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

[Cris_OO7]

Seems some turbos have a quick death and others die slowly giving u guys these no/intermittent starting problems . If the bearings are on there way out they will not spin freely and choke the engine.


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[brad281]

Seems some turbos have a quick death and others die slowly giving u guys these no/intermittent starting problems . If the bearings are on there way out they will not spin freely and choke the engine.


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It would still turn over though. When I have this issue, mine doesn't crank at first. Then I have to turn off the mmi and try starting again from scratch. That's when it cranks longer than usual and has a rough idle for a few seconds.

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[pez81]

It would still turn over though. When I have this issue, mine doesn't crank at first. Then I have to turn off the mmi and try starting again from scratch. That's when it cranks longer than usual and has a rough idle for a few seconds.

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I'm pretty sure our issues isn't turbo related. Hofa has new turbos and mine were checked. And had no issue since temps dropped.

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[Purplehaze38]

So I've also had these exact same issues. Anyway I decided to let the dealer look at it. On the trip there out of the blue I get remove oil warning. So the dealer tells me that both High Pressure Fuel Pumps are leaking and caused both the hard start and of course oil issue. They are changing the pumps now.

[pez81]

It seems this issue is affecting more and more but earlier this year it seemed v few had an issue. These cars are far from reliable.

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[brad281]

It seems this issue is affecting more and more but earlier this year it seemed v few had an issue. These cars are far from reliable.

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Isn't that the truth.

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[Hofahome]

So I've also had these exact same issues. Anyway I decided to let the dealer look at it. On the trip there out of the blue I get remove oil warning. So the dealer tells me that both High Pressure Fuel Pumps are leaking and caused both the hard start and of course oil issue. They are changing the pumps now.

Oil issue?


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[Hofahome]

I just took my car for a drive and noticed that it just smells more like exhaust. Came home and let the car cool down. Decided to check my turbos and they seem ok, but the bank 2 turbo intake smelled like gas. This is the bank that typically has the neg fuel trims and also has the pcv connection as well.
I then opened the oil cap and it smells like gas. Not just a little but like I just filled my fucking engine with 91 oct.


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[pez81]

I just took my car for a drive and noticed that it just smells more like exhaust. Came home and let the car cool down. Decided to check my turbos and they seem ok, but the bank 2 turbo intake smelled like gas. This is the bank that typically has the neg fuel trims and also has the pcv connection as well.
I then opened the oil cap and it smells like gas. Not just a little but like I just filled my fucking engine with 91 oct.


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What do you think it could be?

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[GlacierS5]

My guess will be leaking fuel injectors. May need to check the fuel pressure

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[Cris_OO7]

My guess will be leaking fuel injectors. May need to check the fuel pressure

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Hope not thats a engine out repair


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[wwhan]

Hope not thats a engine out repair


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taking out engine might be easier: https://www.audizine.com/forum/showt...1#post12822960

"Got in there. No need to pull the engine if its on the passenger side. Lots of work to get at the injector, but it can be done."

"So I'll take a moment to elaborate.. while it is very possible to get at the manifold and injectors with the engine in the car, i dont suggest it. I got it all back together, fired it up only to find a waterfall of gas under the side i just worked on. Engine comes out tomorrow. Im defeated for today. It is impossible to see the injectors and make sure o rings dont get pinched or cut going back in. Ill know more tomorrow once its all in front of me."

[wwhan]

Update on same engine as above: https://www.audizine.com/forum/showt...1#post13342032

[Hofahome]

My guess will be leaking fuel injectors. May need to check the fuel pressure

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Ya I think either leaking HPFP into valve cover or leaking injectors. Fuel pressures are good (both low and high) assuming sensors are ok. Rail pressure at bank 2 is ok - cannot log bank 1 rail for some reason. I wish I could log injector timing but no dice. I did see misfires for cyl 5 was like 800 and cyl 8 was 500+. All others were 100-200 range. Again, I do not have any codes.
Luckily I have a good aftermarket warranty and am good friends with my mechanic.
I'm trying to read up on our HPFP to see if it is possible for it to even leak into the valve cover.

[kpriv]

I did see misfires for cyl 5 was like 800 and cyl 8 was 500+. All others were 100-200 range. Again, I do not have any codes.

Those misfires counts don’t seem abnormal. How many miles since you last flashed your ecu? 2-4K Miles?



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[pez81]

I'm about 9 days in with no start up issues. For once I'm happy it's cold

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[Hofahome]

Those misfires counts don’t seem abnormal. How many miles since you last flashed your ecu? 2-4K Miles?



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ya something like that. Funny that we see 800 misfires as "normal" haha.

[Hofahome]

I'm about 9 days in with no start up issues. For once I'm happy it's cold

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Mine has been better lately too. started up great the last 2 days.
Do me a favor and smell your oil cap after going for a drive.

[pez81]

Mine has been better lately too. started up great the last 2 days.
Do me a favor and smell your oil cap after going for a drive.

Yeah I was gonna do that after I read your post. One thing I've been doing differently is when filling her up not try and add extra. I always push it until it literally keeps clicking off.

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[Hofahome]

Update: I took my car in to get this looked at. He agreed my car drives fine otherwise. His plan is to check for rail pressure difference after leaving it to cool off.


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[brad281]

Yeah I was gonna do that after I read your post. One thing I've been doing differently is when filling her up not try and add extra. I always push it until it literally keeps clicking off.

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I have never added extra fuel to mine once the pump clicked off.

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[Hofahome]

New update. My mechanic said he is 95% sure it is from leaking injectors, although hard to say which one or ones at this point. The car is loosing rail pressure and is not keeping up with what spec should be after turning the car off for set period of time. He is doubtful that it is bad hpfp given fuel smell when starting up, meaning cyl are flooded.
It is engine out. A joy for everyone involved.
We agreed on new plugs all around although mine are relatively new.
Told him about the turbo oil strainer tsb and since it was not done at time of prior turbo install we agreed to do this along with the pcv module.




