Yep !

In the same time I will change spark plugs, clean the MAF and the throttle bodies, and change the intake gaskets.

And of course, all the reset/learning ecu stuffs !

 

good luck . . . please keep us posted

 

Any HR guys running standalone? do you still have this problem? because I don't any more and need to find someone to confirm it.

 

just how i suspected. it's the ECU causing the problem. I was getting the sputtering problem just about every single time i started the car. and didn't let it get warm. yesterday I decided to Hook up Cipher and let the ECU do the target A/F relearn. no more sputtering as of yesterday. I'll keep you guys updated to see if it slowly comes back. but i think it might be something with the cold start / fuel enrichment program.

 

is there any way to complete reset teh ECU? what's CIPHER?

 

resetting instructions . . .
http://www.technosquareinc.com/350reset.htm

haven't been able to do it myself . . . definitely need a stopwatch . . good luck

CIPHER is a data logging proprietary cable/program from Uprev that connects to your OBD2 port and can read / write values to the ECU

http://uprev.com/products.php#product_cipher

 

Greg, do you have any updates?

 

Not yet, still waiting for the gaskets to start the job...Next week I hope !

In the mean time, if your Z's 100% stock let try a full reset ECM ! As explain in previous post, I know that the timing is a little bit hard

 

you waiting on header gaskets ? ?


Also about the ecu reset . . . what if the Z is not stock . . ? ? usual intake, cats, exhaust . . etc . . ??

im considering buying a CIPHER myself, itll be great if someone can confirm that CIPHER a/f ratio relearn can fix the issue . . . .

 

negative, mine started sputtering again today. *sigh* i really really believe the problem lies on the ECU's self learn / cold enrichment program.

 

Just an FYI, I never heard of this issue on the G35 sedan's (HR). It seems only the Z's have them, which would mean it's not a mechanical issue but software. Has anyone tried using Uprev to tune the cold starts? I don't know if its even possible :/

 

Absolutly not, intake and throttle bodies one's

 

I'll talk to my tunner about this, it's what i have been suspecting for the longest.

-Juan

 

I think it might be a combination of the ECU's Cold enrichment and a faulty sensor. Mine will sputter and carry on 2 min after i start the engine and begins to warm up and then run normally 30 sec. to 1 min after that, however the engine will always perform what feels like a timing retard at 1800 rpm regardless of how long that its been running. There is no "rev-limiter" effect as when its warming up but it will bog for a split second and then continue running normally. This happens any time there is no to very little load on the engine. I performed a full ECU reset with all the corresponding sensor relearning tasks, and still no change to either problem. I was reading the service manual the other day and happened to stumble upon something in the ECU called 'No Load Fuel Cut' that basically said that when the engine operates over 1800 rpm, that after a certain time it would cut fuel until it engine speed fell below 1500rpm. While i dont think this might be the problem because those that watch the AFR have said nothing is out of normal, it may be conflicting with another program/map in the ECU based on bad info from a bad sensor. Just throwing this out there as it may be a step in the right direction or at a minimum its a little more info than we might have had.

 

thanks for the update . . . saved me some

 

**** it i might sell and get a 370Z lol.

 

I agree it can't be only an ECM issue, as a brand new car don't sputter...

I was able to check the front O2 sensor and Short Fuel Trim datas during sputtering, they became crazy, up and down... I guess that the ECM try to correct datas which are wrong, but from wich sensor(s)

 

i think it might be the primary O2's mine at 60,482 miles just threw the code for primary sensor for bank 2.

 

Regarding the front O2 sensors, we'll soon know more about it...



But we can note that 2007 HR and 2008 HR had different front O2 sensor...

 

fawk . . tonite i got my first code while sputtering: P0300 random multiple cylinder misfire detected. Got it while revving aroudn 3k~4k range while sputtering. This is actually damaging the engine in the process. From now on Im gonna warm up the engine @ idle for 10 mins before taking off.