up4speed

Kevin, thanks for all the great ideas! It was great talking to you on the phone the other night. Based on your recommendations, I made this contraption today so I can pressure check the engine. I will post results as soon as I complete the test.

up4speed

I wanted to give you guys a follow up on my progress with my troubleshooting.
I pressure tested the intake today with the tool that I made shown above.
It worked great! I used only about 7-10 psi and unfortunately/fortunately
(maybe it will fix the issues!) I had a leak. I found it with soap and
water and I tried to use an inspection camera to get a better look but I
still couldn't determine which part it is. The leak was from the joint of
the F-pipe where it goes into the blowoff valve. Unfortunately it was the
deeper valve, the one I can't reach! It figures, ughhh
I can't tell if it's an issue with the rubber hose, or a crack in the valve.
It appears to be leaking at the seam of the connection.
What are the symptoms of a leak at that location? Would it cause the rough
idle issues, or surging?
Is there a way to remove the assembly (F pipe and valve) to allow me to
inspect it more carefully so I can determine what needs to be done? I can't
even get my hand in there! It seems impossible. I have to assume that the
engine needs to be lowered a little?
Any help would be appreciated.

I also changed the MAF, MAP and the transmission mount today. It all went smoothly, however, I didn't test drive it yet because I wanted to fix the air leak first. Once that's fixed, I will also change the motor mounts. I will report back with the results at the end with hopes that I can help another person in the future.

jeanmarcboilard

Lowering the engine is extremely easy. I did it for the first time the other day. Wish I had tried it sooner. From underneath the car, around the area of the exhaust tips, about 8" in and 12" up you'll see a large 19mm nut. It's directly below the motor mounts when looking from the top side. Loosen those (one on each side) until they are at the bottom of the bolt. That's it. It won't drop much, just enough to slid your hand around the DV's.

up4speed

Great, thanks!
I'm going to take a crack at it today. I'll post results

up4speed

I finally found the actual cause of the leak!!

It was frustrating to find because initially the air seemed to be coming from the F pipe joint of the forward blowoff valve. Well after taking it all apart and inspecting, I found nothing wrong. So I re-assembled it being very careful that the clamps were straight and everything was pushed on tightly, and unfortunately it STILL leaked!!! I then took it apart again and used regular worm gear hose clamps and reassembled again, it still leaked! I had to take it apart a 3rd time, this time really pissed that the car was defeating me. Before I took it apart a 3rd time, I decided to lower the engine a little more to give me even more access since I was determined to find the problem. This time I reached in all the way and after pressurizing it, I realized that it was the Y-pipe under the blowoff valves! It was difficult to find because the hole aimed the air right at the F-pipe connection and made soap suds (I used a soap/water mixture to help me find the hole) on the F-pipe instead of the source (It's not like I could see the whole Y-pipe with everything hooked up anyway).

The craziest part is that the Y-pipe looked perfect even after I removed it! The only way I was able to see the hole is if I stretched the Y-pipe apart, see the photo. (first photo I stretched it apart and second photo, I left it relaxed)

Well I ordered the part and will follow up with an update after it's in. It will probably take about a week.

If there is any good news about this story, it's that I can now change blowoff valves in about 15 minutes flat without too much trouble! Lol

jeanmarcboilard

While you're in there you can check other components too. Check that the DV's themselves are functioning properly (search threads for different testing methods), inspect the circular check valves (one-way valves), ensuring they pass air one way and not the other. (there are pics of marked up parts diagrams that show the air flow direction somewhere in these threads).

up4speed

I checked the DV's by pushing up the diaphragm, then I plugged the vacuum hole with my finger. The diaphragm stayed up until I released my finger and let air in. I have to assume that since they held a vacuum, they are most likely fine.

jeanmarcboilard

Yep, that sounds right.

up4speed

I finished all the work on the car.
just for a summary, here is everything I did to it so far:

Changed fuel filter
Changed air filter
Cleaned throttle body
Put Techron in the tank
Replaced MAF sensor
Replaced MAP sensor
Changed transmission mounts
Changed engine mounts
Pressure checked intake and replaced V-pipe with hole in it (as shown above)
Re-synchronized throttle after restoring battery power

I'm happy to report that the car seemed smoother, the transmission didn't
kick when dropped into 1st gear (tiptronic), and the boost built faster and
held constant boost as I stayed on the throttle and didn't dip off like before.

There is some bad news though. After I finished all the work, I let it sit over night and started it again today and it still had the same exact cold start characteristic that it had before any of this work. It idles very smoothly at about 1,200rpm, then after a few seconds, the engine dipped down in rpm's, then back up. It then runs rough and feels like an off balance motor until it warms up a little and the rpm's drop to approx. 800 where it stays when warm and idles smoothly.

