Jump to content
SAU Community

Problem with flat spots with higher boost

GunMetalR33

By GunMetalR33,
in Engines & Forced Induction

 Share

Recommended Posts

GunMetalR33 Mentor

GunMetalR33

Posted
Posted

I have a 1994 R33,

I just turn my boost up to 11 pound using a single stage turbo smart boost controller. Since then I am having a problem with flat spots between 4,000 and 5,000 rpm. A mate of mine said that the R33's have factory boost limiters maped into the computers?

An suggestions would be helpfull.

Thanks...

predator Grand Master

predator

Posted
Posted

Super AirFlow converter.. by Apexi.. it hooks into the oxygen and air flow meter sensors of the car and into the ECU .. basically a correction factor so the ECU "sees" less or more air than actually going in for each rev range. With a different reading "seen", the ECU adjusts the fuel mapping accordingly resulting in a richer or leaner mixture than factory. This generally can be used to give the car a 20-30% power increase with the right tuning.

Its what you use when you don't have a full aftermarket computer (around $1000 more) where the fuel maps (and other things) can be adjusted internally a lot more accurately. Hope that helps.

GunMetalR33 Mentor

GunMetalR33

Posted
  • Author
Posted

Thanks for your reply,

I was going to buy an after market computer. By reading your post above it looks like that will solve my problem.

Ps, Is it true that the standard R33 computer has a over boost restricter? because the problem only exists at 10 pound and over

Sydneykid Grand Master

Sydneykid

Posted
Posted

Hi GunMetalR33, the issues and solutions are;

1. Over boost protection, the ECU cuts fuel and ignition when boost goes over 11 psi. Solution device called boost cut defeater. Cost a couple hundy.

2. 180 kph speed limiter, the ECU cuts fuel and ignition when the speed goes over 18o kph. Solution device called speed limit defeater. Cost a couple hundy.

3. Fuel mixture enrichment, the ECU increases the fuel supply as boost increases. Solution device called SAFC as explained above. Cost a few hundy.

4. Ignition timing retard, the ECU retards the ignition timing as boost increases. Solution device called ITC similar to SAFC except it modifies the timing signal such that the ECU does not retard the ignition. Cost a few hundy.

So if you add all these together you will find that the total cost ends up more than a Power FC. Particularly if you can pick up a used one. If you want to fix all of these issues we always recommend the PFC, if you are happy missing out on more than one fix then maybe the SAFC is worthwhile.

Hope that helps

Jay95R33 Grand Master

Jay95R33

Posted
Posted

Andrew (Jayson here :) ),

I was just thinking, it could be the gap in your plugs !!!

Damn, if I would've thought about that last night we could re-gapped them then :P

Seems your car is one of the rare ones that are totally stock, I'd say your plugs are still gapped at 1 or 1.1mm !!

Damn (hitting myself in the head), I should've thought about that !!

Cool, we can re-gap your plug's a little on the weekend and see how it goes?

J

  • 3 years later...
gts-4 dreamer Mentor

gts-4 dreamer

Posted
Posted

my car was stock.. but shite, after putting on exhuast and fmic... YOU CNT GO BACK !!!, soooOOOo much more efficient, seriously that smic is sooOOO shithouse its not funny....

GunMetalR33 Mentor

GunMetalR33

Posted
  • Author
Posted
Sorry I am new to forums & Skylines, what does SAFC mean?

ha ha ha, I cant believe I asked this type of question :)

Its amazing how much you can learn from this forum... I went from "What does SAFC mean" to installing after market ecu, turbo, injectors and clutch etc :)

man, this takes me back to the first couple of weeks that I had the car :)

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

    • oHBoy.
      Starter motor replacment teeth count.

