Intermittent hard or no start on 4.0T S6 S7 RS7- possibly solved

**s4nicetry** · 11-19-2018 08:41 AM

Symptoms sound quite similar to BMW's issues they were having with their HPFP's when they started to dye.

**pez81** · 11-20-2018 08:05 PM

Bit of an update: temps have dropped a bit here and since they hit below 9-10 C I've not had a single start up issue. The issue first started when we got the summer weather.
All signs point to evap and temps so far.

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**pez81** · 11-22-2018 01:01 AM

I'm about 3-4 days no start up issues. It has to be temperature related as it's much colder here now. Not a single start up issue.

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**Hofahome** · 11-22-2018 09:04 AM

Originally Posted by pez81

I'm about 3-4 days no start up issues. It has to be temperature related as it's much colder here now. Not a single start up issue.

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Good to hear man.
Mine is still doing it unfortunately.
I logged updated fuel trims and bank 2 is pretty neg at idle. it corrects pretty fast though when you give it a little gas if you look at the logs.

My plan for now is to pull the plugs this weekend on bank 2. My current thought is leaking injector. I would like to log injector pulse width but it does not look possible with vag com.

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**pez81** · 11-22-2018 01:51 PM

Originally Posted by Hofahome

Good to hear man.
Mine is still doing it unfortunately.
I logged updated fuel trims and bank 2 is pretty neg at idle. it corrects pretty fast though when you give it a little gas if you look at the logs.

My plan for now is to pull the plugs this weekend on bank 2. My current thought is leaking injector. I would like to log injector pulse width but it does not look possible with vag com.

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Hi buddy yeah it's nice to not have a car that embarrasses me for a bit. I dont think its the injectors though unless they are sensitive to temperature change. I am pretty sure we have the same issue and my issues started in summer. It's never really warm where I live but as soon as it went above 10-12 degrees the problem started. Now it's cold, ZERO issue. What else could it be if it's temp related?

**aFOURstance** · 11-23-2018 07:42 AM

I second that embarrassment part, I was at Caesar's hotel valet parking and the valet person had trouble starting it lol Anyway, my car sat for a week and just started it yesterday with no issues, drove around parked the car, started it again zero problems, this morning decided to take the S6 sled to work today and also fired right up :\ so weird

**Hofahome** · 11-23-2018 09:27 AM

Originally Posted by aFOURstance

I second that embarrassment part, I was at Caesar's hotel valet parking and the valet person had trouble starting it lol Anyway, my car sat for a week and just started it yesterday with no issues, drove around parked the car, started it again zero problems, this morning decided to take the S6 sled to work today and also fired right up :\ so weird

My car started happy this morning after sitting for 48h.
Wtf!

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**pez81** · 11-23-2018 11:25 AM

Originally Posted by Hofahome

My car started happy this morning after sitting for 48h.
Wtf!

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Maybe it's just time of the month for our girls?

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**Hofahome** · 11-24-2018 10:59 AM

Originally Posted by pez81

Maybe it's just time of the month for our girls?

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Ya no kidding lol.
I was reading up more on fuel trims and multiple sources said a neg fuel trim at idle and positive when on throttle points to maf/map issue. Given that the starting issue seems better with temp change, this might make sense. I planned on cleaning the map sensor today but my wife apparently planned my day to put up xmas lights and shit. Hopefully tomorrow then. Btw our map sensor part number (same for S and RS), is 03890651K.

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**JD S4** · 11-24-2018 04:18 PM

You’re about at the same point in the “tune it til you ruin it” timeframe where you sold the S4.

What’s next?

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**pez81** · 11-25-2018 06:15 AM

Originally Posted by Hofahome

Ya no kidding lol.
I was reading up more on fuel trims and multiple sources said a neg fuel trim at idle and positive when on throttle points to maf/map issue. Given that the starting issue seems better with temp change, this might make sense. I planned on cleaning the map sensor today but my wife apparently planned my day to put up xmas lights and shit. Hopefully tomorrow then. Btw our map sensor part number (same for S and RS), is 03890651K.

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I think we may finally be on to something. The fact it's not happening all the time and when it's warmer must indicate it's not a permanent hardware issue surely? I'm going to clean the map sensor and see if that helps. Keep me posted due and thanks for all the work on this.

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**pez81** · 11-25-2018 11:51 AM

Originally Posted by Hofahome

Ya no kidding lol.
I was reading up more on fuel trims and multiple sources said a neg fuel trim at idle and positive when on throttle points to maf/map issue. Given that the starting issue seems better with temp change, this might make sense. I planned on cleaning the map sensor today but my wife apparently planned my day to put up xmas lights and shit. Hopefully tomorrow then. Btw our map sensor part number (same for S and RS), is 03890651K.

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Mate do you have an engine guide diagram where the map sensor is please? I've ordered some contact cleaner.

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**wwhan** · 11-25-2018 12:15 PM

Originally Posted by pez81

Mate do you have an engine guide diagram where the map sensor is please? I've ordered some contact cleaner. ....

**pez81** · 11-25-2018 12:47 PM

Thank you very much

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**MKEAudi** · 11-26-2018 07:51 AM

Picking my car tonight. Turbos were beyond fucked so I'm hoping that fixes my issue otherwise I'll soon regret buying the car

**brad281** · 11-26-2018 10:42 AM

Having the same issue. Thought it was the battery, as mine was not even cranking on the first try. I'd reset the ignition and try again and it would crank but take a few seconds to start and idle rough until I hit the throttle. I replaced the battery last week and it happened again last night. When it happened last night, my car was in the driveway and I pulled it in the garage. Smelled a strong scent of fuel.

This issue has never happened when starting the car in the garage. Happens about once or twice a month.

