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

    • Maf is a question mark but TPS  I have set at 0.47, the fact that I’m getting proper voltage range out of it with the key on leads me to believe it’s functioning properly. I’m getting proper voltages on basically everything. I still need to look up voltage ranges for z32 maf and test that 
    • Honestly no not at all, but it’s a very basic tune, it’s stock injectors q45 tps and z32 maf. Other than that it’s a completely stock base map. The file is from nistune and from my understanding if it was tune related I would be able to unplug maf and tps and it would still start even if it was a really shitty start. I have tried starting it with coolant temp, maf, and tps unplugged none of those 3 togethor or individually changes anything 
    • 🏆 Skyline Supremacy Meets Mount Panorama Magic 🏆 Join SAU NSW as we take the long way to Bathurst, the home of GTR greatness. Saturday 30th August 2025 7:00AM Meeting Hanna Park North Richmond 7:30AM Departure Cruise Via Bells of Line Road 9:00AM Arrival to Stop 1: Golden Poplars Meadow Flat 9:45AM Arrival to Final Destination: Mount Panorama Motor Racing Circuit Meet Location: Hanna Park North Richmond Stop 1: Golden Poplars Meadow Flat Final Destination: Mount Panorama Motor Racing Circuit   *Disclaimer* There will be a lead and follow car so no one should get lost. If you would like to attend or bring others along please put your name down and a +1 as numbers will be needed prior! This is NOT a race and we will all be adhering to all road rules. If this is what you want please come to one of our many track days. This is an official SAU:NSW event and will be run under a CAMS permit. One of the things that really sets our club apart is our commitment to being true enthusiasts. When on normal roads we strive to maintain good relations with the authorities as well as the public in general. When attending one of Skylines Australia NSW events please try to: • Be aware of surrounding environment and act accordingly. • Drive courteously on the state’s roads as a true enthusiast should. • Understand how important it is to maintain the good name of SAU NSW and thus, treat others accordingly. • Any misbehavior will not be tolerated and you will be asked to leave.
    • What does it look like with highway driving? And yes, I had a similar thought as Duncan. It looks quite similar in my Stagea and I have made myself accept it as normal. Might have to look into it some day   Highway gets as low as 10l/100km on my end so I'm not as worried about it being a mechanical issue. More likely just the tune on the haltech.
    • While I was waiting for the new parts to come in for the charge pipe and radiator I decided to do some turbo modification. The drive pressure (exhaust backpressure) was a lot higher that I thought it should be. For 32lbs of boost drive was 55lbs. The turbine housing is a 1.10AR and my turbo builder has suggested to go to a 1.25AR. To test if a larger AR would do anything to reduce drive pressure AND not spend any money I decided to hog out the divider in my current housing. I removed it from the inlet and the whole way through the housing.  After reassembly and testing it doesn't look like this modification did anything for reducing drive pressure or requiring more fuel (making more power). Oh well, it was worth a shot. We'll get some data at the track if it makes it past the 60ft. I also machined a $7 shift knob off Amazon to fit my Stillway shifter since I didn't like the Stillway shift knob. Next on the list was the radiator replacement and fabrication of a new intercooler tube that had no silicon coupler. No pictures of this - I was short on time each night after work to get this done and didn't stop to take pictures.  Next was to get the clutch disks out and replaced. Previously when installing the dogbox I had ordered a set of the same sintered iron disks I had been running because I switched to the 26-spline input shaft. I thought it was odd that they didn't have any markings or brand name on them like all my old disks had but installed them anyway. At the track I could not get the clutch to lock up using my normal strategies. After two track nights I reached out to the clutch manufacturer and ask their thoughts. They said they had to switch the material out because they were having trouble getting the original material and that this new material would not take to being slipped very well.  So out with the first set of 26-spline disks and in with the correct material 26-spline disks. While I had the trans out I added an inspection/service hole. I've wanted one of these for a while. Now I can have a look at things and change the front cover shimming when needed (clutch wear). I hustled and got the clutch change done in a few hours on a Saturday. Hopped in the car and drove home. On the way home I did a 1-3 pull. When shifting from 2nd to 3rd the core plug in the back of the cylinder head popped out and dumped all the coolant. Thankfully I was only 30 seconds from home and coasted it there. Datalog showed nothing unusual and 2.5psi of coolant pressure. That plug has been in there since 1992 but I guess it worked its way out. Pulled the trans AGAIN and replaced the plug, JB welded it in, and made a brace. Also deleted the head drain I had added in during the bearing issue fiasco.  I am currently changing my boost control plumbing to make it cleaner. After that is done I'll make another attempt at getting past the 60.
×
×
  • Create New...