R32 GTS (RB20DE) Injectors Replacement

[GabsReDeal]

On 06/07/2025 at 4:16 AM, MBS206 said:

make sure you're fully covered up, you don't want that shit on you, especially face/eyes

Despite having minimal clothing because of the hot weather right now, I did have rubber gloves and safety glasses on just in-case for most of the time.

On 06/07/2025 at 10:04 AM, joshuaho96 said:

You can probably scrub the rust with a toothbrush or something. After you get the rust off flush well with water to neutralize and you will probably want to also use a fuel tank sealer to keep it from rusting again.

Yes, I was scrubbing with my gloves on before, but brushing with a brush removes the remaining rust. To neutralize, I was thinking distilled water and baking soda, or do you think that would be overkill?

[MBS206]

23 minutes ago, joshuaho96 said:

The sodium citrate solution is designed to buffer the citric acid to keep it from attacking metal quite so much, the guy that came up with that recipe did a ton of testing on how much metal loss occurs over time and it's nothing crazy unless you forget about it for months: 

 

The sodium acetate, mixed with citric acid, doesn't actually buffer each other. Interestingly though, if you used Sodium Acetate, and acetic acid, THAT becomes a buffer solution.

Additionally, a weak acid that can attack a metal, is still a weak acid that can attack a metal. If you don't neutralise it, and wash it off, it's going to be able to keep attacking. It works the same way when battery acid dries, get that stuff somewhere, and then it gets wet, and off it goes again breaking things down.

There's a reason why people prefer a weak acid, and it's because they want TIME to be able to be on their side. IE, DIY guys are happy to leave some mild steel in vinegar for 24 hours to get mill scale off. However, if you want to do it chemically in industry, you grab the muriatic acid. If you want to do it quicker at home, go for the acetic acid if you don't want muriatic around.

At the end of the day, look at the above thumbnail, as it proves what I said in the earlier post, you can clean that fuel tank up all you want with the solution, but the rust that has now been removed was once the metal of the fuel tank. So how thin in spots is your fuel tank getting? If the magazine on the left, is the actual same magazine as on the right, you'll notice it even introduces more holes... Well, rust removal in general actually does that. The fuel tank isn't very thick.

So, I'll state again, look to replace the tank, replace the fuel hanger, and pump, work out how the rust and shit is making it past the fuel filter, and getting into the injectors. That is the real problem. If the fuel filter were doing its job, the injectors wouldn't be blocked.

[joshuaho96]

14 hours ago, MBS206 said:

The sodium acetate, mixed with citric acid, doesn't actually buffer each other. Interestingly though, if you used Sodium Acetate, and acetic acid, THAT becomes a buffer solution.

Additionally, a weak acid that can attack a metal, is still a weak acid that can attack a metal. If you don't neutralise it, and wash it off, it's going to be able to keep attacking. It works the same way when battery acid dries, get that stuff somewhere, and then it gets wet, and off it goes again breaking things down.

There's a reason why people prefer a weak acid, and it's because they want TIME to be able to be on their side. IE, DIY guys are happy to leave some mild steel in vinegar for 24 hours to get mill scale off. However, if you want to do it chemically in industry, you grab the muriatic acid. If you want to do it quicker at home, go for the acetic acid if you don't want muriatic around.

At the end of the day, look at the above thumbnail, as it proves what I said in the earlier post, you can clean that fuel tank up all you want with the solution, but the rust that has now been removed was once the metal of the fuel tank. So how thin in spots is your fuel tank getting? If the magazine on the left, is the actual same magazine as on the right, you'll notice it even introduces more holes... Well, rust removal in general actually does that. The fuel tank isn't very thick.

So, I'll state again, look to replace the tank, replace the fuel hanger, and pump, work out how the rust and shit is making it past the fuel filter, and getting into the injectors. That is the real problem. If the fuel filter were doing its job, the injectors wouldn't be blocked.

It's sodium citrate, I misspoke earlier. It's a citrate buffer solution. And yes, depending on how thin the metal in the tank is this may or may not be a wise decision but if it's just mild rust it should clean off and it should be fine. 

[GTSBoy]

This is why rust converter is phosphoric acid. The iron phosphate left behind stays attached to the parent metal. It's not steel (iron). But it's also not a hole.

[GabsReDeal]

After my last update, I went ahead with cleaning and restoring the entire fuel system. This included removing the tank and cleaning it with the Beyond Balistics solution, power washing it multiple times, drying it thoroughly, rinsing with IPA, drying again with heat gun and compressed air. Also, cleaning out the lines, fuel rail, and replacing the fuel pump with an OEM-style one.

