Neimad

What is the (fully warm) idle speed at?

N80

Around 800 rpm and smooth.

And I guess I should clarify what the problem is. My initial description was not exact.

What happens is that as you apply throttle slowly, like when letting out the clutch to engage 1st or second gear at low speed or driving very slowly in second gear, the RPM's drop suddenly when you reach about 1200 RPM. It is always in the same place, right at 1200. You can feel and hear the drop. Once you get past 1200 RPM all is back to normal. If you apply the throttle quickly and go past 1200 RPM quickly then you hardly notice it at all. As mentioned, on the track it was never an issue.

At first it felt like it had something to do with the clutch but it does not. Driving slowly in second gear if the RPMs drop to 1200 or move up to 1200 then the RPMs drop too even if not shifting.

It does, however, making shifting at low speed difficult because if you are letting the clutch out at about 1200 RPMs, the RPMs drop and you start to stall...or if you try to gas it to quickly get past 1200 you lurch.

In a nutshell, there is a sudden drop off in RPMs when you hit 1200 RPM whether it is in gear or out. Clutch in or out.

Neimad

I searched IATN and found one case with a 07 350Z with similar symptoms. He ended up fixing it with a dealer reflash. Have you had any TSB's done on the car? I would keep driving it and hope a code pops up. I might put the old battery back just for fun too. I've had a lot of spooky weird problems solve themselves by just redoing the whole process.

N80

Thanks man. Only one TSB and that was the clutch slave cylinder replacement and that was nearly a year ago. No problems following that.

A reflash might be the way to go and shouldn't be too pricey. I'll try to get the tech to ride with me and to drive it. It is hard to explain and my wife had to drive it before she got what I was trying to explain. It is very easy to feel it when you drive it.

binder

iTrader: (8)

Hmm, I've never driven my car or any other 350z I've worked on below or near 1200 rpms. Even cruising through a parking lot really slow every car runs like crap and is jerky if below 1500 rpms.

So, that being said, I think this engine does not like pulling the car at that low of rpms.

N80

Well, first off, this is a big difference from the way it was before the battery change. So it is not just a natural characteristic of this engine/clutch/throttle.....which is already a bit clunky at low rpms anyway.

And, its not a matter of driving it right at 1200 rpms. In second gear, in a parking lot I'd say you'd typically be down around 2000. The problem is that if the rpms are increasing slowly from idle to 1200 (and paying close attention yesterday it is anywhere from 1200-1500) you hit a "flat spot" where the rpms rapidly try to drop all the way down to idle. That is when the engine starts to lug, of course. And of course the natural response is either to give it more gas or feather the clutch....which works but can still be jerky.

Just think about what you'd see on the tachometer when this happens:

Idling at about 800rpm
Slowly increase revs and they increase normally up to 1200-1500rpm.
When they hit that point they drop suddenly back down to 800rpm.
As you continue to depress the gas the revs jump back up.

If all of this is done quickly, and the revs move up from 800rpm past 1200-1500rpm rapidly, all you see is a very brief blip in the tach needle.

As you can see, this is only an issue at very low speeds, typically when operating the clutch between neutral, first and second.

N80

Three things:

1) Watching the tach today it is amazing how fast the needle drops when this happens. It doesn't just drift down like when you push the clutch in, it snaps downward almost to the point of stalling the car.

2) Several times when this has happened the 'Slip' light flickers. I think it is just because the car lurches and not because this is a TC malfunction of some sort.

3) I don't think I'm doing the Idle Air Volume Learning procedure correctly because the CEL never starts flashing. I've done it like 10 times but the CEL stays on the whole time the ignition is in the 'on' position. It is supposed to be on, then blink and then come back on again. It does not do this (Note: my CEL is not on at all when the car is cranked and running.)

Will try it a few more times tomorrow and then off to the dealer next week. I wish that he could use Consult-III but I'm not sure if it will work on an M/T model or not.

Neimad

Does it do it when TC is off?

N80

Yes.

