Boost "sputtering", low power, possible camshaft issues

BEW Boost "sputtering", low power, possible camshaft issues

Greetings,
I've got a perplexing one. I think it may have be the result of a handful of contributing factors, or just a big coincidence.
The car is an '04 Jetta with about 130k miles.
I'm about 2 months into this one... Car was working fine as far as I could tell. My wife drove it while following me in a work truck to the mechanic. I noticed unusual smoke from the car in my rear view mirror. She doesn't have the lead foot that I have.
When I got in to drive home the car was very sluggish and smokey. Boost guage registered boost lower than normal. I have a tune by Kerma so 17-20 is to be expected as long as I watch for boost creep.
I have:
- checked for boost leaks (none apparent).
- checked MAF with VCDS and by unplugging (appears to be good).
- checked intake for clogging (not signifigant, though did clean EGR).
- checked for turbo play (there is movement radially but not enough to touch the housing, no signifigant axial play).
- bought a mitivac and determined the turbo actuator was leaking.
- replaced actuator with modified VNT-17 actuator. (adjusted on table to actuate between 3-18psig.
Test drove car. Boost was all over the place, had spikes into the high 20s. Gingerly limped the car back home.
- determined turbo vanes were sticky. removed turbo and cleaned thoroughly.
Test drove car. boost no longer spikes, but "stutters" as it moves through it's range. I don't have power like I should. By stutters I mean that the needle flutters by about 3 psi as it moves up and down. I can also build 5-8psi of boost at idle by revving the engine which I don't remember as normal.
Car was idling very rough around 1200 rpm, but that got almost entirely normal after I ran a can of diesel purge directly into the fuel lines at the fuel filter.
- looked at camshaft again, but closer and after I'd found pictures of a "bad" camshaft. There's a tiny bit of wear on the rocker arm lobe, but not any kind of indent like some pictures had. The valve lobes are worn so that maybe 1/2" from the apex does not have the chamfer on the edge anymore.
At this point the main symptoms are:
- loss of power
- boost flutters potentially into overboost (>20 psi) range if I keep my foot down.
Are those symptoms that could be caused by the cam alone at this point? or is there other diagnosis that I should do?
Thanks!

Try unplugging your EGR and see how it runs. I just had a very similar condition on an 04 Beetle PD.

dweisel said:

Try unplugging your EGR and see how it runs. I just had a very similar condition on an 04 Beetle PD.

Click to expand...

Good idea, same result however.

There's definitely potential I have the actuator set wrong, bit I don't think it's "that" wrong.

I've got a video of the guages uploading right now.

This video was just taken after I put the valve cover back on and left the EGR disconnected. It acts the same with the EGR connected.

The skip in the video is where I put my seatbelt on.

https://youtu.be/7BBd-Vh1BUo

Watched your video. There appears to be a real serious boost issue, but boost is more appropriately measured when transmission is engaged and doing a pull. 3rd gear, starting at 35mph, the boost should come on strong at about 40mph.

My initial reaction is you either have a massive vacuum leak or your N75 is on the fritz. Check vacuum coming off of the top line going to the N75. At idle, it should register 27in vacuum. Check next line down on N75. This line goes to your turbo actuator. At idle, it should register 18in. Actuator should be pulled to the 'full boost' position, or against the stop.

Check for a split in the hose to your brake booster. Check to see all vacuum lines are in good shape. No splits, no collapsing hoses.

One great check is to see if pulling and holding vacuum on the actuator causes the engine to run with power. Only thing is, don't drive too aggressively. If boost then exists, you can blow up the turbo. If you still have no boost, you can bet it's either some severe exhaust flow problem, no fueling or a bad turbo.

BTW: your 'no load' acceleration shows blue smoke, which is either a worn engine with blowby, stuck rings or a bad turbo. Add it all up and you very likely have a bad turbo and/ or your rings are worn. Loosen oil cap and see how hard the exhaust blows.

Evan Sussman said:

Good idea, same result however.
There's definitely potential I have the actuator set wrong, bit I don't think it's "that" wrong.
I've got a video of the guages uploading right now.

Click to expand...

A little wrong can make a difference. Also check the stop screw on the turbo. The nut was missing on mine which let the screw itself up and limit the travel causing an under boost problem.

Blue smoke and very late turbo action is NOT a stop screw issue. without the stop screw, you could have an overboost issue, but you have a very late boost issue, which should be at full boost pressure at no later than 2000 rpm. It's way off.

Franko6 said:

Watched your video. There appears to be a real serious boost issue, but boost is more appropriately measured when transmission is engaged and doing a pull. 3rd gear, starting at 35mph, the boost should come on strong at about 40mph.

My initial reaction is you either have a massive vacuum leak or your N75 is on the fritz. Check vacuum coming off of the top line going to the N75. At idle, it should register 27in vacuum. Check next line down on N75. This line goes to your turbo actuator. At idle, it should register 18in. Actuator should be pulled to the 'full boost' position, or against the stop.

Check for a split in the hose to your brake booster. Check to see all vacuum lines are in good shape. No splits, no collapsing hoses.

One great check is to see if pulling and holding vacuum on the actuator causes the engine to run with power. Only thing is, don't drive too aggressively. If boost then exists, you can blow up the turbo. If you still have no boost, you can bet it's either some severe exhaust flow problem, no fueling or a bad turbo.

BTW: your 'no load' acceleration shows blue smoke, which is either a worn engine with blowby, stuck rings or a bad turbo. Add it all up and you very likely have a bad turbo and/ or your rings are worn. Loosen oil cap and see how hard the exhaust blows.

Click to expand...

Thanks Frank,

During this diagnosis I did replace vac lines going to the actuator, from the t to the N75, and to the EGR cooler valve. The rest of the hoses appear to be in good condition.

At idle the top line at the N75 shows 26", the output of the N75 reads 18". When I run the output test on the N75 with VCDS the pressure doesn't drop immediately when the duty drops to 4.8%, it drops for a split second after it kicks back to the 95% part of the output test. If I bleed the pressure on the Mitivac during the low duty cycle it will read 0" until it goes to 95% again.

The brake booster hose does have a crack. It has had one for years. I taped it, but that gave out. I did however tape it again during this process. I'm 99% sure I tested the check valve on the booster line when I had that out to re-tape it.

I tried pulling 18-20" on the actuator line and test driving. It very well may have normal power (I did flash back to stock tune), but I have to get off it quickly to avoid overboosting which is pretty much what I have to do with the actuator line connected to the N75. The boost still flutters too which I don't ever remember happening. Boost guage is a NewSouth tapped just above the intercooler on the intake side.

I checked the smoke again, I don't think it's blue. That mirror is from a junkyard and had blue tint on it. Smoke looks black / grey in person.

Re: loosen oil cap and check exhaust, do you mean out of the oil cap, or the tail pipe? Here's a video.

https://www.youtube.com/watch?v=Bu1YpJuzUWA

dweisel said:

A little wrong can make a difference. Also check the stop screw on the turbo. The nut was missing on mine which let the screw itself up and limit the travel causing an under boost problem.

Click to expand...

The set screw and nut were definitely there and I did not move them. What I did do is set one of the nuts on the rod so it was tight at rest and snugged up the other nut. I confirmed that it started moving at 3-4" and stopped around 18". It did do that.

I have not gotten to fine tuning with logs because the car doesn't run well enough to do a full throttle run.

So, I'm pretty silly. Evidently I swapped the VAC and OUT lines on the N75 when I replaced the vac lines. Boost log now spikes and settles after 1-2 passes over the requested line.

Thank you for your help!