Jump to content
SAU Community

Recommended Posts

After your remove the upper an lower intake to clean carbon buildup. I see the ignition coils on both left an right on the valve cover an in the middle there is 6 pot cylinder like holes with carbon build up. Is that were the fuel injectors located plus could you also remove that to clean up all the deposits. Looks like some small valve butterflies in it build up with carbon deposit

This is in reply to the original post in 2009.

I don't have a view on the GDI systems, but I disagree that the purpose of EGR and PCV systems are to re-burn unburnt fuel.

The purpose of an EGR system is to effectively reduce the displacement of the engine under certain operating conditions.

It does this by replacing some of the gas with gas that doesn't have oxygen in it (ie exhaust gas).

An analogy would be running your car at the top of Mount Everest - less oxygen, less fuel, less power, but better economy when cruising.

Thus EGR system is for economy, but not primarily by reburning unburnt fuel.

My understanding, of PCV valves, which might be wrong, is that the vacuum in the intake manifold helps draw out the small amounts of blow by that occur in an N/A engine. (Doesn't work with boost pressure). This would help prevent water and fuel vapour contaminating the oil.

By putting a catch can in place is a good fix if it is correctly hooked up. It also stops these vapours venting out to atmosphere.

Therefore, PCV (valve cover breather) systems are for engine longevity, and reducing blow by "emissions". I can't see how it is a method of increasing fuel economy.

Just my 2c on those points!

There are plenty of hydrocarbons left over from the combustion process, re-introducing these back into the cylinder can improve economy, more so if the recirculated gasses are cooled beforehand.

You are quite correct with the PCV operation, but catching the moisture will only mean you are emptying another can, for no real gain.

There are plenty of hydrocarbons left over from the combustion process, re-introducing these back into the cylinder can improve economy, more so if the recirculated gasses are cooled beforehand.

You are quite correct with the PCV operation, but catching the moisture will only mean you are emptying another can, for no real gain.

Note I said "not primarily by reburning unburnt fuel". Some stuff will certainly burn, but the exhaust gas is mainly an inert gas that reduces the effective displacement. I'd say any economy gains would be 90% due to the effective reduction in displacement, and maybe 10% due to reburning fuel.

Or ok. Am question my skyline is running rich an the only code am getting is the p0100 is this the reason my I have a engine running rich cuz I dis suspect fuel injectors

If you do a simple search on the code you will find it relates to the AFM. You can either buy a new AFM from Nissan for $330au or I sell aftermarket ones on my site for much less. ;)

http://scottyscustoms.com.au/product/nissan-m35-stagea-aftermarket-afm/

After your remove the upper an lower intake to clean carbon buildup. I see the ignition coils on both left an right on the valve cover an in the middle there is 6 pot cylinder like holes with carbon build up. Is that were the fuel injectors located plus could you also remove that to clean up all the deposits. Looks like some small valve butterflies in it build up with carbon deposit

The swirl butterflies are usually caked with crap, you need to clean the entire plenum and runners, right down to the valves.

spector171, on 14 Jul 2014 - 9:02 PM, said:

After your remove the upper an lower intake to clean carbon buildup. I see the ignition coils on both left an right on the valve cover an in the middle there is 6 pot cylinder like holes with carbon build up. Is that were the fuel injectors located plus could you also remove that to clean up all the deposits. Looks like some small valve butterflies in it build up with carbon deposit

The ignition coils are in the middle of the black plastic valve cover. The injectors are down in the V under the lower plenum. You can quite easily see they have hard fuel lines bolted to them.

Whatever you do, don't remove them. They are not your fault, the AFM is faulty.

Were can I buy intake manifold upper an lower gasket for the 2003 Nissan skyline v35 250gt online. The g35 gasket shape different online so who have a website that sells these gasket

They are re-usable metal gaskets.

I have a 2003 Nissan skyline v35 250gt and upon removing the top intake manifold I discovered alot of this black carbon build up also after removing the middle section I also discover oil in the intake coming from the pcv valve. Why is oil in the intake manifold plus what's the purpose of all that black soot looking carbon on the valve butterflies etc. Anybody need help

All modern engines suck oil fumes in from the crankcase and burn them to lower emissions.

The black soot is because your engine has an 'EGR' valve (Exhaust gas recirculation) to improve emissions and get greater fuel economy when cruising and on light load. It needs to be cleaned out every 50,000k's or so.

Or ok I'll try this week end. Since the gaskets them are reuseable

You should be fine, as long as you don't damage one.

Degreaser, kero, tooth brushes and scrapers. You will need plenty of rags too.

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now



  • Similar Content

  • Latest Posts

    • Don't even try to run it on the stock ECU if you're going to have the boost controller bring boost above ~10 psi. I've already told you that. If you use the Nistune ECU, you will need to CAREFULLY read the available documentation for Neo tuning, and read some threads on the Nistune forums, to discover the various things you have to do to prevent the ECU from going bananas when the boost is too high. The is a table associated with th boost sensor that must be modified to prevent it from shitting the bed. This is just one of the things that you will need to do to the tune in Nistune, because the Neo turbo ECU will be expecting to see a number of things (such as the TCS) that are not there, and you have to block the DTCs on those. It is totally not surprising to me that you are having the problems that you are, but the solutions to these problems have been known for >15 years. So just get it done.
    • Hi. Sry iam not a mechanic and iam not at the car atm so i dont know 100% but they told they measure those and even try to change those. AFM they have two. Coils are new a they have my old one too. Plugs too. ECU...we have 25 NEO stock and Nistune 25 NEO.   But i dont know if any one those could be the problem and why/if/what can cause this, Only thing they did not check is fuel...but that walbro 255 is new(like 1,5 years)... That fuel pressure gauge idk...but i let them know Any suggestions?   EDIT: how can they know if it is like you say he ECU pull power when it reaches a specific boost level that is too high? Tha car has boost controler
    • Can you clarify what you mean by boost cut, do you mean it misfires both when under load (driving) and when stationary and out of gear? Or does the ECU pull power when it reaches a specific boost level that is too high (boost control issue)? Does it occur at idle with no throttle? When you say "the ECU is OK", what ECU is it and why do you think it is OK? Have you used the NEO ECU, and if so do you have a MAP sensor attached? Same for the AFM, why do you think it is OK? Do you have any way to put a fuel pressure gauge on it (even just a mechanical one between the fuel filter and fuel rail)?
    • Hi.. Just another problem. So maybe you can help. I(my mechanic) done swap from my RB20DE NEO to RB25DET NEO. Everything is OK but we have a boost cut. Coils/Plugs are ok...AFM is ok. ECU is ok. I have Walbro 255 but it "changed" sound few months ago(you can hear it ouside) you did not hear that when it was new(maybe faulty?) Sooo...what now? What can cause this boost cut? It is even when you standing still...
×
×
  • Create New...