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[pez81]

Oh that sucks. Hope it at least fixes the issue for you. I'm still confused why mine hasn't done it for 2 weeks.

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[Cris_OO7]

New update. My mechanic said he is 95% sure it is from leaking injectors, although hard to say which one or ones at this point. The car is loosing rail pressure and is not keeping up with what spec should be after turning the car off for set period of time. He is doubtful that it is bad hpfp given fuel smell when starting up, meaning cyl are flooded.
It is engine out. A joy for everyone involved.
We agreed on new plugs all around although mine are relatively new.
Told him about the turbo oil strainer tsb and since it was not done at time of prior turbo install we agreed to do this along with the pcv module.




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That suks sorry to hear that. Since they going to be in there curious to see how clean the intake valves are and if any cleaning is needed. How many miles does it have?


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[JD S4]

New update. My mechanic said he is 95% sure it is from leaking injectors, although hard to say which one or ones at this point. The car is loosing rail pressure and is not keeping up with what spec should be after turning the car off for set period of time. He is doubtful that it is bad hpfp given fuel smell when starting up, meaning cyl are flooded.
It is engine out. A joy for everyone involved.
We agreed on new plugs all around although mine are relatively new.
Told him about the turbo oil strainer tsb and since it was not done at time of prior turbo install we agreed to do this along with the pcv module.




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Dude. Brutal. Sorry man. If you didn’t have bad luck, you’d have no luck at all


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[Hofahome]

The warranty approved injector replacement and we are doing them all since we couldnot pinpoint which one. We are also doing intake valve cleaning since it is out.
My mechanic said in the future he wants me to buy Japanese cars only lol


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[brad281]

The warranty approved injector replacement and we are doing them all since we couldnot pinpoint which one. We are also doing intake valve cleaning since it is out.
My mechanic said in the future he wants me to buy Japanese cars only lol


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Warranty cover the whole thing?

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[Hofahome]

Warranty cover the whole thing?

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Not the valve cleaning or pcv replacement/oil screen but yes to everything else.


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[brad281]

Not the valve cleaning or pcv replacement/oil screen but yes to everything else.


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I'm sure the labor is greatly reduced for those repairs with the engine already being out. Hope that corrects your issue.

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[15 Phantom S6]

Hard to fully tell by the picture, but those valves appear to be pretty "carboned" up.. Is it possible that the carboned up valves is the cause of your issues? What is the mileage of your ride?

[Hofahome]

Hard to fully tell by the picture, but those valves appear to be pretty "carboned" up.. Is it possible that the carboned up valves is the cause of your issues? What is the mileage of your ride?

I have 72k miles. The valves are not likely to be the issue since we saw that the rail pressure could not hold steady after turning the car off.


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[MKEAudi]

Hard to fully tell by the picture, but those valves appear to be pretty "carboned" up.. Is it possible that the carboned up valves is the cause of your issues? What is the mileage of your ride?

That's nothing, especially for 72k miles

[russjameson]

hHas anyone gotten any more insight from the Stealership on this.
All they want me to do it come in and let them flash it back to stock and have me pay $270 bucks for the TSP to be performed.
I think that sounds like a waste of $270 bucks for me.

I got my Stage 3 APR reflashed, and still the same, no difference at all.

[Hofahome]

hHas anyone gotten any more insight from the Stealership on this.
All they want me to do it come in and let them flash it back to stock and have me pay $270 bucks for the TSP to be performed.
I think that sounds like a waste of $270 bucks for me.

I got my Stage 3 APR reflashed, and still the same, no difference at all.

Just got my car back tonight. No issues so far but reserving any further judgement until I get a few days in.
$270 seems like a waste. Thats like 2.5 hours labor for a ecu flash...


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[russjameson]

Just got my car back tonight. No issues so far but reserving any further judgement until I get a few days in.
$270 seems like a waste. Thats like 2.5 hours labor for a ecu flash...


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What did you get done while it was away?
I have a guy that wants me to bring it by so he can mess with it but my daily is down with a blown turbo so I'm driving the S6 around every day cussing at it...alot. He seems to think it's a fuel pump issue. I'll let him poke around for free if he wants. Lol

[Hofahome]

What did you get done while it was away?
I have a guy that wants me to bring it by so he can mess with it but my daily is down with a blown turbo so I'm driving the S6 around every day cussing at it...alot. He seems to think it's a fuel pump issue. I'll let him poke around for free if he wants. Lol

Well my car threw a cel today for both intake runner flaps stuck closed. For my mechanic’s sake I hope it is just an unplugged vacuum line, however I cringe to think that the intake manifolds were reinstalled with the flaps in the “down” position and are getting stuck on the metal dividers when trying to open. The only way I could see to fix this would be engine out again. Ugh.
Car is starting without issue now though.

Does your oil cap smell like gas?


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[JD S4]

Ugh. Awful. Sorry this is happening guys


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[Hofahome]

Ugh. Awful. Sorry this is happening guys


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Hey man thx. ya frustrating to say the least. How is the sq with a tune? I just rode in a coworkers new one and was impressed, although she fucked up and got it in blue.
Gotta get together for a beer again soon. Maybe I'll uber down to you lol.

[aFOURstance]

Did you guys determine that this is due to leaky injectors?

[Hofahome]

So I was free of the hard starting issue for about a month, now it’s every other day. Did we determine that this is due to leaky injectors? I’m tired of looking like a fool in the parking lot with an expensive car that won’t start lol

It has not come back for me. You have any codes?


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