Closed loop?

[owned by pandas]

Sr20det
550 injectors
gt30
n62 maf

Ok I read online after doing some research that there was a guy having similiar problems to what I have been experiencing for the past two weeks. Basically if I got and start my car it will sit there and run super lean for about 10-30 seconds and then out of no where to back to running fine. On the AFR(AEM wide band) it will run lean --- then its like something just changes and it goes to normal idle 13.5-14.9 afr. Now while driving the car(crusing) it drives good no issues mainly but if I get it some gas it goes pig rich, AFR reading 10.0, If I let off the throttle a little it goes back to normal.?.?.?

I have replaced a lot of stuff thinking it would be the problem but even still it has not fixed my car. I did how ever pull a code which was 34(knock sensor) and I dont know if it threw the code b/c it was running so lean or the knock sensor is actually messed up in a way. There was a thread and this guy basically described the same thing I said and someone said something about the closed loop in the ecu but no one followed up on it. Does anyone have any idea about this.

Things I have checked or replaced:
Boost leaks-checked all couplers for tears and gaskets are fine
Fuel pressure
Vacuum hoses
Swapped ecus
Ignitor
MAF
FPR
CTS
TPS
BOV
Checked injectors they all read at 11 ohms
I pulled my harness out yesterday and went through the whole thing fixed some broken parts and repaired everything

Someone please help me!!!

[owned by pandas]

also my o2 sensor has never been hooked up even when it ran good. I know a lot of people say the o2 sensor might be the problem but on sr's they really dont do anything, especially at idle.

[chrislikesthings]

What are you tuning with?

[owned by pandas]

Before I had a nistune on the car and kept a Apexi Neo with it for simple tuning cleanups or if I change some parts out I didnt want to send my Nistune back to them everytime. Now it has a daughterboard ecu(which doesn't change timing) and a apexi Neo.

[RalliartRsX]

A NISTUNE board is essentially a mini me standalone, so I don't see why you are sending it back for a retune...........You can do it yourself.

Another incorrect assumption: daughterboard not changing timing. Unless you specifically said stock timing, you have no idea if the "tuner" changed timing.

Third incorrect assumption: The AFC is doing anything. I have a feeling your AFC is set incorrectly or skewing the incoming signal too much.

I have no idea why you are running both a "standalone" and a AFC.........The standalone NISTUNE is a MUCH better tuning device than the horrendous AFC.

If you are pulling a code for a knock sensor, why not start there??

[owned by pandas]

A NISTUNE board is essentially a mini me standalone, so I don't see why you are sending it back for a retune...........You can do it yourself.

Another incorrect assumption: daughterboard not changing timing. Unless you specifically said stock timing, you have no idea if the "tuner" changed timing.

Third incorrect assumption: The AFC is doing anything. I have a feeling your AFC is set incorrectly or skewing the incoming signal too much.

I have no idea why you are running both a "standalone" and a AFC.........The standalone NISTUNE is a MUCH better tuning device than the horrendous AFC.

If you are pulling a code for a knock sensor, why not start there??

While trying to diagnosis this problem I was unable to get any codes with the nistune. The nistune however when I pulled it apart and looked at the board had a burn mark on one of the Xilinx chips, which I was unable to find anyone here locally to fix it.

The daughter board doesnt feel like it does anything with timing to me. Compared to the Nistune it is literally a night and day difference. It feels like its just a stock ecu.

The AFC has been set on the same settings as before. Nothing was changed except the in and out on the hotwire screen. With the nistune it ran much better at 6 in 6 out, but with ecu it runs better at 2 in and 6 out.

I was running the Nistune with the AFC b/c I got the Nistune from friend of mine, his set up was sr, blow by n62, gt28, 550, freddy intake, tubular manifold. Mine is sr, blow through n62, GT30, 550, stock intake, stock manifolds. After putting the nistune it, it didn't run good, I had to make minor adjustments with the AFC and after that it ran amazing. If I knew of anyone locally that tunes Nistune I would have taken it there sold the NEO and made some money but I cant seem to find any one with the software.

Besides the fact that I already sent my Nistune to them, the problem still persist regardless of what ECU I am running. Ran like poop with the nistune and it also runs like poop with this other ecu.

I pulled that code last night, I was going to pull my intake manifold off and test it b/c I can not find the sub harness for it.

[RalliartRsX]

Regardless of what the AFC is set to, all it does it "fool" the computer into thinking something else. Not good in my opinion.

Also, if the ECU had a burnt up board, there is a good chance you had an electrical short and burnt it up. ECU's dont just burn up on their own. Also, to compare a burnt up Nistune (which you have no idea on when this occured) to a properly running daughterboard, is not a direct comparison.

