B4V help.....still low power

TDITim83

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Oct 17, 2010
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Ocala, FL
TDI
96 Passat Wagon TDI B4V Storm Gray 258k, 98 Jetta TDI 260k (retired for spare parts)
I have recently removed my engine and redone everything exterior to the engine. Minus a few components. I have the car up and running Idles great and is timed slightly advanced. Seems I still am on the slow side for power.....better than it was. I am wondering if the Turbo Pressure Converter Valve 7.21903.70.0 would cause it to be sluggish in its power? I am able to get 12 to 14 pounds for turbo boost but the car is on the sluggish side. I am going to unhook exhaust and take it for a spin soon....prior owner did that with no change. But the turbo was bound by carbon so who knows.
Wondering what the Turbo Pressure Converter Valve 7.21903.70.0 does as far as its function. maybe compared to the N75 which controls the waste gate. I need some more info on it.

All vacuum hoses and coolant hoses replaced. Vacuum Pump replaced and much much more.

Another question separate from those......Any site or reference page on what values are standard for these cars.....such as MAF flow, certain vacuum number to look for anything that shows up on VAGCom
 

jdulle

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Feb 4, 2017
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Ithaca, NY
TDI
96 B4, 97 B4
I would look at the n75 valve, I was having an issue with boost rising and falling at full throttle, and replacing the n75 fixed that. What I was experiencing was not quite a limp mode but boost was all over the place. Also could you see any carbon buildup in the head when you had the exhaust off? Have you done a compression check?
Have you checked the quantity adjustment? A graph on the vag-com of an acceleration run would show if you are getting enough boost and fuel. How are the injectors?
 

jdulle

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96 B4, 97 B4
Not that I am pro with these cars, but these are the things I went through when trying to solve my issue.
 

Abacus

That helpful B4 guy
Joined
Nov 10, 2007
Location
Relocated from Maine to Dewey, AZ
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Only the B4V left
First, congratulations on the great rebuild.

Second, please order a new timing belt tensioner since yours is tensioned the wrong way.




Third, make sure you don't have the 3rd injector plug swapped with the temp sensor. They are color coded but I've seen people swap them before, which will create the condition you describe. The 3rd injector plug is brown, not black.
 
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TDITim83

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Ocala, FL
TDI
96 Passat Wagon TDI B4V Storm Gray 258k, 98 Jetta TDI 260k (retired for spare parts)
Already done!!!

I would look at the n75 valve, I was having an issue with boost rising and falling at full throttle, and replacing the n75 fixed that. What I was experiencing was not quite a limp mode but boost was all over the place. Also could you see any carbon buildup in the head when you had the exhaust off? Have you done a compression check?
Have you checked the quantity adjustment? A graph on the vag-com of an acceleration run would show if you are getting enough boost and fuel. How are the injectors?
New N75 Valve, carbon was not an issue. Its not a compression issue, last owner had that checked. Quantity adjustment? where do I find that in vag-com? I hooked a gauge up and Im getting 12 to 15 boost, the pump was rebuilt 5 years ago ash. Rebuilt turbo and Injectors were rebuilt within 6 years. I've replaced a lot of known issues. That other valve I need to learn what its function is.
 

TDITim83

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Oct 17, 2010
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Ocala, FL
TDI
96 Passat Wagon TDI B4V Storm Gray 258k, 98 Jetta TDI 260k (retired for spare parts)
Say What?????

First, congratulations on the great rebuild.

Second, please order a new timing belt tensioner since yours is tensioned the wrong way.




Third, make sure you don't have the 3rd injector plug swapped with the temp sensor. They are color coded but I've seen people swap them before, which will create the condition you describe. The 3rd injector plug is brown, not black.
Hey, Abacus......thats how the tensioner was when I took it out. It only has one way to go that I know of. Could you elaborate more on this so its more clear.
same with the 3 injector thing. Need more info.....thanks. Do you have a pic of both the tensioner and the Injector? I haven't messed with my injectors yet
 
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Abacus

That helpful B4 guy
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Relocated from Maine to Dewey, AZ
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Only the B4V left
Hey, Abacus......thats how the tensioner was when I took it out. It only has one way to go that I know of. Could you elaborate more on this so its more clear.
same with the 3 injector thing. Need more info.....thanks. Do you have a pic of both the tensioner and the Injector? I haven't messed with my injectors yet
Well, they tensioned it backwards then. The half moon shape should be on the top. The tensioners are tensioned clockwise on the TDI but counterclockwise on the 1.8t gas engine. I've seen quite a few like this and been able to prevent a timing belt failure.






