Brand New BHW Build Running Poorly

GoremanX · Jan 31, 2016

I just completed a new BHW build from the bare block with mostly new components. I recently got the engine started up, and it's running extremely poorly. I'm still doing diagnosis on stuff, but my experience with TDIs is limited and I'm hoping someone can offer up some advice on where to look for the problem(s).

First, the build:

- 2005 BHW from a Passat
- new oversize BHW pistons
- rotating assembly balanced
- block deck machined for a 3-hole head gasket
- mildly ported head (just some minor gasket matching)
- Colt Cams Stage 3 cam
- high lift valve springs
- Bosio 783 race nozzles on original injectors rebuilt by DBW
- GTB1756VK turbo
- 2.5" downpipe with high flow cat
- custom tune from Malone Tuning
- cam bearing cap modifications to double oiling at the cam
- BSM deleted, ALH oil pump with BRM pump cog and chain

Everything else is OEM.

Symptoms are rough idle, many misfires above 3000rpm, and a ton of white smoke from the exhaust. Idle Stabilization (measuring block 13) shows the values maxed out on every cylinder, but in different directions. -3.0 gr/str on cylinders #1 and #4, +3.0gr/str on cylinders #2 and #3. Sometimes Cylinder #2 stabilizes at idle, but then climbs back to 1.5+ as I rev it up. I get no DTCs, except sometimes the misfires on cylinder 3 get bad enough to trigger the engine light. I haven't taken the car off jack stands yet.

Here's what I've checked out so far:

- timing belt is spot on, confirmed both physically with lock tools and via the Torsion Value (measuring block 4). I have the Torsion Value set to +0.5 degrees at idle. It climbs to +1.0 degrees when I rev the engine a bit. This tells me the cam sensor is working fine.

- compression on every cylinder is 450psi, +/- 10psi

- internal fuel pressure at the tandem pump is just over 50psi at idle, and quickly climbs to over 100psi beyond 2500rpm

- oil pressure from the oil pump is 70psi at cold idle, 25psi at warm idle, climbs to over 70psi by 2500rpm

- sent the injectors back to DBW for cleaning, inspection and testing. They tested fine on the bench

- just in case, I replaced the injector wire harness in the head with a brand new one

- brand new ceramic glow plugs all test fine and draw exactly what they're supposed to, all tightened down to 10 ft-lb

- when I sent the injectors in for testing, I also inspected the cam. Engine had been run for about 20 minutes at 2000rpm prior to inspection. The cam lobes look perfect. Everything in the valvetrain looks good.

- no fluid leaks anywhere

- all air bled from the fuel system

- burning brand new, known good diesel from a clean plastic bottle with a lift pump in it through a brand new fuel filter (to eliminate any possibility of bad fuel from the tank)

- all grounds are solid, resistance from the engine block to the negative battery terminal is 0.2 ohm

As a test, I tried flashing the original tune back to the ECU (intended for OEM injector nozzles, cam and turbo). The engine started right up and idled just as poorly, but with slightly less white smoke from the exhaust. Misfires started slightly earlier in the rev range.

DBW suggested trying a different set of injectors, in case my original set somehow got damaged in shipping and the damage isn't evident on their test bench. There were some wonky results in the initial rebuild, and 2 of the injectors got dropped on concrete during tear-down. Also, I accidentally over-tightened the adjustment screw on one of them during initial installation (turned clockwise instead of counter-clockwise when backing off). So I've got a known good set coming early this week.

I'm really not sure what else to check. I don't know how to test the crank position sensor. I suppose it could be bad, or the wire harness that leads to it, although I spotted no damage when I installed it. Is there some testing procedure to determine if the sensor or the sensor wheel on the crank are causing issues somehow?

What else should I be looking at to try and solve this? What can cause the Idle Stabilization to be so far off?

vwztips · Jan 31, 2016

Normally CPS is either good, bad or can be intermittent but it will be very random if intermittent.

I have been following your build thread. You should also mention the engine is now in a A4 Avant.

