PASSAT BHW- Rough Idle when cold and High fuel consumption/Low power

[ericskmsn]

Ericskmsn
Have you done either of the above recommendations? I don't see where you posted the results.

Egr is unplugged (connector) and blocked right now so that rules that one out.

As for the turbo I have checked it with a vacuum pump and VCDS and its within specs. I also did logs and its following request and actual very closely.

I will unbolt the cat tomorrow just to rule out the backpressure problems.

 

[PickleRick]

Dumb questions here but is the air filter clean? No mouse nest in the air box inlet hose? Have you ran a bore scope down the intake to see it's carboned up enough to restrict air flow? Also leaks in charge pipes. A leak (small split or damaged o ring) could cause it to not build enough boost for power but just enough not to flag a cel. Look for wires or hose clamps hitting flex pipes.

 

[oilhammer]

OK, yeah, if an ALH/automatic felt peppier, than something is for sure wrong. A stock BHW Passat will easily blow the doors off of any [stock] 1.9L TDI.

Have you access to a back pressure gauge? These plug into the oxygen sensor hole. That will very quickly confirm if there is any exhaust restriction.

 

[PickleRick]

Does the exhaust on the bhw have issues of clogging? I've not tore into even a fraction of these as you. Old diesels had dirty exhaust and were known for clogging resonators and mufflers.

All 3 of my bhw motors with 180k to 271k have clean exhaust but filthy in intakes.

They have stayed much cleaner since the egr delete.

 

[oilhammer]

As I stated in an earlier post in this thread, I've never seen a BHW clogged up an exhaust. However, ruling it out is probably wise at this stage.

He did say the car sat... for all we know, a troop of chipmunks made a nest in the muffler in that time. Who knows, stranger things have happened.

He may have said this, but I'm still not clear on it, if the car has full power with the intake flap/EGR unplugged or not. Sounds like it does not.

A clogged exhaust would:

Cause low power, especially the faster the engine spins.

Cause high exhaust backpressure, which would mean far more EGR flow than intended, which would cause poor combustion, and thus low power.

The ECU will run the engine perfectly fine with both the intake throttle flap and EGR unplugged. A stock engine with those items disconnected will still be capable of making 100% of its maximum power. Because even with those items working, they'd both be in the same position as they would be unplugged if the ECU commanded full power anyway.

So if those items are off the table, and the engine STILL cannot make full power, then it would be narrowed down to some sort of air flow restriction (may not even be in the exhaust, for that matter, could be the intake or charge air tract), or severe underfueling. I have seen low power from severe underfueling in VE TDIs from incorrectly stored injectors... and they will start and run and idle perfectly fine. Smooth idle numbers will even be good, amazingly. But they will barely get out of their own way. And no DTCs at all. The only "clue" I ever got with those, was the oil was still whistle-dick clean, and in both cases, it was fortunate that the engines had just been put back together and fresh oil was in there. Otherwise I may not have realized what was going on. Once the injectors were remedied, the engine(s) ran great, and the oil was normal black within a few miles.

 

[chickensoup2180]

I removed and gutted the cat on my '05 BHW. It actually seemed pretty clear despite over fueling all the time. I will warn you removing the factory downpipe is a PITA. Worth it IMO, but very difficult, even with the sub-frame dropped. Your knuckles will be very bloody when all is finished.

At 238k miles, my tandem pump called it quite's. I would invest in a new pump. The springs break, brake fluid leaks into the fuel side of the pump, and in my case the shaft broke as well! I bought a new cheap $140 pump off ebay and I was very impressed! Fit and QC is very good at least on the outside.

I tried buying a rebuild kit, however BE WARNED: The kits that say they fit the BHW pump IS NOT TRUE. Im honestly not sure if anyone even makes a repair kit for the BHW pumps.

When my tandem pump was going out, it would stumble at high rpm and lacked power.

Also: BUY A QUALITY FILTER AND T! The cheap filter assemblies supply a valve that literally has too small of nipples and causes massive leaks.

 

[MEgearhead]

If there's brake fluid near the tandem pump you have much bigger issues than a tandem pump.

 

[oilhammer]

No kidding, never heard of something like that before....sounds frightening.