For the third injector plug, the injector with the wire coming from it is the 3rd injector, which is the reference injector against which the other 3 dummy injectors are measured. The plug for it has the same configuration as the G72 intake manifold temp sensor, so they can inadvertently be swapped. Since it's located next to the OOD (Orb of Death, or main engine connector), it would have been separated when you pulled the engine. Same thing with the G72 manifold sensor.

This setup is incorrect, the brown plug should be on the 3rd injector and not plugged into the G72 as shown here. The G72 plug should be black.




This is how it should look, with the black plug in the place.




And here is the brown/brown plug of the 3rd injector next to the OOD.

 

iluvmydiesels

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Nov 21, 2015
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phila area
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AHU
to elaborate some on the 3rd injector. i ve got an A3, so i dont see what your B4 has in the engine compartment. but take to wire off 3rd injector and trace. right at/by the OOD theres clips for the connections, check yours it connected correctly.

one of the things id check. pull off turbo intake pipe. check how turbo spins by hand. and check play, side to side, and axial. it should spin freely.
 

TDITim83

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Location
Ocala, FL
TDI
96 Passat Wagon TDI B4V Storm Gray 258k, 98 Jetta TDI 260k (retired for spare parts)
Ok...Im listening

Can I reuse the Tensioner.....Its brand new? I matched the lines up according to what the manual or instruction paper said.
Also I have removed the Orb Of Death.......very scary....lots of WD40
My Connectors are properly placed, none issue. The turbo is brand new rebuild, spins freely. I feel its that Valve I mentioned earlier.....PIERBURG 7.21903.70.0 TURBO PRESSURE CONVERTER VALVE. Need more input here on this Valve.
It makes sense.....its part of the EGR system and I believe it has a diaphragm in it. It is original from what I can gather. Being as its part of the EGR system.....I have deleted the EGR properly
 
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Abacus

That helpful B4 guy
Joined
Nov 10, 2007
Location
Relocated from Maine to Dewey, AZ
TDI
Only the B4V left
No, I would not reuse the tensioner since it was tensioned backwards. It is too critical of a piece to have fail and they are not that much money.

The OOD isn't that bad, I made a video some time ago explaining how to remove it.

https://youtu.be/TrFuGYLz8yI

The valve you reference is the N18 valve that controls the EGR function. Specifically, it uses the vacuum from the vacuum pump to pull the EGR open, with the other port connected to the air cleaner to relieve the vacuum. It has nothing to do with the turbo since the turbo uses pressure and not vacuum. Newer TDI's use vacuum and the N18 and the N75 on them can be swapped.

And what do you mean, you have deleted the EGR properly? Did you get a tune? If not, that may be your problem. Can you post pictures of *how* you deleted the EGR? If the EGR inlet is not blocked off physically but the hose is, the EGR will hang open and cause a low power problem. I have seen the same when people plug the EGR weep hole without blocking it off. The EGR is a simple piston that moves up and down on a diaphragm to let exhaust into the intake tract, and if the inlet side is not blocked off, it can hang open and not close all the way. If the ECU doesn't see the EGR working it will reduce power, which will show up with low MAF readings. You can fake out the ECU into thinking the EGR is working when it's not but that takes some extra parts so it's more than just blocking things off.

And unless your car is tuned, 13 psi is normal for turbo output.

I have some EGR screeshots on my Smugmug account, feel free to look around at them, but keep in mind my cars are tuned with the EGR turned off, which is why the MAF requested reads 1000 instead of being close to actual.
 