Also, in regards to your problem. If the problem was the knock sensor before, and you are only now just getting a code, what makes you believe it wasn't the knock sensor all along??

Again, if you just figured recently the knock sensor was throwing a code, I would start with that first. The knock sensor is critical to the ECU (up to about 4800 or so RPM). I do not recall the failing parameters off the top of my head, but typically if it fails, the ecu should go into "rich" limp home mode and not dip too much into the lean side as a failsafe.

Also, a A/F problem to me, if everything else checks out would have me thinking injector. Regardless of what OHMS it's seeing, if the injector itself is clogged or there is a tear in the O-ring, that will have a drastic effect on your readings.

Also, for reference, do you know what closed loop operation is??

[owned by pandas]

Regardless of what the AFC is set to, all it does it "fool" the computer into thinking something else. Not good in my opinion.

Also, if the ECU had a burnt up board, there is a good chance you had an electrical short and burnt it up. ECU's dont just burn up on their own. Also, to compare a burnt up Nistune (which you have no idea on when this occured) to a properly running daughterboard, is not a direct comparison.

Also, in regards to your problem. If the problem was the knock sensor before, and you are only now just getting a code, what makes you believe it wasn't the knock sensor all along??

Again, if you just figured recently the knock sensor was throwing a code, I would start with that first. The knock sensor is critical to the ECU (up to about 4800 or so RPM). I do not recall the failing parameters off the top of my head, but typically if it fails, the ecu should go into "rich" limp home mode and not dip too much into the lean side as a failsafe.

Also, a A/F problem to me, if everything else checks out would have me thinking injector. Regardless of what OHMS it's seeing, if the injector itself is clogged or there is a tear in the O-ring, that will have a drastic effect on your readings.

Also, for reference, do you know what closed loop operation is??

The ecu had a burn mark b/c of the a short which I found that was in the harness near the connector to the ecu.

That is why I am some what confused. I figured that if it were a knock sensor then it would make more sense for the ECU to increase the fuel of the mixture instead of leaning/decreasing it out. I will investigate the Knock sensor today.

For a second there i thought i could be the injectors but the fact that is is a intermittent problem, I was leaning more towards a electrical issue. Its almost like clock work. I can go to my car right now start it and it will run lean and after 10-20 seconds it goes to a good AFR. I can turn it right off afterwards and do the same thing over again. Thats what makes me thing its not a clogging injector issue b/c it is almost on a consistent basis.

I might not be correct with the closed/open loop scenario but from what I understand closed loop changes the timing to base timing and reads off of the O2 sensor?

[RalliartRsX]

I had somewhat of the same issue and it turned out to be an injector wire by the ecu.
However, another gentlemen had similar problems and it turned out to be a torn injector o-ring.

My point is, though people have similar problems, it could be several things which cause the same problem. My bet is still something along the injector line at this point.

Also, it seems you are misguided on what closed operation is. Closed loop operation reads off the O2 sensor (not duing WOT mind you) which the signal is sent to the ECU and with a pregrommed MAP or fuel table, the ecu will adjust the injector pulsewidth to get as close to stoich (or whatever setting) as possible for the Air Fuel Misture. Timing (NOT Base timing) will adjust based off several other parameters.


It's not in good diagnosis sense to suggest a problem is based off closed loop without even knowing how closed loop operates.

[Chaluska]

also my o2 sensor has never been hooked up even when it ran good. I know a lot of people say the o2 sensor might be the problem but on sr's they really dont do anything, especially at idle.

Whoever you were told that from is full of shit.

no different than saying your car doesn't really NEED gas to run.

without an O2 sensor, the ECU will always stay in open loop, and run pig rich. if you tune around it, it is still dangerous, because the engine will be running off pre-programmed MAF load readings for fuel injection. if it does run "good" without an O2 sensor hooked up, it will run GREAT with an o2 sensor. once you get into closed loop the timing gets much more aggressive.

and for code 34, check for continuity between the ecu pin and the knock sensor pin connector. if that is OK, check the resistance of the knock sensor itself. my brand new one was about .550k ohms. I had to run a new shielded cable all the way from the ecu to the knock sensor to fix my code 34 (also another reason your car would run odd... if its suddenly loosing knock signal, it will retard the shit out of the timing)

[owned by pandas]

I had somewhat of the same issue and it turned out to be an injector wire by the ecu.
However, another gentlemen had similar problems and it turned out to be a torn injector o-ring.

My point is, though people have similar problems, it could be several things which cause the same problem. My bet is still something along the injector line at this point.