 

[chickensoup2180]

yeah, not sure then on that one. When i pulled the old pump apart, the vacuum side for the booster had oil i it. Ill find some pictures if need be.

 

[ericskmsn]

Well i will have to rule out the cat, i have disconnected it today and still the same thing no power/rough idle with flap and egr conneted like stock and with them disconnected still no power.

I think the car either has to much back pressure before the turbo or there is something timing related.
From what i understand reading if the torsion value is good and sprocket is in the middle of the screws car should not be out of timing? Is that correct?

As for the back pressure before turbo, I'm not too sure. Someone suggested the limiting screw on the actuator might be too far out, but even if i pull only 10 hg vacuum on the actuator the car still sounds like its chocking. And I also checked the threads of the screw on a spare turbo i have and they are the same +/-half a thread.

The turbo is new, installed from previous owner its a Garrett (made in uk), so I don't think something might be wrong with the turbo but at this point I'm not ruling it out.

Intake is clean, took it out again today just to double check, air filter is new, i checked all the hoses/intercooler for any restrictions still nothing, pressure tested for any leaks, still nothing.

I was really hopping it was the cat. I don't even know where to go from here. I might try to retime just to rule that out as well.

 

[Windex]

if the adjustment screw was set wrong, not likely that your requested and actual boost would be in line as you have indicated.

Have you placed the engine at TDC and inserted the pin in the cam to ensure that the crank/cam alignement is sound?

 

[A4QTDI]

if the adjustment screw was set wrong, not likely that your requested and actual boost would be in line as you have indicated.

Vane stop screw only has effect at idle, when vanes fully closed. It will not change fuel economy or power, just idle/low speed drivability problem.

 

[ericskmsn]

if the adjustment screw was set wrong, not likely that your requested and actual boost would be in line as you have indicated.

Have you placed the engine at TDC and inserted the pin in the cam to ensure that the crank/cam alignement is sound?

That's my next step to check timing as it was changed by previous owner and I have no idea if it was done right but from what I read online if torsion value is right, then timing should be correct too.

 

[ericskmsn]

Took a short video when I had the cat disconnected. In this video at the beginning I have no vacuum to the actuator, a couple o seconds later I vacuum the actuator fully closed and I get this loud hiss out of the turbo. Not sure if this will help give an idea.

TDI BHW.mp4

drive.google.com

It has this deep exhaust note and struggling feel when I am trying to accelerate, this is with everything bolted back up. And in neutral when I try to rev it to 2500-3000rpm and I let off it makes this sound like a boost hose leaking but its not, ( don't know how to explain it). Its like the turbo is still trying to boost even after letting off. but sound comes out of the exhaust side of the turbo( like a whooshing of air).

 

[zzdiesel]

Are you positive the cam is good?

 

[ericskmsn]

Are you positive the cam is good?

Yes I checked it and has no wear on it.

 

[chickensoup2180]

Are you sure the lifter faces arent worn? The lobes are harder than the lifters. I had lobes that looked decent but literally put a hole in the lifter face.

 

[zzdiesel]

Also, since you don't know the service history it might be worth adjusting the injectors lash.

 

[chickensoup2180]

yeah, not sure then on that one. When i pulled the old pump apart, the vacuum side for the booster had oil i it. Ill find some pictures if need be.

Ok, I was going through the photos on my phone and found the pictures of my old tandem pump. In this picture I had already cleaned the fuel side, however you can see the oil in the vacuum side. It honestly looks more like engine oil? IDK. doesnt matter much as I already replaced the assembly.

I would however, like to note that the kits sold for rebuilding the BHW (or at least my tandem pump), is incorrect. The seal is too small on the OD AND ID. Im not even sure what else fits as I stopped when I hit that road block.

 

[A4QTDI]

Kit may be for different pump. Pump can be pierburg or bosch or borshung. Vacuum pump is always filled with oil. Oil is pumped into inlet for sealing and lubrication, look at passage in mounting face. If pump is dry, then is problem.