During the cleaning process, I replaced several hoses - including the breather hose on the fuel tank, which turned out to be the cause of the earlier fuel leak.

This is what the old fuel filter looked like:

Fuel tank before cleaning:

 

Fuel tank after cleaning (some staining remains):

Both the OEM 270cc and new DeatschWerks 550cc injectors were cleaned professionally by a shop.

Before reassembling everything, I tested the fuel flow by running the pump output into a container at the fuel filter location - flow looked good. I then fitted the new fuel filter and reassembled the rest of the system.

Test 1 - 550cc injectors

Ran the new fuel pump with its supplied diagonal strainer (different from OEM’s flat strainer) and my 550cc injectors using the same resized-injector map I had successfully used before. At first, it idled roughly and stalled when I applied throttle.

Checked the spark plugs and found that they were fouled with carbon (likely from the earlier overly rich running when the injectors were clogged). After cleaning the plugs, the car started fine.

However, it would only idle for 30–60 seconds before stalling, and while driving it would feel like a “fuel cut” after a few seconds - though it wouldn’t fully stall.

Test 2 – Strainer swap

Suspecting the diagonal strainer might not be reaching the tank bottom, I swapped it for the original flat strainer and filled the tank with ~45L of fuel. The issue persisted exactly the same.

Test 3 – OEM injectors

To eliminate tuning variables, I reinstalled the OEM 270cc injectors and reverted to the original map. Cleaned the spark plugs again just in-case. The stalling and “fuel cut” still remained.

 

At this stage, I suspect an intermittent power or connection fault at the fuel pump hanger, caused during the cleaning process. This has led me to look into getting Frenchy’s fuel hanger and replacing the unit entirely.

TL;DR:
Cleaned and restored the fuel system (tank, lines, rail, pump). Tested 550cc injectors with the same resized-injector map as before, but the car stalls at idle and experiences what feels like “fuel cut” after a few seconds of driving. Swapped back to OEM injectors with original map to rule out tuning, but the issue persists. Now suspecting an intermittent power or connection fault at the fuel pump hanger, possibly cause by the cleaning process.
 

[joshuaho96]

1 hour ago, GabsReDeal said:

After my last update, I went ahead with cleaning and restoring the entire fuel system. This included removing the tank and cleaning it with the Beyond Balistics solution, power washing it multiple times, drying it thoroughly, rinsing with IPA, drying again with heat gun and compressed air. Also, cleaning out the lines, fuel rail, and replacing the fuel pump with an OEM-style one.

During the cleaning process, I replaced several hoses - including the breather hose on the fuel tank, which turned out to be the cause of the earlier fuel leak.

This is what the old fuel filter looked like:

Fuel tank before cleaning:

Fuel tank after cleaning (some staining remains):

 

Both the OEM 270cc and new DeatschWerks 550cc injectors were cleaned professionally by a shop.

Before reassembling everything, I tested the fuel flow by running the pump output into a container at the fuel filter location - flow looked good. I then fitted the new fuel filter and reassembled the rest of the system.

 

Test 1 - 550cc injectors

Ran the new fuel pump with its supplied diagonal strainer (different from OEM’s flat strainer) and my 550cc injectors using the same resized-injector map I had successfully used before. At first, it idled roughly and stalled when I applied throttle.

Checked the spark plugs and found that they were fouled with carbon (likely from the earlier overly rich running when the injectors were clogged). After cleaning the plugs, the car started fine.

However, it would only idle for 30–60 seconds before stalling, and while driving it would feel like a “fuel cut” after a few seconds - though it wouldn’t fully stall.

Test 2 – Strainer swap

Suspecting the diagonal strainer might not be reaching the tank bottom, I swapped it for the original flat strainer and filled the tank with ~45L of fuel. The issue persisted exactly the same.

Test 3 – OEM injectors

To eliminate tuning variables, I reinstalled the OEM 270cc injectors and reverted to the original map. Cleaned the spark plugs again just in-case. The stalling and “fuel cut” still remained.

 

At this stage, I suspect an intermittent power or connection fault at the fuel pump hanger, caused during the cleaning process. This has led me to look into getting Frenchy’s fuel hanger and replacing the unit entirely.

TL;DR:
Cleaned and restored the fuel system (tank, lines, rail, pump). Tested 550cc injectors with the same resized-injector map as before, but the car stalls at idle and experiences what feels like “fuel cut” after a few seconds of driving. Swapped back to OEM injectors with original map to rule out tuning, but the issue persists. Now suspecting an intermittent power or connection fault at the fuel pump hanger, possibly cause by the cleaning process.
 

