Jump to content
SAU Community

Recommended Posts

Hey guys,

I acquired my r33 gts-t almost 2 weeks ago now.

This past sunday the 22nd Feb i serviced it. Changed the oil, oil filter, fuel filter and spark plugs.

With regards to the spark plugs, i replaced them with brand new standard nissan plugs. Just before u did the service the car was well running quite smooth and fast. Just after i completed the service and put everything back in the engine bay as i took it out, it started to boost-cut? My brother did reset the computer by d/c the battery and holding the brake.

Mods-wise, the car has an FMIC, turbo-back exh, dump pipe, and greddy profec b spec 2 boost controller.

The other thing that has been done (by my brother also lol) is the gasket for the stock nissan blow-off valve was taken out and a solid gasket was put in, so the blow-off valve effectively does not work and i get the turbo-flutter effect.

Any ideas why it is boost-cutting? (i'm running 10psi)

Cheers fo your help guys

Link to comment
https://www.sau.com.au/forums/topic/258390-r33-gts-t-boost-cutting/
Share on other sites

  • Replies 44
  • Created
  • Last Reply

Top Posters In This Topic

Top Posters In This Topic

It could also be the coils breaking down i had the same problem in my R33 GTST after i serviced it and put new plugs etc and tried turning the boost up to 10psi. it sounds almost the like the car is pinging badly when it does it.

I used to run around 9.6psi once the coils where replaced in my 33 and it was fine much more than that and it would hit boost cut.

Try turning down the boost to see if the problem goes away.

Are you sure it's boost cut, and not plug break-down ?

I am pretty sure it's boost-cutting. Foot flat in 3rd, 4th gears erc and by about 4000rpm the boost just drops and the car just lurches forward becuase there is no acceleration for a split second then it comes back on...

I am pretty sure it's boost-cutting. Foot flat in 3rd, 4th gears erc and by about 4000rpm the boost just drops and the car just lurches forward becuase there is no acceleration for a split second then it comes back on...

That does sound like boost cut you sure by disconecting the battery you havnt reset the boost controller i have the same controller in my 34 just out of curiosity what percentage of boost do you have set on the controller and what is the set/gain level?

Ok, first of all i'll wind down the boost to about 5-7psi and give that a shot.

If that has no effect, i'll take out the coils, check them and put them back in. The coil packs are factory.

Do you guys think that blocking off the stock blow-off valve would be effecting it at all?

Ok, first of all i'll wind down the boost to about 5-7psi and give that a shot.

If that has no effect, i'll take out the coils, check them and put them back in. The coil packs are factory.

Do you guys think that blocking off the stock blow-off valve would be effecting it at all?

No this should have no effect under acceleration boost is controlled by the wastegate which is controlled by the boost controller. you could also check you dont have a leak in one of the intercooler pipe joins or in the boost controller pipeing.

No this should have no effect under acceleration boost is controlled by the wastegate which is controlled by the boost controller. you could also check you dont have a leak in one of the intercooler pipe joins or in the boost controller pipeing.

Yeah i have already played around with the boost controller settings as to how fast the wastegate opens and closes, and it didnt seem to have an effect on the boost-cutting.

I will double check all vacuum lines/piping/etc tonight to make sure it is on properly. Although just before i changed the plugs it was all fine.

Would resetting the stock computer have anything to do with this?

Boost cut occurs when the AFM's max's out, normally this occurs if you wind extra boost into the car, which equates to more air flow. But it can obviously also occur if you have a boost leak, as to get your 10psi with a leak the turbo will be pushing alot more air through. Shouldn't have anything to do with the ECU.

Yeah i have already played around with the boost controller settings as to how fast the wastegate opens and closes, and it didnt seem to have an effect on the boost-cutting.

I will double check all vacuum lines/piping/etc tonight to make sure it is on properly. Although just before i changed the plugs it was all fine.

Would resetting the stock computer have anything to do with this?

Not 100% sure about if it would effect it but it may of because the computer does self learn a little bit i believe so it gets used to the higher boost resetting it might of confused the computer but i doubt that would be the problem.

So do you know the settings you have on you Greddy boost controller ive only just got mine and am trying to set it to 10psi?

Off the top of my head i'm not sure, but i will check my settings and post what i have them set too.

Ok well i'll wind the boost down to 7psi, check all the intercooler piping and the coil packs and then see if it still does it.

Thank you very much for all of your help guys! Much appreciated :(

Off the top of my head i'm not sure, but i will check my settings and post what i have them set too.

Ok well i'll wind the boost down to 7psi, check all the intercooler piping and the coil packs and then see if it still does it.

Thank you very much for all of your help guys! Much appreciated :(

Cool would be good to see if i have mine set anything like yours.

I played around with the boost settings on my boost controller last night and it seemed to stop boost cutting once i had turned it down....then i was driving to work this morning and it boost-cut :) I also checked the coil packs last night and all piping and everything seemed to be on properly/fine.....

My brother recommended sending the car to Hyperdrive/Ovaboost/etc to have the boost controller tuned properly for 10-12psi....

Any other suggestions before i book it in for a dyno tune?

I played around with the boost settings on my boost controller last night and it seemed to stop boost cutting once i had turned it down....then i was driving to work this morning and it boost-cut :) I also checked the coil packs last night and all piping and everything seemed to be on properly/fine.....

My brother recommended sending the car to Hyperdrive/Ovaboost/etc to have the boost controller tuned properly for 10-12psi....

Any other suggestions before i book it in for a dyno tune?