      By oHBoy. · Posted

      I had 3 counts over the last couple of weeks once where i got stranded at a jdm paint yard booking in some work. 2nd time was moving the car into the drive way for the inspection and the 3rd was during the inspection for the co2 leak test. Fix: 1st, car off for a hour and half disconnected battery 10mins 4th try car started 2nd, 5th try started 3rd, countless time starting disconnected battery dude was under the hood listening to the starting sequence fuel pump ect.   
    • GTSBoy
      Mistakes were made, my R34 Story

      By GTSBoy · Posted

      This. As for your options - I suggest remote mounting the Nissan sensor further away on a length of steel tube. That tube to have a loop in it to handle vibration, etc etc. You will need to either put a tee and a bleed fitting near the sensor, or crack the fitting at the sensor to bleed it full of oil when you first set it up, otherwise you won't get the line filled. But this is a small problem. Just needs enough access to get it done.
    • suko
      J50 clock date suddenly reset to January 1

      By suko · Posted

      The time is always correct. Only the date is wrong. It currently thinks it is January 19. Tomorrow it will say it is January 20. The date and time are ( should be ! ) retrieved from the GPS navigation system.
    • MBS206
      Mistakes were made, my R34 Story

      By MBS206 · Posted

      Buy yourself a set of easy outs. See if they will get a good bite in and unthread it.   Very very lucky the whole sender didn't let go while on the track and cost you a motor!
    • Kinkstaah
      Mistakes were made, my R34 Story

      By Kinkstaah · Posted

      Well GTSBoy, prepare yourself further. I did a track day with 1/2 a day prep on Friday, inpromptu. The good news is that I got home, and didn't drive the car into a wall. Everything seemed mostly okay. The car was even a little faster than it was last time. I also got to get some good datalog data too. I also noticed a tiny bit of knock which was (luckily?) recorded. All I know is the knock sensors got recalibrated.... and are notorious for false knock. So I don't know if they are too sensitive, not sensitive enough... or some other third option. But I reduced timing anyway. It wasn't every pull through the session either. Think along the lines of -1 degree of timing for say, three instances while at the top of 4th in a 20 minute all-hot-lap session. Unfortunately at the end of session 2... I noticed a little oil. I borrowed some jack stands and a jack and took a look under there, but as is often the case, messing around with it kinda half cleaned it up, it was not conclusive where it was coming from. I decided to give it another go and see how it was. The amount of oil was maybe one/two small drops. I did another 20 minute session and car went well, and I was just starting to get into it and not be terrified of driving on track. I pulled over and checked in the pits and saw this: This is where I called it, packed up and went home as I live ~20 min from the track with a VERY VERY CLOSE EYE on Oil Pressure on the way home. The volume wasn't much but you never know. I checked it today when I had my own space/tools/time to find out what was going on, wanted to clean it up, run the car and see if any of the fittings from around the oil filter were causing it. I have like.. 5 fittings there, so I suspected one was (hopefully?) the culprit. It became immediately apparent as soon as I looked around more closely. 795d266d-a034-4b8c-89c9-d83860f5d00a.mp4       This is the R34 GTT oil sender connected via an adapter to an oil cooler block I have installed which runs AN lines to my cooler (and back). There's also an oil temp sensor on top.  Just after that video, I attempted to unthread the sensor to see if it's loose/worn and it disintegrated in my hand. So yes. I am glad I noticed that oil because it would appear that complete and utter catastrophic engine failure was about 1 second of engine runtime away. I did try to drill the fitting out, and only succeeded in drilling the middle hole much larger and now there's a... smooth hole in there with what looks like a damn sleeve still incredibly tight in there. Not really sure how to proceed from here. My options: 1) Find someone who can remove the stuck fitting, and use a steel adapter so it won't fatigue? (Female BSPT for the R34 sender to 1/8NPT male - HARD to find). IF it isn't possible to remove - Buy a new block ($320) and have someone tap a new 1/8NPT in the top of it ($????) and hope the steel adapter works better. 2) Buy a new block and give up on the OEM pressure sender for the dash entirely, and use the supplied 1/8 NPT for the oil temp sender. Having the oil pressure read 0 in the dash with the warning lamp will give me a lot of anxiety driving around. I do have the actual GM sensor/sender working, but it needs OBD2 as a gauge. If I'm datalogging I don't actually have a readout of what the gauge is currently displaying. 3) Other? Find a new location for the OEM sender? Though I don't know of anywhere that will work. I also don't know if a steel adapter is actually functionally smart here. It's clearly leveraged itself through vibration of the motor and snapped in half. This doesn't seem like a setup a smart person would replicate given the weight of the OEM sender. Still pretty happy being lucky for once and seeing this at the absolute last moment before bye bye motor in a big way, even if an adapter is apparently 6 weeks+ delivery and I have no way to free the current stuck/potentially destroyed threads in the current oil block.
×
×
  • Create New...