still not reving

[CursedGTR]

Maybe my comment was a little too black and white. In the case where you have a very large leak it will affect revs. But if you have a leak this big anyways, it should be very noticeable.

Anyways I responded the way I did because of the countless SR's and RB's that I have seen with rev problems. And the number 1 culprit is improper wiring. The maf itself, turbo or wastegate are really the last culprit.

I was actually wondering if you guys were on the same page as the threadstarter. To me, a car consistently cutting out at a certain rpm is a maf problem. And obviously the car isn't going to make boost since its cutting out at 2k without load.

by the way cursedGTR, I would really like a more detailed explanation of why you believe a turbo motor requires its turbo to run properly other than the lack of boost

-Bluefire

Here is a more detailed explanation on why I beleive what I do. Just so I am up front and get my tone across, I am not here to argue I am here to share my experiences so others may benefit and to be taught something myself hopefully.

Turbocharged motors are not naturally aspirated motors and get their intake charge from the turbines spooling. Even at idle we can all agree that a turbo spins at a certain speed in orer to make the required pressure for the engine to run. Once you put the engine under positive boost or you start building pressure in your pipes and the pressure leaks out you will have revving problems. Then you are dealing with a lack of air to go with the specified amount of fuel in your fuel map. Fix the leak, fix the problem. I have seen bad MAF's cause all kinds of problems as well, but our main problem here is the actual sensor going bad and causing us to have to replace it (mainly on R32 motors where they are a bit older). Typically on my RB25DET I moved into the positive boost realm at about 2500 RPM that is where I transitioned from Vacuum to boost every once in a while because of the heat and climate conditions here, a grommet would dry rott a little and cause a boost leak (usually cracked at the part where it went from 70-90mm), thus preventing me from going above 2.5K RPM. Also take a turbo car and remove a hose clamp from the intercooler piping and then go drive it around and see how it works for you, I guarantee it won't work very well at all.

I am not saying a motor will not start and run without boost. I am saying that it will not run properly when loaded (i.e. moving the weight of the car) mainly because the turbines will not be putting the amount of air they need to be into the intake manifold.

Also, I did overlook the fact that RB and SR's are nothing but swaps in the U.S. so I am sure you guys come across your fair share of F'ed up wiring.

[NightKids2]

My friend was gunna come over and help me, but he skipped out on me so it didnt get fixed yet...BUT I did buy a Z32 MAF today off eBay, maybe itll come in soon and tie up any other loose ends.

[Andrew85cm]

I dont know if you are correct cursedgtr. I blew off a intercooling pipe on the long drive from NC to PA where I go to school. My motor could get to what ever rpm I wanted. The main issue with a boost leak is that your turbo will keep spooling up and the wastegate won't open. You can easily overspin or rev your turbo and blow it to bits if the air is not going into the motor. I could rev my car just like I could with boost but it had no power and I was spinning the crap out of my turbo. If you have a boost leak you can rev but not make boost or not make much boost. So it will rev but its slow as balls.~ANDREW~

[CursedGTR]

REad what I said and you are saying the same thing. My problem was I could not build POSITIVE BOOST meaning that I could not build anything past vacuum. As long as I went soft on it (not over 2.5K RPM) I was just fine. I had my entire engine set up to build boost as fast as possible. Therefore I built positive boost at 2,500 RPM. once I hit the positive boost realm there was nothing for me. That is my point. You will run fine as long as you are under vacuum (most engines will rev through the entire spectrum under vacuum as ong as you do not put a load on them), once you go beyond vacuum and need positive boost it is not going to work out very well for you. I limped my GTR all the way to the south of Okinawa (about 50km) with a blown pipe, you and me did the same thing. once you put the requirement for positive boost on your engine you are not going to be running very well at all and will most likely stall. That is why I say Turbo engines need the turbines to run. Otherwise you can just call it a turbo assisted N/A motor which makes no sense.

[Bluefire]

Actually that doesn't explain your idea that a turbo needs its turbo. Obviously if you blow a pipe the car will run like crap because the air coming into the motor is different than the amount being metered through the maf. But I don't see any reason why the motor wouldn't run ok assuming all the piping is hooked up including the maf...