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TDITim83

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Ocala, FL
TDI
96 Passat Wagon TDI B4V Storm Gray 258k, 98 Jetta TDI 260k (retired for spare parts)
Will Replace....Thanks

I am gonna replace the tensioner for sure...thanks

I deleted the EGR Valve by putting a block off plate on the backside of EGR and blocking the Exhaust. No ECM adjustments yet, but the point I need to make is that the car had low power before I did all this stuff. I also plugged the vacuum hose connect to the EGR. I did the same exact thing on my AHU and I've never had low power. I can't figure out my low power. New Vacuum lines including in the ECM. New N75, intake is clean, all new pipe hose clamps for intake, Intercooler was cleaned out. What are the possibilities of the Exhaust being clogged....like the CAT Specifically?

I do have more power than before restoration
 

TDITim83

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Ocala, FL
TDI
96 Passat Wagon TDI B4V Storm Gray 258k, 98 Jetta TDI 260k (retired for spare parts)
Yepper

I have Vag Com.......No Codes thrown. I haven't visited the low power forum in a bit. I have diagnosed and fixed this type of issue before. Like, replaced Vacuum Line in ECU, new vacuum pump and hoses, new fuel pump, injectors were rebuilt 6 years ago ish, rebuilt Turbo(intercooler flushed and checked) MAF is working fine.....Only a few things haven't been replaced
I need a good forum of site that will show me what the specs should be on most things in Vag Com so I can start there. (I am curious what that little valve is for that comes off the Vacuum Pump and then splits) What else could it be.....Like most stuff has been replaced. Im gonna be upgrading to the Boise 502 Injectors I have on my sedan after I rebuilt them.
 

TDITim83

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Ocala, FL
TDI
96 Passat Wagon TDI B4V Storm Gray 258k, 98 Jetta TDI 260k (retired for spare parts)
I am needing to look into running a 2.5" pipe for exhaust.....first were do i get a 2.5" flange for coming off the turbo? Second, how do I get a Cat the will work for my car? Or should I gut the cat? I am wanting the car to stay quiet and still have plenty of air flow, I will get rid of stock silencer and exhaust. Would like to replace it with something that you can hear a small growl maybe. Though I do not want it loud and absolutely hate a droning noise
 

john.jackson9213

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Mar 14, 2007
Location
Miramar, Ca. (Think Top Gun)
TDI
1996 B4V
I am needing to look into running a 2.5" pipe for exhaust.....first were do i get a 2.5" flange for coming off the turbo? Second, how do I get a Cat the will work for my car? Or should I gut the cat? I am wanting the car to stay quiet and still have plenty of air flow, I will get rid of stock silencer and exhaust. Would like to replace it with something that you can hear a small growl maybe. Though I do not want it loud and absolutely hate a droning noise
You are running the stock turbo at stock boost with stock factory tune???

Based on my 11 years playing with the B4V: A 2.5 inch down pipe will do nothing for you at all. The stock turbo does not need a 2.5 inch down pipe. Even with bigger nozzles and a tune up to 18-20 psi of boost. Been there, done that on the dyno.

The stock turbo simply is very small and can not flow enough air to get more than a 40 to 45% increase in power over stock.

Changing your complete exhaust to bigger pipes can/will introduce "unpleasant" sounds to your cabin. No fun to ride from L.A. to Las Vegas in a car with that system.
 

TDITim83

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Ocala, FL
TDI
96 Passat Wagon TDI B4V Storm Gray 258k, 98 Jetta TDI 260k (retired for spare parts)
First of all....Thanks for the very good info on exhaust pipe john. I will probably just gut my cat and run a good flowing muffler out the back.

Second....Abacus....thanks a bunch man, I got the new Tensioner in and its installed correctly. I have not clue why I did it that way, my manual says differently. Life Saver

Back to my issue at hand....
I unhooked my exhaust and I feel not difference in power. Note....when in neutral and I tap the accelerator the RPM jumps up faster than with exhaust attached. So I do feel I have restriction. Though getting up to speed is about the same.

I am gonna run VAGCOM soon, what specs or readings should I look for that could be an issue. Assuming I throw no codes. If i have done an EGR delete, and haven't adjusted anything in VAGCOM would that be a possible issue for power?

Please read what I've done to the car so far, and ask further questions on parts if need be. I really want this car running awesome. No problem with idle and timing. But after acceleration it just kinda goes slow up to speed. I know the difference, I've driven two stock B4V's in the past year
 

TDITim83

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Ocala, FL
TDI
96 Passat Wagon TDI B4V Storm Gray 258k, 98 Jetta TDI 260k (retired for spare parts)
Is there a way to tell if I'm getting enough fuel via VAG?
 