I would put a fuel pressure gauge between the filter and the fuel rail, see if it's maintaining good fuel pressure at idle going up to the point when it stalls. Do you see any strange behavior in commanded fuel leading up to the point when it stalls? You might have to start going through the service manual and doing a long list of sensor tests if it's not the fuel system for whatever reason.

[GabsReDeal]

On 10/08/2025 at 6:02 AM, joshuaho96 said:

I would put a fuel pressure gauge between the filter and the fuel rail, see if it's maintaining good fuel pressure at idle going up to the point when it stalls. Do you see any strange behavior in commanded fuel leading up to the point when it stalls? You might have to start going through the service manual and doing a long list of sensor tests if it's not the fuel system for whatever reason.

I got ahold of a fuel pressure gauge and did just that. The pressure is strong and stable, even to the point of stalling. 3.0 bar on ignition, 2.5 bar on idle, 3.0 bar on idle with FPR vacuum removed.

It idled for longer with the FPR vacuum removed but eventually still stalled. Then I tried one final time and revving was also just cutting up – I now assume that the plugs are fouled again.
 

[joshuaho96]

7 hours ago, GabsReDeal said:

I got ahold of a fuel pressure gauge and did just that. The pressure is strong and stable, even to the point of stalling. 3.0 bar on ignition, 2.5 bar on idle, 3.0 bar on idle with FPR vacuum removed.

It idled for longer with the FPR vacuum removed but eventually still stalled. Then I tried one final time and revving was also just cutting up – I now assume that the plugs are fouled again.
 

Reading through the engine service manual their advice is do a cylinder balance test. Unplug one injector at a time and see if the idle drops a consistent RPM. You can also do this using a Consult cable which is easier. They also call for unplugging the power transistor, then with the engine off and the fuel rail unhooked from the manifold verifying that you have good fuel flow (even injection, no dripping/leaks, etc) when you twist the CAS by hand. Also verify the spark by pulling the spark plugs and allowing the plugs to ground and turning the CAS by hand. I would also start doing the sensor checks and idle valve checks in service manual. Make sure the MAF tests reasonably, the intake air regulator is sane, etc. You may have to get new spark plugs.

[MBS206]

What air filter are you running?

Is it a panel filter in the stock air box, or a pod filter?

Is the air filter the type that is oiled?

 

If you unplug the IACV, what rpm does the engine idle at?

Edited Thursday at 05:38 AM by MBS206

[joshuaho96]

As MBS suggested if this is happening when the engine is cold you're going to want to remove the intake air regulator and verify resistance + that the shutter is physically opening and closing. At -20C should be fully open, 20C half open, over 60C fully closed. At 20C should be 70-80 ohms. For AAC valve testing using a Consult cable see if you can raise and lower the idle by commanding more or less AAC duty cycle. Hopefully it's pretty linear as well, shouldn't be like 30% AAC valve is barely idling and 40% is 1500 rpm.

[GabsReDeal]

On 21/08/2025 at 7:37 AM, MBS206 said:

What air filter are you running?

Is it a panel filter in the stock air box, or a pod filter?

Is the air filter the type that is oiled?

 

If you unplug the IACV, what rpm does the engine idle at?

It is the stock air box with the panel filter. Everything else is stock except the exhaust at this point, as I also went back to the cleaned 270cc injectors.

I will check the RPM when the IACV is unplugged and report back.

[MBS206]

35 minutes ago, GabsReDeal said:

It is the stock air box with the panel filter. Everything else is stock except the exhaust at this point, as I also went back to the cleaned 270cc injectors.

I will check the RPM when the IACV is unplugged and report back.

Is the panel filter one that is oiled? Have you ever cleaned or touched the AFM?

[GabsReDeal]

On 21/08/2025 at 10:22 AM, MBS206 said:

Is the panel filter one that is oiled? Have you ever cleaned or touched the AFM?

No, the panel filter is the standard dry one.

Yes, I did clean the AFM with electrical contact cleaner.

[GTSBoy]

1 hour ago, GabsReDeal said:

Yes, I did clean the AFM with electrical contact cleaner.

Time for some swaptronics.

[GabsReDeal]

On 21/08/2025 at 3:43 PM, GTSBoy said:

Time for some swaptronics.

You think its the AFM? I know its a common issues on R32s.

I find it coincidental how this issue raised right after cleaning the fuel system. As everything except the fuel system was fine before.

