BNR32 RB26 , motec M84 missfire

[Nightcrawler_32]

Hi guys. 

New to the RB26 scene. 

Bought the car last month and plan o. restoring it bit by bit ...

Engine Mods on the car: 

- Motec M84 

- walbro 525 pump 

- Aeromotive fuel regulator

- ARC intake box 

- Intercooler 

- HKS intercooler pipes 

- Titanuim down pipes and catback.

- Greddy spark plugs 

 

issue, cat had RPM hesitation before and when i got it i did a full replacement for old oils and consumables and installed the motec and tuned it on 0.6bar ... cat drove fine for couple if days then started missing 

 

took back again to the tuner, he said it shows that there isnt enough fuel, so i installed the  pump, regulator and returned .. got good gains.. car drove very nice when i took it from the tuner, next day the car stated missing again and RPM wouldn't go and car will start backfiring at 4-5k RPM . 

 

No maffs any more as motec uses Map sesnor. 

 

any ideas ?? 

 

 

 

 

 

[r32-25t]

Coil packs or spark plug gap would be the first thing id look at 

[GTSBoy]

If you replaced the coils and now it still misses then the most likely ignition cause is the ignitor.

There's various other things like worn CAS bearings, dirty plug contacts on CAS and AFM and so on that can also start to play up only when you get it hot enough. But the ignitor is the most likely.

[Nightcrawler_32]

Update: 
After long checking we found that the pipes in the fuel pipes was worn out and when on pressure the pipes will leak which causes drop in the fuel pressure and gives hesitation. 

anyways .. car is ok.. retuned again after fixing it .. 

6 PSI: 210 WHP

10 PSI: 310 WHP

all above on dyno jet. 

 

 

next mods on the way: 

• Nitto Oil pump 
• N1 water pump 
• Tomie timing belt. 
• PRP R35 coils conversion kit. 
• Nismo thermostat 
• Nismo Bushings (gear and engine)
• Carbonsignal Center console Gauges set for the R32 
  • Boost gauge 
  • Oil Pressure 
  • A/F ratio 

After the oil pump will top the boost to 1 bar and see how it goes. 

 

[Dose Pipe Sutututu]

Stock timing belt, stock thermostat save your money for new single turbo, because we all know the twin turbos belong in the bin.

And before anyone says, but it's a GT-R it needs twin turbos.. yeah how many fast/responsive/great transient response/powerful Toyota Supras do you see with twins?

 

[joshuaho96]

Twin turbos make sense if your power goals are something like 300 kw.

[Dose Pipe Sutututu]

A nice, well thought out twin scroll single turbo makes sense too for 300kW, thing would be on so much earlier than a pair of gay twins

 

[KiwiRS4T]

What he said...stock belt, stock thermostat, stock water pump and single turbo!

http://www.goodezilla.com/rb26dett-skyline-gtr-single-turbo-vs-twin-turbo

[joshuaho96]

10 hours ago, Dose Pipe Sutututu said:

A nice, well thought out twin scroll single turbo makes sense too for 300kW, thing would be on so much earlier than a pair of gay twins

 

But why bother for such conservative power goals? The HKS GT3-SS turbos are pretty good at modernizing the mid-range of the RB26, the rest is just the limitations of fixed valve timing and low compression ratio that comes with an engine designed in the 80s.

I'm not arguing against the logic that a larger single turbo is more efficient and you can run a more modern single turbo to get better response. But I think top mount single raises questions in my mind regarding emissions compliance, long run durability, thermal management, and proper intake design.

I think the answer isn't as clearcut as that Motive video makes it out to be. If the only metric of value is how much power the engine can produce across the RPM range then the answer is simple but there are more variables to consider.

[GTSBoy]

56 minutes ago, joshuaho96 said:

But I think top mount single raises questions in my mind regarding emissions compliance, long run durability, thermal management, and proper intake design.

All of those questions are moot.

• You change the factory twins to something else and the emissions compliance is already f**ked. Not to mention that you will have to be tuning the/an ECU and that is against the rules anyway.
• Any new (big) single will have exactly the same life expectancy, at minimum, as any replacement twins. Probably better, because
• Thermal management should be a walk in the park with a single, compared to low mount twins. Regardless of whether the single is high or low mounted, you don't have one turbo snuggled up against the exhaust outlet of the other, inlet air coming past hot exhaust components. You can insulate the manifold, rear housing and dump more easily when you only have to fit one turbo into the space, instead of 2 turbos and all their associated plumbing. And if you high mount it, you just put some decent shielding on the bonnet also, and make sure some air is ducted up to the top of the engine bay.
• Proper intake design........ at what crazy place in anybody's imagination is a twin turbo intake system easier to get right than a single?

 

[joshuaho96]

33 minutes ago, GTSBoy said:

All of those questions are moot.

