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Going for 500+hp, need advice


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I just installed some Bosch 870cc injectors and now it wont start.. Will there now be a problem that it dumps too much fuel in the engine after installing bigger injectors or should it be plug and play? I thought I could at least start the car and drive it slowly to get a tune but guess not? Do I have to put my old injectors back in and install the 870cc when im at the tuner?

Edited by The Skyline Guy
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On 04/12/2021 at 1:13 PM, Ben C34 said:

It should be fairly obvious you can't double fuel flow and expect the car to run.

Im not the most experienced, thats why I ask you guys. I somehow thought that the ecu knew how much fuel it needed and could regulate the flow... Anyway it started right back up once I put the stock injectors back in.

Looks like ive got a IMPUL ECU in my car "HI-POWER CONTROL UNIT 34GTR 4 6 8" can I just use this ECU for when I get a dyno tune with the upgraded turbos, fuel pump and injectors? Can someone tell me what I need and why?

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On 12/5/2021 at 12:01 AM, The Skyline Guy said:

Im not the most experienced, thats why I ask you guys. I somehow thought that the ecu knew how much fuel it needed and could regulate the flow... Anyway it started right back up once I put the stock injectors back in.

Looks like ive got a IMPUL ECU in my car "HI-POWER CONTROL UNIT 34GTR 4 6 8" can I just use this ECU for when I get a dyno tune with the upgraded turbos, fuel pump and injectors? Can someone tell me what I need and why?

I suggest you just need to sit down and do lots of reading/ research before you do anything else.

all the questions you have asked have been covered multiple times of the past 20 years 

you have gone and bought an AUS $200k car and trying to mess with it without having a clue what you are doing.

my advice. If you have that cash to spend on the car and don’t have a clue about them, just take it to a reputable performance shop, tell them what u want and then hand over more of your money

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Basically, the standard ECU and the IMPUL ECU are effectively locked to a single tune. The ECU works within a set of known parameters, looks at the inputs, processes them and decides what outputs. One (well 6) of the outputs are the fuel injectors and they are fired based on revs, load and some other small adjustments like engine temp, oxygen sensors etc.

With an non-programmable ECU, every input and output has to be exactly the way the factory expected, and so does the engine system itself. So, you can't change airflow meter (input), injectors (output) or turbo (engine system/ total airflow). Also, everything has be in good working order, eg the fuel pump and fuel pressure regulator need to supply the expected fuel pressure and the coils need to supply sufficient spark.

Keep in mind you are dealing with cutting edge electronics from the early 90s.

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You need to purchase and have installed a fully programmable ECU to get more than about 10% more power. Your profile doesn't say where you are so it is hard to recommend, but in Australia Nistune (basic), PowerFC (basic but with a display), Link or Haltech would be the go. But the big factor is that it needs to be tuned, and you need to pick an ECU your tuner is comfortable with or it will cost much more while they learn it. 

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On 12/4/2021 at 5:01 AM, The Skyline Guy said:

Im not the most experienced, thats why I ask you guys. I somehow thought that the ecu knew how much fuel it needed and could regulate the flow... Anyway it started right back up once I put the stock injectors back in.

Looks like ive got a IMPUL ECU in my car "HI-POWER CONTROL UNIT 34GTR 4 6 8" can I just use this ECU for when I get a dyno tune with the upgraded turbos, fuel pump and injectors? Can someone tell me what I need and why?

While what Duncan said is correct that the ECU you have is very much a fixed function piece of hardware, it is important to understand something. No ECU to my knowledge is ever, ever capable of dealing with a silent injector change. You must always change the injector flow rate settings in the ECU any time you change the injector characteristics substantially.

As for your Impul ECU, what kind of fuel do you have access to? If you don't have at least 100 RON gasoline in the tank you should go source a 100% stock factory ECU map, either by replacing the chip on your Impul ECU or sourcing an entire stock ECU. In California we get 91 AKI which is like 96 RON optimistically. Any Japanese chip tune ECU like that is known to destroy engines on our fuel because they run too much ignition timing. If you have the factory boost solenoid my suggestion is to unplug it and cap both ends until you get that fixed. If you think sourcing an ECU is expensive it doesn't hold a candle to having to completely rebuild an RB26 from detonation damage.

To actually get an ECU you can use to tune the car with you have to get something that can be programmed. The R34 ECU cannot be programmed easily, Nistune has some remnants of it in their Type6 board support files but something happened there and the guy working on it disappeared off the face of the earth. To do so requires a discontinued Techtom daughterboard and their 90s-era software, as detailed in this thread: 

If you want to actually tune these cars you have a choice of either Haltech Elite/Nexus (don't get a Platinum Pro, it's no longer actively supported and the feature set is highly limited) or Link ECU. To get the engine to run like factory you will have to do a lot of work to the included "base map", the free base maps provided are not a one for one replication of the factory ECU map. It's just something they made so the engine will start and run but that's it. You should get whatever ECU your trusted (emphasis on trust) tuner recommends. Tuners tend to only learn one method of tuning and one brand's software suite/ECU, so buying anything else is going to be a waste of money.

