Checking injector operation

[Okedokey]

Guys does anyone have a good how to using VCDS to check the injectors are operating as desired. Getting slight misfires detected on cylinder three (3) and have changed the plugs and coil packs. Still pretty rough, particularly when in reverse.

I am thinking of changing the injectors. At the moment the S3 ones are cheaper than the A4 ones. Have I got the correct parts?

I would like to check the fuelling system operation. I have replaced the fuel filter and recently done a carbon clean and HPFP cam follower replacement. If I do need/decide to go ahead with injectors, the S3s are cheaper, I assume I want have any problems nor performance gains doing this, however in the future if I wish to pump the turbo/tune etc, it would be beneficial?

Guide on checking LPFP, rail, HPFP, injectors etc?

Thanks

[james12lucy]

I am happy to confirm you can run S3 injectors without the turbo upgrade, high-pressure fuel pump, tune, or anything else. You'll have no problems in a stock car, or with all of the above upgrades. And, it's pretty great for future proofing a turbo upgrade.


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[Okedokey]

Thanks mate, I wouldn't bother if they were more expensive, however if they're currently cheaper, then I would be silly not too.

On the checking of components?

[jubegnx]

Would like to know this as well.


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[shahk62]

Guys does anyone have a good how to using VCDS to check the injectors are operating as desired. Getting slight misfires detected on cylinder three (3) and have changed the plugs and coil packs. Still pretty rough, particularly when in reverse.

I am thinking of changing the injectors. At the moment the S3 ones are cheaper than the A4 ones. Have I got the correct parts?

I would like to check the fuelling system operation. I have replaced the fuel filter and recently done a carbon clean and HPFP cam follower replacement. If I do need/decide to go ahead with injectors, the S3s are cheaper, I assume I want have any problems nor performance gains doing this, however in the future if I wish to pump the turbo/tune etc, it would be beneficial?

Guide on checking LPFP, rail, HPFP, injectors etc?

Thanks

Can I reccomends throwing in a can of a fuel injector cleaner first (liqui moly do one). The stuff has fixed rough idles that my local indie had no idea what was causing. Especially before you get into tearing the injectors off its a good and cheap start to solving the problem. I get the same somewhat rough idle in reverse but I'll do a fluid change of the tranny to see if that'll solve it soon enough.

Cheers.




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[Sanjman]

There was another thread about this recently this is what I posted:

Unfortunately, there aren't individual pressure sensors for each injector, just the rail pressure which is all four. If one is clogged rail pressure should theoretically increase momentarily before it gets regulated back down to the specified rail pressure. Not sure if VCDS is fast enough to see that initial spike in actual rail pressure.


So basically you can try to log rail pressure actual and specified with Max sample rate, but it would be good if you had some old logs to compare to. Try to message Jake at JHM or Arin at APR. they should be able to get better answers for you.


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[seal66]

You can watch your mean injection time. When I lost an injector it was bouncing like crazy. But it also did this when my low side pump went out as well. You can see low and high side pressures. That is about all you can do.
fuel high side is block 230, low side 103 or 231 and injection time is in block 003 if I remember right.

But, since I have a fuel sniffer I get to use another block to sense ethanol % ha ha.

[Okedokey]

Ok thanks guys. I logged the mean injection time and they were all the same at around 7.7mS IIRC. I have put several bottles of injection cleaner in over the last few months. The misfires have gone now that I have replaced coils and plugs. I through a code for fuel pressure regulation though. My fuel gauge is reading 2/3 when full and when I go in reverse I get a beep and a fuel warning light. I am planning on changing the LPFP and level sensor (awaiting the removal tool) and hopefully that fixes it. I have replaced the fuel filter also. I recently did a carbon clean where I upgraded the PRV on the fuel rail to the RS4 one, new cam follower and oring etc on the HPFP, cleaned injectors and replaced seals/orings.

Oh and I have already done the transmission fluid change a while back. I will probably do another one as I have a slightly dented inline filter line on it and i have the replacement part. So ill change that and do another ATF change.

Im pretty sure I am getting issues from the LPFP. Anyone chime in to confirm from their experience?

Other than the codes being thrown and the rough idle (particularly) in reverse, it runs lovely.

[Okedokey]

BUMP?

[mcpcartier]

Can't help with the posted question....but I did go through miss-fires on one cylinder a while back, was thinking about getting new injectors after growing frustrated doing most of what you noted without any luck. The crazy thing that fixed it was a new dipstick, mine had cracked so wasn't sealing. How that caused miss-fires always baffled me, but it worked.

[Sanjman]

Can't help with the posted question....but I did go through miss-fires on one cylinder a while back, was thinking about getting new injectors after growing frustrated doing most of what you noted without any luck. The crazy thing that fixed it was a new dipstick, mine had cracked so wasn't sealing. How that caused miss-fires always baffled me, but it worked.

I have a gut feeling you may have more than one vacuum leak. The cracked oil dipstick just put you within enough vacuum to prevent misfires. How's your peak boost levels?

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[seal66]

try checking your n80 valve, like just replace it, then look for vacumm looks. Also, sometimes the fuel filter needs be either be audi or mani. For some reason my car liks the 6bar mani filter over the 6bar audi filter. no clue why

[Okedokey]

Forgot to mention, N80 replaced a few weeks ago too. Still rough in reverse. I guess Ill wait until i replace the LPFP and if the issue remains Ill post back. Thanks guys.

[BenMTL]

APR has tips on their website somewhere on how and what to log for general fueling issues...I would go through their process and post the logs here and the vagcom gurus can probably analyze the results for you

Also carbon cleaning my injectors soon too, upgraded JHM internals, upgraded PRV, so will be going through the same process

[Okedokey]

Thanks Ben. Good luck with yours!