Nissan Juke : Juke Forums banner

1 - 12 of 12 Posts

·
Registered
Joined
·
11 Posts
Discussion Starter #1
Hey guys,

I have a 2015 Nismo RS AWD. Uprev tuned about 7 months ago. Have been running the most conservative map (wastegate pressure) since. I seem to remember the boost used to be holding steady at 18 psi (on full throttle?) on this map. Recently, I seem to realize at partial throttle, I'm seeing 17 psi, but at full throttle, it dipped to around 13. Performance wise, I actually do not feel any different from the day it was tuned...

Is this normal? Could it be the problem with my boost gauge, OEM solenoid, leaks?

I've taken a quick video to show it... let me know what you think... Thanks, guys.

 

·
Super Moderator
Joined
·
2,125 Posts
Stock turbo? upgraded intercooler (FMIC)? I know the stock turbo will fall off at higher rpms, I just don't know if it's as much as 4-6psi. Also if you have an upgraded FMIC, there's additional pressure drop there. If you're on the stock intercooler it's much less of a drop. It also could very well be the way the engine is tuned on the waste gate spring map. My only other thought is there may be a leak in the diaphragm in the waste gate actuator. Though that should actually cause an overboost condition. If the right amount of pretension is not applied to the waste gate, that could cause boost to taper off. the turbosmart waste gate you can open it up with a vice and your hands and inspect the rubber diaphragm inside. Also verifying pretension is not very hard and doesn't require removing the waste gate actuator, just the circlip and arm.
 

·
Registered
Joined
·
11 Posts
Discussion Starter #3
Yup, stock turbo, stock intercooler.
Great suggestion, never thought about the IWG, will check it out... Thanks!
 

·
Super Moderator
Joined
·
11,574 Posts
Yup, stock turbo, stock intercooler.
Great suggestion, never thought about the IWG, will check it out... Thanks!
SOrry I did not see this.

Did you ever get an answer on this ?

I would say it is your tuner / Tune.

Have your tried all of your maps ?

If indeed you are on WG pressure. Then you should not see 18 partial and 12 full boost.
 

·
Registered
Joined
·
11 Posts
Discussion Starter #5
Yup, I've tried all the maps. Same turn out. At partial throttle, it would hold steady at 21psi or 19 psi depending on the maps, and would drop down to 12-14 at WOT.
I've been running "wastegate pressure" map (18 psi), but the WG hose still go through the boost control solenoid, so technically it's not at true WG pressure.

Drunkmann Anthony got back to me and said "that's pretty normal it's PTFB and WG creep rate is higher than factory".

So I guess that's normal? Perhaps mine was tuned that way all along, but I still think it was holding steady full boost all the way to WOT before... Nothing added/changed since dyno tuned 7 months ago.
I've cleaned the boost control solenoid, but have not check out the rubber IWG diaphragm yet.
 

·
Super Moderator
Joined
·
11,574 Posts
Hmmm.

Anyone else here tuned by Drunkmann seeing a mid throttle "Lugging" the motor per say high boost ?

I drive with a spare boost solenoid. I have had two fail on me. Always fail on really high boost too. If they are in stock. Usually $70-$80 shipped. Might be worth a swap out just for the effort but lets see what the consensus is here.

@slcjuke @pboglio Have you seen this ?
 

·
Registered
Joined
·
661 Posts
This seems like relatively normal behavior to be honest especially on stock Wastegate Actuator and Solenoid. Even mine with the Mamba Actuator/Spring and GFB EBC will do this to some degree.

If I run my 23 PSI MAP it often will spike to 26 PSI at part throttle but WOT it sticks to around 23 give or take 1 PSI.

Is the car running properly? As in is it Idling fine and no shuddering and weird Air/Fuel Ratios? I'm not necessarily saying there's nothing wrong because you know your car better than anyone in most cases and hard to diagnose over the internet. But if there are no codes and it's driving fine I would just keep a keen eye on its behavior now and just see if you can notice any further future deviations or if it "worsens" so to speak.

And just to throw common sense out there. If the AFR isnt leaning out at high PSI or WOT i'd consider this an investigative problem rather than an "oh s***" thing

Edit: Also as you will read on this forum that stock solenoid is absolute dog poop. I know not everyone has hundreds to throw around buying all these car parts but I'm just saying if you drive it on the high PSI map a lot that thing will tire out fast.
 

·
Super Moderator
Joined
·
2,125 Posts
I have to drive my Juke Thursday so I’ll test out my two higher boost maps (16-17psi and 19-20psi) and report back. I know my “stock” map boosts to 12psi and holds on tight through the rpm range. The few times I have used my 16psi map I’m almost positive it peaks 17psi and holds pretty well. And my pulls are not WOT, usually 1/2 to 3/4 throttle. I rarely anymore have a long enough drive to play with any other map though and my high boost map honestly scares me even easing into it from a rolling start. I have the turbo smart wastegate actuator like OP, but I have a 7psi spring in it.
 