Also, it seems you are misguided on what closed operation is. Closed loop operation reads off the O2 sensor (not duing WOT mind you) which the signal is sent to the ECU and with a pregrommed MAP or fuel table, the ecu will adjust the injector pulsewidth to get as close to stoich (or whatever setting) as possible for the Air Fuel Misture. Timing (NOT Base timing) will adjust based off several other parameters.


It's not in good diagnosis sense to suggest a problem is based off closed loop without even knowing how closed loop operates.

Im only going off of what I read in this previous post about someone having literally the exact same problem and a tech guy was saying it had something to do with closed loop. Also when I spoke with the guy at Nistune he said the same thing. I do understand different problems from all over can cause the same issue. I really appreciate your help and I will look further into the injectors. I happen to have an extra set so that is good.

I just noticed the ground wire from the Alternator was broken so Im going to solder that up and go from there.

[owned by pandas]

I am uploading a video to youtube right now to give you an idea of what it does.

[owned by pandas]

video of how it acts. these are two separate occasions. Sorry for the music in the first video my pandora was on.

https://www.youtube.com/watch?v=qk3I6n2Gl8E

[owned by pandas]

Whoever you were told that from is full of shit.

no different than saying your car doesn't really NEED gas to run.

without an O2 sensor, the ECU will always stay in open loop, and run pig rich. if you tune around it, it is still dangerous, because the engine will be running off pre-programmed MAF load readings for fuel injection. if it does run "good" without an O2 sensor hooked up, it will run GREAT with an o2 sensor. once you get into closed loop the timing gets much more aggressive.

and for code 34, check for continuity between the ecu pin and the knock sensor pin connector. if that is OK, check the resistance of the knock sensor itself. my brand new one was about .550k ohms. I had to run a new shielded cable all the way from the ecu to the knock sensor to fix my code 34 (also another reason your car would run odd... if its suddenly loosing knock signal, it will retard the shit out of the timing)

Will the o2 affect anything on a nistune? Or is that for stock ecus you are referring to?

[cotbu]

yes and it can also be turned off, along with the knock sensor. which i would do to see if it changes anything.
A tune is what make an engine run better, if you have other issues (wiring etc.) no tune will fix that.

Make higher quality vids, and turn the phone horizontally, make slow steady passes of the things you want us to see.

[Croustibat]

Will the o2 affect anything on a nistune? Or is that for stock ecus you are referring to?

Nisture IS a stock ECU, it basically is a daughterboard with eeprom emulators on it, and a (very good) software to acces it. Allow O² feedback and it will affect things, remove it and it wont.

[owned by pandas]

The thing about it is I never had an issue with the 02 not being on before. I drove for almost a year and had no problems at all. All of a sudden this issue comes up.

I just pulled my intake manifold...There is no knock sensor there.

[RalliartRsX]

If you are on a stock based ECU, a knock sensor is pretty much a requirement.......

My advice
1) Get rid of the AFC
2) Get a proper standalone (NISMOTRONIC, AEM, etc) or a dyno tune and a burned chip
3) Take it to a tuner.

You CAN run without the O2 sensor (and disable it in the ECU) and get the tune to be close to run to closed loop (you NEED an ECU which this provision). But the ideal situation is you want to tune your entire fuel table with closed loop feedback off, then once the tuning is done, you re-enable closed loop and have the O2 and ECU do the rest. No one (including yourself) has any idea what tune is on either the Nistune, your new daughterboard or anything else (apart from a "formal agreement" or word of mouth which can still be incorrect. JWT has gotten it wrong from whats on the sticker on numerous ocassions...........).

Also, this quote below worries me as you followed this and actually believed it (which was evident by your misguided info on closed loop). Idle situation is closed loop and the A/F ratio and timing depending ENTIRELY on what imformation the O2 sensor (as well as several other sensors) are feeding the ECU. Typically, the stock systems are engineered much better than any aftermarket system can provide (unless you spend big $$$$$$$$$)

also my o2 sensor has never been hooked up even when it ran good. I know a lot of people say the o2 sensor might be the problem but on sr's they really dont do anything, especially at idle.



You may have some learning to do.

[owned by pandas]

If you are on a stock based ECU, a knock sensor is pretty much a requirement.......

My advice
1) Get rid of the AFC
2) Get a proper standalone (NISMOTRONIC, AEM, etc) or a dyno tune and a burned chip
3) Take it to a tuner.

You CAN run without the O2 sensor (and disable it in the ECU) and get the tune to be close to run to closed loop (you NEED an ECU which this provision). But the ideal situation is you want to tune your entire fuel table with closed loop feedback off, then once the tuning is done, you re-enable closed loop and have the O2 and ECU do the rest. No one (including yourself) has any idea what tune is on either the Nistune, your new daughterboard or anything else (apart from a "formal agreement" or word of mouth which can still be incorrect. JWT has gotten it wrong from whats on the sticker on numerous ocassions...........).

