Leaning out @ higher rpms

[UNISA JECS]

Ok looking for some advice from experienced self tuners, these are people that tune there own ECU with tunable ECU such as Nistune, Calumsult, etc etc.

Ok first of all I let you know that I do have a Q45 fuel pump and have my fuel pump rewired with a relay, I done this to all Nissan I have owned.

I'll just post screen shots of some excel screen shots of a log that shows the leaning out at ~5,000rpm.

Also the car doesn;t feel as though it is leaning out or loosing power.

Tell me what you think or have experienced first hand this situation.

Buy the way I use Nistune and Innovate LM-2 wideband, also the boost reading are funny because I need to make a better custom lookup table but is accurate as far as indication of boost and vacuum, the cross over point is dead on (from vacuum to boost), by the way im boosting 7-8psi rock steady.

Setup
KA24DE (9.5:1)
370cc running @ 3.8 bar static fuel pressure
S13 T25 7-8psi
Q45 fuel pump (rewired)
Nistune
Stock MAF
3" dp to 3.75" catback
stock CAT
LM-2 wideband

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http://i167.photobucket.com/albums/u159/zilvia_album/SP32-20080922-204923.gif


http://i167.photobucket.com/albums/u159/zilvia_album/SP32-20080922-204633.gif

[blu808]

What ENGINE?

parts, turbo, injectors, etc.

[UNISA JECS]

I updated the first post to show that.

[blu808]

What turbo?

Did you pull your plugs out and see if they were either melted or completely white?

To be honest with you and whoever is reading this post. It is alot easier to blow up an engine than most people think.

[UNISA JECS]

what turbo?

s13 t25............

[blu808]

Well your fuel setup seems ok for anything on that turbo. Never underestimate the behavior of a used fuel pump though.

I would say tuning.

If you cant add anymore fuel drop some timing.
And again, running an engine under load and having it lean out could cause permanent damage. Even after one time. Im willing to bet it was detonating like crazy when it leaned out, even if you couldn't hear it.

What pistons?

[UNISA JECS]

Well your fuel setup seems ok for anything on that turbo. Never underestimate the behavior of a used fuel pump though.

I would say tuning.

If you cant add anymore fuel drop some timing.
And again, running an engine under load and having it lean out could cause permanent damage. Even after one time. Im willing to bet it was detonating like crazy when it leaned out, even if you couldn't hear it.

What pistons?

Everything is bone stock 100% internally. I tried a lot of things to get the AFR's in the 11-12 range, lets just say for about 1 hour straight I drove this thing hard, not auditable detonation ofcourse its hard to hear at those rpm's but I checked the plugs and no signs of detonation after and abtupt shutdown, pulled the plugs and they looked fine, compression test is still what it was 6 months ago vacuum is still 535mm/hg like its been, no oil burning no metal shavings on the magnetic oil drain plug.

I guess next im going to log fuel pump voltage and see if it drops off at all during the indicted lean periods, im also gonna see about buying a incabin fuel pressure gauge probably a Defi gauge. For now im a stumped, I also was running BKR6E @ .034 and I regapped to .030 just to see if taht made a difference, none at all.

[blu808]

Im not sure how your tuning program works. But cant you just write a program that is super rich just to see if it changes?

[UNISA JECS]

Im not sure how your tuning program works. But cant you just write a program that is super rich just to see if it changes?

Yea I can, I did that on the fly also yesturday while driving/tunning and its will get lots more richer if I make it run richer and it'll also get leaner if I tune it to be, I can do all this on the fly in real time. It just always seems to happen at roughly ~5,000rpm +/- 500rpm.

One thing stuck in teh back of my head is this, im running the 370cc at 3.8 bar maybe they dont like high of a fuel pressure.

3.8 bar (56psi) + 7-8psi boost ~64psi I dunno, only reason my fuel pressure is this high is because the Q45 pumps outputs a shit load of fuel like teh Z32 TT pump does when hard wired without the fuel pump control module that those cars use to tame the fuel output at idle and cruise. I know my fuel pressure reading because I have a glycerin filled fuel pressure gauge in the engine bay.

[slw240sx]

if im reading this right you have AFR's in the 30's on one page? im no tuner, i have a partner that does that, but i seem to recall it being impossible to even read that high of an AFR with innovate mine wont. I didnt think you could run an engine with numbers that lean, you sure you dont have a problem with the sensor?

did you change anything in the timing map?

[UNISA JECS]

if im reading this right you have AFR's in the 30's on one page? im no tuner, i have a partner that does that, but i seem to recall it being impossible to even read that high of an AFR with innovate mine wont. I didnt think you could run an engine with numbers that lean, you sure you dont have a problem with the sensor?

did you change anything in the timing map?

Nothing in the timing map was changed recently, it is changed form stock ofcourse deffinantly much more retarded than the stock KA map by far.

Yes that correct, im sure yesturday had those really been true I think i'd be without a car as much and as hard as I drove it....instead im leaning towards maybe it being a misfire but I deffinantly cannot fell it by seat of the pants at all.