·
Super Moderator
Joined
·
2,125 Posts
So it’s been rainy all week. I couldn’t get on it as much as I’d like. Today I ran my “stock” 12psi boost map and at WOT my boost climbed to about 11psi and stayed there touching 12psi a couple times. Even at higher speed or rpm (I could only get up to about 60mph and just touching 5500rpm in normal drive mode) the boost never tapered. There were many times I went to 1/2 or 3/4 throttle and The turbo would only hold about 7-8psi boost which is my wastegate spring pressure. Then if I went WOT at that point it would jump to 11-12psi and hold.

I won’t have a need to drive my Juke again until Tuesday and I should be able to go WOT on my 16psi map then.
 

·
Super Moderator
Joined
·
11,574 Posts
So it’s been rainy all week. I couldn’t get on it as much as I’d like. Today I ran my “stock” 12psi boost map and at WOT my boost climbed to about 11psi and stayed there touching 12psi a couple times. Even at higher speed or rpm (I could only get up to about 60mph and just touching 5500rpm in normal drive mode) the boost never tapered. There were many times I went to 1/2 or 3/4 throttle and The turbo would only hold about 7-8psi boost which is my wastegate spring pressure. Then if I went WOT at that point it would jump to 11-12psi and hold.

I won’t have a need to drive my Juke again until Tuesday and I should be able to go WOT on my 16psi map then.
Very insteresting.
 

·
Premium Member
Joined
·
1,254 Posts
I drive with a spare boost solenoid. I have had two fail on me. Always fail on really high boost too. If they are in stock. Usually $70-$80 shipped. Might be worth a swap out just for the effort but lets see what the consensus is here.

@slcjuke @pboglio Have you seen this ?
Definitely sounds like what my RS has been doing for a few months with a bad solenoid. I know that's what the problem is because I stole the solenoid from the other Juke and it solved the problems. (yes, I finally got around to ordering one).
 

·
Super Moderator
Joined
·
2,125 Posts
I got to drive my Juke today (won't have a need to until next monday...). I used two interstate on ramps as my test points, one was uphill, the other was downhill. Both times I was WOT, Normal drive mode, hit about 70mph, ~6700rpm (CVT didn't want to "shift" either because I was in AWD-V and Normal drive mode or VDC detected slip?), 16 psi boost and held mostly stable. On the downhill on ramp which slowly transitions to flat then a slight uphill before merging I did peak at 17psi then it backed off to about 15psi and briefly dipped to 14psi but recovered back to 16psi before I had to let off the accelerator. While at speed I punched it a few times and my boost would seem to correlate with throttle position. half throttle was about wastegate spring pressure of 7psi, more throttle and it would hold about 10-13psi but always smooth and never dropped until I let off the accelerator, back to WOT and it would peak to 16psi and hold. I did a few partial throttle punch and hold at slower speeds (city streets) and my boost would climb to a certain psi (never max) and hold.

This all makes sense to me as the ECU is just reading a boost table for a setpoint based on rpm and throttle (like a fuel table) then the PID loop takes over and modulates the boost control solenoid valve to maintain that setpoint. Depending on the failure mode of the solenoid you could experience one of the following: If the solenoid fails in the closed position or due to debris cannot fully open (blocking boost from getting to the wastegate actuator) then you will experience overboost and the exhaust gas pressure must overcome the full wastegate spring. If the solenoid fails in the open position or cannot fully close (allowing more boost to reach the wastegate actuator) then the wastegate can be more sloppy and the boost reference or the exhaust gas pressure is effectively pushing the wastegate open and overcoming what appears to be a weaker spring. You would see oscillations in the boost and it would manifest itself as the engine surging/oscillating in RPM.

Now as I mentioned earlier, if there is a problem with the wastegate, you'll experience similar symptoms as a bad solenoid. a leak in the diaphragm or too much pre-tension on the wastegate will look like a boost control solenoid failing closed. not enough pre-tension on the wastegate will look like a solenoid failing open.

At this point, I don't think there's a problem with the tune on your Juke OP. I think there's something mechanically wrong around the boost control and wastegate. That or you have a pretty serious boost leak but only at full throttle which doesn't quite make sense because you should see it at any throttle position that is held. The only thing that keeps me doubting my theory that it's not your tune is the fact you said it happens on all maps. Possibly because a boost table was copied and pasted from the first to all the others. If there's any way you can see the actual boost and fuel table for all of your maps that would put the tune theory to bed.
 
1 - 12 of 12 Posts
Top