What the F@%k just happened?

[B5A4coastie]

Hey guys, here's the quick story:

I was trying to fix an oil leak that I thought was from the front main crank seal, when I got to it, it was dry as a bone. My entire underside of the oil pan is covered, so I replaced the pan gasket. Buttoned everything up and it had a horrible idle, loud and shaky like. I thought I might have messed up the timing, so everything came back appart. I did an inspection of the pistons via scope and they are damp, confirming timing. I verified TDC through the #1 cylinder and put her back together, turn the key and now it doesn't start at all, with the same nasty sound and vibrations while turning over. WTF happened here? I've taken this car apart a million times and never had a timing issue.

Now small details that may or may not have anything to do with the issue:

I pulled off the negative battery terminal prior to starting work. I normally don't always do this when working on the car, but since I was raising the motor and trans to replace the oil pan gasket I wanted to be safe. I thought this could be my issue (loss of tune memory or something, but I reflashed my tune and it acts the same.)

I found a broken tranny mount while I was unbolting the transmission from the frame. I replaced it with 034's street mounts, this could be causing what I feel is excessive vibrations, since I have never felt my car idle with them installed.

I couldn't get my pan to fully clear the subframe, so I pulled the oil pump to give me more clearance. The only thing this would have done had I messed it up would be prevent the engine from getting lubricated, that could give the engine a rougher idle, but I'm leaning more to the mounts.

I replaced my forward oxygen sensor, this was to help with a readiness issue I am having. I thought I ordered the rear sensor which is what I believe is causing my problem (I'm still investigating if this was my fault or ECS). I'm 90% sure you don't have to do anything special when you replace these sensors, but even then it would idle right? (This is by far the easiest fix and will try swapping it back tomorrow).

I'm working on this alone, so I can not verify spark on the valve cover, but I know the plugs were dry, but the piston was wet, so I'm leaning to spark is there, but at the wrong time (again with the timing issue).

Lets hear your ideas, I'm so close to part this thing out after the last 4 days of cascading issues.

[Articus]

Are you drive by wire? Tried a throttle body adaptation?

[demonmk2]

^that or an intake leak of some kind.

[CoyneJ]

i have electric throttle body and i encountered same issue after i disconnected my battery, rough idle and stalls but otherwise runs fine

[demonmk2]

If you're drive by cable turn the ignition on with out turn\starting the engine to let the throttle body cycle. You'll hear it buzz ( throttle body) and let me know when you're tired of that gtx2867r..

[B5A4coastie]

If you're drive by cable turn the ignition on with out turn\starting the engine to let the throttle body cycle. You'll hear it buzz ( throttle body) and let me know when you're tired of that gtx2867r..

Are you drive by wire? Tried a throttle body adaptation?

DBC, but I could try a TBA.

I know I will have to sell/part it out prior to me moving in the summer of 2017, this hiccup has me thinking of doing it earlier. Tomorrow is another day, we'll see what it brings.

[B5A4coastie]

I did the TBA this morning and it started but ran like crap. After about 10 seconds I shut it down, misfires on all cylinders. I have a second mark on my timing belt cover that I made when I first got the car, the position where the dash on the crank was almost an inch off. I did the timing to the factory position (usually I mark where the dashes are and just line them back up) this last go around being that I verified TDC before bolting everything back together.

I guess this could be one tooth off and still run without anything binding..... Back apart we go.

[SN95Audi87]

I did the TBA this morning and it started but ran like crap. After about 10 seconds I shut it down, misfires on all cylinders. I have a second mark on my timing belt cover that I made when I first got the car, the position where the dash on the crank was almost an inch off. I did the timing to the factory position (usually I mark where the dashes are and just line them back up) this last go around being that I verified TDC before bolting everything back together.

I guess this could be one tooth off and still run without anything binding..... Back apart we go.

Maybe one of your sensors got messed up. When I got into my fender bender, I punctured my radiator and fluid was leaking causing a misfire. When everything got fixed with oem equipment it went away. I know this is a basic answer but usually the simple things are what we over look.

[Avant Nate]

Pull your valve cover and check you timing using the camshafts

[B5A4coastie]

Pull your valve cover and check you timing using the camshafts

Help me remember, all valves closed on #1 at TDC? It's on the compression stroke right?