And like I mentioned above, I'm pretty sure I'm not doing the re-learning procedure correctly. I'm going to do it over and over again later today and see if I can get it right. If not then off to the dealer.

Neimad

I don't think it's a relearn issue, but I hope I'm wrong. The one thing in that list I'm pretty sure you didn't check was the ignition timing, I remembered to also look for Infiniti's at IATN and found two more that sound very similar, 1000-1200 rpm cut out/stall. Both ended up being sticky VVT magnets that would not set codes. The ECM self-learning might have been working around weak signals from the sensors and anytime the battery is disconnected all adaptive values reset to factory defaults.

N80

Thanks. I will mention that to the tech at the dealership. I've been reading the troubleshooting section in the FSM regarding engine control. There is a whole category of Hesitation/Surging/Flat Spot. I'm reviewing that to see if I can come up with anything but there is a lot of stuff in there.

binder

iTrader: (8)

hmm, that is a strange problem. The relearn might not be the answer but it still needs to be properly performed. Since you are talking to a dealership why not just have a tech there do it for you? I think they can even use the Nistune to do a relearn (or whatever that software they use is called).

It almost sounds like a strange misfire.

N80

I would think any misfire would throw a code. I think the Nissan diagnostic stuff is called CONSULT-III, but it sounds like MT models use CONSULT-II which sounds less sophisticated but I'm just guessing about all that from what I'm reading in the SFM.

One other thing I've noticed is that this seems less likely to happen when the engine is cold.

It will likely go to the dealer next week. Fortunately, even though this problem is hard to describe, it is fairly consistent and easy to demonstrate so the symptoms will be easy for the tech to see.

The biggest mystery is how could it be doing this and not throwing a code?

binder

iTrader: (8)

I've had misfires that don't throw a code many times. Only long ago when the car barely would even stay running did I have a misfire large enough to throw a code. Any of them since then haven't thrown codes but I've seen it in my dyno and even logs from haltech.

N80

My 2000 Maxima throws codes with misfires that you can't even feel. It is always a coil. So who knows.

N80

Update: Took it to the dealership this morning. Drove the service manager around the parking lot and the problem was easy to feel. He said he would have the tech drive it too. He felt like a 'reset' would solve the problem but was selling me hard on a fuel system clean. He said it might need to be done even with a reset.

He also said they could do a 'reset' or maybe he said 'relearn' via the shop computer without having to do all the steps listed in the FSM.

He called back about an hour later and said that the good news was that the 'reset' would be covered under the emissions warranty but that there was a lot of "carbon build up" on the throttle butterfly and that the fuel system needed a cleaning (surprise, surprise). He also said my upper radiator hose was "collapsing" (I know that it isn't) and that my air filters need replacing (which I know that they do not). Total for diagnostic and service would be $270.

I declined on the radiator hose and air filters but went ahead and bit on the fuel system clean. It is $120. Probably not really necessary but the car has 66k on it and it might help a little.

Will update when I get it back to see if problem is solved. I am cautiously optimistic.

N80

Got the car back yesterday and problem completely gone. It is amazing how much easier it is to drive now.

Dealership said the service was covered under emissions warranty but the service order says it was a TSB, NTB11-019. It then says:

"Performed TSB and reprogrammed ECM. Checked OK
Old ECM 23710-EV12A New part # 23710-EV12C"

This makes it sound like they replaced the ECM. Not sure, but don't care since there was no charge for whatever they did and the car drives great.

Fuel system clean, tax and everything came out at $140. Not sure I needed a fuel system cleaning, but I'm pretty happy at this point.

Edit: Google search on that TSB results in nothing but brief description of problem so I have no idea what the recommended or actual service/repair was.

KingBaby

iTrader: (3)

BUMP

I was having similiar issues with my 07...finally ordered a new pedal because DTC codes say so...

car is tuned

car isn't taking the relearn, and now doesn't start?

Well try and test the TB and wires later...Hopefully it's not a short

<---hates electrical issues...on going issue car now finally dead.