TDITim83

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96 Passat Wagon TDI B4V Storm Gray 258k, 98 Jetta TDI 260k (retired for spare parts)
Update on findings.....

After replacing my timing belt tensioner I have ran VAGCOM.....timing is to advanced to plot. So I will resolve that. I also adjusted my settings to from 250 to 375 on the air intake side for the EGR setting.
I am wondering whats going on with my injectors....any input...or could they be off because of the advanced

Injection Quantity 6.4 mg/str
Mod. Piston Displ. 1.620v
MAF (Specified) 375.7 mg/str (originally was 250 I just changed)
MAF (actual) 455.5 mg/str
Intake Air Temp 42.3 C
Inj qty 0.0 mg/str
Inj qty 28.4 mg/str
Inj qty 28.2 mg/str
Injection Quantity CC Active 0.0 mg/str
Barometric Pressure 1031.7 mbar
Manifold 1040.4 mbar

I also threw some codes:

2 faults found
00550 - Start of Injection Regulation
17-00 - Control Difference
01242 - Output Stages in Control Module
27-10 - Implausible Signal - Intermittent
Readiness: N/A
 
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jdulle

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96 B4, 97 B4
I think you might have better power if you adjusted the Injection Quantity to 3 or 4 Mg/str. 6 might be enough to make less power.
 

iluvmydiesels

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phila area
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you have some injector info there. although its been a few weeks since ive had the VCDS screen up. the one reading you give there, inj qty 0.0mg/str. and you have 3 other inj qty readings there. do you have an inj timing reading. although you set the mechanical timing, then the injection (electronic) timing and the timing (and injection)becomes a standard, changing due to advancement across rpms. inj qty X.xmg/str as well changes with rpm, also load, depending on ecm and sensor readings.
did you clear the codes?
 

TDITim83

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Ocala, FL
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96 Passat Wagon TDI B4V Storm Gray 258k, 98 Jetta TDI 260k (retired for spare parts)
Resistor installed

I installed the resistor.....my check engine line went off. Also No power change.
How do I change the settings for Fuel Injectors.....what controls that
Im hearing my lifters taping. So I'm wondering if I have bad lifter springs. Any input?????
 

TDITim83

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96 Passat Wagon TDI B4V Storm Gray 258k, 98 Jetta TDI 260k (retired for spare parts)
I heard when you clear codes form Auto Scan it doesn't actually clear them? Where do I go to clear the codes properly if this is the case?
 

TDITim83

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96 Passat Wagon TDI B4V Storm Gray 258k, 98 Jetta TDI 260k (retired for spare parts)
I have tried another BK ECU and no change, I even tried mine in the other car. My ECU is fine. I changed the Turbo Boost EGR Valve, still low power. Vacuum lines are good. It idles so nice, but makes a valve ticking noise. Also revs like normal until you take off in gear and is just low powered. I am wondering if I have Valve Lash or worn guides.....anyone have any input
 

TDITim83

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96 Passat Wagon TDI B4V Storm Gray 258k, 98 Jetta TDI 260k (retired for spare parts)
So.....I have resolved the power issue. After 4 months of time off I got back into it. I swapped injectors with my AHU Jetta and boom. Now the Jetta is slow and the wagon has the power. I do hear a pinging though. I have decided to have the injectors rebuilt and pop tested. Once they return I will adjust fuel timing and I believe my issues are resolved. All the brakes are redone as well.
 

TDITim83

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96 Passat Wagon TDI B4V Storm Gray 258k, 98 Jetta TDI 260k (retired for spare parts)
Also I had a sketchy rear hatch lock. I removed and modified so it would actually work properly. Added a small thin piece of aluminum with some Gorilla Epoxy and filed it down. Works great!!!! Rear bumper was also bumped into a pole and the hatch would rub when opening closing and rested on it. So I removed it and used a heat gun to shape it back down. Another great fix.
 
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Steve Addy

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Aug 7, 2002
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Iowa
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97 Mk3
FYI my 242k mile AHU in the B3V needed new exhaust valve guides when I pulled the cylinder head.

Steve
 
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