Jump to content
SAU Community

Loss of power when on boost also hunts tiny amount in idle

My r34 always has issues
 Share

Recommended Posts

My r34 always has issues Newbie

My r34 always has issues

Posted
Posted

Hi all I'm having a few problems with my r34 gtt rb25dett neo it's completely stock. It's done 200,000 just got rebuilt with forged rods and pistons. Running 7 psi on the stock turbo.  Iv driven it another 4,000 km roughly and I noticed about a week ago in 3-4 grand rev range in 2,3 and 4th gear it would lose power upon acceleration.  But I drove it today. And it's having the same sort of issue but only when I get boost like runs fine in first but if I hit second and get past 1 psi of boost it like jerks and loses pretty much all go to it. The original issue i couldnt hear the engine really struggling i just sort of felt the lose of power but the issue im having now i can definently hear the engine die. It also hunts slightly when idling I'm thinking it's a fuel issue iv ordered a pump, reg and coil packs. I was just wondering if anyone else has had this issue. It still gets boost if I power through i get to 6 psi and it doesn't feel like it changes or gains more power.

joshuaho96 Veteran

joshuaho96

Posted
Posted
  On 05/10/2023 at 1:00 PM, My r34 always has issues said:

Hi all I'm having a few problems with my r34 gtt rb25dett neo it's completely stock. It's done 200,000 just got rebuilt with forged rods and pistons. Running 7 psi on the stock turbo.  Iv driven it another 4,000 km roughly and I noticed about a week ago in 3-4 grand rev range in 2,3 and 4th gear it would lose power upon acceleration.  But I drove it today. And it's having the same sort of issue but only when I get boost like runs fine in first but if I hit second and get past 1 psi of boost it like jerks and loses pretty much all go to it. The original issue i couldnt hear the engine really struggling i just sort of felt the lose of power but the issue im having now i can definently hear the engine die. It also hunts slightly when idling I'm thinking it's a fuel issue iv ordered a pump, reg and coil packs. I was just wondering if anyone else has had this issue. It still gets boost if I power through i get to 6 psi and it doesn't feel like it changes or gains more power.

Expand  

Idle hunting is a sign of air leaks. It usually means the ECU is trying extreme measures to stay on target idle speed. Easy way to validate this theory is to unscrew the TPS adjustment and tweak it ever so slightly to bump the TPS voltage above idle. This will disable idle control. An engine without vacuum leaks either internal or external should experience a low idle or no change in idle when you do this.

GTSBoy Grand Master

GTSBoy

Posted
Posted
  On 06/10/2023 at 1:09 AM, My r34 always has issues said:

Could that also cause the issues that were occurring when driving. 

Expand  

Less likely. That's more likely to be something electrical/electronic. And that could also cause the idle problems too.

For helping look for vacuum leaks, grab a can of carby/brake cleaner spray and go over the various joints. If idle changes, you've found a leak.

My r34 always has issues Newbie

My r34 always has issues

Posted
  • Author
Posted

Alrighty my driving issues sorted not low on power no more I did check for a boost leak using carry cleaner awesome f*king idea BTW nothing happened, then checked the tps voltage was good and changed with the throttle position. I also unscrewed and tested it didn't get a change in revs. I changed the spark plugs and now it's all sweet. My idle still slightly varies about 50 to 100 rpm but not frequently.

Thank for the help BLOOODY LEGENDS 

joshuaho96 Veteran

joshuaho96

Posted
Posted
  On 06/10/2023 at 11:22 AM, My r34 always has issues said:

Alrighty my driving issues sorted not low on power no more I did check for a boost leak using carry cleaner awesome f*king idea BTW nothing happened, then checked the tps voltage was good and changed with the throttle position. I also unscrewed and tested it didn't get a change in revs. I changed the spark plugs and now it's all sweet. My idle still slightly varies about 50 to 100 rpm but not frequently.

Thank for the help BLOOODY LEGENDS 

Expand  

I have experienced what I would describe as idle dropping out in moments with counterfeit spark plugs but it wasn’t really idle hunting. It felt like a misfire almost. It would drop and then recover as the idle control caught it. Never stalled but noticeably felt strange and was fixed with new genuine plugs. 

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

    • GTSBoy
      Potential MAP Reference Point

      By GTSBoy · Posted

      Getting a decent signal from all 6 throats is a challenge. I don't know for sure, but I suspect that the stock balance tube is not ideal for it. I have done it on an ALFA 4 cylinder (about 35 years ago, so don't ask for too many details). We drilled 4x holes in the manifold runners, put in some fittings and ran hoses to a decent sized (I think it was about 20mm diameter) pipe that ran the length of the inlet manifold. So, it was quite a decent volume. There is a "tuning" balance to be found between the volume of the common plenum on such a thing and the diameter of the pipes running from it to the runners. You need the volume to be large enough to damp out the sharp spikes in pressure signal you get as each runner gets sucked on by its cylinder, but not so large that it becomes too slow to respond to actual changes in MAP. And you need the hoses to be small enough to transmit the signal quickly, but not so small that they delay the signal. You might have to have more than one go at it, if there isn't any actual success based wisdom to be had here. Hopefully there is. Anyway, I would not do it on only a couple of cylinders. I would also not care about "permanently modifying a part". Just bloody drill holes and make stuff better. There is nothing sacred about any GTR unless it is a genuine museum piece that you shouldn't be modifying at all anyway.
    • MBS206
      NC MX5

      By MBS206 · Posted

      He's still joining you, he's just delayed it and won't have the fulleh sick ITBs...
    • Kinkstaah
      R34 GTT front hood lip

      By Kinkstaah · Posted

      The strange thing is this is a URAS front bumper (or clone of it). The bumper actually does not sit flush with the GTT hood - You need the addon to make the hood 'long' enough to reach the bumper. I have no idea why they didn't incorporate this piece into the bumper itself.. instead of sticking it to the hood instead.
    • AdiR34
      R34 GTT front hood lip

      By AdiR34 · Posted

      Another thought on this OLD topic: When you paint your bonnet lip, leave a small unpainted back lip/line along the back of the lip, where it rests on the bumper. That way, the line in the back is much more prominent than the gaps in the front/under the lip - and it breaks the hood-to-bumper connection at the "correct" place, when comparing to a GTR. I'm gonna do this with mine this week, so stay tuned for pics!
    • Radical_Goodspeed
      Potential MAP Reference Point

      By Radical_Goodspeed · Posted

      So I'm in the final stages of assembling my single turbo RB30/26 and had a question regarding MAP reference points.  I've seen several recommendations such as tapping the cylinder 2/3 ITB, tapping the intake manifold at cylinder 2/3, or using a point on IAC. First two are doable but require permanently modify part and the third is "out" as I plan to delete the IAC.  All that to say my question is can I used the "bleeder" in the center of the ballance tube as a MAP Reference? I'm running a catch can so I don't need it for the PCV system. My thought process is it "pulls" from all 6 cylinder, and it's between the ITB and the cylinders making it ideal for MAP reference according to what I can find. Thoughts?
×
×
  • Create New...