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Discussion Starter #1
Hi,

I am new to this forum, just posted intro message in relevant section.
I have a question which I will ask dealer about as well.
Basically I v never driven turbocharged car before so I am big time noob here.
When I want to accelerate rapidly lets say from standstill and i change first second and into third all at around 3.5-4.5k RPM and what happens is that at some point in 3rd or 4th gear something happens that feels like I droped a gear. like a loss of power for the moment, but gear was not changed. It manual 6 gear Nismo RS 2016 make.
like today hapoened twice in 30 minutes.
Does anybidy know what that is and if I am doing something wrong?

Any help would be much appreciated.

thanks,

Milosh
 

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Discussion Starter #3
Thanks for taking time to reply.
Maybe I dont understand but turbo lag is something that is normal and its waiting time before the turbo kicks.
Here i have opposite problem. Turbo kicks in and I change to 3, turbo kicks in, i have decent acceleration and speed(all as expected)i change to 4 and then at some point i feel something equivalent of what happens when you go fast in lets say gear 5 and you go to gear 4 and revs are still too high for gear 4. Its complimented with engine noise and car reaction equivalent to when you drop gear at high speeds. But ofcourse i didnt change gear(i have manual transmission) Is there a known term for this? I assume its something normal but strange to me.
 

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Discussion Starter #4
Tried today full throttle in sixth gear and same happened...like hickup at some point and it felt like I changed to lower gear suddenly. I am going to ask dealer about it. Dont think this is normal.
 

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Tried today full throttle in sixth gear and same happened...like hickup at some point and it felt like I changed to lower gear suddenly. I am going to ask dealer about it. Dont think this is normal.
it is hard to help you with just your explanation. Have someone ride with you and video what is going on. This might bring more members input.

the dealer is also a great option. A mechanic riding with you would be a big benefit to solving your issue.
 

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Take it to a dealership. This sounds like fuel cut, maybe. Usually happens when it's cold outside, boost increases too much and you are at full engine power. Computer senses too much airflow.....and then it fuel cuts. It would be very strong sensation, like hitting the brakes or something. You say "dropping" a gear. Fuel cut feels like someone takes the gear-shifter at full power and throws it into neutral, then back into gear. It's violent.

Normal cars don't fuel cut typically unless the boost solenoid hose is loose and the boost is much too high or something.

Don't drive hard anymore until the dealership has a chance to look at it.
 

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Discussion Starter #8
I v found this on one another non Juke related forum.

'Most OEM ECUs in turbocharged cars will cut the engine if a preset amount of boost pressure is exceeded as a safety feature.'

Perhaps thats whats happening. Just surprised nobody else hasnt had it.
 

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Fuel cut.
 

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Discussion Starter #10
Fuel cut seems like the right guess.
Car is 1 week old so I guess its meant to be like that. Can I do something with driving style to prevent this?
 

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Fuel cut seems like the right guess.
Car is 1 week old so I guess its meant to be like that. Can I do something with driving style to prevent this?
You still need to take it back to the dealer to check and see if there are any leaks in the induction system.

i took it easy on my Juke during the break-in period, (actually, I don't think I ever hit 4500rpms).
 

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Try to keep it to a minimum and not give too much throttle.

My guess is boost is increasing above stock levels for some reason. Cold weather can sometimes increase boost levels in manual boost controllers, but the Juke boost control is feedback, so it should maintain a set point. Even on the stock boost levels, the compressor still gets more airflow in colder weather. Unfortunately the fuel system doesn't provide more fuel proportionately to what is gained at the turbo compressor when it gets really cold, so the fuel system starts falling behind. This is partly why fuel cut exists.

At some point, the engine would fuel cut depending on how cold it got. Very cold weather, say -17*C could trigger it. I don't know how cold your region is when this happens.

Yes, it happens to me on my stock Juke with my bolt-on mods and 15 psi, on the stock ECM tune. With my ECM reflash tune, fuel cut defense is removed, no fuel cut. On a stock Juke, no mods, no it doesn't fuel cut. The Juke RS run more boost and make more power than a stock Juke. If they didn't increase the fuel cut airflow threshold in the ECM, then I could see this happening under the right conditions.

RS owners can comment, I don't own one myself.

Mechanic needs to check the boost solenoid and boost control to see what is going on. I believe RS run around 15-16 psi, please verify that though. Anything near 18 psi could push the airflow high enough to trigger FC. They can log airflow using scan tool or OBDII reader, something like .180 kg/s would most likely trigger fuel cut, that is about 240 h.p. This is about where I fuel cut on my Juke SV (stock ECM flash).
 

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Discussion Starter #13
Thanks very much guys. Very helpful, especially pboglio post, awesome man.
I ll take it easy first 2000km(now at 320km) and if this persists I ll take to dealer. For now I am going to enjoy my new ride :)
Will come back and post final outcome once its solved.
 

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Discussion Starter #14
You never wanna floor in it 6th gear anyways. It puts a lot of strain on the trans low in the RPMs. My car personally accelerates faster at partial throttle anyways when in a high gear.When I pass in 6th gear, I don't let the boost go over 10 psi which is still plenty enough to pass others no problem and no fuel cut. If I floor it at 40 in 4th, I'll hit fuel cut also. Your's being an RS, your boost is already pretty much maximized so we are near the fuel cut for overboost already unlike other Jukes with a much larger window for overboost. A few of us RS owners from factory with boost gauges saw upwards of 21 psi boost spikes bone stock so with colder weather and flooring it in too high of a gear would not be surprising to be hitting fuel cut from over boost. Our turbos are small and build boost very quickly. The RPM's would be too low and too much boost would be built at that point in the RPM's.
Super information! Thanks.
It actually matches what I was doing. I was going from 1st gear to 6th quickly and shifting each at around 4-4.5 (to avoid high revs due to car being new) however with pedal at full(which is wrong) being in 4-5-6gears and at such low rpm causes this to activate fuel cut I guess.
I think once I can go through gears normally with higher revs this should rarely happen. (I ll try this out after 2000km period.
Temperature is around +11degree celsius here these days.
 

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Discussion Starter #15
Today Check Engine Light came on. I am calling dealership tomorrow. Car has 2 weeks and 1000km :/
After googling it seems its faulty Mass Air Filter/Air Sensor - which was reflecting they way it did in my earlier posts. Apparently behavior I was experiencing was not as designed nor fuel cut but rather fault. I ll write back once dealer confirms the problem.
 

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A bad MAF might be it, but I doubt it. Pull the MAF connector off, then go drive. If there is NO difference, it's the MAF.

A dead MAF won't let you rev above 3000 rpms, you will barely be able to get the car moving down the road.

The trouble codes are going to be a huge help. A datalog is even better, it's going to visually show you what's happening to all the output devices real time.
 

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Discussion Starter #17
Okay I went today to dealership for a check and here is the outcome.
Two DTC error poped up, P1808 - Break Pedal Position Switch and P0234 - TC System-B1.
They checked everything and tried driving the car and concluded that connection issue was possible cause and removed the CEL. They told me if it repeats than i shall come back for fix which will include parts replacement and will take few days.
I am thinking if this is connected to those overboosts I had been experiencing. I find it hard to believe that new car does not have system to limit boost level and prevent overboosts/fuel cuts. Isnt the fact i manage to overboost the car proof something is faulty or this is as designed? Let me know what you guys make of this.
 
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