Another issue I noticed on the first drive I took, was a knocking sound which sounded like detonation
under load (~3/4 throttle acceleration) up a slight hill. I think I remember hearing it in the past, but it was so slight that I second guessed it. Now that the Turbo is pushing more boost, I feel like it made the noise a little more pronounced. It sounded like
it was coming from behind me on the drivers side and did it for a second or
two, then went away. I didn't feel any loss of power like the knock sensor
was retarding the timing though. I took it for a drive again the next day (today), and it didn't do it. I took the same route and tried to match the same exact driving that I did yesterday.

Just for the record, I have a fresh tank of Shell 93 octane in
it. Is there anything else for me to check?

"02996ttx50

to me, that just sounds like normal cold startup behaviour. it's richer at startup, hence the rough idle until it "settles" down to the 750/800 as it should.

if the idle "hunted" +/- once warmed up sufficiently at achieved operating temp? that would tend to indicate a vac leak somewhere and/or a failing MAF sensor.
but you've noted it's a "new" maf, so that kinda rules that one out! sort of.

Macster

The initial cold start up behavior is normal.

The RPMs climb to a bit over 1K almost immediately, then a few moments later the RPMs take a mild dip then recover. The engine can be bit rougher running afterwards.

This is the DME selecting the low intake valve lift. There is a quick dip of the oil pressure as the DME selects low lift.

But as the engine idles and gains some heat the roughness diminishes. Once the engine RPMs drop to the near hot idle engine speed the engine's about as smooth as it can be.

Not sure you are hearing detonation. Detonation may not be audible. Besides the knock sensors are intended to detect the onset of detonation and the DME will retard spark to nip any detonation in the bud. Detonation is not good.

You are probably hearing something else. Maybe something in the exhaust system is loose?

If the engine is behaving and running sans any drama I'd say there is nothing more to check.

up4speed

Correct, It hunts +/- RPM's only when it's cold. After it warms up for a few minutes, the RPM's drop and then it's very steady. I feel like it shakes way more than I would expect while it's warming up, but it is exactly as you described, so it may be normal.
I also want to add that it most likely doesn't have a vacuum leak. The reason I say that is because when I did the work on the Y-pipe, the car was sitting over night and when I disconnected the large vacuum pipe I heard air pressure stabilize. Meaning that there are no holes. I'm not sure if that's just one section of vacuum, or if it includes all of the vacuum components though.

I'm just shocked at how rough it actually runs when cold. Other than that, it's exactly as you both describe, so it very well may be normal.
As you mentioned, I may not be hearing detonation, but it definitely sounded exactly like it. It doesn't always happen though. That definitely makes it harder to troubleshoot.

Thanks for all the advice, I'll definitely update if I find out any new info.

"02996ttx50

then it is all "beginning" to sound "normal". i just decatted mine and it now rumbles like a cummins at startup then settles even moreso by comparison than previously. it's quite different, and if i didn't know better, might think something was amiss. when in fact, it's just got no backpressure

many folks i would imagine running catted or stock exhaust probably only appreciate the sound AT startup lol. because stock, it settles at 750/800 to a "whisper". excepting of course for any loose marbles rattling in that "mystery" can your car may have lol. hopefully yours doesnt do THAT.

sounds like you'll have it sorted soon enough.

rmc1148

I can only go by mine which does none of the searching- being rough up at start up etc= I would take it to a good shop that knows what they are doing as its cheaper/easier in the long run. Last time I will suggest that in this post honest lol.

up4speed

LOL, I actually do have a little bit of the rattling marble sound at idle as well, normally that would have made me panic, but I did enough research on it to know that it is an expected anomaly with the car. As a matter of fact I expected it before I even purchased the car.

I hear you...trust me. It's partially that I actually enjoy working on cars and troubleshooting on my own. I don't do it to save money, I'm just an enthusiast and I see it as a hobby. If I decide to bring it to someone, that's going to take more research than for me to research the problem because around here it is very tough to find a really good shop that is thorough, goes by the book, and treats the car with respect. So far, I have had Kevin from UMW help me out a lot. He is helping to guide my troubleshooting steps and has helped a lot already. I'm just VERY picky with my cars and I want it as perfect as possible. Kevin is a great guy and if his shop was local to me, he would have definitely had it in his shop already!
I also concentrated on replacing things that are consumables, so it's not like the money is totally lost even if there is no immediate change to the car. Plus if I eventually give up, it should help a pro out a little to know that certain things were done and can (usually, of course there could be that defective replacement part) be eliminated as the cause.
I appreciate everyone's input and at the end I think I will be happy with the result, hopefully with pride that I did it myself.
I'm up to the point that I may need advice from someone locally just to tell me if there is still a legitimate problem that needs fixing. If there is, I'm sure I will get to the bottom of it one way or another. As you said, it may ultimately cost me more than if I took it straight to the shop though! LOL
Hey look at the bright side, I will have a lot of new parts that won't need attention for a long time!