 

[MEgearhead]

It's common to have engine oil in the vacuum pump. The discharge of the vacuum pump goes into the valve cover area, and I think it is actually lubricated with oil. That's no surprise. I was going to try and rebuild my pump, but I couldn't find the correct kit either, but that was years ago. My pump was a Pierburg.

 

[ericskmsn]

I have no major updates on the problem. Today I decided to flow test the in tank fuel pump and got only 1.8-1.9 liters per minute. From what i read on here it should be around 3 liters per minute. Could this be my problem for the low power?

Im going to do a injector lash adjustment as well next week to eliminate that as well.

 

[zzdiesel]

Any chance the cam may have been changed without the followers being replaced?
Those strange exaust sounds.

 

[ericskmsn]

Any chance the cam may have been changed without the followers being replaced?
Those strange exaust sounds.

Its for sure not from the cam. It was checked and rechecked everything there. Its not the sound of a bad cam. Its very different

At this point i am certain it is under fueling in the higher rpms, i just got to figure out from where. I am going to try a in tank lift pump that will actually flow 3lpm and i will go from there

 

[Windex]

Its for sure not from the cam. It was checked and rechecked everything there. Its not the sound of a bad cam. Its very different

At this point i am certain it is under fueling in the higher rpms, i just got to figure out from where. I am going to try a in tank lift pump that will actually flow 3lpm and i will go from there

Hopefully you have success, but there are a number of older threads on in tank pumps which were completely inoperative.

Symptoms would usually be extended crank on cold start with lower tank levels. Not low power...

 

[MEgearhead]

I had an issue with the in-tank pump, but the engine would just die. For reference, the old pump flowed 0.7 lpm, and the brand new one flowed just over 2 lpm. It was a VDO unit which is the original manufacturer. The new pump was identical to the factory pump. In fact, it came from the same mold. The only difference was that the VW, four rings, and VAG part number were ground off.

Your in-tank pump doesn't seem too far off to me. At 134 hp the engine only needs 0.5 lpm assuming 250 g/kWh BSFC and 0.85 kg/l diesel density. If you were below 1 lpm maybe, but not close to 2 lpm. Again that's just my opinion.

 

[ericskmsn]

Thank you everyone for the response and trying to help

Yeah i figured that the 1.8-2.0lpm should be more than sufficient but i was going off what some other people were saying that it should be close to 3lpm.

Little update

Today i got the chance to do the injector lash and inspect some more around. The injectors were dead on with one slight backed more that 180 deg, so no change there.

Next im going to put a gauge on the tandem pump and drive it around see if anything out of the ordinary shows up, if not might be time to throw another injectors on it as that's my last step.

 

[ericskmsn]

Update.

I have been driving the car as is for the past couple of months, I just blocked the EGR with a blocking plate and left it as is.

Car seemed to have picked up a bit more power since i first started driving it, but not near as much as i think this car should be at. I am looking at swapping out the injectors


Now my question is, injectors look good in group 13 but what about group 23. I see group 23 is still related to injectors but what exactly does it mean and what should the numbers be there. My numbers in group 23 are closer to zero at idle (0, -2 , -3, 0) with it changing ever so slightly. But under load they are (-34, -22, -27, -27)

From a bit of research on the forum i see people reporting high numbers. And with negative numbers being a problem of fuel supply.

Would anyone be willing to post their group 23 numbers as a reference please

 

[MEgearhead]

In this video at the beginning I have no vacuum to the actuator, a couple o seconds later I vacuum the actuator fully closed and I get this loud hiss out of the turbo.

Seems like the turbo vanes are closing too far and you need to adjust the stop screw in a bit.

Possible turbo vanes too far closed at idle. Pull vacuum hose from turbo, idle will improve if so. Vanes too closed will cause huge backpressure and increase EGR flow a lot. You can adjust vane stop screw (or not, if you take majority advice here...)

To check, do charge pressure control test in basic setting. Min/max boost value should be less than 200mbar. 150mbar is better.

 

[MEgearhead]

Finally was able to check the measuring blocks on mine. (I might need to try some diesel purge)

Group 13
-1.15, -0.16, 1.08, 0.24

Group 23
23.0, 17.0, 9.0, 14.0

Not sure if that's going to help you, but there you are anyway.