Also did you hear the engine running before the rebuild? Lastly, you have thrown a lot of variables in other than stock which as you know, makes it difficult to know where to start.

I would say do what you have said and start with some stock injectors and stock tune.

GoremanX said:
I just completed a new BHW build from the bare block with mostly new components. I recently got the engine started up, and it's running extremely poorly. I'm still doing diagnosis on stuff, but my experience with TDIs is limited and I'm hoping someone can offer up some advice on where to look for the problem(s).

First, the build:

- 2005 BHW from a Passat
- new oversize BHW pistons
- rotating assembly balanced
- block deck machined for a 3-hole head gasket
- mildly ported head (just some minor gasket matching)
- Colt Cams Stage 3 cam
- high lift valve springs
- Bosio 783 race nozzles on original injectors rebuilt by DBW
- GTB1756VK turbo
- 2.5" downpipe with high flow cat
- custom tune from Malone Tuning
- cam bearing cap modifications to double oiling at the cam
- BSM deleted, ALH oil pump with BRM pump cog and chain

Everything else is OEM.

Symptoms are rough idle, many misfires above 3000rpm, and a ton of white smoke from the exhaust. Idle Stabilization (measuring block 13) shows the values maxed out on every cylinder, but in different directions. -3.0 gr/str on cylinders #1 and #4, +3.0gr/str on cylinders #2 and #3. Sometimes Cylinder #2 stabilizes at idle, but then climbs back to 1.5+ as I rev it up. I get no DTCs, except sometimes the misfires on cylinder 3 get bad enough to trigger the engine light. I haven't taken the car off jack stands yet.

Here's what I've checked out so far:

- timing belt is spot on, confirmed both physically with lock tools and via the Torsion Value (measuring block 4). I have the Torsion Value set to +0.5 degrees at idle. It climbs to +1.0 degrees when I rev the engine a bit. This tells me the cam sensor is working fine.

- compression on every cylinder is 450psi, +/- 10psi

- internal fuel pressure at the tandem pump is just over 50psi at idle, and quickly climbs to over 100psi beyond 2500rpm

- oil pressure from the oil pump is 70psi at cold idle, 25psi at warm idle, climbs to over 70psi by 2500rpm

- sent the injectors back to DBW for cleaning, inspection and testing. They tested fine on the bench

- just in case, I replaced the injector wire harness in the head with a brand new one

- brand new ceramic glow plugs all test fine and draw exactly what they're supposed to, all tightened down to 10 ft-lb

- when I sent the injectors in for testing, I also inspected the cam. Engine had been run for about 20 minutes at 2000rpm prior to inspection. The cam lobes look perfect. Everything in the valvetrain looks good.

- no fluid leaks anywhere

- all air bled from the fuel system

- burning brand new, known good diesel from a clean plastic bottle with a lift pump in it through a brand new fuel filter (to eliminate any possibility of bad fuel from the tank)

- all grounds are solid, resistance from the engine block to the negative battery terminal is 0.2 ohm

As a test, I tried flashing the original tune back to the ECU (intended for OEM injector nozzles, cam and turbo). The engine started right up and idled just as poorly, but with slightly less white smoke from the exhaust. Misfires started slightly earlier in the rev range.

DBW suggested trying a different set of injectors, in case my original set somehow got damaged in shipping and the damage isn't evident on their test bench. There were some wonky results in the initial rebuild, and 2 of the injectors got dropped on concrete during tear-down. Also, I accidentally over-tightened the adjustment screw on one of them during initial installation (turned clockwise instead of counter-clockwise when backing off). So I've got a known good set coming early this week.

I'm really not sure what else to check. I don't know how to test the crank position sensor. I suppose it could be bad, or the wire harness that leads to it, although I spotted no damage when I installed it. Is there some testing procedure to determine if the sensor or the sensor wheel on the crank are causing issues somehow?

What else should I be looking at to try and solve this? What can cause the Idle Stabilization to be so far off?