Took this from innovate, this shows why a wideband atleast innovate wideband report lean when I misfire occurs: I have teh newer LM-2 but still applies to it.


Heres a quote taken from this thread over at innovate http://www.innovatemotorsports.com/forums/showthread.php?t=3230&highlight=rich+spikes&page=2
"
Here's why and how:
The LM-1 measures Lambda 100-300 times/second and averages those measurements for logging over 1/12th second.
Averaging is done by summing up all the Lambda measurements over 1/12th second and dividing by the number of measurements.
For example if it runs at 120 measurements/second at 0.8 Lambda with one miss, it would read 9 times 0.8 and one time infinite (free air, as in a miss, reads as infinite Lambda/AFR). So you have (9*0.8 + infinite)/10. The result is still infinite and you see the spike.

Conventional Lambda meters by their design actually do not average and measure Lambda, but eta (1/Lambda). Under the same condition they would average 9*1.25 + 0 (1/infinite is 0). The resulting calculated Lambda from that would be 0.89 Lambda. In this case the ignition miss would not be visible as spike, but as just a little lean side change of AFR. Easy to miss (sic). This assumes a wideband with a response of ~8 msec. In actuality, a relatively fast conventional wideband with 100 msec response time would probably not even show a variation that large but more in the order of 0.01-0.02 Lambda.

Regards,
Klaus"

[UNISA JECS]

Another possible indicator if you look at the logs and look at the stock O2 sensor readings at these indicated "lean" periods its still reading in the ~.90 volts range. We all know the o2 sensor is not accurate as a wideband but it'll deffinantly tell you if your lean or rich but not exactly by how much ofcourse. For instance I wish I could post my excel file in here but I can you'll see that during a throttle left-off (deceleration) that 32 AFR is indictaed by wideband and O2 sensors will read next to .01 volts, it takes the stock O2 sensor about 1 second to go from rich to full lean.

[cinnadrift]

did you log injector dutty cycle?

[UNISA JECS]

did you log injector dutty cycle?

Yea my injector duty cycle is no where close to maxing its actually only 68% - 70% tops, the reason its so low is because im running 3.8 bar fuel pressure so my 370cc are actually pushing about 420cc and this is all being done at only 7-8psi.

[deuceforty]

why not try leaving the fuel pressure at stock levels and seeing what happens?

[UNISA JECS]

why not try leaving the fuel pressure at stock levels and seeing what happens?

When I get a adj. fuel pressure reg. i'll do that. But at the point pretty much all my tunning has to be re-done with a fuel pressure change.

[cinnadrift]

yea i was gonna say you should get an fpr and mess around with that..

[UNISA JECS]

Just bought a Defi Link BF fuel pressure gauge, after I get the part and install it i'll post back my results.

[blu808]

take the vacume line off the fpr and see what happens.

[UNISA JECS]

take the vacume line off the fpr and see what happens.

Q45 pump


At idle vacumm attached ~44psi

At idle vacuum disconnected ~56psi

[Carl H]

your maf is railed, remove the boost limiter from the ecu and upgrade to a rb20/maxima maf.
seen this several times before when tuning cars, just because it doesnt look maxed it really is.
also put on an adjustable fpr and pull your fuel pressure down to 43.5psi and rescale for your injectors.

[ROIDMONKEY]

ive seen fuel pumps not getting enought 12v so car usually gets lean at high rpm. run a straight cable from battery to ur fuel pump. first with a test light find the 12v that feed ur fuel pump right at the plug on top. ive seen this with my eyes. some how the oem cables gets weak with the years not letting a good current get to fuel pump.

[UNISA JECS]

your maf is railed, remove the boost limiter from the ecu and upgrade to a rb20/maxima maf.
seen this several times before when tuning cars, just because it doesnt look maxed it really is.
also put on an adjustable fpr and pull your fuel pressure down to 43.5psi and rescale for your injectors.

My ECU isn't boost limited, I am nowhere close to hitting boost cut because I scaled it up about 35 tp higher than my absolute highest tp readings.

[UNISA JECS]

ive seen fuel pumps not getting enought 12v so car usually gets lean at high rpm. run a straight cable from battery to ur fuel pump. first with a test light find the 12v that feed ur fuel pump right at the plug on top. ive seen this with my eyes. some how the oem cables gets weak with the years not letting a good current get to fuel pump.

My fuel pump is re-wired with a relay already, it see's about .20mv less than what the alternator puts out.

I agree the stock wiring sucks balls I seen it to with my own eyes, I do this with every nissan I owned and boosted.

[Carl H]

either way your maf is railed.

[UNISA JECS]

either way your maf is railed.

Elaborate on this more if you could how do you come to that conclusion, do you see something in the log to hint that my MAF is "railed"

[Carl H]

honestly it comes from experience, a stock sr can max the stock maf (which is about the same as the s13 dohc maf) with 10-12psi...and due to the ka's increased capacity i can do that much faster at a lower boost level.
I'd fit a rb20 maf and go from there, but that is what experience has taught me.

