S14 Power Cut at 5500rpm. Why?

[goosegog]

I own a 1995 S14.
When accelerating hard, there is plenty of power throughout the rev range until it hits 5500rpm where the power level drops slightly.
It does so, cleanly and silently almost as if the boost or timing are deliberately altered for some reason.
There is no accompanying noise or misfire. I believe that Nissan have purposly engineered this in to protect the engine or something.
Am I right or wrong and how do I bypass this as it's most annoying!

Also, what is the solenoid thing plumbed into the wastegate actuator hose. It has a two wire connector on it and is mounted near the ABS pump on the left hand inner wing. How and when is it operated?

Many thanks.
Reply here or email or both!

Ferg


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[David_S14]

The eay bit first it's the wastegate control solenoid. It's actuated by an on/off pulse from the ECM. The longer it's on, the longer the wastegate valve actuator is closed.

The torque curve of the engine drops off at ~5500rpm in standard trim (max torque 265Nm @ 4800rpm).

Has the car been mod'd ?
Mine is better since the intake/exhaust mods and now I've got my Traction Control sorted I think it will be a boost upgrade next.

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David Cater
1995 S14
K&N,Mongoose,HKS pump,Blitz FATT-S
RLTC (being fitted on the 15th).
http://www.animfactory.com/animations/school/books/book_page_flip_md_wht.gif
Gather round and I'll continue
the next exciting installment.
Dan's Sig..Chapter 9..."Never mind the length feel the width"

[Bean]

I found that my car was very reluctant to rev over 5000rpm when I first got it.

The problem disappeared when the car was serviced, including an Air Filter replacement.

It could be something that simple?

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Red 1995/S14
K&N, Private Plate

Any views expressed in this message are based solely on personal opinion.

[David_S14]

Could be, with the K&N cone I've got on it amazes me the amount of extra air it needs on boost ( I just love the intake roar http://300zx.co.uk/200sx/ubb/smile.gif )
Have you changed the fuel filter ?
Another thing that could affect it is if the actuator is worn and its not holding boost very well.

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David Cater
1995 S14
K&N,Mongoose,HKS Fuel pump, Blitz FATT-S
Racelogic Adj. Traction Control
http://www.animfactory.com/animations/school/books/book_page_flip_md_wht.gif
Dan's Sig..Chapter 9..."Never mind the length feel the width"

[goosegog]

Thanks for the replies guys

I am convinced it's something else
It really doesn't feel like fuel starvation or air stavation as it's a smooth clean cut in power, not dramatic or lumpy but just a bit of a drop

Any chance someone with a standard car could double check please?
Full throttle, 2nd gear and watch the tachometer as you reach 5500rpm
Is there a slight loss of power?

My car already has a K&N replacement air filter and increased boost by way of an air bleed from the actuator hose but does it with or without this mod

Many thanks

Fergus

[Tom_S14]

Hmm, must say I'm suprised. I've never noticed anything like this on mine. I had it in totally standard trim for almost a year.
Could it maybe be a problem with the variable valve timing ? This might kick in at around 5.5k revs ?

Tom

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1996 Blue/Green S14 (manual)
K&N cone filter
2.5" Tube-torque Cat Back Exhaust.
TechTom MDM-100
Race-Technology AP-22
http://tom.marshall.tripod.com