Will not start

Tiny
DIVIDES
  • MEMBER
  • 2012 AUDI A5
  • 4 CYL
  • TURBO
  • 2WD
  • AUTOMATIC
  • 169,000 MILES
Bought it as is. When I used to try to start it, it would start for a second then shuts off, hitting the gas pedal wouldn't cause it to stay running. Had multiple codes and if my memory serves me well had some fuel related. Had it towed, now I go start it and does not start at all and for some reason all the codes are gone. I may or may not have deleted them when I was trying to start it to see what comes back. I am thinking it may be fuel related. Can you tell me if this one has any fuel pump relays?
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Tuesday, December 21st, 2021 AT 9:14 AM

45 Replies

Tiny
JACOBANDNICKOLAS
  • EXPERT
Hi,

If you are questioning if it is a fuel issue, try this. See if the engine starts for a couple of seconds when using starting fluid. If it starts and then stalls, you'll know it's a fuel-related issue. Also, you could check fuel pressure. Here is a link that explains how it's done:

https://www.2carpros.com/articles/how-to-check-fuel-system-pressure-and-regulator

Also, I attached the wiring schematic below for the pump. There are a couple of relays to check and fuses.

If you look at the schematic, note that I highlighted several of the wires that are all tied together via a relay and fuses. I need you to check the fuse. Under the left side of the dash, locate fuse number 3 (25 amp). Inspect the fuse to make sure it is good and also confirm there is power to and from it when the key is first turned on.

Next, check the engine component power relay in fuse panel B.

If there is another relay that has the same part number, switch them. If there isn't, here is a link that explains how to test a relay:

https://www.2carpros.com/articles/how-to-check-an-electrical-relay-and-wiring-control-circuit

Let me know what you find. Also, you can perform the aforementioned things in any order. However, I do suggest trying with starting fluid first. If it doesn't start, then the fuel system, at least at this point, should be bypassed and focus placed on the ignition system.

Take care,

Joe

See pics below. Note: There were three pages of schematics. I had to cut each one in half to make them readable. So, every two pics are from one page. I did overlap them so you can follow from one to the next.

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Tuesday, December 21st, 2021 AT 5:49 PM
Tiny
DIVIDES
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I forgot to do the starter fluid first before asking the question. I knew I should have.
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Tuesday, December 21st, 2021 AT 5:51 PM
Tiny
JACOBANDNICKOLAS
  • EXPERT
LOL, no problem whatsoever. Let me know what you find. I'll watch for your reply.

Joe
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Tuesday, December 21st, 2021 AT 7:47 PM
Tiny
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Sprayed some starting fluid after removing the throttle hose, but nothing happened. Also, no codes are being set after several times of trying, strange.
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Friday, December 24th, 2021 AT 6:54 AM
Tiny
JACOBANDNICKOLAS
  • EXPERT
Hi,

Based on that, I suspect you lost the ignition spark. If you haven't already, please confirm that for me. I'm suggesting it because if it has spark, then there could be a timing issue or compression issue.

Here is a link showing how to check for spark:

https://www.2carpros.com/articles/how-to-test-an-ignition-system

One last thought. If it's possible, could you record it cranking and upload it for me to hear? Usually, I can tell if there is an issue with timing or compression. If you do it, have a helper crank the engine while you record it from outside the vehicle, near the engine. That way I'll have a better chance of hearing it.

Let me know. Also, if you don't get to it for a couple of days, I wish you and your family a great Christmas.

Joe
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Friday, December 24th, 2021 AT 4:00 PM
Tiny
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I will record a video, but familiar with the sound if an engine which has a broken chain/belt or a lost compression, I know what you mean. I will check spark and send you a video for the engine sound.
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Friday, December 24th, 2021 AT 4:05 PM
Tiny
JACOBANDNICKOLAS
  • EXPERT
Sounds good. I'll watch for your reply.

Take care,

Joe
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Friday, December 24th, 2021 AT 5:01 PM
Tiny
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Not hearing the fuel pump. See if these make any sense.
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Saturday, December 25th, 2021 AT 9:11 AM
Tiny
DIVIDES
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Here we go:
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Saturday, December 25th, 2021 AT 9:15 AM
Tiny
DIVIDES
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Still no codes, did a compression test and they were around 130-135, all very close to that. Added a drop of oil and it was pretty much the same. Even if compression great it should start, I have had Audis with 80 PSI and starting just smoking.
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Saturday, December 25th, 2021 AT 9:45 AM
Tiny
DIVIDES
  • MEMBER
Checked fuses on left of dash all good, same for ones in trunk.
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Saturday, December 25th, 2021 AT 9:50 AM
Tiny
JACOBANDNICKOLAS
  • EXPERT
Hi,

The engine does sound normal when cranking. I agree with you. Is spark lost? As far as the scanner is concerned, either I'm missing it or there is no change. Did you also check the relays I indicated?

Since you don't hear the fuel pump, we need to check power to it. I attached the diagnostics below for the fuel pump. (Pics 1-5). The remaining pics are the diagnostics for the ignition system. I have a feeling there is no spark. I also suspect this is related to the ECM, but I can't be sure until these tests are completed.

Let me know what you find or if you have other questions.

Take care,

Joe

See pics below.
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Saturday, December 25th, 2021 AT 8:37 PM
Tiny
DIVIDES
  • MEMBER
I removed the plugs, and they were dirty. Cleaned them all up and that's the only time it starts for 2 seconds and shuts off. It is smooth when it starts and sounds really good. I took a video of it to see if there is anything you are seeing. No stored codes but pending codes are two misfires which still should have the car run at least.
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Wednesday, December 29th, 2021 AT 1:48 PM
Tiny
JACOBANDNICKOLAS
  • EXPERT
Hi,

The fuel trim at 99.2% indicates it is not in use at that point, so it's nothing to consider. However, am I reading the fuel rail pressure correctly? Is it 15.95 PSI before starting and then drops to 15.5 PSI?

Joe
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Wednesday, December 29th, 2021 AT 5:27 PM
Tiny
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I will have to redo it and see. But yes, it is showing 15.95 then drops to 14.50.
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Wednesday, December 29th, 2021 AT 5:30 PM
Tiny
JACOBANDNICKOLAS
  • EXPERT
The pressure is too low. That can't be right. Let me know. This vehicle has a supply pump and a high-pressure pump. At the rail, it shouldn't be that low.

Please reconfirm if there were any trouble codes at any point, and what they were.

Joe
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Wednesday, December 29th, 2021 AT 5:38 PM
Tiny
DIVIDES
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Possible hpfp or something else, plugs maybe fouled too from all the fuel.
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Wednesday, December 29th, 2021 AT 5:41 PM
Tiny
JACOBANDNICKOLAS
  • EXPERT
Were all the plugs wet? The fuel rail pressure sensor may be bad. I'm questioning of the fuel pressure regulator valve is stuck open. That would dump fuel and not allow pressure to build.

I attached diagnostics below for testing. Let me know if you are comfortable doing this.

Joe

See pics.
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Wednesday, December 29th, 2021 AT 5:43 PM
Tiny
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Yes, pretty much, once cleaned with brake cleaner it started. For 2 seconds, several times.
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Wednesday, December 29th, 2021 AT 5:45 PM
Tiny
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Just like in the video.
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Wednesday, December 29th, 2021 AT 5:46 PM

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