for MAF and Injectors? That's an important part of it. ECU will read the wrong section of the fuel/ignition maps if you don't.

[cadet18]

Update: car is running quite well now afrs where they need to be. much thanks to buddyworm for hooking me up with tuning help! thanks again to everyone who helped me out in this process i love my ca all over again! Again the problem was solved by bad o2 sensor and bad wiring harness. the harness made the biggest change ever. you wouldnt expect how much the little things matter

[Buddyworm]

Great to hear! Always happy to help and spread some knowledge around!

[float_6969]

"Another satisfied customer!"

[cadet18]

just as another update. i finally got it out to do some testing this weekend. i ran a 13.5 at 112 with my clutch slipping badly into 3rd and 4th. gotta find a reasonable upgrade for that. i also ran 4th fastest lap in novice at my 1st ever autocross. this car is awesome now, so much improvement and its finally painted!!

[float_6969]

nice!

[LakaiOrDie]

sorry for the thread jack, but i have had my ecu temp sensor fail recently, replaced with oem and then repaired the wiring, the two wires had been making contact deep inside my (Wiring specialties) harness, anyway
The ecu will not clear the code 13, remains hard to start only when cold and otherwise runs 100% with no o2sensor

would there have been permanent board damage to the ecu from the short, the sensor, anything that makes it throw 13 anytime anywhere i check ecu (its been months)
i really have to take my time starting it cold

and to the OP i like the sounds of your setup, really, lol

[float_6969]

A direct short shouldn't have damaged the ECU. Unless there was 12v applied to that circuit. Then it DEFINITELY would have damaged the ECU.

[cadet18]

do you have a spare ecu? throw that in there and try it. if it comes down to it and unfortunately it is the ecu let me know i have an extra one. have you tried disconnecting your battery and clearing codes that way?

[LakaiOrDie]

Yea I tried to reset this way several times overnight, entering mode 4 of the ecu and successfully cleared many codes that I've had since the sensor was changed but still it's there. weird. can this be affecting the fuel delivery at all
it is only hard to star cold cause it makes a mad firing pattern (injrctors) I can hear it clicking lots but anyway.

only option I've seen to fix from searching sr20 forums is replace ecu prob would like to pick up that from u pm me

[float_6969]

You're comment about "mad firing pattern" makes me think you have a failing CAS. Have you checked the splines on the exhaust cam? Pics of the exhaust cam where the CAS goes into it and the CAS on the part that goes into the cam would be nice.

[LakaiOrDie]

[LakaiOrDie]

they look OK, not pointy and they have been greased before I ever had ran the engine (dunno why but I did that)

last night I was driving it home (warmed up) the engine ran on three cylinders I think, just misfires and then by the next light It was fine
that's the 4th time it's done that momentarily in the past 2 weeks
once or was cold still, the rest it wasn't
maybe it's just my plugs are done (copper) and this is nothing but you may as well know that to

this is not something I was wanting to have to replace so if it is indeed failing can I rebuild myself? I almost wanted to take it apart today but after looking it up in the fsm there's not anything I can imagine going on inside this thing lol

[cadet18]

i dont know about pulling those apart. i know i wouldnt know what i was looking at in there. but if you havent gotten a code and its at least starting it is working for the most part. as for your plugs i find it hard to call your problem plugs if it does a random firing pattern every few weeks but then again i might be wrong. at least pull your plugs and see what they look like i have a feeling they might be a little black. i always like to start with the smallest easiest components first. i have had my butt kicked by a low battery voltage or something dumb like that before.

[LakaiOrDie]

yeah buttts kicked by battery as well alternator dramas and all that jazz is (at least i believe) sorted...i still havent done a compression test lol but plugs look good ive been keepin an eye on them just a sooty black outer ring is all......and advanced my timing some more by eye, no help there

[LakaiOrDie]

ive had an o2 sensor all summer it was brand new this january and i chucked it out since all it did was f*** up my afr making me run rich, poppin gunshots all summer but it sharpened throttle response...thats it haha and the iacv under the tb was relaced for brand new Nissan part....totally unnoticeable. If you plug the bottom port with something and fill this regulator with some penetrating fluid for a hour or two every day it works just as well as a brand new unit..FACT

something just tells the ecu to dump fuel depending on how cold its severly gay starting it under 0 degrees...if i let it flood it self down into 200rpm thats when i notce the injectors CLICLICKLICKLCCLICKCLICKCLICK LIKE MAD

Im afraid of the days i gotta start it up at -15 and have no oil pressure trying to turn it over for a half minute ...good thing its a ca