[flawless]

honestly it comes from experience, a stock sr can max the stock maf (which is about the same as the s13 dohc maf) with 10-12psi...and due to the ka's increased capacity i can do that much faster at a lower boost level.
I'd fit a rb20 maf and go from there, but that is what experience has taught me.

Carl is correct, I believe you maf is stuffed. I have seen this a few times also, and the first time it buggered me too. Slap another maf on there and see what happens.

[UNISA JECS]

Ok I know this from first hand experience also, running the stock KA24DE ECU timing maps and fuel maps, I would max out my MAF somewhere between 3-3.5k car had way to much timing, this was done without any tuning just logging the stock ECU with Nistune. And I actually saw the MAF hit 5.1v in the log also hit everything inbetween 4.2v and 5.1v, thats what got me not thinking it is the MAF, but since I have a few good MAF's at my disposal I 'll give it a shot after I buy and Apexi Dual Funnel ram for it, mo money mo money all the time. Whats up Angel got any of those for sale for a Z32 MAF....

You guys coudl be right I dont doubt you at all, I've pondered about that also but after seeing my MAF read up to 5.1v it just makes me think my MAF isn't max'd out yet....

[slider2828]

Are SR20 mafs and KA mafs the same? IIRC they are very close, but I still wouldn't know why your mafs would be maxed at 7 or 8 psi on a t25. I would fix the mafs first or try another known good mafs and then check out your lean issue.... Since your fuel delivery is unknow but you trust it and your ign timing is ok, then I would work on the mafs...

[UNISA JECS]

Ok just installed the Defi BF fuel pressure gauge, (haven't driven yet) but I need to mak esome corrections to previous specs on fuel pressure, seems my mechanical fuel pressure gauge was way off.

Static fuel psi no vacuum = 50 psi (3.4 bar)
Fuel pressure with vacuum @ idle = 40 psi

Still higher but not as high as previously thought. I'll take it for a drive tonite and see what the highest fuel pressure recorded is and check for any drops in fuel pressure during boost. So if everything is good to go and im boosting 7psi I should see 57psi max hopefully.

[UNISA JECS]

Ok guys the fpr and fuel pump have to be good becuase the fuel pressure holds pressure during boost rock solid at a 1:1 ratio like its suppost to but im still getting the high RPM lean out, or indicted lean out vis teh wideband I says this because I feel no hickup whatsoever in teh power delivery....oh and my fuel pump only see's about .6v less than my altentor puts out so that good. Alternator pumps out 14v and my fuel pump sees 13.4v I dont think thats to bad, it is rewired already, before the rewire is saw less than 12v at teh pump.

I still need to get a MAF adapter to run one of my N60 MAFs, but I do have a B13 SE-R MAF which is a direct bolt on and plug in to the KA24DE MAF but is rated at 250WHP vs the KA24DE that is 190WHP or so (this is according to Nistune).....I guess i'll have to give this a shot, im sick of seeing my wideband lean out only at high rpm's, makes me uneasy...

[UNISA JECS]

Ok went out did some more tunning, and I think I solved the leaning out at high rpms, I adjusted my injection multiplyer down from 26800 to 24900 (actually low 25000 actual shows no signs of leaning via the wideband in higher rpm boost also) I'll fine tune this later im just happy that I finally figured this out. I just knew I wasn't running to lean, turns out was possibly running to rich is why the wideband spikes to lean because not all the air fuel ratio mix was being ignited.

I did about 10 WOT pulls to redline and everytime the wideband read basically high 11's to low 12's all the way to redline, normally that just wasn;t possible. I'll post up some logs later.

[BiG MiKE86]

good stuff - glad you found ur problem

[eclipse_dsm]

Glad you fix the problem. I wouldn't use the N60 maf if you are looking to get more than 280+whp. While this maf is suppose to be rated between 300~350. Mine maxed out 285whp on an FP 20g turbo. This caused the Enthalpy tuned ECU to go to safe mode and pulls timing off. I'm actually looking for some z32 maf and 750cc myself cause i'm running on low boost right now 10psi /w 260whp. GL..

[UNISA JECS]

You would probably be very surprised at how much the stock ECU pulls timing especially on a turbo charged KA24DE even when there is no real apparent knock.....I totally did away with the stock knock sensor, I have absolutely zero faith in it so its been disabled and that made tunning so much easier because before it would just retard the shit out of teh timing, impossible to get any consistant results.

[Om1kron]

You would probably be very surprised at how much the stock ECU pulls timing especially on a turbo charged KA24DE even when there is no real apparent knock.....I totally did away with the stock knock sensor, I have absolutely zero faith in it so its been disabled and that made tunning so much easier because before it would just retard the shit out of teh timing, impossible to get any consistant results.

Got any information as to how I would disable that?

[UNISA JECS]

If you have a tunnable ECU its easy, if you dont have one im not sure exactly how you go about that, i read about wiring in a resistor of a certain value shoudl do the trick.