• You change the factory twins to something else and the emissions compliance is already f**ked. Not to mention that you will have to be tuning the/an ECU and that is against the rules anyway.
• Any new (big) single will have exactly the same life expectancy, at minimum, as any replacement twins. Probably better, because
• Thermal management should be a walk in the park with a single, compared to low mount twins. Regardless of whether the single is high or low mounted, you don't have one turbo snuggled up against the exhaust outlet of the other, inlet air coming past hot exhaust components. You can insulate the manifold, rear housing and dump more easily when you only have to fit one turbo into the space, instead of 2 turbos and all their associated plumbing. And if you high mount it, you just put some decent shielding on the bonnet also, and make sure some air is ducted up to the top of the engine bay.
• Proper intake design........ at what crazy place in anybody's imagination is a twin turbo intake system easier to get right than a single?

 

I'm not speaking about what will and won't pass the local emissions laws. As far as most places are concerned the instant you modify anything between the air filter and the last catalytic converter you've failed emissions. But looking at the header design it seems pretty clear to me that the exhaust manifold on a high mount single RB26 is going to have a longer path from exhaust valve to a catalytic converter. Cold start emissions is a big problem with these engines and I'm pretty confident that will make the problem worse. To me that is a problem but YMMV. A low mount manifold could in theory do better but everything out there doesn't look like a good fit for the use case I'm thinking of.

Everything else is true if you're talking about a clean sheet design. Single turbos are easier to package, less headaches regarding how to merge the two turbos. Modern engines use twin scroll single instead of bothering with this twin turbo nonsense. But this isn't a clean sheet design, the two paths are bolt-on twins vs a single turbo conversion. The bolt-on turbos are a known quantity and the OEM engineers have already gone through the effort of making sure it meets their internal metrics for quality. A single turbo conversion is just not going to measure up to that if the goal is to play it safe and try and keep it as reliable as OEM, if not more so.

Edited January 22, 2020 by joshuaho96

[GTSBoy]

1 minute ago, joshuaho96 said:

Cold start emissions is a big problem with these engines and I'm pretty confident that will make the problem worse.

That makes no sense. Why would you care about cold start emissions specifically but not the fact that your emissions compliance is completely out the window (both legally and in material effect of what's flowing out the exhaust) as soon as you modify? Authorities and OEMs make a big deal of cold start emissions, but in the context of how much it contributes to the total emissions emitted by your car, it's only a really short fraction of the operating time. Worrying about it and not worrying about the rest of the operation is fuzzy logic.

 

5 minutes ago, joshuaho96 said:

The bolt-on turbos are a known quantity and the OEM engineers have already gone through the effort of making sure it meets their internal metrics for quality. A single turbo conversion is just not going to measure up to that if the goal is to play it safe and try and keep it as reliable as OEM, if not more so.

Also makes no sense. It's like saying "I was born with 3 legs and no dick so I'll just stay that way".

[joshuaho96]

Just now, GTSBoy said:

That makes no sense. Why would you care about cold start emissions specifically but not the fact that your emissions compliance is completely out the window (both legally and in material effect of what's flowing out the exhaust) as soon as you modify? Authorities and OEMs make a big deal of cold start emissions, but in the context of how much it contributes to the total emissions emitted by your car, it's only a really short fraction of the operating time. Worrying about it and not worrying about the rest of the operation is fuzzy logic.

 

Also makes no sense. It's like saying "I was born with 3 legs and no dick so I'll just stay that way".

It matters in the sense that it's easy to hide bolt-on twins when they're crammed under a bunch of heat shields and piping, unless you've really attracted some serious attention for whatever reason nobody is going to be trying to carefully read off what the turbo says to identify it as stock or not. Similarly, no one is going to be opening up an ECU or removing the kick panel to verify that you are actually running the stock ECU. As long as the exhaust gas sniffer says you passed and nothing is clearly wrong it's not hard to pass. Rolling up with a high mount single is going to be a very different story.

It's also weird to me that you would make this comparison between being born deformed and the twin vs single turbo choice. Clearly there is still value to twin mono-scroll turbos as seen in the BMW S55 and S58 I6TT engines and they manage a far wider powerband than anything an RB30 is capable of with better BSFC everywhere, higher knock threshold everywhere, significantly lighter weight, and overall much better refinement. Clearly there's something there that is not as simple as single turbo good twin turbo bad. I'm not advocating for cargo cult engineering here but I'd like to know why BMW engineers would elect to go with twin turbos on the S55/58 and single turbo on the N55/B58 when they have the resources to spec a larger single on the higher spec models.

[Dose Pipe Sutututu]

10 minutes ago, joshuaho96 said:

Clearly there is still value to twin mono-scroll turbos as seen in the BMW S55 and S58 I6TT engines and they manage a far wider powerband than anything an RB30 is capable of with better BSFC everywhere, higher knock threshold everywhere, significantly lighter weight, and overall much better refinement.

You forget that's a DI motor, with variable cam & valve timing, better everything from cylinder head design to block & rotating assembly.