On 21/08/2025 at 9:46 AM, GabsReDeal said:

It is the stock air box with the panel filter. Everything else is stock except the exhaust at this point, as I also went back to the cleaned 270cc injectors.

I will check the RPM when the IACV is unplugged and report back.

I tried running it with the IACV unplugged but did not notice a difference and still stalled. However, the RPM gauge is not in the cluster right now, so I will need to connect the laptop again and use Nistune to check the RPM. I will check this weekend.

[GTSBoy]

35 minutes ago, GabsReDeal said:

You think its the AFM?

No. I think it might be the AFM. Hence the use of the terms "swaptronics", which implies the use of swapping out electronics for the purpose of diagnosis. It's about the only way to prove that a small/niggling/whatever problem with an AFM or a CAS or similar is actually caused by that AFM/CAS/whatever. A known good item swapped in that still gives the same problem is likely to be caused somewhere else.

37 minutes ago, GabsReDeal said:

I know its a common issues on R32s.

They're all the same.

Spraying AFMs with cleaner is an each way bet between cleaning it and f**king it.

[joshuaho96]

1 hour ago, GabsReDeal said:

You think its the AFM? I know its a common issues on R32s.

I find it coincidental how this issue raised right after cleaning the fuel system. As everything except the fuel system was fine before.

I tried running it with the IACV unplugged but did not notice a difference and still stalled. However, the RPM gauge is not in the cluster right now, so I will need to connect the laptop again and use Nistune to check the RPM. I will check this weekend.

I forgot you have a Nistune ECU. Use Nistune to do all the tests I mentioned instead of faffing with 30+ year old electrical connectors. You can read MAF volts off that too, there are reference values in the service manual to tell you roughly what it should be in different conditions.

[MBS206]

On 22/08/2025 at 7:31 AM, GabsReDeal said:

You think its the AFM? I know its a common issues on R32s.

I find it coincidental how this issue raised right after cleaning the fuel system. As everything except the fuel system was fine before.

I tried running it with the IACV unplugged but did not notice a difference and still stalled. However, the RPM gauge is not in the cluster right now, so I will need to connect the laptop again and use Nistune to check the RPM. I will check this weekend.

Find out what RPM it was idling at with the IACV unplugged.

It's very weird that the rpm didn't change at all, and then it stalled.

When it stalls is it nearly like a switch off, like you've turned the engine off? Or is it more stutters and sputters and coughs to death over a few seconds? Or does the RPM just slowly keep going down and down?

Have you done a test of trying to start it with the AFM unplugged? Does it still die?

 

 

If you Follow Josh's advice on using Nistune to check the voltages (which is a perfect method!) if you see anything out of wack voltage wise, THEN get the multimeter out and read the voltage directly at the sensor. If the two vary, then you're now looking for a wiring issue vs a sensor issue. So be aware, what the ECU sees, may not be what the sensor is actually saying too...

[GabsReDeal]

On 24/08/2025 at 8:10 AM, MBS206 said:

Find out what RPM it was idling at with the IACV unplugged.

It's very weird that the rpm didn't change at all, and then it stalled.

My bad, I unplugged the one underlined in red instead of yellow before.

With the car started, after unplugging the IACV (the one underlined in yellow), it idled at around 400/500 for 3 seconds before stalling. Attempting to start the car without the IACV will not start the car.

 

On 24/08/2025 at 8:10 AM, MBS206 said:

When it stalls is it nearly like a switch off, like you've turned the engine off? Or is it more stutters and sputters and coughs to death over a few seconds? Or does the RPM just slowly keep going down and down?

It does stutter and sputter for around 5 seconds before dying. However, immediately after starting it, you can already hear some slight sputters from the exhaust.

 

On 24/08/2025 at 8:10 AM, MBS206 said:

Have you done a test of trying to start it with the AFM unplugged? Does it still die?

It won't start with the AFM unplugged. If it is when the car has already started, it stalls in a few seconds.

 

Yesterday, I did take some logs using Nistune of 3 scenarios.

1. Car idling till it stalls
2. Car idling and unplugging the IACV
3. Car idling and removing the AFM

I also have some previous logs of when the Car is idling till it stalls and when driving and it cuts. I am not really knowledgeable enough to understand what to look for.

After every test, car idles rougher and rougher, until I have to stop. It will be fine the day after.

[Duncan]

Sorry I haven't been following all the detail, so you may have tried this.

Does it idle with the tiniest bit of throttle you can add?

You've mentioned the IACV, does it have an AAC valve and have you adjusted it at all (ie, screw the idle adjust screw all the way in, then back it out a couple of turns until idle is stable)?