Surely it should be better than this

absalom

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Copying my post from another thread in its own. As it is now, I have to slip the clutch from a standstill just to get moving. It feels as the car is making all of 9 hp below 1800rpm. That’s with zip tie mod and pressure differentials of around 100 mbar.
Quite frankly, I’m very disappointed with the low rpm driveability of the BRM when contrasted to my recently sold ALH. It’s downright terrifying to pull into an intersection with almost zero acceleration.

The car has cam, lifters, EGR cooler, lift pump all within the last 20k miles. Actuator holds vaccuum.

Is it supposed to drive this way??
 

Rx7145

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I feel my car is the same. Adjusting the turbo is almost a black art.
 

Vince Waldon

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A thought: have you verified proper EGR operation? Specifically, that it is closing all the way?

My bro had a BRM with scary low power until 2000 RPM or so... scary in terms of pulling out into traffic etc. After a long and windy troubleshooting road Oilhammer recommended checking the EGR with VCDS:

- remove it and place it on top of the engine after re-connecting it electrically
- use VCDS's Output Tests to cycle it thru multiple cycles, checking with a flashlight to see if it's closing all the way.

In our case 1 cycle out of 3 it would stay open just a bit... but more than enough to allow a bunch of unmetered air in at low RPMs and really mess up the power.

New EGR... drives like a new engine, with all that low-end diesel grunt we love. :

Just one thing to check... :)
 

absalom

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A thought: have you verified proper EGR operation? Specifically, that it is closing all the way?
My bro had a BRM with scary low power until 2000 RPM or so... scary in terms of pulling out into traffic etc. After a long and windy troubleshooting road Oilhammer recommended checking the EGR with VCDS:
- remove it and place it on top of the engine after re-connecting it electrically
- use VCDS's Output Tests to cycle it thru multiple cycles, checking with a flashlight to see if it's closing all the way.
In our case 1 cycle out of 3 it would stay open just a bit... but more than enough to allow a bunch of unmetered air in at low RPMs and really mess up the power.
New EGR... drives like a new engine, with all that low-end diesel grunt we love. :
Just one thing to check... :)
That's great input. So here's the thing, the power loss is VERY inconsistent, however it seems to be most common after just starting the car; whether it's a cold start or hot start seems to make no difference.

Sometimes, it will drive like I imagine the BRM should drive. Other times, it will have the scary power loss, regardless of pedal position. The difference is very noticeable.

Your saying that the EGR was inconsistently functioning certainly sounds like it could be the cause. If only it were easy to pull the EGR quickly and check ...
 

crazyrunner33

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On top of the zip time mod that was mentioned, inconsistent issues screams some sort of electrical issue. Simple things to also check would be bad grounds and the engine harness, I had similar issues with a bad ground. Make sure that the lift pump is running, there's plenty of articles and threads about it on this site. You can also check the MAF readings on VCDS to check actual vs specified, same with boost.
 

Vince Waldon

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Sometimes, it will drive like I imagine the BRM should drive. Other times, it will have the scary power loss, regardless of pedal position. The difference is very noticeable.
Your saying that the EGR was inconsistently functioning certainly sounds like it could be the cause. If only it were easy to pull the EGR quickly and check ...
My bro's symptoms exactly... and the inconsistencies were because the EGR valve sometimes closed all the way and sometimes didn't. If it closed all the way the car was great.. if not... horrid. :)

When we pulled it it was a bit dirty... but even after being cleaned (which we hoped was all it would take) it was still not passing the flashlight test every few activations.

Only a few minutes to pull the EGR IIRC... fingers crossed for you.
 

sptsailing

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The EGR valve can be pulled out without a great deal of trouble as long as you are willing to crawl under the car and capable of working a little blind. Crawl under the car and use long extensions to remove the two 6mm hex bolts holding the EGR cooler onto the EGR valve houseing. The EGR valve housing is only held on to the intake manifold by three #30 torx bolts, one of which you need a mirror to see. Undo the electric, get a small mirror and carefully remove the three #30 torx bolts. The ASV and EGR assembly will come off for further inspection. Three more #30 torx bolts hold the actual EGR valve onto the housing. My bet is that the EGR is thoroughly gunked up. Your intake manifold will probably look pretty bad too. You will probably need a new gasket between the EGR cooler and the EGR housing when re-assembling it. If this has never been done, it is worth doing.
 