Yes they use twins, but if you look carefully the pressure side pre-IC is near identical in length all the way into the W2A IC core which then it's only merged afterwards reducing turbulence - thus reducing the infamous aids turbo shuffle the RB26DETT exhibits.

The RB26DETT Twin Aids turbo charger layout is simply a hot mess of inefficiency.

[joshuaho96]

1 minute ago, Dose Pipe Sutututu said:

You forget that's a DI motor, with variable cam & valve timing, better everything from cylinder head design to block & rotating assembly.

Yes they use twins, but if you look carefully the pressure side pre-IC is near identical in length all the way into the W2A IC core which then it's only merged afterwards reducing turbulence - thus reducing the infamous homosexual turbo shuffle the RB26DETT exhibits.

The RB26DETT Twin Aids turbo charger layout is simply a hot mess of inefficiency.

I'm aware that it's a DI motor with VVT + VVL and a number of other changes. My point is that even now when BMW has the option to ship a single turbo for an I6 in their 500 hp+ models they elect to continue with twin mono-scroll turbos instead. Clearly it's not as cut and dry as is being claimed by Andrew Hawkins et al.

The RB26 turbo shuffle is a problem but isn't intractable, it seems like much of the problem is related to the twin turbo pipe and the near 90 degree merge. I don't think that alone really justifies the expense and headache of figuring out how to retrofit a single turbo to a motor that never shipped in that configuration.

[Ben C34]

4 minutes ago, joshuaho96 said:

expense and headache of figuring out how to retrofit a single turbo to a motor

expense perhaps, as you need to buy a manifold. Headache? it is easier.

[joshuaho96]

Just now, Ben C34 said:

expense perhaps, as you need to buy a manifold. Headache? it is easier.

The headache is in validating that the thing will fit correctly, won't crack/corrode, that the oil lines and water lines for the turbo are properly routed and won't fail 50-60k miles down the road, that the intake is properly designed to not suck rain into the engine, properly mounted, has appropriate flow characteristics without weird resonances, can fit a MAF without a bunch of signal noise if ITBs are retained, and all the unknown unknowns that come with trying to make significant changes to the intake and exhaust of a turbo car without the experience or knowledge of what works and what doesn't.

I just don't see a convincing case for spending a lot of money on a single turbo conversion when the power goals are conservative and the primary interest is in a reliable street car. The goal is to drive the thing, not to keep it in the garage as a permanent project.

[GTSBoy]

1 hour ago, joshuaho96 said:

The headache is in validating that the thing will fit correctly, won't crack/corrode, that the oil lines and water lines for the turbo are properly routed and won't fail 50-60k miles down the road, that the intake is properly designed to not suck rain into the engine, properly mounted, has appropriate flow characteristics without weird resonances, can fit a MAF without a bunch of signal noise if ITBs are retained, and all the unknown unknowns that come with trying to make significant changes to the intake and exhaust of a turbo car without the experience or knowledge of what works and what doesn't.

None of that is a problem for anyone who can think and who can google a little bit to see what mistakes to avoid. AFM (correct term for a Nissan) is no problem, whether using Nistune or any aftermarket ECU. Can go intake side, can go boost side, can be deleted. Not even worth the time bringing it up. And, here's the kicker.....you say "without the experience or knowledge of what works and what doesn't". Um...this stuff has been done for 30 years now. There is plenty of knowledge and experience. It wouldn't take me 3 minutes to decide on a plan and a shopping list, and I don't even own a GTR.

[joshuaho96]

14 minutes ago, GTSBoy said:

None of that is a problem for anyone who can think and who can google a little bit to see what mistakes to avoid. AFM (correct term for a Nissan) is no problem, whether using Nistune or any aftermarket ECU. Can go intake side, can go boost side, can be deleted. Not even worth the time bringing it up. And, here's the kicker.....you say "without the experience or knowledge of what works and what doesn't". Um...this stuff has been done for 30 years now. There is plenty of knowledge and experience. It wouldn't take me 3 minutes to decide on a plan and a shopping list, and I don't even own a GTR.

I'm aware it's been done for a while now, just not in the form I'm looking for. Not interested in high mount, low mount manifolds are few and far between and generally not recommended, I would really want a cast manifold for longevity reasons, bolt-on kit with heat shields, piping, etc all ready to go with a proper airbox/paper filter/snorkel for cold air intake. I don't think I've seen a single single turbo conversion that actually looks like what I'm interested in.

Also, the HKS GT3-SS really helps with low-end spool and mid-range for a mostly stock car, based on the dyno curves I've seen. The cost benefit analysis doesn't necessarily make sense per se but frankly if I were buying based on performance per dollar I would get a Corvette.

[Dose Pipe Sutututu]

Another reason I advocate buying a BMW M4, spend money on a flash, full TBE,  better IC and it would destroy any R32~34 GT-R around a circuit, and at the drag strip.

Because hey, no matter what @GTSBoy and I say you're going to refute it.