hoses, turbo actuator, N75, VAG-COM and other various matters

[Andrei Rinea]

Minimal data:
Car: 1994 B4 Passat Variant TDI 90 HP 1Z engine 5speed manual, not EGR-equipped, CCV unfiltered
Garret GT15 turbo, Pierburg MAF no DTCs
no air bubbles in fuel lines!

Info (may be skipped): Car will not exceed 140 kph no matter what gear (4 or 5 only as 3 is not enough). Accelerates very vigurous till then and then.... flat! No smoke, no hick-ups, no nothing.

I need to know the following things:

1) Having LanduytG's 42$ kit interface and VAG-COM on a laptop how do I log a limpy B4? I mean the car doesn't want over 140 kph (~90mph) no matter what I do. Now I have the tool to diagnose it but I don't know how to use it ... I would appreciate a step-by-step procedure as VAG-COM software is very new to me. And what should I log to determine what is wrong? what fields in what blocks or stuff like that?

2) How do I check my N75 valve (with a multi-metre) to make sure it is functioning or not? Should I take it off the car and see if crud is inside?
Anyway I hear I should measure its resistance but what is the typical range? Just measure its resistance? No vacuum applied? or ?

3) Step-by-step using VAG-COM how do I check my injection timing? That with shaded areas as I hear but I have only one graph JPEG and am not sure it is useful to me. After I read some fields (#2 and #9 as I recall) I have to check them on the graph but I don't know how to get to the screen where I read them.

I know I know! I read the FAQ but it doesn't really help here as I don't have the Bentley

(and also can't afford it - not even a 4 users group buy)

I hooked up the VAG-COM and went to Measuring Blocks, Group 004 and read:

945 / 924 RPM, 0.1 deg (spec to start), 0.1 deg (actual), 45-46% Cold start valve

To me (using TDI FAQ) it seems retarded. Is it?

4) I cannot afford a new N75 valve and am not sure I would need one so I would like to take other things into consideration.
I will change ALL small rubber hoses (ECU to intake, all 3 hoses to N75), but it is possible to have oil into the turbo actuator? I dunno how is that built and functions but I would like to know what can I change / clean and how. Let's say I change all hoses (removing the sh_t inside them along) I clean the N75 valve (with what exactly?)
WHAT IS LEFT TO CLEAN? I MEAN all those lines from N75 come from somewhere where it could be accumulated sh_tty oil / crud. I need to clean ALL I CAN CLEAN.

What the FAQ says:

"that when you floor it at 2500 rpm, the turbo boost pressure rises to a peak and then drops to about 0.8 - 0.9 bar (12 - 14 psi). Sometimes the wastegate diaphragm gets clogged up with oil from the crankcase ventilation system, and some owners have had success by replacing the red and blue hoses with new clean hoses and cleaning gunk out of the diaphragm housing as best as possible.You're on your own for doing this procedure."

5) I set the idle rpm to 930 or close. The RPM needle went up and stayed there. Saved, closed, unhooked, shut engine off and then left home. Then I saw the idle rpm on the tach back to old indicated value but the sound of the engine is the new sound. Is it in my head? Is it normal?

6) I am forced to take into account a maybe clogged intake. There must be a way (I've seen it before but I can't find the proc.) to log the air flow (actual and requested) and determine if it's true or not (clogged intake).

Thank you in advance for help in any of these 6 matters!

Till now I bothered you with these problems not being able to diagnose them well 'cause I lacked a software and an interface. Now I have them and dunno how to use'em... help?

[ February 20, 2003, 15:54: Message edited by: Andrei Rinea ]

 

[Andrei Rinea]

db used to say in another post:

Well as it turns out the Turbo's Waste Gate was out of adjustment! The selenoid was not keeping sufficient pressure on the wastegate valve to keep it closed under high loads thas causing slow response of the turbo.

I loosened and increased the pre-load (shortened the rod or waste gate actuator rod) by about 4-5mm. So far so good no more codes and no more limp mode! The increase tension seems to be doing the trick at keeping the backpressure contained.

The A3/B4's are adjustable and allow about 1.5 cm worth of adjustment to shorten the rod.

DB

<font size="2" face="Verdana, Helvetica, sans-serif">How can that be done on my car?
I mean can any garage do that? Me.. no wayyy. I dunno exactly how a wastegate works and/or a turbo (well I know but only in theory.. no precision details)

 

[Andrei Rinea]

dzcad90 said:

I bet your wastegate is full of gunk (CCV Oil). The compressor pushes oil into the red hose that goes from the compressor outlet to the top of the N75. This then clogs the blue hose which is connected to the wastegate.

