Multiple Cylinder Misfires -- Both Banks

[fastlx]

Edited thread content as it's now just about doing the engine out full timing service and all new gaskets. :)

I'm on my second B7 S4 and am familiar with potential issues with them but am well equipped to do any kind of work -- used to build them for a living.
I have a 2008 Audi S4 (130k+ mi -- literally all highway from single owner since new) that is having multiple cylinder misfires.

I've concluded it needs the timing system service. So I'm removing the engine and doing the full JHM Audi kit with new cam sprockets, all new chain guides with updated design, and so on.
*** UPDATE ***
Decided since I plan to sell the car soon anyways, and nobody will confidently buy a 100,000+ mi car that hasn't had this stuff addressed (at least, I wouldn't), I'm going to pull the motor and make this whole setup like new. Someone will get a car ready to go and be enjoyed for a loooong time.

Honestly, all these cars that have never had this engine out service with 80,000 mi....I wonder how much buyers worry about how long they get to drive it before they need to address this.

So, whoever buys this one in the coming months, they will be able to see that everything is fresh and ready for 100,000 more miles.






*** UPDATE TWO *** (6/4/15)


All new JHM timing gear installed and putting the covers back on


About to go back into the car with new timing kit, all new gaskets including rear main seal, both valve cover gaskets, intake gaskets, new coil packs, etc. Ready to rack up a lot of miles trouble-free.




All back together and about to get the front bumper cover back on. New coil packs, fresh clutch, all updated timing equipment, new gaskets, all new fluids (brakes, power steering, engine oil/filter, etc)

[SlickFix]

Wait, so when the multiple misfires happen, it still idles fine?

No chain rattle on cold or warm startup?

The only codes it throws are the multiple misfires? Nothing else?

[fastlx]

Wait, so when the multiple misfires happen, it still idles fine?

It idles like a car with a mild aftermarket camshaft setup -- slightly lopey....can subtly hear misfiring. My point was just that it cranks right up and idles without any odd mechanical noises.

No chain rattle on cold or warm startup?

Under no circumstances do I hear chain rattle. Whether it's ice cold with all oil having had tons of time to drain out of everything and all that -- just fires right up and idles quietly with a lopey idle.

The only codes it throws are the multiple misfires? Nothing else?

I'm going to piddle with it in a bit and will see if I can get a video of cranking it up and such. I'll also pull all the codes again and see what pops up now that I fixed the vacuum leak. Last time I pulled the codes before clearing them, it was codes for misfire on literally every cylinder except #7. And it had one for a bank being too lean. Now that I've fixed a couple of issues, I'm going to drive it a good bit and see what codes it gets and will report back.
I had just assumed originally that it was tensioner/chain related, but then with the lack of noise from any of those parts, has me scratching my head.

Does anyone know how to actually test the MAF? Or is there info on what I should see for MAF parameters while the scanner is hooked up?

[breal]

What do your spark plugs look like? I was also wondering cam adjusters, but you have no noise at startup. Does it misfire while driving?

You can try searching for the voltages the MAF should be reading. I haven't logged in a while, but you should be able to view a few MAF parameters in VagCom.

[fastlx]

What do your spark plugs look like? I was also wondering cam adjusters, but you have no noise at startup. Does it misfire while driving?

You can try searching for the voltages the MAF should be reading. I haven't logged in a while, but you should be able to view a few MAF parameters in VagCom.

the spark plugs are brand new. Yes it seems to misfire all throughout the RPM range just consistently. I'm going to go work on it and just a little bit and we'll get a few videos for you guys.
As far as the cam adjusters, again, wouldn't that show up in the compression test, or no? I'm just thinking that if the valve events due to timing related issues are such that the cylinder doesn't fire, then it wouldn't be able to build adequate compression in that cylinder, would it? That's just an assumption on my part, but if you look above, the compression test DID look really good.
Has anyone had problems with the timing and cam adjusters and all that and still shown good compression on all 8 cylinders?

[rocket5979]

Is it literally a P0300 DTC only being thrown or are there other cylinder specific misfire codes being thrown?

[fastlx]

Got preoccupied. This should be a fun thread. :)
Did a bunch of troubleshooting and decided that the cabin just seals off all noise nicely....when standing there with the hood up in front of the car (like I was in making some videos), does kind of sound like a little diesel motor there. And I plan to sell the car anyways, and nobody will confidently buy a 100,000+ mi car that hasn't had this stuff addressed (at least, I wouldn't). Honestly, all these cars that have never had this engine out service with 80,000 mi....I wonder how much buyers worry about how long they get to drive it before they need to address this.

So, whoever buys this one in the coming months, they will be able to see that everything is fresh and ready for 100,000 more miles.

Anyways, here is the update lol






More pix to come in the coming days as I get into the good stuff. :)

[TRIP]

Kinda have the same issue except I have a missfire cylinder 1 only changed coils and plugs still no good any ideas
also sounds like it's cammed at idle

[fastlx]

A little bit more progress. Transmission and everything removed off the engine. Almost time to get the rear cover off there and see how everything looks for the timing system

[SprintBlueWorld]

What timing kit are you going with? Are you going to try the RS4 guide or the JHM updated?