Franko6

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A thought: have you verified proper EGR operation? Specifically, that it is closing all the way?

In our case 1 cycle out of 3 it would stay open just a bit... but more than enough to allow a bunch of unmetered air in at low RPMs and really mess up the power.
New EGR... drives like a new engine, with all that low-end diesel grunt we love. :
Just one thing to check... :)
Although I do think the EGR is something to check, I don't think that is exactly right, that allowing 'unmetered air' into the engine is going to cause the engine to be 'messed up' at low rpms.

The ASV plate is not a throttle body. The EGR does need to open and close correctly, but it should not close down, nor does it need to shut down in order to make the engine have low-end torque. It would be more likely that the ASV is closing too much, choking off air than if it were wide open and let in unrestricted air.

We generally test the poor operation of the EGR by disconnecting it. Understand, the reason the manifold flap closes is to force more EGR gasses into the intake. A diesel engine is simply put, an air pump. The amount of air is 'metered' in a manner, by the EGR system by heating and reduced oxygen. So, what the EGR's purpose is to reduce NOX. It does in no way, improve the low-end torque. If anything, the EGR reduces power by reducing excess oxygen that will be exhausted as NOX.

Reasons that turbos are not performing well at low-speed, which I refer to as below 2000 rpm, are issues with the actuator, N75 or the vacuum pump or vacuum lines. Vacuum at idle to the N75 should register 25-28 inches at the top nipple. The line going to the actuator is the next one down and it should show 18 inches vacuum. The actuator itself is a bit tricky, but at full vacuum, or 18 inches, the lever of the VNT should be against the stop screw.

The business of adjusting the actuator is real 'redneck' stuff. We do not use a zip tie, as none of them are fireproof. It's baling wire... from my redneck repair tool box.. right next to the slip joint pliers and the claw hammer.

It's been written up before. Using VCDS, and pulling the actuator arm up to reduce boost pressure at 1450rpm to around 1050mb will improve many symptoms of slow, smokey or hesitant take offs.
 

absalom

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So, after spending some more time with the car, I am now able to better describe the symptoms.

The issue ONLY occurs after the car has recently started. The temperature, as indicated by the cluster, seems to have no bearing on whether or not the issue will occur.

Once the car has been driven for about 5-10 minutes, usually after a highway run, power is 100% restored and the car is great. For those first 5-10 minutes, it's absolutely terrifying to drive, and resembles the powerband of a 2 stroke GP bike.

Does this help?
 

Vince Waldon

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Although I do think the EGR is something to check, I don't think that is exactly right, that allowing 'unmetered air' into the engine is going to cause the engine to be 'messed up' at low rpms.
Well, unmetered is probably a poor choice of words... I'd have to re-draw the plumbing to be really clear... how about "unexpected"? :)

The ECU thinks the EGR is closed, and meters and then maps accordingly, but unbeknownst to it there's extra air from the EGR loop being drawn in... which, at low RPMs, is significant enough to cause upset the mapping and thus the poor performance.

How I understand it, anyways, and I had a real world example in my own garage. :)

Oilhammer explained it better than I could:

http://forums.tdiclub.com/showthread.php?t=481919
 

oilhammer

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There are just too many to list....
5 minutes, one electrical connector, 3 Torx screws, and a couple steps with VCDS and you can check the EGR valve. Sounds like the typical sticking BRM one to me. I replace about a half dozen a year for this exact same symptom.

If you want to dig a little further, you can take the top portion (the electrical part) of the EGR off, and you'll see oil and soot inside.

Another common BRM issue is of course a leaking EGR cooler, which you said has been replaced. However, if it was bad, chances are VERY good that the air cleaner was sucking soot in and the little thermo-plunger for the preheated air is bad which made the whole air box into a giant low pressure EGR valve.

If you take the plunger out (two screws in the bottom of the air box under the filter, super easy), you can flip it upside down, pry it to the far end (so that the little door would be SHUT) and wedge a 10x1.50 shoulder nut in there, like the ones that hold the ball joint mounting studs to the control arms... grind a flat on to each shoulder. Wedge it in there, and put it back in the bottom of the air cleaner and the door will stay shut. No idea why the BRMs got these, and I am sure if it was bitter cold out it would help, but most of the time it is unnecessary and if you want it to work in the winter you can always open the box back up and take the nut out.
 
