GTNPU Z

iTrader: (17)

+1

I agree we need to have some kind of definitive answer to why it does this. It could be several factors to why it does this, but who knows. So far we have found that it MAY result from:

[1] Shifting into neutral during high speeds. If this is the cause, what is the explanation as to why it does this?

[2] ECU or MAF issues. If this is the cause, what is the explanation as to why it does this?

[3] Bad installation. This one is pretty straight forward.

bullseye

I agree it's an important question. No argument from me there!

But... I can't help but remember a skit on the old tv comedy show Hee-Haw, where a patient would tell his cigar-chewing doctor, "It hurts when I bend my elbow like this." The doctor would hit the patient in the head with a rubber chicken, and say, "Well, then don't bend your elbow like that!"

To rejoin the thread... My guess is the ECU "expects" a certain amount of load on the engine at certain speeds, throttle pedal positions, clutch status (engaged/not engaged), etc., which factors mandate an appropriate shot of fuel into each cylinder. When you pop the car into neutral and coast, I'm also guessing you fool the ECU right off the chart, so to speak: suddenly, there's no load, and that condition is "unexpected". At that point, before the ECU can recover, I bet it causes a very rich condition that lasts just long enough to make the engine stumble, or even stall completely. Other factors, such as ambient air temperature, fuel octane rating, state-of-tune, condition of spark plugs, etc., may combine to determine what actually happens: stumble or stall. Since shifting into neutral is ill-advised, it would not surprise me to learn the stock ECU is not programmed to deal with this rare practice with aplomb, especially at triple-digits...

That's my story, and I'm sticking to it.

BriGuyMax

iTrader: (4)

I installed my popcharger about a year ago and then next day I was coming to a stop from around 40mph and just pressed the clutch in and put the car in neutral and it stalled. Started right back up and has NEVER happened again..and I've put my car in neutral at high speeds plenty of times.

My theory is that the ECU needs time to "adapt" to the difference in air flow from a hi-flow intake and if you regularly reset your ECU you force the car to relearn the idle air flow.

To further back up my theory of ECU learn I installed borla TD exhaust and the JWT clutch/flywheel combo at the same time about a month ago. First few times I drove it when the rpms would come back to idle the car would almost stall...and did actually once. After a couple of days the symptoms when away completely and the car has no low idle or stalling issues. I'd recommend that you avoid resetting your ECU so often. I've never reset mine and as you can see in my sig...my car makes PLENTY of power.

BTW - look at your poll again....there was only one person who claimed their car to be stock and having done this. The other stocker said no....

TXSTYLE

iTrader: (1)

Bulleseye & BriGuyMax... Interesting and seemingly valid points. Let's just say....

Bottom line..... I learned my lesson. No need to tempt fate.
As for my boy's Vette... Well as you can imagine above 100... no substitute for cubic inches and displacement. I do however, give him a run for his money down low.

HarvesterUT

iTrader: (10)

best way to find out......if you have another aftermarket intake....drive your Z at 120 when its real late...then pop it in neutral....see what happens.....

TXSTYLE

iTrader: (1)

jreiter

iTrader: (6)

I have a JWT Popcharger and have never had a problem. However, there are a *lot* of people on the boards who have indeed experienced this after installing a JWT. I have no idea why, of course. It doesn't happen to everyone, and doesn't seem to happen *often* to anyone. I'd also love to see a definite explanation, but that might require some pretty extensive testing and analysis, especially since it's so inconsistent.

Road Warrior

iTrader: (16)

what a great idea....lose control of your car at 120 and at night

nbdyfcnsqnc

That is pretty scary. I decided to coast my dad's hyundai down a slope in a cemetary, and when I got to the turn at the bottom, the car was almost impossible to steer. I was only halfway expecting it, but I had the key ready to go and flipped it on just in time.

Lerxst

iTrader: (2)

Can't find it, but I recall someone posting a link to a fix from JWT on this issue.

jreiter

iTrader: (6)

Really? An official fix from JWT? I'm definitley interested to see what they did.

TXSTYLE

iTrader: (1)

No Doubt! Guess I'll call them tomorrow....

apexi97tsi

I just searched through their tech support section and found this link:

http://www.jimwolftechnology.com/wol...BILITY_FIX.PDF

But i'm not sure if this is the one your looking for. Here's the link for the tech support:

http://jimwolftechnology.com/tech_details.asp

TXSTYLE

iTrader: (1)

Interesting.... Thanks for looking this up. I will be contacting them for a "definitive" answer.

dgz32

iTrader: (9)

Happened to me several times. Each time was when I was slowing quickly from a hard run - like off the interstate onto an exit ramp. I've always put the clucth in when stopping the car, and when coming off a high RPM run, doing so causes the engine revs to drop dramatically. In my case, they'd drop too far and the car would stall. I emailed JWT, but never received a responce. Seems fine now, though. I think the ECU just needs some time to adjust.

phile

Well guys. I'm surprised this hasn't been brought up, but there was a recall a while back for a fualty crank position sensor. It caused the same kind of power failure you guys mention. It only applied to a certain vin # range supposedly, but I have heard of other cars outside of the vin# range with the problem also.

I could be totally wrong about this, but if I'm not, i'd bring your cars to the dealer right away and mention this. Do a little research.

TXSTYLE

iTrader: (1)

Wow! Thanks for pointing this out! My car is definitely an "early production" car: VIN in the low 1000's! I will contact my Service Tech tomorrow.

kopo

iTrader: (4)

I had the same thing after my pop charger install, just retightened everything, and been ok ever since.

phile

You're welcome. I just hope everything gets taken care of. This situation that keeps happening to people is potentially VERY dangerous!

http://www.nissanusa.com/form/0,,act...-51054,00.html

Here is the recall info on their website. Although they say only about 146 350z's are affected, I do not think that particular number has any merit. There were several threads about this issue, and many of the threads pointed out news stories where nissan reported approximately 2 million vehicles were affected that were manufactured between 1998 and 2003.

GTNPU Z

iTrader: (17)

Nice find! This is probably why I never had issues (knock on wood) since my 2003 VIN# is after that range. We should definitely post this notice as a seperate thread & make it a "sticky". Perhaps make it a general thread for all "recall" notices. Hopefully we don't get anymore recalls but we can add more to this thread if any come up. This is something everyone needs to know (at least those individuals who fall within this range).