Jump to content
SAU Community

Stock R33 Series 2 Gtst Flat Spots On Boost

donnaile

By donnaile,
in Engines & Forced Induction

 Share

Recommended Posts

donnaile Rookie

donnaile

Posted
Posted

Hi All

My name is Ed. I am new to Skyline ownership. I have been looking over this forum the past 4-6 months before buying a car, its a great source of information so thanks to everyone. I ended up getting a series 2 r33 gtst. I'm loving it so far but have one nagging issue...flat spots on boost.

I have been researching forums on the issue I'v been having with my gtst but can't find anyone with the same issue. Its completely standard, no exhaust, no pod etc.Everyone with flat spots seemed to develop after mods were added.

I have two flat spots when on boost. Between 4000rpm - 4500rpm & 5000rpm - 5100rpm. It feels like the car is hesitating when it hits these spots and mostly noticeable at full throttle.

Reading the forums I can see its common to have a flat spot between 4000rpm - 4500rpm when you upgrade parts on standard ECU but in my case the car is standard. Before I bought it however I believe it had an exhaust, fmic and pod. The previous owner removed these, serviced and replaced timing belt.

What I have done so far:

Cleaned the AFM
Reset the ECU (disconnect battery/brake pedal)
Replaced plugs

I am running shell vpower. My guess is timing but I don't have the tools/knowledge to check this. I have put around 600km on it since I bought it. Its running sweet besides the flat spot issue. If anyone can point me in the right direction that would be great.

Thanks
Ed

KiwiRS4T Grand Master

KiwiRS4T

Posted
Posted

Depends what you call a flat spot. There is normally a dip on the RB25 as the VCT changes over. Did you gap the plugs down to 0.8mm? Give the coils a good clean? Put your location up on your profile so maybe somebody close by can take a drive to compare or point you to a good RB workshop if there is really a major fault.

donnaile Rookie

donnaile

Posted
  • Author
Posted (edited)

Depends what you call a flat spot. There is normally a dip on the RB25 as the VCT changes over. Did you gap the plugs down to 0.8mm? Give the coils a good clean? Put your location up on your profile so maybe somebody close by can take a drive to compare or point you to a good RB workshop if there is really a major fault.

Thanks KiwiRS4T.

Just updated my location. Have not checked the gap on the plugs yet. Will check it out this weekend. How should I go about cleaning the coils?

Not sure how to describe the flat spot. It feels like the car is holding back from its full potential just after it gets on boost, then boosts hard, then slight flat spot again. Its not as evident on half throttle. Happens in 1st, 2nd & 3rd. Have not had the opportunity to test out 4th or 5th.

Edited by donnaile
89CAL Grand Master

89CAL

Posted
Posted

What boost is it running? I get the impression its stockish now but had some parts on it that have since been removed. If its running any more than 7 psi then you may run into issues with R&R

Keep in mind the stock gauge is in mmHg not PSI

May not be relevant but there was no mention of a boost figure so thought i would throw that in there.

The other suggestions so far are probably on the money if boost is indeed stock

hy_rpm Proficient

hy_rpm

Posted
Posted

Its worth a shot free and my r33 developed the same symptoms as that and it was the o2

Sometimes floor it nothing othertimes it goes ok but power isnt smooth or linear

Got a few basic mods but still a r33s2 there getting old 97 model going on almost 20years old

  • 4 weeks later...
Antek Apprentice

Antek

Posted
Posted

I am too having this issue since upgrading my turbo last week ( yet to be tuned), I opened it up on the freeway the other day, all was going well until i got a pop of air from the engine bay and lost boost, all pipes have been checked and only found one lose which did not fix the problem. I have been told the intake manifold gaskets are known for giving in and have been recommended to replace the gasket with silicon??

donburtron Enthusiast

donburtron

Posted
Posted

I had a very similar problem just after rebuilding my engine and turns out it was the TPS not set properly.

If you only use the first inch or so of your throttle does the problem still persist?

With mine i was able to use about a inch or so of throttle and it was like i was using full throttle but anything past that inch or so it would feel underpowered and completely drop boost for a second around that 5k rpm..

You will need a multimeter to set the TPS but its pretty easy once you find a manual off google on how to set it..

Its abit fidly but i used a small screw driver to tap the sencor once i backed off the screws a quarter turn

Antek Apprentice

Antek

Posted
Posted (edited)

No so, I can gradualy accelerate and its fine all the way up so long as its not under complete pressure. When i apply full throttle it is fine until boost starts to come on at around 4.5-5+rpm it just seems to almost starve it self self all the way up witch is were i littler cannot take it to.

As i mentioned before in my previous post when it first occurred it did seem like something popped, what it is and were it was is a mystery for the moment, but the noise that occurred defiantly contributed to the problem.

Edited by Antek
donburtron Enthusiast

donburtron

Posted
Posted (edited)

Have you checked your piping from the turbo to airbox etc.. i know they can make a popping sound under pressure or even slipt into 2 from crappy clamps done up to tight..

Edit.. also could be a turbo exhaust wheel.. happened to a mates rx7 and he said it made a popping sound.. when he replaced it there was only 2/3rds of the turbine barely holding on

Edited by donburtron
donburtron Enthusiast

donburtron

Posted
Posted

I have, though i will do a through check tomorrow, I did find one lose pipe.. I replaced the clamp.