GoremanX · Jan 31, 2016

vwztips said:
Normally CPS is either good, bad or can be intermittent but it will be very random if intermittent.
I have been following your build thread. You should also mention the engine is now in a A4 Avant.
Also did you hear the engine running before the rebuild? Lastly, you have thrown a lot of variables in other than stock which as you know, makes it difficult to know where to start.
I would say do what you have said and start with some stock injectors and stock tune.

Well this is the B5.5 Passat forum, didn't want to add confusion to the mix

I drove the Passat home from New Hampshire before ripping out its engine. It idled rough... very rough. Worse than it does now. The whole car shook badly, even with the BSM still in place. But once I accelerated, it ran fine with lots of power all the way to 5000rpm. And the exhaust didn't smoke. I never looked into the cause of the rough idle because I planned to rebuild it anyways.

I guess I'm just hoping someone will read this and say "Oh, really bad Idle Stabilization and misfires above 3000rpm can be caused by XXXX thing that you forgot to check!"

vwztips · Jan 31, 2016

Great point. Didn't think of that. I have wondered about damaging the tone when I have had the pan off and handling the block or crank. Pretty easy to do.

GoremanX · Jan 31, 2016

QuickTD said:
The crank tone ring has 56 teeth and 2 gaps of 2 tooth widths. On the scope you would see 28 cycles between each longer cycle (gap). If one tooth were bent in enough for the sensor to "miss" it, it could seriously affect timing and idle stabilization values.

That's EXACTLY the info I was looking for, just didn't know how to ask for it. HUGE thanks for the thorough description.

I hooked up my scope to the crank sensor while the engine was idling, and as you described, I saw groups of (28?) spikes separated by gaps where 2 spikes should be. Unfortunately, I can't get my scope to connect to my PC right now so I can't download the log I took. This makes it hard to count the spikes and make sure there's really 28 of them. My scope's display has very limited resolution. If I could find a way to freeze the display, that would help a lot. But these damn hobby scopes are very limited in their abilities.

In any case, based on what I saw, the groups of (28?) spikes were very even, and the gaps were also very even. So unless I somehow broke the same tooth before or after both gaps, I'm pretty sure the sensor readings check out and everything on the crank tone ring is intact. That's a huge weight off my mind, because that would've been a nightmare to resolve. I never even thought to be careful of the tone ring while handling the crank.

GoremanX · Jan 31, 2016

QuickTD said:
Does the cam sensor should show half engine speed in VCDS?

Not sure which measuring block to read for that. But the cam tone ring is definitely intact and in solid shape.

QuickTD said:
Is the tach stable throughout the misfires? Just trying to rule out electrical gremlins.

Idle is rough, but not loping. The tach runs very smooth.

QuickTD said:
Was the block heavily painted? Maybe the crank sensor is just held out away from the tone ring by paint/rust and the signal just lacks amplitude? That should be self correcting at higher revs though...

Crank sensor is definitely inserted all the way. Here's a shot of my scope at very wide time division:

(yes I know it's upside down)

It's not very good for counting spikes (TD is way too large), but it shows how clean and well-defined the signal is. There are 2 complete rotations on display there. When I lower the TD, each spike is clean and identical to its neighbors.

QuickTD said:
Alternator working and not whining? I've seen an alternator with a bad diode wreak havoc on sensor signals due to electrical noise. Not on a VW but I would pull the alt belt off and try it.

Only whine I hear is from the turbo. I'm running just the downpipe into 4" flexible conduit that goes outside the garage. Everything sounds loud. However my voltage meter claims 14.5v, and VCDS agrees. My Fluke 88v also agrees, and shows a very steady voltage.

QuickTD said:
I'll sleep on it and have a hundred more things by morning...

I spent the last 2 weeks "sleeping on it". This is why I'm running out of ideas. But I'm still holding out hope for one or more bad injectors. Kinda weird, right? Hoping the injectors are bad? But the set I ordered cost a lot of money and I can't return them. Also, after the abuse I put those injectors through, I wouldn't be surprised if one of them turned out to be bad.

GoremanX · Jan 31, 2016

Oops, forgot to mention another reason why I think the injectors are to blame.

