What is the best way to check for these hairline cracks? I have looked over the hoses and not found anything previously by just looking at them, but is there a better way?
Just to expand on this issue:
Before the IM swap, it would go past 6000 without a problem. Using the IM with locked flaps, as the engine reaches around 5700 RPM and climbs to 6000, it’s similar to gradually bending a hose to stop the flow of water. The climb from 5700 to 6000 is slow and then it just runs out of breath. I may try swapping the old IM back on to see if that changes it.
First, we checked misfires with RPM and took it for a 15 minute drive. While idling at around 600 RPM, occasionally will get 1 misfire. Same thing staying under 2200 RPM. Normally accelerating from 2000-3000 RPM, I saw around 25-35 misfires. Beyond 3000 RPM, counter barely goes up. The party is in the 2500-2600 range. When staying in that range, the counter climbs by hundreds in a couple of seconds, every time. It’s also where the vibration is the worst.
We then went for another drive and checked misfires according to cylinders. Not much under 2200 and above 3000 RPM on any of the cylinders. Going from 2200 to 3000, cylinders 2, 6, 7, 8, 9, and 10 showed 1 or 2 misfires on the counters. Cylinders 1, 3, 4, and 5 showed between 3-10. The number of misfires on 1, 3, 4 and 5 rapidly grew between the 2500-2600 range.
The CEL did not flash at any point during the drive. Didn’t take it beyond 5000 RPM, but that’s the only spot where the CEL does flash. I might just pick up a cigar or something to do a vacuum leak test today, I’m becoming more and more convinced that’s where the issue is.
Best way is changing them 
@dzow I dont like changing parts just for the sake of it, so will look into some other ways to test for leaks. That main PCV hose isnt cheap!
@GreetingsWench It is somewhat comforting to find someone who describes the exact same issues I am dealing with. Hopefully we can get to the bottom of this. I have a gutted intake manifold, so mine is in the short runner position. I can say that I have no issues with revving past 6K RPM. Mine takes off around there as that is around where the intake would go to the short runner and pulls all the way to redline. The one thing in common is that we both have IMs that have been messed around with.
One thing another member had mentioned that I havent got around to yet is looking at adapting the throttle bodies through VCDS? I have just received my cable to will look into how this is done this weekend. Apparently they might need this adaptation if they have been roughed up a bit in the IM removal/install. I am not getting my hopes up that that is the issue, but worth checking.
I disconnected the MAFs and car ran pretty much exactly the same. I also did a throttle body adaptation and it made no difference (@spencerprince car on, engine off, in VCDS go to Engine > Basic Settings > Group 060 > click ON and wait about a minute, then click OFF).
I did hear a loud hiss coming from the bank 1 side. I pinched the hose circled in the photo and the noise stopped. Did not change the idle or sound of the engine. No idea if the sound is normal, can’t recall if it’s always made that noise. I took the line coming from the brake vacuum pump off to check if it was dirty or broken but it looked fine.
I then took the oil cap off. There was a massive amount of suction keeping it down and engine began to stutter once it was removed. I did the same on a Q5 with a 3.2L V6 (no codes, car is in perfect running order). Did not feel any suction and there was no stutter with the cap removed. I put my old oil separator on and it was exactly the same. I’ve seen people on both sides of this, saying there should be lots of suction or there should be very little suction. I assumed there should be suction, but then I’ve got no idea why the other car has no suction.
Lots going on so here we go.
Best way to check PCV parts is to water test. submerge the part into water. Usually you can use an oil drain tray or pan. Submerge the part cap off one end and feed air into the other end (low pressure) don’t go crazy. You should see bubbles if there is a crack or leak.
Check the drain line going to the oil pan as well. Also make sure the oil separator diaphragm is good. If you feel really manly you can take it apart and see the diaphragm itself.
Always check fuel trims when this is happening.
The drain line is the one that was cracked on mine… cheap part that costed me a lot just to find it… if i would do it again i would immediately change it with the PCV…
Not sure what changed overnight, but the engine is now able to go up to redline. Still get a flashing CEL as I go past 5500 or so, but doesn’t feel restricted at any point. It seems to upshift a lot quicker in manual mode as well. Going to clear all codes and start fresh this evening, I’m looking in way too many directions at the moment
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that’s it indeed
Got around to looking at my car this weekend. First step was looking at the fuel trims. I cleared the codes and looked at groups 032 and 033. In group 033, the values were hovering around 10% after the reset at idle. Is this high enough to conclude a vacuum leak?