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absalom

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This forum needs a goddamn like button ... it's 2018 for Petes sake.

Oilhammer, thank you for the checklist, looks like I'll be busy tonight.
 

absalom

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Here's a video I took of it's range of motion:

https://youtu.be/lY-3JL1NINc

Now, when being cycled by VCDS, it goes from 4% to 65% duty cycle. When at 4%, there is a small sliver of light that shines through, as it's clearly not making a complete seal.
Haven't had a chance to test drive, but is this normal? Operation was consistent to the video.
 
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sptsailing

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Aha, so you have a gunked up EGR valve. This means you will also have a gunked up intake manifold and intake ports in your cylinder head. In my TDI's case, my car was blowing oil that wound up in the intake port due to a longstanding vacuum system leak, and was producing excess soot due to severely worn exhaust cam lobes. This combination of conditions produced intake problems from gunk buildup.

These conditions are all correctable, but require quite a bit of thought and wrenching to correct. A short term fix may only require either a replacement of the EGR valve or a thorough cleaning of the one you have. I found that soaking an EGR valve's carboned up area with "Red Line SI-1 Complete Fuel System Cleaner" softens all the gunk sufficiently to remove it, although simple mechanical removal probably works almost as well.

You can rely on advice from Franko6 and Oilhammer. Mine, not so much, but I understand experimental results and physics and I try.

From what I have read here, it is quite possible for a newly replaced cam to promptly fail if it is not broken in correctly. Search for relevant posts about cams by Franko6 to carefully read.

Another point to remember is that the VCDS reported EGR values are not able to be directly measured, rather, they are calculated from all the other points which VW is able to measure, such as, but not limited to air temperature and MAF. Any air leaks in the intake will then result in erroneous EGR readings.

Good luck!
 

Vince Waldon

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IMO that there's a bad EGR valve. Light thru the valve when it's supposed to be closed = bad. :)

That said... don't quite understand the 4%... and don't remember what range I was able to ask for.

Did you try to push on it when it was closed? On the one I had apart you could nudge it closed... which was confirmation that it could do better than it was doing.

Watching the video again, what I seem to see is:

- the first time you ask it close it tries but doesn't close all the way... and there's light shining thru
- the second time it actually snaps closed

If you commanded it both times to do the same thing... it's not. :)
 
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absalom

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What I don’t understand is why ALL of my driveability issues disappear completely once the car is completely warmed up.
 

oilhammer

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There are just too many to list....
Because the ECU operates things differently hot vs. cold.

If you can see light around the EGR valve opening, that is at least part of your problem, certainly A problem, that needs to be corrected regardless.

You can try cleaning it, and then have VCDS run it and see if it seats properly. That may be all you need, but more times than not it'll act up again and will need to just be replaced.
 

absalom

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Because the ECU operates things differently hot vs. cold.
If you can see light around the EGR valve opening, that is at least part of your problem, certainly A problem, that needs to be corrected regardless.
You can try cleaning it, and then have VCDS run it and see if it seats properly. That may be all you need, but more times than not it'll act up again and will need to just be replaced.
Just to clarify, the EGR % shown in VCDS when cycling EGR in output tests, is that requested or actual? The reason I ask is because VCDS was showing 4% and 65%, and 4% was when the light was visible through the crack.

Should VCDS be showing 0% and some higher value?
 

oilhammer

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There are just too many to list....
The MAF requested and actual is what you look at for EGR, since that is how the ECU monitors the EGR flow. There is no EGT sensor for EGR flow, no differential pressure sensor, etc. There is an oxygen sensor, and I am still not 100% sure how or what its input is used for. It isn't even mentioned in the PD self study guide, and is briefly mentioned in the V10 TDI self study guide as a backup for EGR control under high load conditions. But to the best of my knowledge, so long as the MAF is working correctly, the BRM's ECU is using that as its primary means of controlling EGR. The duty cycle is just what the ECU is using to control the EGR valve itself, which on all the PDs has a built in position sensor.
 

Vince Waldon

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Should VCDS be showing 0% and some higher value?
My understanding is that the output test cycles between open and closed and VCDS shows you what the position sensor is saying, so in your case VCDS is telling you even when asked to be closed all the way your valve was 4% open. Again, just my understanding... been a while since I've been to that particular screen. :)

All of that said... and Post 20 into this thread... if you're still in doubt: you could make double-sure the EGR is closed all the way and then re-install it, leaving it unplugged.

