R32 GTS (RB20DE) Injectors Replacement

[GabsReDeal]

Back in January, I noticed my car felt noticeably weak. I had the injectors cleaned, which seemed to solve the problem -- until now.

Recently, the car suddenly lost power again while driving. Suspecting the injectors, I brought it to the mechanic. He recommended replacing them entirely, saying the current ones were getting unreliable and fiddly to work with.

I could not find a direct replacement for my current injectors. The closest match I found were 440cc injectors. This led me to look into the possibility of upgrading -- and of course, that would mean remapping the ECU.

From my research I found:

• The OEM Part numbers are 16600-72L20 and 16600-72L21
• Both the RB20DE and RB20DET use the same 270cc injectors.
• There are much better options out there over the old OEM injectors.
• Nistune could be a viable tuning option. While the RB20DE isn’t explicitly listed on their site, the ECU is essentially the same as the GTS-T version - just with a different map. The ECU code on mine is listed as supported. One concern is finding a tuner who works with Nistune.
• Aftermarket ECU like Haltech and Link, but this would be the most expensive choice (and possibly overkill for a mostly stock RB20DE)

I admit that I am very new to the tuning scene and would appreciate any insight or recommendations regarding this.

 

These are some SAU links where I got some of my information from for reference:
https://www.sau.com.au/forums/topic/380324-rb20de-injectors/
https://www.sau.com.au/forums/topic/477396-factory-270cc-injectors/

 

[Murray_Calavera]

First thought, have your current injectors flow tested. If they test fine, keep the diagnostics going. It's not the injectors.

If the injectors are the issue, find some new or used (cleaned and flow tested) injectors. 

While I really love a good excuse to get a modern ECU installed, just needing new injectors probably isn't a good enough reason to do so. 

[GTSBoy]

^This.

If you have to do injectors, and you have to buy bigger ones, get the smallest Bosch EV14 based injectors of the correct length that you can. This will be about 500-525cc most likely. The stock ECU (with Nistune) will be fine to run those.

Then, use a Nistune. Tune it yourself. If all that you are doing is changing injector size, then you literally only have to change one number to do it, and then maybe some fine tuning of that number. You will not need to touch the fuel or ignition maps at all.

[joshuaho96]

Nistune is pretty easy if all you want to do is change the injectors. TIM + latency change will do it. But I am very skeptical your mechanic has actually diagnosed the issue. As others have said flow/function test your injectors. 

[GabsReDeal]

Thank you all for you assistance.

I contacted Nistune regarding the support for the RB20DE along with my ECU Code (23710-10U00). They do have a map for it and added the RB20DE as a purchasable option now as well. They also added Malta as a Billing and Delivery options as this was missing. I was honestly amazed at their quick response and action, it took less than 24 hours.

I also looked again at direct fit options for injectors, just in case I were to replace them. DeatschWerks seem to use a Bosch EV14 base and makes ones that fit mine at 440cc lowest, but also have 550cc at the same price.

I tried looking for other direct fit options and managed to find one (also Bosch EV14 based) which includes a plug and play adapter on ebay.

Did a small test with a Noid Light on the troubled injectors and all seems good, so they are pulsing properly electrically. One weird part is that they are missing on the same two cylinders as before I got the injectors cleaned. Mechanic also found this weird as he did not label the injectors and it is unlikely to have the faulty injectors be installed in the same cylinders.

 

[joshuaho96]

8 hours ago, GabsReDeal said:

Thank you all for you assistance.

I contacted Nistune regarding the support for the RB20DE along with my ECU Code (23710-10U00). They do have a map for it and added the RB20DE as a purchasable option now as well. They also added Malta as a Billing and Delivery options as this was missing. I was honestly amazed at their quick response and action, it took less than 24 hours.

I also looked again at direct fit options for injectors, just in case I were to replace them. DeatschWerks seem to use a Bosch EV14 base and makes ones that fit mine at 440cc lowest, but also have 550cc at the same price.

I tried looking for other direct fit options and managed to find one (also Bosch EV14 based) which includes a plug and play adapter on ebay.

Did a small test with a Noid Light on the troubled injectors and all seems good, so they are pulsing properly electrically. One weird part is that they are missing on the same two cylinders as before I got the injectors cleaned. Mechanic also found this weird as he did not label the injectors and it is unlikely to have the faulty injectors be installed in the same cylinders.

 

Swap the injectors around and see what happens. If the misfire follows the injectors then that's a signal, if it doesn't it's probably not the injectors.