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**brad281** · 11-26-2018 10:55 AM

I'll add that the issue typically happens after I've driven the car hard and it's then sat for 30-120 minutes.

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**pez81** · 11-26-2018 11:01 AM

Originally Posted by brad281

Having the same issue. Thought it was the battery, as mine was not even cranking on the first try. I'd reset the ignition and try again and it would crank but take a few seconds to start and idle rough until I hit the throttle. I replaced the battery last week and it happened again last night. When it happened last night, my car was in the driveway and I pulled it in the garage. Smelled a strong scent of fuel.

This issue has never happened when starting the car in the garage. Happens about once or twice a month.

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Hmmm are we all APR?

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**brad281** · 11-26-2018 11:01 AM

Originally Posted by pez81

Hmmm are we all APR?

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I am.

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**pez81** · 11-26-2018 11:02 AM

Wonder if it's the stage 2 file update.

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**brad281** · 11-26-2018 11:02 AM

Originally Posted by brad281

I am.

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But I wasn't having this issue until about 2 months ago. I've had APR on my car for over a year.

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**brad281** · 11-26-2018 11:03 AM

Originally Posted by pez81

Wonder if it's the stage 2 file update.

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Stage 1 here. Last flash was in April.

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**pez81** · 11-26-2018 11:03 AM

Originally Posted by brad281

But I wasn't having this issue until about 2 months ago. I've had APR on my car for over a year.

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I think it's temperature related. What's it like where you are and did the temps change 2 months ago?

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**pez81** · 11-26-2018 11:03 AM

I think that's when mine started too

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**brad281** · 11-26-2018 11:05 AM

Originally Posted by pez81

I think it's temperature related. What's it like where you are and did the temps change 2 months ago?

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I live in Florida. First day it happened was in September, probably about 85 degF. Last night was around 68 degF.

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**pez81** · 11-26-2018 11:08 AM

Originally Posted by brad281

I live in Florida. First day it happened was in September, probably about 85 degF. Last night was around 68 degF.

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Oh mate you're still way hotter than what we have.

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**brad281** · 11-26-2018 11:11 AM

Originally Posted by pez81

Oh mate you're still way hotter than what we have.

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How often are you guys dealing with the issue, and can you smell fuel after it happens?

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**pez81** · 11-26-2018 11:18 AM

Originally Posted by brad281

How often are you guys dealing with the issue, and can you smell fuel after it happens?

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Was everyday until it got cold

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**brad281** · 11-26-2018 11:20 AM

Originally Posted by pez81

Was everyday until it got cold

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That would drive me nuts.

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**pez81** · 11-26-2018 11:22 AM

Originally Posted by brad281

That would drive me nuts.

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You're right it did. I considered flogging the car for a loss. It's always after a 30-60 cool down. But since it dropped below 10 not a single issue for well over a week

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**brad281** · 11-26-2018 11:32 AM

Originally Posted by pez81

You're right it did. I considered flogging the car for a loss. It's always after a 30-60 cool down. But since it dropped below 10 not a single issue for well over a week

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Would be interesting to see if anyone was having this issue on a stock tune.

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**Hofahome** · 11-26-2018 12:56 PM

Happened to me this morning after going out for breakfast. It is 38F here in CO. The interesting thing is that when I opened the door, I could hear the fuel pump priming. It sounded a little more high pitched and went for like 4-5 sec. I actually told my wife that I bet her it would not start. It turned over then died right afterward. Took several tries to start up but no issues on the way home.
I bought a LPFP last week and it showed up to my house yesterday. I plan on putting it in and cleaning the MAP sensor in the next 2 days since I have them off. If not helpful, I might replace my MAP sensor. I might also replace my primary O2 sensors - although could be worth swapping them from side to side to see if this makes a difference in fuel trims. Thankfully the O2 sensors (pre-cat) are easy to access.

**MKEAudi** · 11-26-2018 12:57 PM

Originally Posted by brad281

Would be interesting to see if anyone was having this issue on a stock tune.

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I'm on stock tune

**brad281** · 11-26-2018 03:26 PM

Originally Posted by MKEAudi

I'm on stock tune

Same issue?

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**MKEAudi** · 11-26-2018 06:29 PM

Originally Posted by brad281

Same issue?

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Yes, you clearly didn't read all the posts in the thread lol

The issue starts after the cars been driven for only a few minutes. Initial startup is fine. If I let the car sit for an hour it starts up fine again. Drove fine but died as soon as it hit idle. Shop I'm having replace the turbos is still working on the car, should be able to pick it up in the next hour or two. Praying that was my issue otherwise I don't have a car

**brad281** · 11-26-2018 06:31 PM

Originally Posted by MKEAudi

Yes, you clearly didn't read all the posts in the thread lol

The issue starts after the cars been driven for only a few minutes. Initial startup is fine. If I let the car sit for an hour it starts up fine again. Drove fine but died as soon as it hit idle. Shop I'm having replace the turbos is still working on the car, should be able to pick it up in the next hour or two. Praying that was my issue otherwise I don't have a car

I read the whole thread, but I didn't memorize all 74 comments and who said what.

Hope it works out for you.

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**russjameson** · 11-26-2018 06:57 PM

Originally Posted by pez81

Hmmm are we all APR?

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Having the same issues.
2013 S6
Stage 3
APR tuned
3 inch catless Downpipes

Shit will die and smell like gas after trying to start it with no accelerator pedal.
I have even had it stop running while sitting at idle within 2 minutes of starting it while waiting to pull out into traffic. Had to shift back to park and restart with full throttle to get it to keep running.
Car runs like a raped ape all the time. Just idles weird sometimes and doesn't start about 25% of the time.