R33 Gts-t Keeps Spiking Out At 5000rpm

[pete87]

it has a had a bigger turbo put in not sure what it has a intercooler.. before it spikes out it is pushing nearly 15psi and there is no boost tap... how can i bring it down???? will a boost tap bring it down

[lachlanw]

NO and dont post again untill you tell is about all of the mods to your car

Edited March 16, 2010 by lachlanw

[pete87]

NO and dont post again untill you tell is about all of the mods to your car

I JUST BROUGHT IT ALL I NO IS THAT IT HAS A BIGGER TURBO... IM A CHICK YOU DONT HAVE TO BE RUDE I WAS JUST ASKING A QUESTION...

[lachlanw]

is it running fine ?

[WYTSKY]

lol, firstly what does being a girl have to do with anything... its the net... no discrimination against sexes... just abuse to anyone basically... unless you show boobs.. then maybe you wont get abuse.

2. what is the model of the car?

3. anything written on the bigger turbo?

4. Does it have a tune?

5. work out what mods it has

we cannot give you any advice or thoughts without more information...

in regards to the "boost tap": a boost tap will not bring it down, it can only make the boost (psi) go up....

[mad082]

firstly, i don't want to sound mean, but saying you are a girl is no excuse. without knowing mods we can't help you properly. simple as that. no sexism there (in fact it's equal rights), just stating the fact.

secondly, what do you mean by the boost is spiking at 5000rpm? do you mean the boost is dropping after 5000rpm? or when you get to 5000rpm the boost is increasing (which is what is usually meant by boost spiking)?

without a better explaination of what is going on, and what mods the car has we can't help you. and again i don't want to sound mean, but it really sounds like you bought a car you know nothing about, which means there is a good chance you are going to run into troubles down the track and leave yourself open to getting ripped off (which you may already have been).

come back to us with a proper list of mods and a better description of what is going on. but to answer the only question you have really asked (and which i can't even answer correctly based on the lack of info you have provided), if there is no boost controller and it is running 15psi then it will be set by the wastegate. if the wastegate actuator is adjustable then altering it will lower the boost. if the wastegate isn't adjustable then adding a boost controller (boost tee/tap) won't let you lower the boost, only raise it.

[pete87]

the car is a 95 r33 gst-t manual

it has a bigger turbo and dosent say nothing on it that i can see

it has a intercooler

when the car hits 5000rpm it starts to make a big spluttering sound...

my brother inlaw is a mechanic and has put it on the computer and it all says everything is fine.

i just want to no how to lower the boost.....

[mad082]

take a pic of the turbo and the vaccum hose running to the turbo so we can see what it has and possibly give you a better idea on how to lower the boost. as i said, it could be that you need to either adjust the wastegate actuator (if it is adjustable) and buy a whole new wastegate actuator rated at a lower pressure to lower the boost..

as for the spluttering sound, it sounds like it has the typical missfire caused by either old spark plugs or failing coil packs. hooking it up to a computer won't tell you much about anything going wrong in this regaurd though. it would on a r34, but not on a r33

[Birds]

lol.

Sounds like actuator/wastegate is jammed shut, maybe because of a vacuum hose leak.

[mokovicz]

so i may have a similar problem. I have a 1990 gtst with a couple upgrades (greddy profec bspec 2 turbo programmer, apexi air controller/power commander, turbokentiks turbo, intercooler and full 3in exhaust). I had the same problem of my turbo spiking from 14psi-20ish with my engine rpms being governed out at about 5000 because of my blow off valve releasing my pressure. I went to a jdm shop and the guy told me that even though i had an upgraded turbo, turbo programmer, air programmer and power commander since i set my turbo programmer over 12 psi and i dont have my ecu chipped it locked it self at the 20psi it was set at once upon a time. I was wondering if anyone has heard of this happening? he said my only options were taking a chance with him plugging in another ecu and removing the battery cable while the car is running then plugging mine back in hoping it will continue at the settings of his or i can buy a new ecu then drive it to Calgary(300km away) to get it dyno tuned which in all would set me back about $1200cnd. Anybody know if i have any other options?

[mad082]

what is an air programmer, turbo programmer and power commander? i'm guessing that the turbo programmer might be an electronic boost controller, but other than that i have no idea what you are talking about.

if the blow off valve is opening up and releasing air then the pressure should drop not rise, and the car would run like crap due to it running rich.

[mokovicz]

sorry my terminology is a bit shaky. By air programmer i mean i have a controller that electronically decided when it should feed the turbo extra air directly through the turbo intake housing skipping the filter entirely( obviously keep it completely shut off under dusty or wet conditions. Turbo programmer i meant electronic boost controller. My power commander adjusts my fuel pressure/supply to corralate with increased boost pressure. The blow off valve doesnt open until it hits just over 20psi and then it just modulates to keep it at 20psi. The car runs great when when i shift before 4000psi. Has anyone heard of such an ecm lock that would no longer allow the electronic boost controller to limit boost?

[mad082]

if the electronic boost controller isn't part of the ecu then the ecu can not affect the boost in any way at all. however if you are getting to 5000rpm and the car is developing a missfire or just plain cutting out then i'm guessing that the ECU has reached a point in it's mapping where it is outside of what the parameters of the ecu are mapped for and it is shutting down. only solution is an aftermarket ecu that you can tune properly.

also your air programmer sounds a bit...... dodgy. i am assuming it is to allow more air into the turbo without the AFM knowing about it, and is the reason why you need need the power commander.

my suggestion to you would be to scrap both the air commander and the power commander and get an aftermarket ecu and a z32 AFM (unless you get an ecu that uses a map sensor) and stop using the BOV as a boost controller (leave that to the wastegate). then you can tune the car properly and won't have the issue that you seem to be having (providing that i understand what you are saying correctly).

[mokovicz]

My only thing with that is that the car ran phenominal before i began playing witht he boost controller trying to raise my boost. Now according to my gauges i keep hitting 20psi when i have a limiter set at 16. The controlelr is hooked directly to the ecu adjusting the parameters. Im going to order a chip off ebay to try and reset my parameters or just go for a new ecu alltogether. Ill elt you guys know how it goes