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Few questions after latest tuning session.

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Hey guys, rather then making multiple threads I thought id just make one... I feel I learn something new after every tuning session but also have just as many new questions.

#1 Fuel pressure:

I Fit a 450LPH in tank pump in preparation of upgrades in the future but at the moment still have stock rail/injectors but using a Turbosmart FPR800 fuel pressure reg. I noticed that even with the FPR wound right out the pressure at idle was 46-47psi... I was planning to set base pressure at 3bar/43.5 psi But obviously couldnt and didnt think it a good idea to have the FPR wound right out so I set base pressure to 50psi.

Now this didnt really present any problems during tuning but I do have a concern as it doesnt seem normal... and not sure if it could cause any problems in the future if for example the fuel filter was restricted etc? Also wondering what the cause would be, Im thinking its because of the Large fuel pump and also maybe the stock restrictive fuel rail another factor?

#2 Inducing Knock

What is the best RPM/Load range to try and induce light knock in order to setup/check your knock monitoring system is working? also steady state or ramp run? do you just advance timing or lean the mixture out or both.... I tried inducing knock at 2000rpm just off full throttle by advancing the timing but got to 50 degree's and couldnt hear anything... was worried it was knocking and I just couldnt hear it so didnt go any further... which didnt inspire confidence in my knock detection system. I increased the frequency range and sensitivity in the gizmo k-mon settings but still didnt hear anything... was centered on 6.7hz on RB25DET with 87mm bore. I didnt hear knock at all throughout tuning the car but was only going up to 13psi so didn't really expect any either

#3 PID Settings for wideband o2

Used Haltechs CAN WB o2 for the first time... there is only P and I settings for it and no D.... Stock haltech settings are 110 Proportional and 5 Intergral I found this a little slow to respond and never actually made it to target in steady state. I settled with 110P and 8 I which seemed better but I still not sure Ive got it as best as it can be. So yeh just curious whats the best way to setup o2 PID's? just sitting at idle... steady state or ramp runs etc? P didnt seem to have all that much effect at all but I did very much so

#4 RIP Hi-Flow OP6

We originally had a Hi-flowed OP6 turbo supposedly done by GCG (was bought second hand) the bearings felt nice before I fitted it... had it on the car and got to 300rwhp then the next run boost and power fell greatly... some quick investigating and found the turbo;s bearings were shot! the wheels were fine besides some minor touching on the housings. So just curious what the causes could have been... Had full oil pressure to the turbo. was no numbers on the core at all but from wheel measurements think it was around a 30/71. I guess it could have been dirt ingress at some point as the sump was off the engine for awhile. was abit of a bummer but still made 275rwhp on 13psi with the stock turbo.


Bout your fuelpressure issue. I'm pretty sure you are just overwhelming the regulator and possibly the return system with that large pump of yours. How do you have it hooked up? Running full 14 volts all the time, or is something regulating it?

1. If the return port on the regulator is too small, this will result in an inability to drop the pressure to your target. The fuel pump you're using is probably a touch large for an FPR 800 and hence it can't flow enough through the return port. A really crude and coarse calculation to work out potential power from fuel flow is that you require 1.0 litres/min for every 200 hp. At a rated 450 lph, this pump can support somewhere around 1500 hp on petrol so it's a little way above the suggested use of the FPR800. The flow from that pump is dependent on pressure too and from the online data you're more likely to be around 400 lph at 50 psi pressure and 13.5 volts. This is still sufficient fuel for 1300 hp or thereabouts.

2. I induce knock in steady state at WOT and perhaps 2000-3000 rpm. You can usually/often find that under light load conditions such as 2000 rpm cruise, you won't be able to physically make the engine knock regardless of the timing.

3. I haven't found the need to alter the P & I settings from their factory default in our 350Z plug in ECU, although they are dramatically different to what you've mentioned. Load up a Z33 base map and have a look. The only thing I did need to do was to alter the recalculation rate which is essentially how long the ECU will wait before applying a further adjustment. Under low rpm/low load you need to have a longer delay due to the lower exhaust mass flow.

