this problem all started with a small vacuum/boost leak.

-it was a rather small leak that only lead to slightly higher initial idling, but was small enough to fix itself within 30secs of run-time.
-this leak got a bit bigger over time. general idle started to remain a bit rough, though it still drove well. albeit lacking the proper boost to make effective use of my turbo.
-1 day, it got suddenly rougher at idle. quite a bit rougher. sounds pretty bad type of rough. i was out and about at the time and drove home.
-important: although it runs extremely rough at idle, the engine completely levels out at and over 2500rpm. smooth as butter.

so...
i took my car to a mechanic that specializes in Audi. he says they turned the car on and immediately turned it off because it sounded so bad.
he's come back to me with this perspective:
-there are marks on the top of the tensioner belt. this was replaced ~ 3 years / 12k miles ago along with the water-pump and other crap. so he wants to replace the tensioner and belt before he attempts to diagnose further.

i stated once more that things level out @ and above 2500rpm's, and questioned "if these parts were bad, would they get better at 2500rpm?". "not likely" was his response.
so this leads me to wonder why the hell i want to pay for this.

i've requested him to look at the vacuum/boost leak and try addressing that first, but he says he can't without running the engine, and he won't run the engine until he replaces the timing belt.

so currently my "HUGE" concern is that after he replaces the timing belt and tensioner. the rough idle doesn't fix because of the vacuum leak....
so... he still won't want to run the engine and/or be able to diagnose any of the other issues.


i'm not an expert, but i'm concerned.
could anyone help alleviate or validate my concerns?

was your check engine light on?

what year and make car?

im not a mechanic. i play d2r. i can ask a guy if i knew more.

yes
2003 audi TT quattro. it's not your stock mk1 225 though.
i've already requested the start of this project. i was going to request this thread be removed, but i'll just give an update to my story for shifts and giggles.

to start, although the mechanic and I started on a shaky leg, he better explained his concerns after posting this.
until this point, a timing belt / tensioner seemed more like a shot in the dark diagnosis. this further expanded as a bore scope didn't seem to really show any extra need for concern. but.... the belt does show faint signs of slapping around with minor marks on the top of the belt.

as i was reading through some stuff, i remembered a separate issue i was having. a very small tick that was only heard during idle. it was pretty easy to determine it wasn't a rod knocking, but i never confirmed it to be anything.
i was assuming by what i was hearing, that it was the charge-pipe clamps having very slight slack and causing a small rattle. but as i thought about it, it very well could have been the belt just faintly slapping something.

without getting too far into it. i also have reason to believe the motor mount that needs to be taken apart to do this job, may be faulty. so i've requested some extra focus on that part while they touch it in passing.

i already know i have a vacuum issue that i'll have to also address after this. but after some time/research/conversation. i've also determined it best to address the timing before addressing anything else.
even if this job is mostly out of abundance of caution. i have experience that correlates to a reason to be cautious.

Ok so coming from a bmw perspective, we have chain driven cam and crank timing. Rough idle can be attributed to a slacked timing system. Could possibly be “leveled” out as you get higher in the rpm because the car has its own knock sensor system and adjust advanced/retard timing to try and compensate for the roughness. Unless codes get pulled to help pinpoint if this cam or crank sensors or vacuum leak causing unmetered air etc, you’re kind of shooting in the dark. If it’s not throwing codes he may be right looking towards internal. If he is saying the tensioner and belt referring to the serpentine belt “for the balancer power steering alternator” yes when they wear out they make noise at idle can cause idle vibrations and make horrible noises at low rpm’s until the belt stops slipping or the bearing spins properly in the idler pulley or tensioner.

there was a code for vacuum issues, albeit not a very descriptive code. it was the initial reason i started looking for a mechanic. the rougher idle just helped me make a decision quicker.
i'm pretty positive it's not the lines. but i read you need some special tools to be able to test components of the vacuum system in a vehicle with turbo. so after testing the lines i decided it best to take it to a shop for diag.
i'm imagining after the timing is addressed, i'll have to replace something like the MAF sensor or IAC valve.

Find another mechanic? Is it possible to pressure test these systems without starting the engine? Red flag when shop does guess not test.

partially, yes. fully, i don't believe so.

i stuck with the same mechanic and, i should be thanking him for adamantly refusing to address issues in the order i requested.
the timing was off 1 tooth and the inside of the belt was nearly shredded, but that wasn't the big surprise. although that story is going to wait.

good news is that i got an update today and the car runs well. there are still a couple issues before it's in tip-top shape, but nothing catastrophic happened. which is purely phenomenal considering.
on Monday he's going to document everything to this point and start on what else it needs. i'll likely copy/paste that over, because i don't think anyone is going to believe this story without documentation.
i'll update then.

This post was edited by tagged4nothing on Dec 1 2023 02:39pm

ran into a couple more things to address before i picked the car up, so that's why i didn't post monday.
so... what was the major issue?


i drove for nearly 3 years / 12k miles with a timing system that allowed free movement of the belt by hand. the tensioner was actually in good shape but it had nothing to bolt to, so it was basically just a tracking guide if anything.
after getting the car back it runs smooth. there doesn't even seem to be a vacuum leak. the codes i got for them are gone, (just checked) and i am making proper boost.
i am mechanical, but i am not a mechanic. these guys legit saved me from catastrophic engine failure by not just saying "the customer is always right".

since it wasn't a vacuum issue. for my car to level out ~2700rpm, i can only assume the timing was jumping back on track at that point. or... idk... it might as well be another wonder of the world to me.

there were a few things wrong with the suspension as well that i had them take care of.
-rear passenger coil-over completely unbolted
-the strut mounts for my front coil-overs were the wrong size and left a vertical gap.
-front passenger tie rod end had to be cut off and replaced

after that they replaced the front driver door latch assembly and set my keyfob.
they also corrected all my tires. i had winter tires put on the wheels just before this and i guess all the treads were rotating backwards. i actually didn't know that was a thing, but i might not take it to belle tire next time.

they've stated that i have exhaust mounts that have failed. everything will be fine as is, but if 1 more goes it will likely be trouble.
i'll be bringing this back in the spring to address those and install a rear sway bar and cat-back system.
i'd also like to look into making it easily hot-swappable ot the catalytic converter. i have a test-tube to replace that when i'm off public roads.

i'm a happy tagged. the tune is working as intended and the boost is being created.
anyone gets too close to my rear bumper and i'll shatter their headlights as i let the launch control rapid-fire my exhaust before takeoff.
....at the likely cost of the operational use of the catalytic converter

This post was edited by tagged4nothing on Dec 8 2023 11:58am

sounds expensive. worth it to get fixed right though.

dont go back to last mechanic.

listen to this man. Sound that the mechanic doenst know well