You'll eventually get a CEL for the EGR, but you should quickly be able to find out if a partially-open EGR is contributing to your drivability issues.
 
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absalom

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Well, after a full day of driving with the cleaned EGR valve, I am very impressed. I'm no longer plagued with near-0% power after starts/restarts. The EGR only closing to 4% and leaving the gap still concerns me, and I will add an EGR valve to the budget over the next few months.

Thanks all for your help! Time to start enjoying the car :)
 

absalom

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Well, it's back. If you were me, which exact groups would you want to see graphed in VCDS? Tell me exactly what to log, and I'll do it.
 

Vince Waldon

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Are you still suspecting that?]
Yes, yes I am. :) Or, to put it another way, in my mind it's not been ruled out as the prime suspect, particularly since there's video that shows it to be defective. :) :)

how can such a small slit in the EGR valve cause such issues?
The way I think about it is: air/fuel metering is a precise balance... doesn't take much unexpected air to mess that up, particularly at low RPMs. And, lots of air can get drawn thru a tiny hole.

Sure sounds to me like it simply worked OK for a day or two post-cleaning and is now back to its old tricks, but as posted above... simple to test this out once and for all, if you're not yet willing to replace it outright.
 

absalom

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These two codes came up today. Are we thinking wiring harness before the EGR valve, or are we thinking the electronics inside the EGR valve?

I should mention, the car has a very BOOOOOMY note to it now, similar to the boominess that occurs when cycling the boost in VCDS.


Thursday,02,August,2018,16:27:07:23138
VCDS Version: Release 18.2.1 (x64) Running on Windows 10 x64
www.Ross-Tech.com

Address 01: Engine Labels: 038-906-016-BEW.lbl
Control Module Part Number: 03G 906 016 AB HW: 028 101 223 8
Component and/or Version: R4 1,9L EDC G000SG 7550
Software Coding: 0050071
Work Shop Code: WSC 00066 000 00000
VCID: 6393534C17501E3F0C6-8036
2 Faults Found:

001031 - EGR Sensor 2
P0407 - 000 - Signal too Low - Intermittent
Freeze Frame:
Fault Status: 00100000
Fault Priority: 0
Fault Frequency: 1
Reset counter: 255
Time Indication: 0

Freeze Frame:
RPM: 0 /min
Speed: 0.0 km/h
Load: 0.0 %
Lambda: -1.4 %
Mass Air / Rev.: 850.0 mg/str
Mass Air / Rev.: 0.0 mg/str
Bin. Bits: 00000000

000665 - Boost Pressure Regulation
P0299 - 000 - Control Range Not Reached
Freeze Frame:
Fault Status: 01110000
Fault Priority: 0
Fault Frequency: 1
Reset counter: 255
Mileage: 348285 km
Time Indication: 0
Date: 2000.00.00
Time: 14:05:55

Freeze Frame:
RPM: 2772 /min
Speed: 70.0 km/h
Load: 100.0 %
Voltage: 13.60 V
Bin. Bits: 00001000
Absolute Pres.: 1887.0 mbar
Absolute Pres.: 979.2 mbar


Readiness: 1 1 0 0 0
 

crazyrunner33

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This sounds like an issue in the wire harness. That code for your actuator is likely causing your drive-ability issues. It's possible that these can be separate issues, or a vacuum related issue as well, but the the wiring harness is problematic on these cars. I'd check the harness, confirm your actuator on the turbo is holding vacuum and check for vacuum leaks.
 

absalom

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Ok, so I replaced the EGR valve with a brand new Pierburg unit. The VCDS cycling test was identical. Light shone through the gap, the values were 5% and 65%, and movement looked identical.

The above codes were repaired by mending 3 chaffed wires in the EGR valve harness, and repairing a cracked actuator vacuum line as a result of the zip tie mod (zip toe rubbed through an already fatigued line).

The car drives mostly very well now. There seems to be no more issue of low-to-no power immediately after starting the car, and power is great.

However, one issue seems to remain. If I take off from a stop at about 40-50% throttle, power is very linear, almost restrained, but as soon as I hit 2,500 RPM, it's as though a ghost is stabbing the throttle with a broom stick. What could cause this?
 
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