-Bluefire

[CursedGTR]

Read the post, at positive boost you would have problems (you know those little things called fuel maps that need a certain amount of air to go with the fuel value that exists at certain RPM's???). If an engine is a turbo motor it needs the turbo's to work. You just said it yourself with the comment of having the piping hooked up correctly. This shouldn't be a debate, if there are no holes or major leaks in his airflow than it is obviously not the problem. So go address the MAF's, The simple idea of an engine being a pump and requiring certain amounts of air and fuel to compress and make little booms out of should not be a new idea.

This is getting dumb and quite boring so why don't you explain to me why a turbocharged motor does not require it's turbine to run, I am pretty sure it would be worth it to read that. or better yet go put headers on your turbo motor and an intake pipe and tell me how that works out for you.

[themadscientist]

I have only read the last couple of posts so this is specifically aimed at those not the original question. If your flow meter is no longer reading the air going ito the motor it will barely run and usually die the minute you give it gas. If howere the method the computer uses to read the air coming in the motor will run fine, it will just behave as a low compression engine.

I have blown off at pipe on an older skyline with a physical shutterdoor AFM and the car just lost about 50hp in the blink of an eye but other than that ran fine. The reason was I was blowing through the AFM and the pipe popped off the front so the AFM was still reading the correct air content. If you blow a pipe after the AFM it no longer reads the actual air that enters the engine so it will not run properly or even at all.

[USMCgetsome]

ok had somewhat of the same problem. Try checking to see if your ic piping is switched around. Maybe something you already checked but shows the same symptoms.

[Bluefire]

Read the post, at positive boost you would have problems (you know those little things called fuel maps that need a certain amount of air to go with the fuel value that exists at certain RPM's???). If an engine is a turbo motor it needs the turbo's to work. You just said it yourself with the comment of having the piping hooked up correctly. This shouldn't be a debate, if there are no holes or major leaks in his airflow than it is obviously not the problem. So go address the MAF's, The simple idea of an engine being a pump and requiring certain amounts of air and fuel to compress and make little booms out of should not be a new idea.

This is getting dumb and quite boring so why don't you explain to me why a turbocharged motor does not require it's turbine to run, I am pretty sure it would be worth it to read that. or better yet go put headers on your turbo motor and an intake pipe and tell me how that works out for you.

I am not here to argue with you. I really just don't see why the motor wouldn't run ok. I figure the ecu should be able to compensate for the smaller amount of air coming in.

-Bluefire

[CursedGTR]

Bluefire, if you are not here to argue then watch how you word stuff man. I am a reasonable guy and have been dealing with nothing but RB25's and RB26's for the past 4 years. I am not saying that I know everything, but madscientist knows me personally and can tell you if it can be broken I probably broke it at one point. Hell I even had a water pump's blades completely dissintegrate on me.

As for ECU compensation, it will not do that. If the MAF reads a certain amount of air (which is translated into a voltage signal to the ECU) than that amount of air needs to get to the intake plenum for all to work properly because that MAF signal is being used to determine fuel enrichment to the motor.

However, ECU compensation is correct when dealing with Manifold Absolute Pressure sensors (such as those found on the Power FC D-Jetro Model) because those sensors read what pressure is actually in the intake manifold, and elminate the MAF all together. You wil still have problems if you have a boost leak and will not be able to take your car into positive boost (I have experienced this, I use an SDS EM-3 engine management system with a MAP sensor vice MAF's) but you will be able to put a load on the car and drive around as long as you do not gun the crap out of it and there is a decent amount of airflow to the manifold (i.e. piping leak o.k., missing pipe or too big of a leak not o.k.) mainly because then the MAP sensor reading is not reading what it should be along with the throttle position sensor thus causing the values in the fuel map to be incorrect and your engine to run really really bad.

[themadscientist]

madscientist knows me personally and can tell you if it can be broken I probably broke it at one point. Hell I even had a water pump's blades completely dissintegrate on me.

you could break a nerf ball.

[CursedGTR]

One could only hope to achieve my level of destructiveness. Wait until you see what I will be toting into the Shop Soon. I promise you will like it.

[NightKids2]

Got my new Z32 MAF in, while installing it I took the tape off my MAF wires only to find that there were like 2 wires that pulled out of the butt connectors...

Put them back in, and the car runs like a champ lol.

[Carl H]

Got my new Z32 MAF in, while installing it I took the tape off my MAF wires only to find that there were like 2 wires that pulled out of the butt connectors...

Put them back in, and the car runs like a champ lol.

ugh, butt connectors; solder that crap.

[Bluefire]

GLad to hear you figured out the problem

-Bluefire