GabsReDeal

In my head it does make sense to be a fuel problem since that is what I touched when cleaning the system. When I was testing with the fuel pressure gauge, the pressure was constantly 2.5 bar with the FPR vacuum removed. When stalling, the pressure was going up to 3.0 bar (which is how it should be on ignition).

I never touched it, it should have. I'll try to give it an adjust. With IACV plugged in, it idles at around 1120RPM on average. Max 1200 RPM, Minimum 1025RPM before it starts dropping right before stalling. Took the data from the Nistune logs.

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. 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. 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. Car idling till it stalls Car idling and unplugging the IACV 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.

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.

No, the panel filter is the standard dry one. Yes, I did clean the AFM with electrical contact cleaner.

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 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.

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: Dirty Fuel Tank.mp4 Fuel tank after cleaning (some staining remains): Clean Fuel Tank.mp4 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. Fuel Flow Test.mp4 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.

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. 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?

I found the ingredients at larger amounts from a Coffee Shop. 1kg Citric Acid for €8.50 500g Baking Soda for €2.50 I tried it out tonight distilled water (I got from my ACs) and dish soap. It does get bubbly with dish soap. In just two hours the hanger has improved significantly and rubbing against any remaining rust seems to flake it off. I'm going to leave it a little bit longer and see how it goes. I have read that someone even used this solution in an ultrasonic cleaner to clean a seized water pump which brought it back to life.

Thanks a lot for this, it does look promising. I imagine I'm going to need a lot of the solution for the tank to get fully clean (or I guess I could rotate it around especially since it does not lose its effectivity). I will see if I can get the ingredients to try this out with the hanger first.

That would really suck. I'll have to check that out as well. The older injectors did get clogged before changing the filter, but having them switched would obviously peed up the process greatly.

I haven't yet, but the fuel filter has only 2 months of usage on it (1800kms at most). But considering how the new injectors got very dirty in 3 days, I can only imagine what's inside the filter right now.

I removed the fuel pump to take a look at the tank. The sender unit is very rusty. Took a look at the tank and it is also quite rusty. Right at the base of where the fuel pump sits, there's a buildup of what seems to be rust particles. I did find new OEM fuel tank (17202-01U01) and sender unit (25060-01U00) from amayama which would set me back around €900 including shipping and customs. I most likely would need a new fuel pump as well. I'm going to be honest, I have been driving for around 6 years now and this is the only mechanic I went to apart for once (Last year I took my Porsche 924 to a guy who specializes on them). I've got a good relationship with him and he's always there to assist, even coming over to my garage at times for my convenience since the car was not starting. I believe he's got over 20 years of experience, but this is not the first time he let me a bit down on some basic diagnosing. I do not want to switch over to someone else, but I'd be lying if I said that it did not cross my mind.

That is what I have deduced, unfortunately. I had a suspicion that the fuel tank has a leak as I start smelling fuel when filling around half of it and can visibly see some liquid streaks. I imagine it was opened before, possibly previous owner suffered from this issue. I have asked my mechanic to investigate this when I took it to him before, but may have focused on the issue at hand instead.