# No top end power (hesitation) PLEASE HELP



## chocalx (Feb 13, 2013)

I have searched and searched for answers with no real luck, I dont know what to ask i guess.
I have a 2005 Altima V6 3.5L 5speed with 114k miles on the clock.
I just bought this Altima at auction (cheap) and I am experiencing a sort of high RPM power loss. While in gear and under full throttle I cannot get over 4500-5000 rpm. It feels like I was hitting the rev limiter. I do not have any codes popping up or no CEL. But if the car is in nuetral I can get it to go to the rev limit around 6800 RPM ( so i doint hink it could be cam or position sensors).
I did a spark plug replacement (PITA to do the rear bank) and it did not fix the issue even though the plugs were pretty worn and a bit over gapped. 
I did notice while doing the spark plugs, that under the intake manifold the front cylinder intake ports have oily residue (light coverage not sludge) on them and the rear cylinder ports are nice and clean. I am sure that has something to do with it. 
Also under full throttle there is a very throaty sound to engine, like if it had a cold air intake kit. But it is all stock. 
Maybe a bad front Cat or injectors maybe fuel pump or filter??? any advise.
Under intake manifold:







https://skydrive.live.com/?cid=d52780202b223917&id=D52780202B223917%21644#cid=D52780202B223917&id=D52780202B223917%21678
Rear intake ports







https://skydrive.live.com/?cid=d52780202b223917&id=D52780202B223917%21644#cid=D52780202B223917&id=D52780202B223917%21679

Front intake ports







http://skydrive.live.com/?cid=d52780202b223917&id=D52780202B223917%21644#cid=D52780202B223917&id=D52780202B223917%21677


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## rogoman (Dec 16, 2004)

The oily residue in the intake ports may be caused by the PCV system not working properly. There is a hose connection between the valve cover and the intake manifold. Pull the hose from the intake manifold and see if you're getting any excessive blow-by.

Being able to rev the engine to the red line while in neutral, is different then when driving the car. In neutral, the engine is free-wheeling making it much easier to over-rev it without much HP required. 
As far as being unable to rev beyond 4500 RPM while driving, there are several possibilities:
- Dirty MAF hot wire or defective MAF.
- Weak ignition.
- Vacuum leak in the intake system.
- Insufficient fuel pressure.
- Dirty air filter.


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## chocalx (Feb 13, 2013)

*All good points, Thanks*



rogoman said:


> The oily residue in the intake ports may be caused by the PCV system not working properly. There is a hose connection between the valve cover and the intake manifold. Pull the hose from the intake manifold and see if you're getting any excessive blow-by.
> 
> Being able to rev the engine to the red line while in neutral, is different then when driving the car. In neutral, the engine is free-wheeling making it much easier to over-rev it without much HP required.
> As far as being unable to rev beyond 4500 RPM while driving, there are several possibilities:
> ...



Thanks for your advice, I have checked the coils, put new plugs and air filter in.
I am trying to get my hands on a exhaust backpressure gauge kit, to test the flow through the front Cat. 
I will check the vacuum lines for leaks and Hg value as well as picking up a can of MAF sensor cleaner.
Thanks

Anyone else have a recommendation!!!


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