I had an issue with boost pressure surging, and I found out that the wastegate auctuator was full of oil by accident! I was using a vaccum gun to test the hoses and auctuator to see if it held vaccum. When I released the vacuum, a bunch of oil came out. I ran some alchohol through the blue hose and into the auctuator, and then sucked it all out again with the vaccum gun. It ran like a champ afterwards. I also ended up replacing all the hoses associated with the N75.

<font size="2" face="Verdana, Helvetica, sans-serif">Could this help me?

 

[dzcad90]

See if you can get a mechanical boost gauge in there. When the car starts to "limp" see if boost is limited to around 12PSI (About .81 BAR). If this is it, you are for sure getting limp mode.

Another thing you can check is get out on a straight-a-way and when the car starts to limp, throw it in neutral, switch the key off and then restart the car. See if you have any power back then.

It's possible that your intake manifold is clogged. Remove the rubber hose that goes into the intake manifold and peek in there. There may be gunk so thick that it's simply preventing enough air to get in there. Not likely with European fuel, but the car is signifigantly older than any TDI we have seen on this side of the pond.

 

[Andrei Rinea]

Originally posted by dzcad90:
It's possible that your intake manifold is clogged. Remove the rubber hose that goes into the intake manifold and peek in there. There may be gunk so thick that it's simply preventing enough air to get in there. Not likely with European fuel, but the car is signifigantly older than any TDI we have seen on this side of the pond.

<font size="2" face="Verdana, Helvetica, sans-serif">I took off the flexible rubber intake hose from the air filter to the intake and there was only an oil film (well quite a film) from the CCV hose but no hard gunk. Nothing hard... only oily stuff

Never tried the key switch off thing. I will.
How much can a mechanical boost gauge could cost?
And isn't there a way to use the VAG-COM to log that boost?

Thanks dzcad! you really help!

 

[Andrei Rinea]

I could get a mechanical boost gauge but I should know first a graph for normal boost pressure to compare it with. I don't have that. Anyone?

 

[VelvetFoot]

Why not graph requested boost vs actual boost? I don't now the blocks but I think by poking around VAG-COM you can find them. (Following are some cut and paste, maybe they can help.)

Checking conditions

No DTCs stored in Diagnostic Trouble Code memory

Repair group 01; On Board Diagnostic

No leaks from intake and exhaust systems.

No stored DTCs from engine and fuel injection system, e.g. start of injection, fuel injectors and compression pressure.

Engine oil temperature 80 C minimum.

Test sequence

Observe following if test and measuring instruments are required during a test drive:

Test and measuring instruments must be secured to the rear seat and operated by a 2nd person from this location.

CAUTION!

If test and measuring instruments are operated from the front passenger seat and the vehicle is involved in an accident, there is a possibility that the person sitting in this seat could receive serious injuries when the airbag is triggered.

- Connect VAG 1551/1552 Scan Tool

Repair group 01; On Board Diagnostic II

- Start engine and let idle

- Press 0 and 1 buttons to select Address word 01 "Engine electronics"



Display will appear as shown

- Press 0 and 8 buttons to select Function 08:"Read measuring value block"

- Press Q button to enter input



Display will appear as shown

- Press 0, 1 and 1 buttons to select Display Group 11

- Press Q button to enter input



- Display will appear as shown

- Accelerate vehicle in 3rd gear from about 1500 rpm under Wide Open Throttle.

- Press VAG 1551 PRINT button at approx. 3000 rpm.



Specification: 1700 to 2200 mbar (in display zone 3)

If specification not obtained:

- Perform Output Diagnostic Test Mode to activate the Wastegate Bypass Regulator valve:

Repair Group 01



Display will appear as shown

Notes:

The valve must function and the Boost pressure control rod must move to and fro (at least 3 to 4 times), as long as there is a vacuum in the vacuum reservoir.

If rod moves but pressure specifications are not obtained

- Replace turbocharger.

If rod does not move because solenoid valve is not working:

- Check Wastegate Bypass Regulator valve N75

Page 21-12

- Check vacuum hoses

Page 21-6

If rod does not move but solenoid operates:

- Connect VAG 1390 vacuum pump to Wastegate Bypass Regulator valve and check rod for ease of movement.

If rod does not move easily

- Replace turbocharger assembly.

Wastegate Bypass Regulator valve N75, checking

- Switch OFF ignition.

