Jump to content
SAU Community

Atr43G3 Lag Monster After Rebuild

Daza33

By Daza33,
in Engines & Forced Induction

 Share

Recommended Posts

Daza33 Contributor

Daza33

Posted
Posted

Hi guys, so I am just after a bit of advice about this problem of mine. Last year I did a forged rebuild on my rb25 after burning out exhaust valves and scoring the bore. Since the rebuild my atr43g3 is 1000rpm laggier than before the build.

I get 19psi at 5000rpm, whereas I used to get that at 4000 before the build. I am thinking it may have to do with my cam timing since I had the head skimmed and the block decked. I dropped the standard cams back in, lined up the marks but didn't adjust my exhaust cam gear so it is currently set to 0 degrees. The car sits at 18mmhg at idle when it used to be at 22-24mmhg before the build as well.

Other than the turbo lag the car runs smooth, makes 301rwkw but only sees 220rwkw at 5000rpm, making it a nugget off boost.

I am thinking of retarding the exhaust 2 degrees tomorrow, but thought I'd get your opinions before I do.

Link to comment
https://www.sau.com.au/forums/topic/444721-atr43g3-lag-monster-after-rebuild/
Share on other sites
Ben C34 Grand Master

Ben C34

Posted
Posted

Skimming the head and block would retard the cam timing, but only very slightly.

Regarding the exhaust cam will mean you will pull even less vacuum.

I would consider advancing both cams and seeing what happens.

Is vct functioning correctly?

scotty nm35 Grand Master

scotty nm35

Posted
Posted

Last year I did a forged rebuild on my rb25 after burning out exhaust valves and scoring the bore. Since the rebuild my atr43g3 is 1000rpm laggier than before the build.

If all is mechanically ok, there is a chance the high exhaust temps from the failed valves have warped the rear housing on the Hypergear, and now the wastegate puck won't seal fully. I have seen this before, it's not hard to check if the back of the turbo is flat still.

  • Like 1
Daza33 Contributor

Daza33

Posted
  • Author
Posted

Well 2 months ago I fried my power fc when the Vct solenoid died. Got it repaired and put a new solenoid in, I can see it switching through the hand controller. Guess I'll disconnect it and take for a drive.

As for the wastegate, I've got close to 5mm of preload on it and have fabbed up a screamer for the internal gate, doesnt creep open it just snaps open and makes a shitload of noise.

One last thing, if I were to adjust the cam timing is it going to throw out my tune at all?

scotty nm35 Grand Master

scotty nm35

Posted
Posted

It doesn't matter how much preload you put on the puck, if the back of the turbo is only a little warped, it will never make a seal.

Cam timing would need to be out a fair bit... Yes it will affect the tune.

hypergear Grand Master

hypergear

Posted
Posted

The wastegate flapper has a smaller tolerance of play that is to compensate for any changes might be during heat expansion and contraction of the turbine housing. beside Jay, your rear housing was cut and welded to suit an external gate.

This particular car has an external screamer. For 1000RPMs difference, The take would be half of the 38mm gate. It will be making a very noticeable sound. OP have replied on an earlier post as the screamer does not make any noises till the gate opens. Plus this behavior was not present after the new engine was assembled. In my opinion The waste gate assembly on this turbocharger is unrelated.

I'm not sure how bad the older engine was damaged. If bit of failed engine ended up in the turbine housing, then it might be accounted for a damaged turbine wheel. It could rise the lag issue also, how ever on the same time it is not capable of making any power.

I have experienced similar issues in the past when my VCT was dis-engaged, since it has been previously burnt, functionality of the part might be questionable. Simply unplug the solenoid and feel for the changes in drive ability. No differences usually means malfunction in the VCT assembly.

The adjustable exhaust gear makes pretty much no differences working with stock cams, It was the first thing I've tried improving boost response and that was a waste of dyno time.

Daza33 Contributor

Daza33

Posted
  • Author
Posted

So vct definitely works, so I can rule that out.

Only other thing I can think of, and will check tomorrow, is that I changed the exhaust after the rebuild. It now has a nismo kit from cat back and now has a mid muffler and oval rear opposed to the cannon that it had before.