4. There are so many potential reasons for a turbo to fail that it's hard to know where to start. It doesn't take much running with debris in the turbo oil feed to damage the bearings. It's always a risk I guess with 2nd hand product too.

Does the car have a pump speed controller? It might be an idea if the rest of the fuel system is too restrictive to use one. Using a PWM pump speed control you can reduce the flow without straining the pump from trying to work with lower voltages, that is a killer for some pumps.

Second hand turbo's are a complete lottery, when they are removed from the previous engine any manner of contamination could get in there, I have also seen turbo's killed from not being primed properly, running the engine before the turbo has had a proper flush of fresh oil will wear the bearings, journal more than bb, leading to premature failure. The people fitting the turbo's never understand why the vehicle leaves fine but has a turbo failure within days, weeks or months.

#1 Cheers guys, yeh its just constant 12V ill recommend either a larger Reg or PWM controller for him....

#3 I had a look at the Z33 basemap Andre and its O2 control scheme is VERY different to what they have for the base R33 RB25DET tune. Ive attached the tune file ive got for this particular car... If ya get a chance feel free to look over the rest of the tune and let me know if anything seems odd/wrong

Attached Files

For the FPR issue you can run a long hose from the FPR return into a fuel can or a bucket and see if the pressure drops, if it does then maybe you have a restriction in the fuel line or tank fitting (crushed line etc) if the fuel pressure remains the same then you will know the fpr is just not able to bypass the fuel. Ive installed walbro 450 pump and Aeromotive FPR A1000 and didn't have issues in a r32 rb26 setup but that's a little different from yours.

Good day gentlemen.

Just a curious observation having read through the thread, but with the suspicions surrounding the fuel system, wouldn't it be interesting to see what the peak rail pressure was and in addition the consistency of the differential fuel pressure? Unless I was responsible for the fuel system setup I am always skeptical enough to fit fuel temperature and fuel pressure sensors. In most cases it has been more than what has been needed but the data presented has always been insightful for clients.

Also, there are two operational conditions of a fuel which are almost always going to be paramount. Fuel flow is one, but I find that fuel pressure data is highly overlooked. Especially when it comes to the advertising of fuel system components. Most fuel pumps give a fuel flow but rarely ever mention the peak rail pressure which it can support. This sort of information can weigh in quite heavily if the fuel system in question isn't going to be used at the traditional differential fuel pressure. Fuel Pressure regulator also have a supported fuel pressure beyond which point that don't work as intended, but this is hardly ever mention in the advertising.

One last detail of interest for fuel pumps has been the fuel pressure and fuel flow slopes as they relate to voltage, I was amazed at the data supplied by some common manufacturers. Or private test bench scenarios for that matter.

These are a few of the instances I wanted to share based on my work experience which is somewhat relative to this thread.

I hope that my contributions have added some merit and not caused any ills.

In this case Damien the information for the Walbro 450 lph pump is quite thorough and available fairly widely online - http://walbrofuelpumps.com/walbro-f90000267-fuel-pump-e85

My own experience with aftermarket regulators has been that the high end of their pressure control is seldom an issue - Put it this way, I've never run out of adjustability with a regulator where I couldn't achieve a high enough fuel pressure. on the other hand I've had several situations where the return port on the reg restricted flow enough to artificially limit pressure on the low side.

Andre, thanks for following up.

The data provided is exactly what I was referring to. The advertised fuel flow rating is only available at a voltage of 13.5 and even then the supported pressure is 30 PSI. My illustration was based on having seen poorly put together fuel system based on poor advertising information. Why not make a small notation for supporting voltage and pressure of this 450 LPH rating? To combat this I find that having fuel pressure data has helped clients make sense of advisories.

With respect the fuel pressure capability for regulators, I've had lots of issues but they've been related to poor quality units mostly. One easy tell tale sign would be port sizes. Setting the desired (above the usual 3BAR) differential pressure at idle isn't too bad, however, while the fuel system is supporting an engine under load then there are inconsistencies; especially when the engine load has raised the pressure demand of the fuel pump past the fuel flow requirements.

Perhaps I'm just a little over dramatic to explain myself in a manner which is helpful (sharing) or I'm splitting hairs with bad forum manners but these are some of the hiccups I have encountered.


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