And more of a general VCDS question, but is it normal for the “Adv measure blocks” to be greyed out for our car? My product is registered. Even when I go in thorugh the normal measuring blocks, I am unable to view the cylinder specific misfire counters, I believe these are MB 15, 16 and 17. Are any of you able to get into these? If so, I guess I need to follow up with Ross Tech.
I did do the Throttle body Adaptation and the Intake Flap Adaptation. I dont believe the Intake Flap adaptation worked because I have the flaps removed? Is there another one for the motors that control the swirl flaps?
Anyways, the car does seem to be running better after these adaptations. Will wait to hear back from the group on checking the misfire counters and the possible vacuum leak. If this is a possibility, I will water test the two PCV lines.
Which module are you checking for the cylinder specific misfires in? Misfire monitoring is carried out by the slave ECU (ie. engine 2)
This is why this forum is invaluable! I was definitely in ECU 1. Will check ECU when I get to use VCDS again later next week.
@GreetingsWench when is the last time you replaced your battery? Have you tested it? Another thing we have in common is that our cars had sat for quite a while. I am going to try boosting my battery today and see if it makes any difference.
For anyone, do people like to replace there battery with a specific model? Or just find one that matches the old on?
I replaced the battery about a month ago. Still had the original battery in there but it was on its way out. I replaced it with the same size and just made sure the CCA was equal or higher.
Smoke test showed no leaks, so I’m gonna order that PCV hose @dzow mentioned and see what changes, if anything. Running out of ideas at this point and I’m no closer to finding the source of this vibration
Hello @GreetingsWench
I had weird misfire shit going on and had the PCV hose replaced (due to cracking) as well as the Y plenum air distribution housing the throttle bodies mount to.
If the PCV hose does not fix the problem, don’t feel too bad about spending the money. The hose will break eventually.
As for the plenum, I had a leak from the throttle body fastener cracking the threading of the plenum, as well as a hairline crack in the rear of the plenum.
Did you go with new intake manifold gaskets by chance?
Lastly, even if the new battery matches the specs of the old, does the car need any teaching or adaptation for the new battery regardless?
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Hi @Revolv0,
That’s my thinking, removing the intake manifold has become almost second nature to me, so I might as well go through that process and replace the hose. No big loss if it doesn’t fix the issue. I didn’t notice any damage or cracks on the Y plenum, but I’ll give it a more thorough look when I’m replacing the hose, thanks for bringing that up.
I did get new intake manifold gaskets, waiting until everything is running right to get the JHM spacers as well. I do recall reading that when replacing the battery, it needs to be coded in order for the car to “see” it, but I never actually had to do anything. I’ve read multiple forum posts where others did not have to code it either, so not sure if this is just a way for dealerships to make a few bucks or what.
I was talking to a friend who had a similar issue on a BMW he previously owned and it turned out to be a bad crankshaft pulley/vibration damper. He had very similar symptoms: slight vibration at idle in all gears; very bad vibration at around 2000 RPM; random cylinder misfires; and at higher RPM the vibration would seemingly disappear. I’ll replace the hose first, and if that doesn’t work, I know what I’ll be trying next
Any updates on tracking down your issues?
No, I ended up parking it back in the summer. Didn’t want to risk damaging the engine with that constant misfire/vibration.
I’m thinking about pulling the engine this spring. Too cold to work on it right now. But unless I go through it all, I don’t think I’ll find the source of this problem. And it’ll be a good opportunity to give it a new lease on life.
When I pulled my engine I replaced the oil separator, and PVC breather hose that leads to the valley, and a new PVC cross hose (one that connects the two heads) all OEM parts
I still have cold start vibrations AFTER the enrichment cycle however. VCDS does not count them as misfires though the engine feels lumpy when cold. I usually just drive the car thru this at around 2k rpm
When warmes engine idles with 0 vibration now, I can sometimes not tell it is even on if it wernt for the exhaust.
I removed the PCV and blocked it off at the intake. It also removed any vibration caused from misfire and bad idle.
The PCV can cause tons for issues when it doesn’t work correctly.