What do you mean by "slipping into 2"

By splitting into 2 i mean splitting in half and if your on boost at the time it can make a pretty load pop when it lets go..
Antek Apprentice

Antek

Posted
Posted

right-o well.. cheers for the input fellas once again, I been out in the shed looking over all the pipe work on the induction side, yet they came across tight as i wiggled every one of the with some decent force though, it wasn't until i came across a section that was tucked away were i noticed a seep of oil that seemed to spread it self.. long story, lose clamp..

donburtron Enthusiast

donburtron

Posted
Posted

right-o well.. cheers for the input fellas once again, I been out in the shed looking over all the pipe work on the induction side, yet they came across tight as i wiggled every one of the with some decent force though, it wasn't until i came across a section that was tucked away were i noticed a seep of oil that seemed to spread it self.. long story, lose clamp..

Awesome.. has it fixed the problem?
75coupe Grand Master

75coupe

Posted
Posted

I am too having this issue since upgrading my turbo last week ( yet to be tuned), I opened it up on the freeway the other day, all was going well until i got a pop of air from the engine bay and lost boost, all pipes have been checked and only found one lose which did not fix the problem. I have been told the intake manifold gaskets are known for giving in and have been recommended to replace the gasket with silicon??

Yet to be tuned with an upgraded turbo, but opened it up on freeway.

Nah i cant see any problem there

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
 Share
Go to topic listing


  • Similar Content

  • Latest Posts

    • djr81
      R32 update from 1990's spec.

      By djr81 · Posted

      New CAS just turned up from NZ Wiring. Looks like a nice bit of gear.  So, yeah. Triggered, bro. Realised I may as well do the cam belt while mucking about with it so will order one of them.
    • MBS206
      Duncan's V37.......race car?

      By MBS206 · Posted

      Even more fun, leave all the ADAS stuff plugged in, but in different locations, hopefully avoid any codes!   And honestly, all these new cars with their weird electronics. Pull all the electronics out Duncan, and just shove an aftermarket ECU and if needed a trans controller in, along with a PDM. Make it run basic but race car styled!
    • Duncan
      Duncan's V37.......race car?

      By Duncan · Posted

      To follow up a question from earlier too since I had the front bar off again (fking!) This is what is between the bumper and the drivers side wheel And this is the navigator side, only one thing but its a biggy! So basically....no putting coolers in the wheel arches without a lot of moving other stuff. Assuming I move to properly race prepping this car I'll take that job on and see how the computers respond to removing a whole bunch of ADAS modules
    • Duncan
      Duncan's V37.......race car?

      By Duncan · Posted

      So I prepped the car for another track day on Wednesday (will be interesting to see coolant temps post flushing out and the larger reservoir, with a forecast of 3-14 being 20o cooler than last time I took it out). Couple of things to mention; since I am just driving the car and not taking a support vehicle, I took the rear seats out and just loaded the back up Team Trackday style. Look at all that space! To cover off removing the rear seat....it is weird (note the hybrid is probably different because it wouldn't have folding rear seats) Basically, you remove the lower seat base, very similar to a r series but it is a clip that pulls forward to release the base rather than it being bolted down. Easy Then, you need to remove the side section of the rear seat on each side. There is a 14mm head nut at the bottom of the side piece, the it slides upwards off a hook at the top to release; you also need to unhook the seatbelt from the loop at the top. Then the centre piece is weird. You need to release/fold the seats forward with the tab in the boot on each side From there, there are 2,x12mm headed bolts holding the rear of each seat to the folding bracket, under the trim between the rear seat and the boot (4x christmas tree clips there, they suck). The seat is out but you can see where the bolts attach to the bracket
    • RP1421
      S15 Spec R

      By RP1421 · Posted

      As discussed in the previous post, the bushes in the 110 needed replacing. I took this opportunity to replace the castor bushes, the front lower control arm, lower the car and get the alignment dialled in with new tyres. I took it down to Alignment Motorsports on the GC to get this work done and also get more out of the Shockworks as I felt like I wasn't getting the full use out of them.  To cut a very long story short, it ended up being the case the passenger side castor arm wouldn't accept the brand new bush as the sleeve had worn badly enough to the point you could push the new bush in by hand and completely through. Trying a pair of TRD bushes didn't fix the issue either (I had originally gone with Hardrace bushes). We needed to urgently source another castor arm, and thankfully this was sourced and the guys at the shop worked on my car until 7pm on a Saturday to get everything done. The car rides a lot nicer now with the suspension dialled in properly. Lowered the car a little as well to suit the lower profile front tyres, and just bring the car down generally. Eternally thankful for the guys down at the shop to get the car sorted, we both pulled big favours from our contacts to get it done on the Saturday.  Also plugged in the new Stedi foglights into the S15, and even from a quick test in the garage I'm keen to see how they look out on the road. I had some concerns about the length of the LED body and whether it'd fit in the foglight housing but it's fine.  I've got a small window coming up next month where I'll likely get a little paint work done on the 110 to remove the rear wing, add a boot wing and roof wing, get the side skirt fixed up and colour match the little panel on the tail lights so that I can install some badges that I've kept in storage. I'm also tempted to put in a new pair of headlights on the 110.  Until then, here's some more pictures from Easter this year. 
×
×
  • Create New...