[GabsReDeal]

On 17/04/2025 at 10:03 AM, joshuaho96 said:

Swap the injectors around and see what happens. If the misfire follows the injectors then that's a signal, if it doesn't it's probably not the injectors.

That is what I will be doing next

[GabsReDeal]

Swapped the injectors around and the misfire followed.

I went ahead and ordered the Deatschwerks 550cc injectors and am currently waiting for them to be ship and arrive.

In the meantime, I've had my Nistune soldered to the ECU. Tested it, and and tried it out with the software. Everything should be prepared for when the injectors arrive.

 

[joshuaho96]

6 hours ago, GabsReDeal said:

Swapped the injectors around and the misfire followed.

I went ahead and ordered the Deatschwerks 550cc injectors and am currently waiting for them to be ship and arrive.

In the meantime, I've had my Nistune soldered to the ECU. Tested it, and and tried it out with the software. Everything should be prepared for when the injectors arrive.

 

I really hope those injectors work for you. I have recently heard from another person with an RB20DET about how they cannot get their car to idle at all and they are tearing their hair out. I never really knew what the issue was but to me it had to be either the ECU or fuel injector. Suddenly on the wideband after sitting in closed loop idle for a bit it would lean out and stall.

[GTSBoy]

2 hours ago, joshuaho96 said:

Suddenly on the wideband after sitting in closed loop idle for a bit it would lean out and stall.

Usually an RB20 won't stay in closed loop idle anyway. The O2 sensor gets too cold, stops swinging.

[joshuaho96]

On 17/05/2025 at 11:21 PM, GTSBoy said:

Usually an RB20 won't stay in closed loop idle anyway. The O2 sensor gets too cold, stops swinging.

It's not even O2 feedback, it's just simply when the ECU sees the closed TPS signal for whatever reason the idle will start steadily dropping until the engine dies. With the TPS adjusted to not trigger closed TPS it will idle at some ridiculously high RPM and something like 6 degrees of timing. In the absence of getting eyes on it personally and a lot of quality time doing diagnostics I couldn't tell you what the real problem was but it was interesting nonetheless

[GTSBoy]

Yeah, sort of blurring two different things together, aren't we?

I just meant O2 feedback closed loop. I used to have a 0-1V LCD meter on my dash, wired directly to the O2 sensor signal. So you could easily see what it was doing. Normal running it would flick back and forth nicely. Slow down to an idle and it would keep flicking, as the ECU tried to servo to maintain stoich, but it would slow down as each swing happened until it would stay at one end of the scale. As I said above, the sensor heater is not enough to keep it hot enough when there is also little heat in the exhaust flow.

Give it a blip and it would start swinging again, then peter out again.

Meanwhile, idle speed control would run just fine, because unrelated.

[joshuaho96]

31 minutes ago, GTSBoy said:

Yeah, sort of blurring two different things together, aren't we?

I just meant O2 feedback closed loop. I used to have a 0-1V LCD meter on my dash, wired directly to the O2 sensor signal. So you could easily see what it was doing. Normal running it would flick back and forth nicely. Slow down to an idle and it would keep flicking, as the ECU tried to servo to maintain stoich, but it would slow down as each swing happened until it would stay at one end of the scale. As I said above, the sensor heater is not enough to keep it hot enough when there is also little heat in the exhaust flow.

Give it a blip and it would start swinging again, then peter out again.

Meanwhile, idle speed control would run just fine, because unrelated.

Yeah, I still don't know why the idle speed control can't catch the falling RPMs. In the Consult logs I see the AAC duty cycle rising, but suddenly it goes lean and the engine stalls. Anyways, the relevance here is the DW 550cc injectors are probably the same. So if OP has similar issues I would be tempted to finger those injectors as problematic for whatever reason vs the ECU failing for some reason.

[GTSBoy]

I suspect 550s are on the large side for happy operation with a stock/Nistune RB20 ECU. The Hitachi ECU doesn't love short pulse width operation, and the RB20 doesn't need much fuel at idle. Big injectors can be unpleasant. This could be contributing.

[MBS206]

9 hours ago, GTSBoy said:

I suspect 550s are on the large side for happy operation with a stock/Nistune RB20 ECU. The Hitachi ECU doesn't love short pulse width operation, and the RB20 doesn't need much fuel at idle. Big injectors can be unpleasant. This could be contributing.

And if you can't drive bigger injectors with peak and hold as low impedance injectors during low pulse width, it's even harder to get a nice clean known amount of fuel.