Help miss fire

[Tower101]

Hi, I have a 2013 S4 155k. I had an intake flap solenoid go bad. No big deal could only get the whole intake and fuel rail but whatever, I replaced both sides. Put it all back together, car has a miss, cylinder 4.

I have tried.

Moved spark plugs
moved coil
Moved and resealed injectors.
Check every wire and hose many times.
Checked compression 180ish on all.

No change at all.

I picked up a noid light test kit but it is a cheap one and non of them fit well and could not get it to work.

I have a track day on the 15th and need this working.

Does anyone have any advice on what I need to check next?

Thanks

[B6ayfour]

thats brutal, and there was no miss before doing the intake and fuel rail?

[Tower101]

Nope, the car ran fine. Now it will not even start, just cranks. I sprayed a small amount of starting fluid into the intake, and the car started perfectly and ran great for 10 seconds. I checked the LPFP, and it seemed fine, a little loud, so I swapped it for a spare, no change, car will not start. I also swapped the HPFP from my S5, but there was no change, and the S5 started fine.

I have tested all the injectors using VCDS, and I can hear them working.

Still, no codes.

I am coming to the end with this car, if I cannot get it running very soon, it is going away as I have nothing left to check. Honestly, I have had a few BMW track/run around cars, and although an e90 330i does not have the power, it never let me down. Sadly, that is all this car has done. Last year 14 track days and 11 mechanical days, 5 ending my day early. Have over 7k in parts over the last year.

Love my S5 and will be tracking it on the 15th as even if I get the S4 running, I will not have time to prep it.

[B6ayfour]

Nope, the car ran fine. Now it will not even start, just cranks. I sprayed a small amount of starting fluid into the intake, and the car started perfectly and ran great for 10 seconds. I checked the LPFP, and it seemed fine, a little loud, so I swapped it for a spare, no change, car will not start. I also swapped the HPFP from my S5, but there was no change, and the S5 started fine.

I have tested all the injectors using VCDS, and I can hear them working.

Still, no codes.

I am coming to the end with this car, if I cannot get it running very soon, it is going away as I have nothing left to check. Honestly, I have had a few BMW track/run around cars, and although an e90 330i does not have the power, it never let me down. Sadly, that is all this car has done. Last year 14 track days and 11 mechanical days, 5 ending my day early. Have over 7k in parts over the last year.

Love my S5 and will be tracking it on the 15th as even if I get the S4 running, I will not have time to prep it.

sounds like its a fuel issue. you're definitely getting fuel at the rail?

[Tower101]

When I undo the fuel line, fuel comes out under pressure. I forget the numbers but VCDS shows fuel pressure in the correct range. I have ordered a better noid light, it will be in tomorrow. Also coming tomorrow is a new fuel line to relocate the line to the HPFP and new fuel pressure sensors for both the rail and the HPFP. I will be pulling all the fuel lines I can to check them.

If you can think of something I am missing, please let me know. Thanks

[B6ayfour]

When I undo the fuel line, fuel comes out under pressure. I forget the numbers but VCDS shows fuel pressure in the correct range. I have ordered a better noid light, it will be in tomorrow. Also coming tomorrow is a new fuel line to relocate the line to the HPFP and new fuel pressure sensors for both the rail and the HPFP. I will be pulling all the fuel lines I can to check them.

If you can think of something I am missing, please let me know. Thanks

well then, honestly you already checked everything that I would have at this point. hopefully someone else chimes in because idk.

[LowKeyLoki]

Testing the injectors via VCDS won’t tell you anything. You would have to take them out and send them off to have them flow tested on a bench that can do DI injectors. If you are on the original injectors at 155k miles, then I start by throwing a new set in. Most people preventatively replace them well before 155k. Since you’ve already pretty much replaced everything else on the fuels system, might as well throw a couple new injectors in for $1k.

[Tower101]

The injectors were replaced last year, or about 6k ago, with Audi injectors, costing $1,700.

Hopefully, my next post is it's fixed and it was this stupid thing, but it might be junk yard is on the way to pick it up.

[STXA7]

The injectors were replaced last year, or about 6k ago, with Audi injectors, costing $1,700.

Hopefully, my next post is it's fixed and it was this stupid thing, but it might be junk yard is on the way to pick it up.

Yikes dont let the frustration get to you man. I am sure plenty of people would jump on the opportunity to use it as a parts car. Sending you chill vibes.


Sent from my iPhone using Audizine Forum

[Tower101]

I will be removing parts I want over the rest of the weekend, and the car goes away next week. Got the car last year for 10k and have looked up most of what I have done over the year. It is just over 12k, not counting brakes and tires. I was shocked. So I am out 22k.

It was fun a few times, but mostly heartache.

[Midnight_Rider]

you try checking battery and alternator?