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Gtr Power / Boost Loss. Suggestions?

JJGTR

By JJGTR,
in Engines & Forced Induction

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JJGTR Rookie

JJGTR

Posted
Posted

Hi guys,

I picked up a GTR a couple of days ago and everything seemed fine, it drives very well and boost builds from ~2000rpm and will hold at ~7.5psi all the way from 3k odd to redline.

Felt pretty gutless and thought it was a bit down on power but put it down to the hot weather and the cars bolt ons being pretty sedate (just dump pipes, hiflow cat, cat back and pod filters).

Gtech+Iphone confirmed my arse dyno predictions, apparently making between 150-170kw at the wheels which is a bit of a worry so I went to see how much it would make with 1 bar and the restrictor on the solenoid line is already missing!

I cant find any boost or vacuum leaks, but it absolutes refuses to make over 7psi. Aside from the power and boost the car runs perfectly and cleanly.

I'm hoping the solenoid is f**ked or the cat is clogged up and the workshops I want to go to are still closed from the xmas break.

TLDR version:

Car is running 7psi with boost restrictor removed and making underwhelming power with no other symptoms.

Any suggestions I can easily check?

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https://www.sau.com.au/forums/topic/349395-gtr-power-boost-loss-suggestions/
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J - Rad Veteran

J - Rad

Posted
Posted

Hi guys,

I picked up a GTR a couple of days ago and everything seemed fine, it drives very well and boost builds from ~2000rpm and will hold at ~7.5psi all the way from 3k odd to redline.

Felt pretty gutless and thought it was a bit down on power but put it down to the hot weather and the cars bolt ons being pretty sedate (just dump pipes, hiflow cat, cat back and pod filters).

Gtech+Iphone confirmed my arse dyno predictions, apparently making between 150-170kw at the wheels which is a bit of a worry so I went to see how much it would make with 1 bar and the restrictor on the solenoid line is already missing!

I cant find any boost or vacuum leaks, but it absolutes refuses to make over 7psi. Aside from the power and boost the car runs perfectly and cleanly.

I'm hoping the solenoid is f**ked or the cat is clogged up and the workshops I want to go to are still closed from the xmas break.

TLDR version:

Car is running 7psi with boost restrictor removed and making underwhelming power with no other symptoms.

Any suggestions I can easily check?

Have the exact same problem with the same mods. Was making 154kw at 7psi and starting to detonate. Willall stopped the run. Was just on the dyno to get a power reading before an ebc install but have a Mines ECU installed (came like that from Japan last year). Didn't fix the problem because I was only gonna wind it up before doing my turbo swap so I started my turbo swap earlier.

Keen to see what your problem seems to be.

paulr33 Grand Master

paulr33

Posted
Posted

check wastegate / actuator operation

if the gates are held open, the car will be sluggish, lack power, make some levels of boost (low) and wont blow smoke etc, but will be sluggish

check the actuator signal, where does that vac line run to? and check actuator operation, does it open? is it stuck open?

JJGTR Rookie

JJGTR

Posted
  • Author
Posted

Boost hasn't changed at all, however I took note of when it comes on boost and it around 1800rpm in 3rd it starts building boost. Full boost around 2700rpm.

Stuck wastegate would not have this much low end in my opinion

Ambient temps have gone from 35 to 20 degrees yet my power output dropped to 160kw atw on the first test.

Second run noticed it started to lose a bit of power the longer I let it stretch is legs.

Put 1+1 together and immediately stopped.

Sounds like lean condition / fueling issue plus a separate boost issue.

J - Rad Veteran

J - Rad

Posted
Posted

Boost hasn't changed at all, however I took note of when it comes on boost and it around 1800rpm in 3rd it starts building boost. Full boost around 2700rpm.

Stuck wastegate would not have this much low end in my opinion

Ambient temps have gone from 35 to 20 degrees yet my power output dropped to 160kw atw on the first test.

Second run noticed it started to lose a bit of power the longer I let it stretch is legs.

Put 1+1 together and immediately stopped.

Sounds like lean condition / fueling issue plus a separate boost issue.

Have a suss what ECU its running, probably a Mines or similiar.

Rolls Grand Master

Rolls

Posted
Posted

open the ECU up and see if its been chipped, I know my rb20 had a mines chip in the ECU, advanced the timing massively and was way too rich, basically was running on the knock map permanently and very rich, resulted in worse than stock performance.

  • Like 1
JJGTR Rookie

JJGTR

Posted
  • Author
Posted

open the ECU up and see if its been chipped, I know my rb20 had a mines chip in the ECU, advanced the timing massively and was way too rich, basically was running on the knock map permanently and very rich, resulted in worse than stock performance.

Factory nissan seals still intact on the ECU so I assume it hasn't been opened. Is it possible to open it without damaging the seal, and if so would someone really bother?

EdGTR Enthusiast

EdGTR

Posted
Posted

Its going back to the beginning but you have checked all the basic things like air and fuel filters? It might also be worth a look at the front of the cat just so you can rule that out but if it doesnt drop off its probably ok. Also that much power at that boost is a little low but not way down. If everything else looks ok i would be checking the vacuum lines and making sure its not seeing straight manifold pressure at the actuators. If a waste gate was stuck open it would be alot laggier than that.

Good luck

MAZ Rookie

MAZ

Posted
Posted

HI Guys,

Im in similar situation, probably worse.

Just picked R32 GTR from Japan.The car is immacutlate condition,the engine bay is pristine and looks like timing belts were done recently.

I can see actuators have been chaged to hks units and rstrictor removed from solonoid.

The Car starts and idles normai and revs freely, but its like driving a natuarlly aspirated car, There is litlle or no boost coming.

intercooling piping has been checked and there seems to be no leaks.There is no smoke coming from exhaust .The only thing i can find out of the ordinary in the engine bay is what looks like a vac pip that been blocked.

off that comes from somewhere under the inlet manifold

what do you guys think, are why turbos gone ?

trick Proficient

trick

Posted
Posted

I had similar problem with my 33 GTR. Would go into limp mode and reduce the boost km standard. Turned out to be the factory ecu. If you can get hold of a fc plug it in and see if the problem goes.

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