GTRNUR

Hi everyone, I've been making reasonable headway with the tune of my d-jetro on my new engine but have been having low speed stability issues. I have no doubt that part of it is due to the GTRS shuffle issue. But I think the other factor is that the engine makes boost below 2000 rpm in the taller gears and I just dont have enough resolution in the low end of the RPM scale to get the transitions right. So I was thinking I could re-scale the RPM axis by sacrificing high end RPM load points, and then add more low resolution load points where I need them from 1500 to 3000. I figure if I set a 8500 RPM max map RPM and then drop the resolution to 500 RPM load bands down to 3000. So the RPM scale would look like this: 800 1200 1500 1750 2000 2250 2500 2750 3000 3500 4000 4500 5000 5500 6000 6500 7000 7500 8000 8500 My questions are has anyone else done this? Am I on track here to sort out my issue, or am I going to cause more issues by lowering the resolution in the above 3000 rpm load bands... (I figure 100 rpm isnt a lot). Suggestions appreciated. Cheers, Ian

Any idea's as to what month next year this will be held in next year? If its after March I may be able to take 2 weeks off work and drive or transport my car down. It would give a good reason to get CRD or Racepace to tune my car too.

Doesn't explain the lag though. They should spool like stock turbo's, or near enough too. Before any major retune I suggest doing the following: 1. Check the wastegate line pressure that the wastegate flap begins to move at. Adjust them to be identical. The stock actuators lift off at 0.6 bar from memory. 2. Pressure test the intake system from the MAF sensor hoses through to the plenum. The smallest leaks all contribute to LAG and an inaccurate tune. There is no point tuning a car if you can't guarantee your intake system is leak free.

+1 The base maps are enough to get your sensor calibrations correct and to drive off boost, but you certainly couldnt drive it on boost. One other thought... If your going to use twin GTR maf sensors on an ecu with only one MAF sensor input you are going to have a tune stability issue. There is always some difference between the output voltages of both sensors. The GTR ecu uses a mathmatical calculation that adds the two voltages (maf sensor values) together to work out the actual airflow. You can not do this with the RB20 pfc so the active load point will be off on occasion by at least 1-2 load cells. Tieing the two maf output signals together will not work. Their values must be read independantly and then processed. Your only option will be to use a single maf sensor, and have a single air input path to the engine.

Have a look in the folder that you installed FC Edit universal and you will see there is a bunch of maps that get installed with it. There is an R34 GTR RB26 v8.0 something map there as well. You can use the software to open the map offline and get the data that you need that way. All the GTR maf sensors have the same scale so using the R34 map for reference will be fine.

Check the front CV boots before purchasing, and also front wheel bearings. Map sensor vacuum line from the back of the plenum goes hard and splits. Then its the usual stuff. Signs of repairs, over-spray on things that shouldnt have paint like rubbers, splitter/diffuser/undertray. Look for differences in appearance of the clear coat to spot repairs. Then cold compression test, check for dodgy stereo wiring, modifications to the ecu wiring and any changes in the engine bay that are other than stock. Modifications are ok if done properly, but you'll spot those that arent pretty quickly. Having someone that already owns an R34 check it out is a good idea as well, because shopping for your dream car can be overwhelming so you can have blinders on that prevent you from seeing things that others cant.

Ive got a spare. You have a pm.

Shuffle is when one turbo begins to spool up and flows more air than the other, resulting in the slower turbo slowing down. Then an oscillation sets in as a result of exhaust back pressure and the two turbos switch back and fourth. Its really easy to see when logging with a power fc and watching the MAF sensor voltages. I was seeing at worst around 2V of difference between the two MAF sensors when under light cruise at 2000 rpm, and also if I free revved the engine to 3500 or so the maf sensors would also fluctuate wildly. As the ecu uses an average of both sensor readings this was playing havic with the tune as the percieved load point isnt actually valid. Look at my previous video with the laptop in the engine bay and watch the cursor. It should go back to the top row on the left after a rev, but instead it drops 1/2 way down the load scale as one maf sensor was reading 0 and the other was about 2v. According to the ecu it was seeing boost at idle, and as a result would over fuel the engine and it would nearly stall out. (The running lean issue I had at the time that would happen moments later was due to throttle body gaskets not sealing properly, and a split hose in the BOV opening vacuum hose which allowed the engine to injest un-metered air) Using a single MAP sensor instead of MAF solves the ECU side of the issue and allows the tune to be stabilised. The shuffle is still there and you can feel it as an instability in how the car feels when I accelerate by slowly leaning into the throttle from 2000 rpm. It doesnt feel like a dead spot like a lean or overly rich condition does as the engine is still seeing constant boost. The difference is that if you just stand on the throttle hard at 2000 rpm it doesnt shuffle, and acceleration feels much smoother. At sustained higher revs it disappears completely. The painful part of it though is that the engine drives nicely a good 1000 rpm below where the RB26 did, but that same RPM is right where the shuffling starts. ~2000 rpm.