When I first started the rebuilt engine, most of the misfires happened on cylinder 4. When I removed the injectors and sent them to DBW for testing, I didn't label them. So when I re-installed them, they most likely didn't end up in the same order. Now the misfires mostly happen in cylinder 3, and cylinder 4 isn't getting any at all.

I wish moving injectors around was easier and less expensive. Those damn one-time-use bolts cost a lot of money.

imo000 · Feb 1, 2016

Move them around and just reuse the bolts until you know for sure it IS or ISN'T an injector problem.

GoremanX · Feb 1, 2016

imo000 said:
Move them around and just reuse the bolts until you know for sure it IS or ISN'T an injector problem.

It's not just the one-time-use bolts, it's also the tedious time it takes to set the backlash, purge the cylinders of fuel through the glow plug holes, and so on, and so forth... not to mention removing the boost tube at the back of the engine to putz around with the injector harness plug, bleeding the fuel rail again, etc, etc, etc... the whole thing takes hours every time. I already need to do this 2 more times as it is.

At this point, I can't think of anything else but injectors. I've diagnosed everything I can possibly think of that would cause this issue. My last great fear was the tone ring on the crank or the crank position sensor failing, but it turns out that's fine. Even the service manual is telling me to try new injectors. I've already done more diagnosing than the manual suggests.

imo000 · Feb 1, 2016

Even though it's new, it could be the harness.

GoremanX · Feb 1, 2016

imo000 said:
Even though it's new, it could be the harness.

omg I'm not going through THAT nightmare again... I never imagined that such a simple harness could be so difficult to install.

When I did the initial build, I had already checked the old harness for continuity and it checked out fine. The only reason I changed it is because the engine vibrations *might* have been causing an intermittent issue that's not easily detectable otherwise. Putting in a new harness changed nothing, so I'm 100% sure that's not the cause.

I'm not gonna throw another identical $120 new part at the engine to see if it fixes the issue the second time around. I already wasted $120 the first time.

peiphil · Feb 1, 2016

I was thinking the same thing new harness might have 2 wires crossed!
Might be 2 injectors firing fuel at the wrong time and there is your white smoke!

GoremanX · Feb 1, 2016

I should clarify: the idle's not THAT bad. Nothing like cross-firing injectors would cause. And from 1200 to 2300rpm, it's actually quite smooth. I just can't go beyond 3000rpm because of misfires.

imo000 · Feb 2, 2016

A can of gas and a lighter?

GoremanX · Feb 2, 2016

imo000 said:
A can of gas and a lighter?

not funny

peiphil · Feb 2, 2016

GoremanX said:
I should clarify: the idle's not THAT bad. Nothing like cross-firing injectors would cause. And from 1200 to 2300rpm, it's actually quite smooth. I just can't go beyond 3000rpm because of misfires.

You are wrong

GoremanX · Feb 2, 2016

peiphil said:
You are wrong

That could very well be, certainly wouldn't be the first time

In any case, the new set of injectors seem to have resolved the problem. I received them today, spent the afternoon pulling the old ones and installing the new ones. I never received a tune for stock injectors from Malone Tuning, so I just started the engine using the tune meant for Bosio 783 race injectors. Once it caught, it idled WAY smoother than before. Idle Stabilization numbers were still a bit off, but nowhere near maxed out. Three of the cylinders were in a good range (-0.1 to -0.5 gr/str or so), and one was high (+1.2 gr/str). But I attribute that to running stock injectors with a tune meant for race nozzles.

Once warmed up (85c), had a steady 840rpm idle. Everything runs silky smooth from idle to about 2500rpm, at which point the engine starts to stumble and miss. Again, that's probably due to the incorrect tune.

Despite how frustrating this problem was, I kinda feel relieved because it pushed me to diagnose every part of this freshly built engine and confirm it was put together right.

Huge thanks to everyone for all the advice and insight!

peiphil · Feb 2, 2016

Still got the white smoke?

GoremanX · Feb 2, 2016

peiphil said:
Still got the white smoke?

Nope, not an ounce of visible smoke out the tailpipe.

Brand New BHW Build Running Poorly

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