Also, this quote below worries me as you followed this and actually believed it (which was evident by your misguided info on closed loop). Idle situation is closed loop and the A/F ratio and timing depending ENTIRELY on what imformation the O2 sensor (as well as several other sensors) are feeding the ECU. Typically, the stock systems are engineered much better than any aftermarket system can provide (unless you spend big $$$$$$$$$)





You may have some learning to do.


I understand what you're saying. Honestly I never paid attention to computing for the engine b/c it always worked fine. Regardless of the fact of my lack of knowledge, this still doesn't fix the issue here. The nistune was just a ecu that was previously in the car and I though it might have something to do with my problem simply b/c of the burned part on the chip. It still runs the same with the stock or whatever motherboard eu I am currently running.

Once again, the 02 was never been hooked up since I've had the car(over a year), the nistune has been in the car for several months with no issues. So its kind of hard to focus on things like a o2 and the nistune when they were both either present or not present when the car was running fine. I never had a hick up, no leaning, no back firing. The car ran great, my afrs were great, it pulled through the power band with no issues.

Since the video was hard to see, basically I start the car it runs really lean, I wait 30 seconds, by itself it goes to a richer afr and will sit there. If I go and drive the car or even at idle give it throttle it will rev fine go back to idle and be back an lean. Now while driving, the car still runs a good AFR while driving(cruising speeds), now if I happen to mat it or get on it a little bit it goes pig rich. With that said, dont assume this is b/c I'm running a stock ecu now and the neos tune is different from the setting I had on the nistune b/c it was doing the same thing with the same exact tune on the nistune before I removed it.

I think my problem is a little more in depth than a o2 and a nistune, but then again...thats why I am asking. The only thing I have compared my problem to pretty much to the tee is this post...

http://forums.nicoclub.com/car-switches-between-open-and-closed-loop-in-idle-leans-out-no-codes-thrown-t259580.html

[RalliartRsX]

If the knock sensor is not working or whatever got burnt up in the ECU, the failsafe is pig rich in any open throttle condition. That could also explain the lean at idle condition (and if something in the ECU burnt up, what make syou think something in the AFC didn't bit ethe dust as well?? Also, what makes you think no other sensor or ciruitry didn't alos bite the dust??)

If you want to keep the AFC, go right ahead. But condiering it's a signal interupter and nothing else, don't be surprised if it's a combination of the AFC as well as the missing knock sensor, no closed loop feedback enabled or all the above that's causing you the headache...........

And my focus wasn't on the O2 sensor (as mentioned before), but educating you since you seem to be misguided on several sensors operation and how they tie into the overall system.

Goodluck!

[RalliartRsX]

BTW, I just read through the thread, and it presents no answers or anything of the sorts. It has a total of 5 posts with 2 of them restating the problem and 1 stating where the O2 sensor is and another stating how a Altima O2 sensor works.

I wouldn't use that thread as a basis of your diagnosis.

[owned by pandas]

Ok sorry that might have been the wrong one, I have like 20 of them saved trying to gather information haha. Im just going to check the injectors for voltage, and maybe swap them out. If that doesnt work Ill just swap the harness out. i dont have time to work on it much, I work 7 days a week mostly. I do appreciate your input and help, it really has assisted me a lot.

[owned by pandas]

let me ask you this, if the ecu were going in and out of close/open loop wouldn't it create the symptoms I am experiencing?

[RalliartRsX]

Depends on the variance in tune/fuel table/map/etc. between the two. You can get an open loop tune (no O2 feedback tune) close to how it would run in closed loop at idle (did it on my standalone and had it running like that for weeks including 2 HPDEs before I enabled closed loop. Mostly for the cruising MPGs, closed throttle enrichment, etc).

AGAIN, I urge you to start with the knock sensor instead of throwing money and time at this blindly. Then if that doesn't work, move on to the fuel areas (injectors, wiring, etc).

[owned by pandas]

Ok understood. I guess Ill have to buy a knock sensor and a sub harness b/c I just pulled my intake manifold off and the knock sensor wasnt there. This is so weird.

[owned by pandas]

Fixed it, thanks everyone for your help.

[jr_ss]

Fixed it isn't exactly what you need to put here. You need to explain what the fix was. Someone in the future may have the same problem, stumble apon this thread and get no where because there isn't a fix at the end.

[owned by pandas]

diaphragm in the wastegate was getting stuck open and closed on separate occasions.