# 300zx tt stock boost



## fc3sRage (Jul 30, 2004)

what is the stock boost on a 91 300zx TT. My friend just bought one but its only pushing about 6, and its really not as fast as it should be. I suspect one of his turbos is gone or going. Any ideas?
:loser:


----------



## Spongerider (Nov 18, 2002)

fc3sRage said:


> what is the stock boost on a 91 300zx TT. My friend just bought one but its only pushing about 6, and its really not as fast as it should be. I suspect one of his turbos is gone or going. Any ideas?
> :loser:


9.5 psi. Your friends Z is in safety mode (6 psi).


----------



## asleepz (Feb 24, 2004)

what determines if you are in safety mode?


----------



## M.U.L.E. (Aug 1, 2004)

SKD_Tech said:


> what determines if you are in safety mode?


Usually the detonation sensor Code 34. Run your ECU for codes to see what's up. http://www.ttzd.com/ Tech section-ECU Diagnostic


----------



## enrique22n (May 3, 2005)

Spongerider said:


> 9.5 psi. Your friends Z is in safety mode (6 psi).


my car is also on safety mode occasionally. how can i make sure it is not the detonation sensor??
TX 's Z


----------



## Spongerider (Nov 18, 2002)

enrique22n said:


> my car is also on safety mode occasionally. how can i make sure it is not the detonation sensor??
> TX 's Z


1 way to tell if your sensor is bad is to full up the Z with race gas 100 octang then reset your ECU. If you car goes back into safety mode then your Det. Sensor could be bad.


----------



## scottb8855 (Mar 31, 2005)

*300zx twin turbo*

i have 14 psi of boost on my car is that normal.


----------



## Spongerider (Nov 18, 2002)

scottb8855 said:


> i have 14 psi of boost on my car is that normal.


Look at your ECU? You most likely have a aftermarket ECU.


----------



## enrique22n (May 3, 2005)

Spongerider said:


> 1 way to tell if your sensor is bad is to full up the Z with race gas 100 octang then reset your ECU. If you car goes back into safety mode then your Det. Sensor could be bad.


where can i get race gas? or can i do an octane booster? since here where i live i can only get 90 gas? what if i add two octane booster bottles to one full tank?? will that make it 100 oct or similar? which octane booster do you recommend. ?? please help ...


i*s detonation * when you sort of step on it and suddenly the engine JERKS back violently then when you stop accelerating its back to normal??? please help.


----------



## enrique22n (May 3, 2005)

or could this be happening because the engine temperature. could the engine temperature be cold? i just removed the thermostat to get the engine colder/// is this affecting anything on my 300zx?


----------



## Spongerider (Nov 18, 2002)

enrique22n said:


> where can i get race gas? or can i do an octane booster? since here where i live i can only get 90 gas? what if i add two octane booster bottles to one full tank?? will that make it 100 oct or similar? which octane booster do you recommend. ?? please help ...
> 
> 
> i*s detonation * when you sort of step on it and suddenly the engine JERKS back violently then when you stop accelerating its back to normal??? please help.



Check some gas stations or full up with the highest octane gas and add octane booster (read the instruction). 

If it's detonating you will hear knocking from the engine. Note that some people are detonation deaf.


----------



## Spongerider (Nov 18, 2002)

enrique22n said:


> or could this be happening because the engine temperature. could the engine temperature be cold? i just removed the thermostat to get the engine colder/// is this affecting anything on my 300zx?


Never boost when the engine is still cold.


----------



## enrique22n (May 3, 2005)

ill try using a good octane booster and putting back the thermostat. hopefully that will fix my prob. thankssssssssssssss


----------



## JDM240Turbo (Jan 21, 2005)

enrique22n said:


> where can i get race gas? or can i do an octane booster? since here where i live i can only get 90 gas? what if i add two octane booster bottles to one full tank?? will that make it 100 oct or similar? which octane booster do you recommend. ?? please help ...
> 
> 
> i*s detonation * when you sort of step on it and suddenly the engine JERKS back violently then when you stop accelerating its back to normal??? please help.


Detonation occurs when the combustion pressure goes so high that the inlet charge explodes before the spark plug fires. When this happens, combustion takes place while the piston is still moving up in the cylinder, which causes a termendous shock to the pistons, rods, and crackshaft. Under normal circumstances, the flame speed across a cylinder is 120-200 miles an hour. But when fuel detonates -- the flame speeds goes up as high as 2,000 miles an hour, and the shock destroys your ring lands and pistons. 

A richer mixture or one that is less compressed is cooler, so it's less likely to detonate. Also, devices called intercoolers can cool the compressed air before it goes into the engine, which helps prevent detonation.


----------



## MATTLW (Oct 14, 2010)

*300ZX TT BOOST PRESSURE*

I just bought a 300zx TT and its only running about 5-6 psi (and it idles at -10 is that normal?). It did have some adjustable boost controllers in before and the previous owner told me that somebody broke in and robbed the control pod off the dashboard, so i guess the other bits in the actual turbos are still there? Anyway, just wondering if that sounds feasable, or is he full of BullS. 
I guess the next stage would then be to replace the boost controllers or put it back to standard running at 9.5psi (I think)?


----------



## zxrodster (Nov 9, 2010)

*Check for loose connections*

I found I was loosing boost pressure due to loose connections, especially on a twin turbo. There's a lot of fittings on the piping from the air intake, turbo, intercooler to the air plenum which must be completely sealed. I had a 2 lb leak due to a loose fitting at the driver side turbo inlet. Hard to reach to tighten, but the 2 lb gain was worth it.

This pressure loss is frequently overlooked. 

Hope this helps.

zxrodster.


----------



## Jeckyll (Aug 10, 2013)

I've got this same issue, 6psi on a cool night or when the engine has only been running a short time and isn't hot yet and 5 on hot days/engine has been running for a while.

I ran the ECU self-diagnosis and I got a code 55, which I understand is nothing is wrong.
I just has the stock boost gauge (-7 to +7).

Any ideas? Wondering if I just have a boost leak somewhere.


----------



## Spongerider (Nov 18, 2002)

Jeckyll said:


> I've got this same issue, 6psi on a cool night or when the engine has only been running a short time and isn't hot yet and 5 on hot days/engine has been running for a while.
> 
> I ran the ECU self-diagnosis and I got a code 55, which I understand is nothing is wrong.
> I just has the stock boost gauge (-7 to +7).
> ...


Is your Z stock?


----------



## Jeckyll (Aug 10, 2013)

As far as I can tell, no mods have been done.


----------



## Spongerider (Nov 18, 2002)

You should recheck the vacuum hoses that the BC was installed to. If you don't know the plumbing of the BC I would suggest you do a Search on Google to find what you are looking for.


----------



## Jeckyll (Aug 10, 2013)

Thanks, will do. Only had this car for two months, still getting to know her.
Though, I don't what you mean by BC.


----------



## Spongerider (Nov 18, 2002)

Jeckyll said:


> Thanks, will do. Only had this car for two months, still getting to know her.
> Though, I don't what you mean by BC.


Sorry for some odd reason I thought you had a BC = boost controller installed by the old owner. Just recheck and replace the old vacuum line one at a time. This will also give you a chance to learn more about your Z engine.


----------