[fastlx]

What timing kit are you going with? Are you going to try the RS4 guide or the JHM updated?

Not sure yet. First just going to get in there and see what exactly failed and then decide what I believe to be the best route. Likely will go JHM though -- just need to see the state of the cam adjusters and those sort of things. I'm curious to see which part(s) actually failed.

[SprintBlueWorld]

Not sure yet. First just going to get in there and see what exactly failed and then decide what I believe to be the best route. Likely will go JHM though -- just need to see the state of the cam adjusters and those sort of things. I'm curious to see which part(s) actually failed.

Looks like a mighty clean shop your working out of. I would love to see the step by step disassembly of the timing gear. Im not sure anyone has done that on here.

[rocket5979]

It is quite easy once you see it in person. That is one of the very few aspects I like about the design of these Audi BHF engines is that you literally lock the crankshaft and camshafts before taking the timing chains off. There is literally no chance of valves accidentally hitting pistons once the chains are removed, or of mistiming the engine when doing reinstall. An individual would literally have to really try to screw up retiming this engine. About the only way I could see someone being able to do it is if they didn't properly torque the cam adjusters to the camshafts and things slipped.

[fastlx]

It is quite easy once you see it in person. That is one of the very few aspects I like about the design of these Audi BHF engines is that you literally lock the crankshaft and camshafts before taking the timing chains off. There is literally no chance of valves accidentally hitting pistons once the chains are removed, or of mistiming the engine when doing reinstall. An individual would literally have to really try to screw up retiming this engine. About the only way I could see someone being able to do it is if they didn't properly torque the cam adjusters to the camshafts and things slipped.

Is it very common for them to have been able to actually skip time....jump a tooth from enough slack? Or is that unheard of?
I ask because if it's possible and might have happened, locking the gear in beforehand would lock it into incorrect time.

I should have everything available just to do it from scratch. We've done a bunch of the Gallardo engines which is an Audi V10 all the way down to the logo on the block lol. They look pretty similar to this engine, just with 2 extra cylinders. Well, heads are 4v per cylinder and not 5, but the timing setup on the back of the engine and how it's laid out shares a lot in common with the Gallardo...use of triple square sockets for tooling, and so on.

[rocket5979]

Is it very common for them to have been able to actually skip time....jump a tooth from enough slack? Or is that unheard of?
I ask because if it's possible and might have happened, locking the gear in beforehand would lock it into incorrect time.

I should have everything available just to do it from scratch. We've done a bunch of the Gallardo engines which is an Audi V10 all the way down to the logo on the block lol. They look pretty similar to this engine, just with 2 extra cylinders. Well, heads are 4v per cylinder and not 5, but the timing setup on the back of the engine and how it's laid out shares a lot in common with the Gallardo...use of triple square sockets for tooling, and so on.

Not usually. I could be mistaken, but I believe that by the time a tooth has been skipped, then pistons will be hitting valves. At least that's the way it is in many other high performance interference engines. That has happened to some on here, thus destroying their engines, but it seems to have been a rarity.

Once you see the manner in which the camshafts themselves lock into time then you will understand that there is ZERO chance to lock them in incorrectly. The reason for this is that on the part of the cams that faces forward in the car (opposite from the cam adjusters/sprocket gears) there is a slit machined into the actual end of the camshaft itself. That slit is purposely machined off center so that the camshaft cannot be locked down 180* out of time. This is why they literally cannot be locked down out of time. So when you are ready to lock your cams down all you need to do is get a 3/16" piece of flat bar steel (don't buy the $100+ tool for this, because it's a waste of money) and manually rotate the crankshaft until all of those slits line up parallel with each other, and are above the horizon of the top mating surface of the cylinder head. I just bought 3/16 x 1" steel flat stock, cut two pieces about 10" long, and then drill a hole in the location where one of the cam cover bolts are. Insert the locking bars into the camshaft ends and then use one of your bolts to keep it in place. After that, then remove the plug on the bottom of the passenger? side of the engine and you will see the crankshaft itself will have a machined hole into it where your locking tool will go.

The only tools I bought to do the cam timing on this engine were the cam adjuster reluctor wheel tool (I forget what Audi refers to it as) and the crankshaft locking pin tool/bolt. Having drill bits in smaller sizes to be able to lock your timing chain tensioners in the collapsed position isn't a bad thing too; but I cannot remember specifically what size. Maybe around 3/32" or so?



Edit: I thought of a way that someone could screw the re-timing of this engine up, besides obvious things like not retorquing properly and other obvious things. When you are re-installing the hydraulic cam adjusters and about to torque those bolts down to spec on the camshafts, if the inner part of the adjuster itself isn't clicked into place in its base setting then that portion which actually attaches to the camshaft would be clocked wrong compared to the outside of the adjuster that has the sprocket on it.