- Disconnect Wastegate Bypass Regulator valve.

- Measure resistance between valve terminals.





Engine code ALH

Specification: 14 to 20

If specification not obtained:

- Replace Wastegate Bypass Regulator valve N75.

If specification obtained:

- Switch ON ignition.





- Measure supply voltage at valve connector terminal 1 and at engine Ground.

Specification: approx. battery voltage

If specification not obtained:

- Switch OFF ignition.





- Connect test box VAG 1598/22 to ECM wiring harness.

- Check wiring for open circuit between Test Box and harness connector using Wiring diagram.

Up to MY 1999

Terminal 1 + sockets 2 + 28

Terminal 2 + socket 15

From MY 2000

Terminal 1 + sockets 1+ 2

Terminal 2 + socket 62

Wire resistance: 1.5 maximum

- Check wires for short to one another, to vehicle Ground and to battery Plus.

Specification:

If wiring OK

- Replace Engine Control Module J248

Repair group 23

[ February 22, 2003, 20:06: Message edited by: VelvetFoot ]

 

[dzcad90]

Karl posted some great info above.

I don't see a performance chip listed in your mods in your signature, but I think that about 1 BAR is where your boost ought to peak. It's been a while since I've worked with a stock car, so that number may be a little off. You will definately know though by watching the gauge behaviour before the limp mode kicks in, then comparing it to how it acts when limp mode kicks in.

 

[VelvetFoot]

It doesn't sound like a limp mode to me. That's not really a limp mode, like you would see if the turbo wasn't being controlled properly.

Here is a quick way to check air flow with vag-com (from an old resource):

Tech Tip #2:

All Models with TDI Engine

If you receive a complaint of low power with a TDI engine, check the Mass Air Flow (MAF) sensor reading in measuring block, group 00, field 10 (01-08-00). The value should reach 255 under full load. If the reading is low, check the air filter and air box for restrictions. If ok, suspect the MAF is at fault.

[ February 23, 2003, 04:42: Message edited by: VelvetFoot ]

 

[VelvetFoot]

I don't use vag-com that much but you must go to basic settings to read those timing numbers. Make sure the engine is warm. On my car, the glow plug light will blink when you are in basic settings. Here is some more cut and paste, but remember, this is for the 1551/1552 tool, which vag-com emulates:

Work sequence

- Connect VAG 1551/1552 Scan Tool Page 01-8 .

- Start engine and let idle.

- Press 0 and 1 buttons to select Address word 01: "Engine electronics"



Display will appear as shown (example only)

- Press button.



Display will appear as shown

- Press 0 and 4 buttons to select Function 04: "Basic setting"

- Press Q button to enter input.



Display will appear as shown

- Press 0 button three times to select "Display group 0".

- Press Q button to enter input.



Display will appear as shown (1 to 10 = Display zones)

- Check Engine Coolant Temperature in Display zone 7.

Specification: less than 73 (equates to 85C)

Continue check only when Engine Coolant Temperature is obtained.

Start of injection (in Display zone 2) is dependent on the Fuel temperature in Display zone 9.

A - Display zone 2 Start of injection

B - Display zone 9 Fuel temperature

C - Specified range for Start of injection

Example:

Value 90 in Display zone 9 (B) corresponds to a numerical range from 35 to 74 in Display zone 2 (A).

Notes:

If, when checking Start of injection, the specifications are within zone - C - , no adjustment is required. After repairs, e.g. removing and installing injection pump or adjusting timing, Start of injection must be set to the mean value (dashed line) in zone - C - .

 

[Andrei Rinea]

Thank you so much guys!!!
I have many things to check out now!
I will get my hands on the VAG-COM which was group-bought by the 3 of us and check these out. (Andi TDI & me & Dragos)
Another thing : I set the idle RPM to a higher value and after I closed the software and then shut off the engine it "forgot" the new setting. Was there a procedure error? Or maybe because I have an old ECU (1994 September 9 - date of whole car including ECU).

Thank you so much guys! You are the greatest!!!

 

[VelvetFoot]

I don't know why it didn't take. It has been a long time ago. It seemed to work for me, but I didn't want it. I think it idles too fast as it is.

 

[Andrei Rinea]

well I will keep you posted on how all goes .. as for the software not writing correctly... it might be at fault (the soft).

 

[VelvetFoot]

Did you see MOGolf's excellent post?

 

[Andrei Rinea]

MOGolf's posting is great.
I will do checkings now.