The lifter noise isnt that bad in person. I think its the microphone on the camera. I picks up wind noise when there isnt any wind... You could probably hear me breathing if the car wasnt running.

Update. 900k's on the engine now. All still going well. Installed the Greddy radiator breather to better extract air from the cooling system, and added a cooling panel. That and having re-installed all the under panels, front lip and splitter have got the temps sitting very nice now. Still have more work to do on the tune but thats been slow progress as work has been pretty flat out lately. Not far off being able to so some more fun on boost tuning. Already though I can say this. In the lower gears (2+3rd) the engine achieves wastegate boost of 0.8 bar at 4400 rpm. Turbos are making positive manifold pressure of 0.2 bar at around 2200 rpm. Im keeping the knock below 10 across the entire map so its still a very soft tune too. Here's a few pictures, and the latest video: http://www.youtube.com/watch?v=xhXiq6evj3k Cheers, Ian

Bump again

Your injectors are way too big for a BP ultimate tune. Switch to 700's or 800's and you'll be able to get it to idle with a sane AFR... but 1600's! Unless your using E85 they are pointless. And 350awkw would be achievable.

Z442 is the best way to go. The 145a is a right pain in the ass to fit,as you cant grab it properly to do it up. And to remove itto the proximity of the front diff breather and other hoses and wires located around the filter make it a pain of an experience.

Sorry wasnt tryting to have a go at anyone... Sometimes I come off a little blunt. I guess the point I was making is you have to do well to round out the end of a grade 12.7 high tensile bolt. Your only option is you cant get anything to grab it will be to get yourself a 12mm cobolt drill bit, and slowly drill the head of the bolt off. Use PLENTY of drill/cutting lube and drill it slowly. If you go fast you'll burn the cobalt bit and it will not cut anymore. Done properly a cobalt drill bit will drill high tensile steel like its butter.

BUMP!

Indeed patience grasshopper... Don't compromise. The longer you wait for the right car to come along the better the chance of scoring something really good.

Update. I bit the bullet and installed the PFC D-jetro on the weekend. Like everyone says they are slower to setup, but once you start to get the low speed area sorted out the rest of the map falls into place quickly. I'm using a single 3 bar map sensor, wired in parallel to both maf sensor inputs instead of having to drill cylinder 2+5 throttles and install additional vacuum connections. Since the engine has stock cams I'm not having sensor fluctuation issues, and the engine produces excelent vacuum at idle and low speeds. -450 at idle when hot @ 950 rpm. I've completed the low end fuel mapping and a little of light boost tuning. Drivability and throttle response is MUCH better than the L-jetro was, and the transition onto boost is much smoother now. Although the turbo shuffle is still there and you can feel it around 2500 rpm, you can drive through it and it goes away. I have installed my earls oil cooler and remote filter setup. Street tuning on the weekend has just over 800km on the engine. Oil temps are now within 10 degrees of water all the time now. But temps in general are getting pretty out of control when stuck in traffic (mid 90's). Outside ambient air temp was 41 degrees when driving around at midday on saturday, and I still havent bolted on the under trays and front splitter yet... which I have learned are instrumental in having your radiator NOT re-circulate hot air when your idling along in traffic. In the 80km/h+ zones temps drop to high 70's which is acceptable considering how hot it is outside. Thankfully the air conditioning works really well. I've just ordered a greddy air seperation tank and cooling panel from high octane, which will go a long way to sorting out the heat issues at low speed. The last compression test had all cylinders within 10psi but Im holding off doing on boost tuning till I have at least 1000k's on the clock. What I have done on boost though is just awesome to experience.