Alright, here we go using the factory marks: (you can see my second mark to the right, that's where I have found it in the past)



Spot on



The valves are in fact closed.



The Cam timing marks line up...

[B5A4coastie]

I have a compression tester in route and I'll check spark the same day.... Besides the cam position sensor, I'm not sure what else would need changed.

[zandrew]

Your not going want to hear this but I had the exact same issue. It turned out being my maf which was brand spanking new. I have always wondered if the a8 maf get screwed up the maestro. The stock maf heats up after you turn the car off for about 5 seconds to clean the element. With the voltage clamped on the a8 maf they might not be getting cleaned or worse cooked. I changed to an old maf and the car ran fine. Now I remove the maf before working on the car.

I know it sounds silly but if you an extra maf try it. Mine would still run but it ran like shit.

[viceprp]

When you had misfires in all cyl, did you pull plugs to see if they were wet?

Just an FYI, if you have excessive fluid in the cyl that cannot be burned off quick, you can bend a rod.

Check your crank sensor connection. Pull, clean & reconnect. Did you disconnect all hoses when raising? Could have disconnected or torn.

[B5A4coastie]

Your not going want to hear this but I had the exact same issue. It turned out being my maf which was brand spanking new.

My MAF sensor is also a few months old....

When you had misfires in all cyl, did you pull plugs to see if they were wet?

Just an FYI, if you have excessive fluid in the cyl that cannot be burned off quick, you can bend a rod.

Check your crank sensor connection. Pull, clean & reconnect. Did you disconnect all hoses when raising? Could have disconnected or torn.

The first go around they were dry, now they are wet. I disconnected as little as possible when I raised everything. I was pretty careful but it's worth looking over everything.

[walky_talky20]

My brother was freaking out when he put his car back together after a timing belt and some other stuff. Wouldn't idle, ran super rough. He thought the worst. Then I put my finger over the vac port he left disconnected at the manifold and everything was fine. ;)

[demonmk2]

When did you install the icm delete fsi conversion ?

[B5A4coastie]

When did you install the icm delete fsi conversion ?

15K miles ago, I made sure everything was still tight. I'll be checking spark and compression today when my g/f gets home.

Walkie, I would be so happy for it to be that simple. You are more than welcome to come down and finger my engine.

I've been taking small steps lately, only spending an hour or two tops out there because (1) it's cold now and (2) so I don't get super frustrated.

[B5A4coastie]

When you had misfires in all cyl, did you pull plugs to see if they were wet?

Just an FYI, if you have excessive fluid in the cyl that cannot be burned off quick, you can bend a rod.

Check your crank sensor connection. Pull, clean & reconnect. Did you disconnect all hoses when raising? Could have disconnected or torn.

Are you sure AEB has a crank position sensor? I feel like that's something I would know it has.

Edit: yep, should have googled this first.... I thought this was strictly a tachometer.

[B5A4coastie]

I found the reason it doesn't run, however I still don't know what caused it.



Drum roll please..................


Zero as in (0) compression in the #4 cylinder

I'll continue the rest of this journey in my build thread.....

[viceprp]

You pull the head? Melted piston?

[redline380]

My brother was freaking out when he put his car back together after a timing belt and some other stuff. Wouldn't idle, ran super rough. He thought the worst. Then I put my finger over the vac port he left disconnected at the manifold and everything was fine. ;)

LOL, I just replaced a piston on a 2006 Chevy Colorado. First start up and the thing hardly idled and shook a ton. My mind was racing, but I kept cool and looked around. Plugged a massive vacuum line back in and the thing purred.

unfortunately, doesn't sound like OP had the same luck

[B5A4coastie]

You pull the head? Melted piston?

I hope to pull the head today. The piston looks ok via scope.

[Nollywood]

Possibly a bent valve.

One thing to note - it's not always a good idea to use the crank pulley marks as a timing reference. I have come across pulleys where there's been so much slop, the timing marks varied between 1 and 3 teeth on the timing belt. Worn sprocket keyway can make things worse.

The most reliable timing reference is on the flywheel, via the "window" on the top left of the bellhousing.

[B5A4coastie]

That'll do it. The piston has the smallest mark where they touched..... It didn't take much.