Jump to content
SAU Community

Why R&r At Partial Throttle And Not Full Throttle?

Andi

By Andi,
in Engines & Forced Induction

 Share

Recommended Posts

Andi Experienced

Andi

Posted
Posted

Hey all, I just took the car for a proper test drive and I've noted a few symptoms when the car is on higher boost. From what I've researched so far it seems that I am definately hitting the infamous rich and retard, but whats weird is that it only kicks in at partial throttle (70%) but does not at full throttle. The car viscously stops like power is cut at 5000rpm and then kicks back in and then does it again towards redline.

This is the true effect of R&R yes?

But when at 100% throttle the viscous cuts do not happen, what happens instead is that it doesn't feel like the car is pulling smoothly as it should. There would be very small and hard to feel stutters and flat spots towards redline.

If the above at 70% throttle is R&R, then what am I experiencing at 100%?

So why does the power cuts happen at 70% and not 100% throttle?

Car is R34 GTT. Mods are turbo-back exhaust, fmic, apexi pod and profec B2 set to 12psi. I tapped up the coilpacks earlier today and with those runs above I didn't hear any actual mis-firing but scenerio 2 (100% throttle) could very well feel like it.

Thanks,

Andy :)

P.S - yes I've done a fair bit of searching over the past few days but couldn't find anything directly relating to my partial throttle problem so please keep the 'flaming' to limited if this has been covered before. :)

AdamsR33 Mentor

AdamsR33

Posted
Posted

ECU sees throttle at a certain point through the TPS but reads more air going in through the AFM, works out that there shouldn't be that much air going in at that throttle position and whacks in R+R. When full throttle is used, sees throttle fully open, heaps of air should be going in so... you get the picture?

Andi Experienced

Andi

Posted
  • Author
Posted

I get the first part, but at full throttle shouldn't the amount of airflow the AFM is sensing still be more then what the ECU would usually allow? Of course there would be a higher threshold for more air at higher TPS but one would assume R&R is even more likely to kick in at 100%?

R31Nismoid Grand Master

R31Nismoid

Posted
Posted

100% you have "X" air, ECU is happy with that

70% you have "Y" air, the ECU isnt happy, as it expect "X".

Its relative of the throttle position.

So @ 70% throttle ECU expects "X", and your running 12psi so its getting "Y" and its cracking the sads.

Make sense?

At full throttle there might not be enough air to trip the ECU over as its expecting around that amount because your at 100% throttle, and because your at full throttle the ECU doesnt mind it like it did @ 70%

T04GTR Grand Master

T04GTR

Posted
Posted

turn the gain don on the boost controler.

il tell you whats hapening. part throttle theres more boost in the piping compard to the manifold...

ie: your got compressor surge. wich is your turbo trying to push more air than the engines using.

please stop calling tis problen r and r, i cringe at the very thuoght of it, that is the gayest term ive ever heard. sory but it shits me all teser wanker terms floating aroud and to every mechanic is painful to read. :P

AdamsR33 Mentor

AdamsR33

Posted
Posted
turn the gain don on the boost controler.

il tell you whats hapening. part throttle theres more boost in the piping compard to the manifold...

ie: your got compressor surge. wich is your turbo trying to push more air than the engines using.

please stop calling tis problen r and r, i cringe at the very thuoght of it, that is the gayest term ive ever heard. sory but it shits me all teser wanker terms floating aroud and to every mechanic is painful to read. :P

so whats the name for it then smarty??

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

    • Celticsfan03
      Original window sticker?

      By Celticsfan03 · Posted

      Hey everyone. Is there a way I can get the original window sticker (maroney label) for my 1995 R33 GTST? I doubt I’ll be able to ever get it but it’s worth a shot to ask
    • fatz
      Neil's R33 Gts-t Build

      By fatz · Posted

      Have a vb in honour of the car comming back
    • The Bogan
      Neil's R33 Gts-t Build

      By The Bogan · Posted

      It was a great, but typical track day, and some VB was ingested at the night time debrief 🤪
    • Duncan
      Neil's R33 Gts-t Build

      By Duncan · Posted

      And so, to round this out, I couldn't be happier to confirm @MBS206 has decided to buy the car. He drove down from sunny QLD with a trailer last week and it is off to its new home today. I'll let Matt confirm on next steps but I understand broadly that the plan is to leave it pretty much as is, and just get some quality wheel time with a nicely balanced car that is pretty much track ready. There are a few a jobs still to be done first but nothing too major and I think its a very smart buy Dinner last night at the Paragon with a round of VBs (mostly) for Neil
    • Duncan
      Neil's R33 Gts-t Build

      By Duncan · Posted

      Well, 50 pages and the end of a chapter for this car. We took it out for a shakedown at Wakie yesterday, and everything went well. There were a couple of niggles: - Oil cooler fitting leak - tightened, cleaned, stopped leaking - Radiator cap overflow fitting was leaking....Mark called it, the overflow fitting was threaded in and not tight....tightened, tested and held pressure - Small oil leak at the rear of the block, probably the turbo oil feed - too hot to get at it comfortably but probably just needs to be nipped up - leak at the driver's side rear brake line where it meets the hardline. Fitting wasn't loose, so Matt backed it off and back on, no further leaks - there's also a leak somewhere on the top of the fuel tank, maybe that cross over fuel line - that was has been left to fix when its on a hoist Otherwise than those niggles the car went great, turned great and stopped great so it was a very successful day out. I'm always really nervous when a car first hits the track after a long break, especially with a brand new engine as well but it was great. VID-20251011-WA0007.mp4  Big thanks to @The Bogan who dropped by and helped out, @MBS206 and my nephew Lachlan the apprentice.  Neil's wife Mel also surprised the hell out of all of us by dropping by; she's up in Tamworth these days but was travelling to Melbourne so had plausible deniability for turning up at the garage, it was great to see her but also obviously a bit sad all round.
×
×
  • Create New...