Jump to content
SAU Community

Recommended Posts

Hi Lads,

Rex Has his KingPinny 'budget hack' on the Dyno the other day for its post-build, pre-thrash checkup. It makes respectable grunt with AFR's sticking nicely between 12.3 and 11:1 for the whole run.

However at the top of the run just prior to limiter (perhaps 500rpm) the AFR suddenly makes a dead vertical up past 14:1 which is where the operator jumps off the acceleratix. We repeated the run three times, peak power was within 2-3rwkw and the same massive sudden vertical leanout condition.

The dyno was done as a favour so no fault finding was performed, Rex was thinking that perhaps the AFM may be faulty (NIssan's are renowned for them) causing the ECU to basically drop the injector duty cycle right off.

The engine R32 RB20DET and is stock, along with the ECU and turbo etc. Only modifications are filter, exhaust and intercooler setup. Boost is un-modified but up to 11psi due to removal of restrictions in pipework etc.

Rex has considered AFM maxing however it seems more likely that Mr ECU would just go massively rich safety-like instead of lean.

Anyone seen/heard similar problems? He has seen a couple of other graphs with the same problem, but not an explanation.

Rex has some diagnosis to do on Mondey such as AFM peak voltage etc, but would be good to have some things to check if He runs dry ideas wise. It also seems very unlikey to be a fuelling issue because of the shape of the graph.

Have included printout below if it helps...

KingPinnyupload.jpg

Thanks Lads

Rex

Link to comment
https://www.sau.com.au/forums/topic/142860-massive-sudden-lean-out-rb20det/
Share on other sites

Rex considered fuel pump not to be the problem because surely if pressure couldn't be maintained the AFR would rise gradually. PUMP is R32 GTR

Fuel injectors maybe, but supposedly they are good for 230odd rwkw at 100% DutyCycle. HOWEVER with stock reg, He knows not.

Sounds like Rex may need a slightly different Multimeter...

As for the power, trust Him, Rex cannot believe it either. Approx 140rwkw would've been a delight but the 192.6rwkw peak almost made Rex pass-out.

Edited by Rex_Kelway
Rex considered fuel pump not to be the problem because surely if pressure couldn't be maintained the AFR would rise gradually.

Fuel injectors maybe, but supposedly they are good for 230odd rwkw at 100% DutyCycle. HOWEVER with stock reg, He knows not.

Sounds like Rex may need a slightly different Multimeter...

Injector size: 270 cc/min injectors(25.7 lbs/hour)

Number of injectors: 6

BSFC: 0.65

Duty cycle: 100%

This combination will supply fuel for 237 horsepower

237hp = 182kw...

I knew this was going to happen, believe Rex he has heard it muchly since the day it was dyno'ed.

The engine is approx 60,000kms ex-GTS4 R32 from around 1993 He believes. Wether or not they use a different turbo (M-spec or whatever??) He knows not, but it IS the turbo that came in the half-cut. On Mondey he shall get serial no's to confirm.

Rex works for an importer, and yanked the motor out himself.

The car was 100% stock, no filter not even a timer or boost gauge. all of the factory bolts/sheilds/gaskets/retainers were in place with no signs of ever have being removed. Thats whay leads Rex to believe its stock.

Believe it or not the turbo is not the 'be all and end all' of the intake system. It is VERY dependant on the systems around it.

This was designed to be a help diagnose thread, not a 'you're a liar' thread. The Dyno may be wrong, but the operator has done it a thousand times. The car does feel that fast.

Back to the problem...

Fuel pressure shall be checked on Mondey to be sure

Edited by Rex_Kelway

no one is calling anyone a liar. the figures quoted are at the top end of the believable scale.

all we are doing is trying to help diagnose a problem. if you get as many suggestions as possible, you can eleminate them one by one.

craig

Yep, maybe a bit premature ;) ...

Rex is just geared for the 'Thats too much power, its impossible...You're a liar!!!' arguement that is likely to follow that printout and specs list.

Edited by Rex_Kelway

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


  • Similar Content

  • Latest Posts

    • Mate you saved be from dying in the Perth summer. AC wasn't changing direction and just going into diagnostics mode fixed it. You're a legend and I would shout you a beer if I could!
    • Unfortunately effort gone to waste, you will have substantial issues with how the manifold and wastegate have been integrated. You would be so much better off with a modified stock manifold like this: https://hypergearturbos.com/product/rb25detexgatedmanifold/   OR literally just getting a off the shelf Sinco or 6Boost manifold as myself and others have mentioned.  
    • Yuck. But it's kinda the same principle, moving timing around to make car run bad but sound good.... I went for a more spirited tuning drive to iron out a few things. Car no longer stalls, and it loved to dip RPM low when you clutch in. After tuning this (and the 4-5 tables that HPTuners/LS1 OEM ECU wants for idle air correction) it's now behaving somewhat normal. All expected because there's a new TB, new Intake manifold and that new TB which is 102mm vs 78... has an entirely different IAC passage which is smaller because ????? Unfortunately at this point I went to make further fine tuning changes to avoid it flaring up, you know... _tuning_ the HPTuners dongle died. Well to be more accurate - The USB cable died in a fashion that anyone who has ever charged a phone will recognize. After the app demanding I resync it 50 or so times (which all 'succeeded' but all failed) the device does not want to sync and I've logged a ticket with support to see if it's fixable. US Support said it was a 'storage issue' but after removing the SD card inside it and formatting it/fixing it the issue does persist. Unfortunately usually the fix is "Turn in your old dongle and pay $700 for the upgraded one" it's cheaper because I get some free licence credits I unfortunately don't need. However I'm 10 minutes down the road from HP Tuners AUS/VCM so at least I won't need to post it, and logged a new ticket for support over here. Definitely drives different. My SOTP dyno believes it's probably making 310-320kw instead of the 280 before.  It scrambles for traction a little now whereas it previously different. It drives like a bigger cam car up top even though the cam is smaller, likely due to the cam not being advanced 6 degrees. The timing is deliberately low and the fuel is very rich so who knows if this will improve on the dyno. It may, imperceptably. Also funny is removing the pineapples definitely makes the car squat more and axle tramp less. So this behavior of having more top end, squatting more, and scrabbling for traction more makes me think = more power. But I could have just been sitting on the threshold of that kind of behavior before. Time will tell if my butt dyno is calibrated right. I need the exhaust leaks fixed before dyno tune for obvious AFR related reasons - I repositioned the pipes but I'm not confident it's fully sealed even if it is better. At least the car does drive around while I cannot tweak/tune it for now. And I have aircon again. medium success!
    • Don't use that manifold. Please don't use that manifold. Sunk cost fallacy is not worth the later pain. None of these will be relevant to the change that will come from the different turbo and manifold. As in, the effect of the exhaust will be nil, regardless of what else is changed. And all the cam and fuel system stuff is not changing either way, so has no effect. The turbo and manifold (and to a small extent the wastegate)....big change.
×
×
  • Create New...