Hey guys,

it's been a while since i last posted on the forum, had been away for a few months for personal reasons...anyway a few days ago i was back to my normal life and my 7 as well. It's been sitting for a while so i took it for a few short drives in town just to check that everything was ok and did the usual maintenance. Finally yesterday evening i decided to try to go into some boost and after warming up, did a couple pulls but something happened and the car was suddenly not running ok; i immediately let go of the gas pedal and found out that:

- idle was extremely rough, not stable and lower than usual (used to be around 950, then bouncing between 5-700), even the sound was not smooth at all
- vacuum reading at idle was strongly and quickly bouncing around -15in/hg while it used to be a solid -19in/hg (same reading in the pfc as well)
- if accelerating, i could hear a ticking sound coming from the engine bay, with a growing tempo

moreover, to my impression, exhaust smells a little bit more of gasoline than usual. Temperature readings were optimal when this happened (water 85°C, ait 23°C) and boost was 13psi. Luckily i was only a few hundred yards from home so i was able to quickly recover it without running on it and without boosting again.

Engine has got 20k miles; my 7 is a TT with usual bolt-ons (see my signature); i would like to know what do you guys think could be the cause of this (except a blown motor of course)? i've already checked the map sensor but everything looks ok on that side...next on the list:

- spark plugs
- injectors (though they have been substitued less than 3k miles ago)

any suggestion on things that i might want to check before surrendering and open the engine? if it can help i will make a video of it.

Thanks everyone in advance for your help, praying i dont have to rebuild...

 

check the map sensor line it might have blown off.

 

So far I'm learning that if you have to hope its not blown its probably blown

I wish you luck man

 

it's the first thing i checked and it's intact (unfortunately!)

no luck in these days for me...still hope though!

 

Quit foolin' around and DO A COMPRESSION TEST. It's easy, it doesn't take long, and that will answer your question 100%. If you know your motor is good, continue troubleshooting other things. If not, then you know the engine needs to be gone through.

Until you do the compression test you're just guessing.

Dale

 

yep Dale you're right...guess i will have to tow it for a few dozens miles to the garage then! was only hoping it could be something else to avoid that.

 

You should be able to hear compression loss from a apex seal failure. Take one leading plug out at a time and listen for three even pops. More than likely you hear whoosh, wish, wish, whoosh...

My bets is on your gas losing octane from setting that long. The Ethanol in the gas makes it go bad much quicker. That would be my guess since it sounds like you actually heard the detonation.

 

i will definitely go for the compression test over the weekend (this or the next); anyway, gas was fresh from the pump, 95 octanes, and when the car sits for more than a couple weeks i try to leave the least possible gas in the tank.

 

it could also be a clogged fuel filter after so much years of storage which lead to a lean condition...

 

i dont think that would be the case...it's only been in stopped for 3 months and the AFRs were fine while driving.

 

If your boost gauge is bouncing at all rpm when you are driving and at idol and it sounds like a Harley then its an apex seal. DO NOT RUT IT and be extra care full when doing comp check. If it is in fact an apex, even running it for compression check will ruin a housing beyond repair and could possibly ruin a rotor and your hotside of your Turbo (if you boosted durring driving) if everything under the hood is hooked up its more than likelyan apex.if you have to ask then you already know.