 

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On 04/12/2021 at 11:35 PM, joshuaho96 said:

While what Duncan said is correct that the ECU you have is very much a fixed function piece of hardware, it is important to understand something. No ECU to my knowledge is ever, ever capable of dealing with a silent injector change. You must always change the injector flow rate settings in the ECU any time you change the injector characteristics substantially.

As for your Impul ECU, what kind of fuel do you have access to? If you don't have at least 100 RON gasoline in the tank you should go source a 100% stock factory ECU map, either by replacing the chip on your Impul ECU or sourcing an entire stock ECU. In California we get 91 AKI which is like 96 RON optimistically. Any Japanese chip tune ECU like that is known to destroy engines on our fuel because they run too much ignition timing. If you have the factory boost solenoid my suggestion is to unplug it and cap both ends until you get that fixed. If you think sourcing an ECU is expensive it doesn't hold a candle to having to completely rebuild an RB26 from detonation damage.

To actually get an ECU you can use to tune the car with you have to get something that can be programmed. The R34 ECU cannot be programmed easily, Nistune has some remnants of it in their Type6 board support files but something happened there and the guy working on it disappeared off the face of the earth. To do so requires a discontinued Techtom daughterboard and their 90s-era software, as detailed in this thread: 

If you want to actually tune these cars you have a choice of either Haltech Elite/Nexus (don't get a Platinum Pro, it's no longer actively supported and the feature set is highly limited) or Link ECU. To get the engine to run like factory you will have to do a lot of work to the included "base map", the free base maps provided are not a one for one replication of the factory ECU map. It's just something they made so the engine will start and run but that's it. You should get whatever ECU your trusted (emphasis on trust) tuner recommends. Tuners tend to only learn one method of tuning and one brand's software suite/ECU, so buying anything else is going to be a waste of money.

 

RON 98 is what we got here and the car has been using it for 5 years now.

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The Impul ECU goes in the bin. It is a technological dead end, like all the equivalent Jap brands' hacked ECUs. Can't do anything with it.

Haltech, Motec, Link, Syvecs, etc. You need one of these. You're not going forward without one.

DO NOT do any more random part changes. The next one could cost you your engine.

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Doesn't matter what ecu you have,you always need to change injector data and have the tune checked as there is differences on how injectors perform.

A Link g4x plugin with a can lambda sensor is simple plugin setup. Find a reputable/competent tuner to tune it best thing would be to have it towed there.

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When i was upgrading i used a Wolf 550 ecu as my local tuner is very experienced with this type of ecu i was able to do all the work to my car at home and plug in ecu as it was a direct plug in. I contacted Wolf told the the mods and they sent me a setup to load into ecu so i could drive my car to to tuner safely the other reason i got the Wolf was its an Australian company with a life time warranty and i upgraded from the series 4 wolf to the 550 unit. I would suggest you check your local tuner and find out which ecu he is most experienced with tuning your car and purchase that one  but beware its going to lighten your pocket and wallet a fair bit but its the only safe way unless you like giving your money away. My gtst rb25 makes 353kw 473hp at rear wheels using BP 98 ron fuel and has done this for the past 7 years with no problem 

Edited by Dasmbo
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On 12/5/2021 at 2:13 PM, Dose Pipe Sutututu said:

Better as a door stopper or as a wheel chock. Going into the bin isn't good for the environment unless it goes into an e-waste bin.

Sell it as rare Impul ECU old logo, an American will snap it up for extra JDM tyte points at the next cars and coffee.

  • Haha 1
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  • 3 weeks later...
On 12/22/2021 at 10:59 AM, The Skyline Guy said:

Another question I got is about engine oil. What do you think of Shell Helix Ultra 10w60 compared to Castrol Supercar 10w60? I can get the Shell oil for half the price of the Castrol oil.

You should start by looking at how hot your oil is getting first. Motive's 10W60 recommendation really only makes sense for track cars. The factory bottom-end was specced for "7.5W30" for street use, so if you're just driving slowly around town and the oil barely hits operating temperatures then just use a 5W30 or 5W40 oil. If you're going on track and oil temperatures are skyrocketing then start thinking about a high viscosity oil.

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On 23/12/2021 at 5:59 AM, The Skyline Guy said:

Another question I got is about engine oil. What do you think of Shell Helix Ultra 10w60 compared to Castrol Supercar 10w60? I can get the Shell oil for half the price of the Castrol oil.

Same shit different sticker 

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On 12/22/2021 at 9:01 PM, GTSBoy said:

Don't use 5W oil either, unless the engine is reasonably fresh. Any RB with some miles under its belt is almost certainly** better off with 10W.

**Unless you live in the frozen shithole of Hoth.

Is it really a problem? I see 5W40 recommended on the Nismo engines which are presumably built with basically stock clearance. It's going to shear down over time but oil change intervals on these engines are super short anyways. I dumped the oil in my R33 after just 1000 km because it seems like it picked up a bunch of deposits in suspension.

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