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
      R33 Fuel Pump & Brakes after alarm swap

      By GTSBoy · Posted

      Power is fed to the ECU when the ignition switch is switched to IGN, at terminal 58. That same wire also connects to the ECCS relay to provide both the coil power and the contact side. When the ECU sees power at 58 it switches 16 to earth, which pulls the ECCS relay on, which feeds main power into the ECU and also to a bunch of other things. None of this is directly involved in the fuel pump - it just has to happen first. The ECU will pull terminal 18 to earth when it wants the fuel pump to run. This allows the fuel pump relay to pull in, which switches power on into the rest of the fuel pump control equipment. The fuel pump control regulator is controlled from terminal 104 on the ECU and is switched high or low depending on whether the ECU thinks the pump needs to run high or low. (I don't know which way around that is, and it really doesn't matter right now). The fuel pump control reg is really just a resistor that controls how the power through the pump goes to earth. Either straight to earth, or via the resistor. This part doesn't matter much to us today. The power to the fuel pump relay comes from one of the switched wires from the IGN switch and fusebox that is not shown off to the left of this page. That power runs the fuel pump relay coil and a number of other engine peripherals. Those peripherals don't really matter. All that matters is that there should be power available at the relay when the key is in the right position. At least - I think it's switched. If it's not switched, then power will be there all the time. Either way, if you don't have power there when you need it (ie, key on) then it won't work. The input-output switching side of the relay gains its power from a line similar (but not the same as) the one that feeds the ECU. SO I presume that is switched. Again, if there is not power there when you need it, then you have to look upstream. And... the upshot of all that? There is no "ground" at the fuel pump relay. Where you say: and say that pin 1 Black/Pink is ground, that is not true. The ECU trigger is AF73, is black/pink, and is the "ground". When the ECU says it is. The Blue/White wire is the "constant" 12V to power the relay's coil. And when I say "constant", I mean it may well only be on when the key is on. As I said above. So, when the ECU says not to be running the pump (which is any time after about 3s of switching on, with no crank signal or engine speed yet), then you should see 12V at both 1 and 2. Because the 12V will be all the way up to the ECU terminal 18, waiting to be switched to ground. When the ECU switches the fuel pump on, then AF73 should go to ~0V, having been switched to ground and the voltage drop now occurring over the relay coil. 3 & 5 are easy. 5 is the other "constant" 12V, that may or may not be constant but will very much want to be there when the key is on. Same as above. 3 goes to the pump. There should never be 12V visible at 3 unless the relay is pulled in. As to where the immobiliser might have been spliced into all this.... It will either have to be on wire AF70 or AF71, whichever is most accessible near the alarm. Given that all those wires run from the engine bay fusebox or the ECU, via the driver's area to the rear of the car, it could really be either. AF70 will be the same colour from the appropriate fuse all the way to the pump. If it has been cut and is dangling, you should be able to see that  in that area somewhere. Same with AF71.   You really should be able to force the pump to run. Just jump 12V onto AF72 and it should go. That will prove that the pump itself is willing to go along with you when you sort out the upstream. You really should be able to force the fuel pump relay on. Just short AF73 to earth when the key is on. If the pump runs, then the relay is fine, and all the power up to both inputs on the relay is fine. If it doesn't run (and given that you checked the relay itself actually works) then one or both of AF70 and AF71 are not bringing power to the game.
    • Kinkstaah
      My BMW E39 528i touring

      By Kinkstaah · Posted

      @PranK can you elaborate further on the Colorlock Dye? The website has a lot of options. I'm sure you've done all the research. I have old genuine leather seats that I have bought various refurbing creams and such, but never a dye. Any info on how long it lasts? Does it wash out? Is it a hassle? What product do I actually need? Am I just buying this kit and following the steps the page advises or something else? https://www.colourlockaustralia.com.au/colourlock-leather-repair-kit-dye.html
    • GTSBoy
      My BMW E39 528i touring

      By GTSBoy · Posted

      These going to fit over the big brakes? I'd be reeeeeeeeaaaall hesitant to believe so.
    • PranK
      My BMW E39 528i touring

      By PranK · Posted

      The leather work properly stunned me. Again, I am thankful that the leather was in such good condition. I'm not sure what the indent is at the top of the passenger seat. Like somebody was sitting in it with a golf ball between their shoulders. The wheels are more grey than silver now and missing a lot of gloss.  Here's one with nice silver wheels.
    • soviet_merlin
      My BMW E39 528i touring

      By soviet_merlin · Posted

      It's amazing how well the works on the leather seats. Looks mint. Looking forward to see how you go with the wheels. They do suit the car! Gutter rash is easy to fix, but I'm curious about getting the colour done.
×
×
  • Create New...