You need a metrinch socket set, or at least a loan of a socket that will fit the head bolt. They grip the flat of the bolt. There is a chance that will get you out of trouble. If you've managed to stuff the head bolt too, I dare say that most thing mechanical are best not done by you. Ive seen whole cars destroyed by people that have their ambitions mixed up with their capabilities, the result of which was a good 1/2 of everthing removed from their skyline was rooted. Some people shouldnt have tools, and especially hammers.

PFC d-jetro removed from sale... Im keeping it. L-jetro is being sold instead now. http://www.skylinesaustralia.com/forums/topic/346525-r34-gtr-l-jetro-power-fc/ Injectors are still for sale: 6 x R34 GTR Vspec 2 injectors. Approx 35,000km on them $300

For sale. 1 x R34 GTR L-Jetro power fc with hand controller. $900. Selling because I've switched to d-jetro. Pm or call me on 0434 147 478. Cheers

The best choice at the moment would be the new GTX3582R. Better than GT35R response with more flow than a TO4z.

You can pull the pin heights for an RB30 piston from 32mm (stock) back to 27mm with a custom piston height and a stock 21mm gudgen. Then you can use common 6" rods on the 95mm crank. That would be my choice to keep the rod ratio up. The other option is to use a custom piston with a less agressive pin height change (say 28mm) and then use old "school approach" with a thicker gasket (1.5mm) to accomodate a positive deck and achieve a good 1mm deck height. I think many of you are missing the point of the stroker engine. The whole point is that you dont have to rev them, so frankly who cares if it cant rev past 8000 rpm. Look at what the R35's rev too. Displacement really does make a huge difference. And not just in when a turbo starts to respond, or hit wastegate boost. The off boost drive is much better. Throttle response is much quicker. Also matching a head and cam configuration to the added displacement to "optimise" the package for peak power or torque isnt necessarily the ideal goal anymore. This is the conventional thinking with a stock displacement Rb25/26, to try and ring every last kw/nm out of the displacement. However suppose you can reach your power goal without having to run crazy cam and port head porting. The result will be an engine that has street manners. It will be easier to drive than an identically powered smaller engine because it will idle like stock, and produce usable torque below 1500 rpm.

2-3 seconds of detonation can break an engine easy. Pick your failure. Broken ring lands, or spun bearings as a result of the rod bearings taking a hammering. Also, by "its a 100k old engine thats been modded and leaned on", White R32 meant an engine thats been tuned to within an inch of its life. Not an engine that has been tuned with a lean air/fuel ratio. Most, if not all tuners tuning random cars off the street will always tune to the safe side of things. This means a little richer than makes optimal power and a little less ignition advance in order to keep it safe. Only when you show up at a workshop with a bucket of money and request a massive horsepower goal will a tuner go for broke on a tune. And in some of those situations a potential engine failure during tuning/R&D is factored into the quotation. As for the evo, only a forensic examination will tell the story.

Interesting that the pipe mod isnt a cure-all after all then. Ive been thinking more about why the shuffle is so bad with my setup, and I think it comes down to the extra displacement. The GTRS's are an un-balanced turbo, known for having shuffling issues on everything from 2.6lt upwards. I think the difference is however that the smaller displacement engines arent producing enough exhaust gas flow to get the turbo anywhere near spooling under light load or even load up a hill in a tall gear. But when you kick back a gear or two and rev from 5-9k, as engines with these turbo's commonly do, both turbos are spooling up evenly as a more or less matched pair with near identical exhaust restriction. I've discovered that if I load up my engine up in a tall gear I can actually get positive manifold pressure (0.1-0.2 bar) below 2000 rpm. So the the moment the engine loads, up the gas flow is there and ready to start making boost. So on the bright side I have more or less achieved my "like stock" response, there is just the matter of the shuffle to resolve and thats it. Ive also discovered that if I drive the car in what would be the "normal" rev range that the RB26's drive comfortably in (one gear lower generall), the shuffle problem isnt as evident. Because at a higher RPM in a lower gear the engine is under less load (running in higher vacuum), but when I stand on the throttle, the turbo's skip the shuffle and immediatly jump to 0.5 to 0.7 bar. Im still driving the car to work every day. Only 300K to go till I can crank a power tune into it so Ive got to make a decision about a map based ecu soon.

Ive got an R34 Djetro here that I can use so i'll probably give that a go next week, but I am also considering Vipec. Cams changes are a ways off, but at the most it will end up being 260 poncams or possibly something custom.