Cant really think of anything else that you can do sorry, be interesting to see what they come up with i def want to know what settings they put your boost controller on im thinking of taking mine somewhere to get checked.

Any other suggestions before i book it in for a dyno tune?

What do you have for them to tune ? If you had an SAFC then that would modify the AFM signal going to the ECU. It's the AFM signal maxing out that causes the boost cut issue.

What do you have for them to tune ? If you had an SAFC then that would modify the AFM signal going to the ECU. It's the AFM signal maxing out that causes the boost cut issue.

When i brought the car almost 2weeks back it had an SAFC2 in it, but i have since taken it out and sold it....

When i brought the car almost 2weeks back it had an SAFC2 in it, but i have since taken it out and sold it....

Umm, why ? You'll need the SAFC if your planning on making more mods etc. Any more than 10-11psi will see you hitting boost cut otherwise.

Umm, why ? You'll need the SAFC if your planning on making more mods etc. Any more than 10-11psi will see you hitting boost cut otherwise.

My brother recommended to take it out to improve fuel economy as modifications to the vehicle are currently limited to an FMIC, air pod and turbo-back exh.

After i took out the SAFC2 the car was running perfectly normal, no boost cuts, smooth as silk; it was only once i had changed the plugs that i got the boost-cuts.....

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

    • Hi,  Just joined the forum so I could share my "fix" of this problem. Might be of use to someone. Had the same hunting at idle issue on my V36 with VQ35HR engine after swapping the engine because the original one got overheated.  While changing the engine I made the mistake of cleaning the throttle bodies and tried all the tricks i could find to do a throttle relearn with no luck. Gave in and took it to a shop and they couldn't sort it. Then took it to my local Nissan dealership and they couldn't get it to idle properly. They said I'd need to replace the throttle bodies and the ecu probably costing more than the car is worth. So I had the idea of replacing the carbon I cleaned out with a thin layer of super glue and it's back to normal idle now. Bit rough but saved the car from the wreckers 🤣
    • After my last update, I went ahead with cleaning and restoring the entire fuel system. This included removing the tank and cleaning it with the Beyond Balistics solution, power washing it multiple times, drying it thoroughly, rinsing with IPA, drying again with heat gun and compressed air. Also, cleaning out the lines, fuel rail, and replacing the fuel pump with an OEM-style one. During the cleaning process, I replaced several hoses - including the breather hose on the fuel tank, which turned out to be the cause of the earlier fuel leak. This is what the old fuel filter looked like: Fuel tank before cleaning: Dirty Fuel Tank.mp4   Fuel tank after cleaning (some staining remains): Clean Fuel Tank.mp4 Both the OEM 270cc and new DeatschWerks 550cc injectors were cleaned professionally by a shop. Before reassembling everything, I tested the fuel flow by running the pump output into a container at the fuel filter location - flow looked good. I then fitted the new fuel filter and reassembled the rest of the system. Fuel Flow Test.mp4 Test 1 - 550cc injectors Ran the new fuel pump with its supplied diagonal strainer (different from OEM’s flat strainer) and my 550cc injectors using the same resized-injector map I had successfully used before. At first, it idled roughly and stalled when I applied throttle. Checked the spark plugs and found that they were fouled with carbon (likely from the earlier overly rich running when the injectors were clogged). After cleaning the plugs, the car started fine. However, it would only idle for 30–60 seconds before stalling, and while driving it would feel like a “fuel cut” after a few seconds - though it wouldn’t fully stall. Test 2 – Strainer swap Suspecting the diagonal strainer might not be reaching the tank bottom, I swapped it for the original flat strainer and filled the tank with ~45L of fuel. The issue persisted exactly the same. Test 3 – OEM injectors To eliminate tuning variables, I reinstalled the OEM 270cc injectors and reverted to the original map. Cleaned the spark plugs again just in-case. The stalling and “fuel cut” still remained.   At this stage, I suspect an intermittent power or connection fault at the fuel pump hanger, caused during the cleaning process. This has led me to look into getting Frenchy’s fuel hanger and replacing the unit entirely. TL;DR: Cleaned and restored the fuel system (tank, lines, rail, pump). Tested 550cc injectors with the same resized-injector map as before, but the car stalls at idle and experiences what feels like “fuel cut” after a few seconds of driving. Swapped back to OEM injectors with original map to rule out tuning, but the issue persists. Now suspecting an intermittent power or connection fault at the fuel pump hanger, possibly cause by the cleaning process.  
    • For race cars, this is one part where I find having the roll cage bar having gone through a hole in the floor better than the build it up on a ledge inside... The Merc I help on, the main hoop ends are marked on the car, and the jack is marked... Jack goes under a few inches and lifts one whole side of the car up... Removes that fight for long slim jacks for race car duties!   My biggest issue for the daily drivers I work on, is my jacks don't go high enough. The jacks start out on a few blocks, jack it up, then start a second jack under it on more blocks, and then I can get an axle stand under it. My axle stands are presently in use, and are nearly fully extended. The car is sitting with barely more than a cm of clearance to get the wheel off the studs! Sarah's Kluger is the same, as it has an ungodly amount of droop available in the suspension and a distinct lack of good jacking points!
    • Happy? Yep, my to do list is getting shorter and shorter. Either this light approaching is the end of the tunnel, or I'm about to be hit by a train... Ha ha ha   Also, Duncan isn't that far out of town that you need to make a multi day drive out of it. 😛
×
×
  • Create New...