How to troubleshoot low power on an A3/B4 engine

rdkern

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May 21, 2004
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Humboldt Co CA
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Passat 1997 silver (sold after 11 years), Jetta 2000 atlantic blue
Hissing probably isn't good. Are you getting any codes? Is it warm enough for you to recognize any codes?
 

tornadored7

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Jan 25, 2007
Location
GMTLand
TDI
Golf MK3
Firstly many thanks for an excellent and well written diagnostic guide.

I have been experiencing low power at higher revs. Having just replaced the MAF I knew it probably wasn't that.

A local mechanic performed a VAG-COM fault code scan revealing one error:

00575 Intake Manifold Pressure, 17-10 Control Difference - Intermittent. The symptoms seem to match closely.

I was snooping around the engine, aquanting myself with the various hoses (required in step 2 of the diagnostic procedure), red, blue, black and Air intake (Intercooler-engine) to ECU hose.

Two main things alarmed me;

1) There seems to be engine oil leaking from a few places, but mainly from around the a) Crankcase breather regulator valve, b) the Camshaft cover and also from c) the Air intake pipe (Intercooler to engine) to ECU sensor hose.

2) Removing the Air intake (to ECU) hose, revealed engine oil leaking out.

Issue 2 is the most suprising. At low engine revs, air pressure can be felt, but at about 1600 RPM oil starts leaking out in addition to air.

Since this is hose is coming from an air intake pipe, I think something is clearly very wrong somewhere.

Would appreciate some advice on what is likely to be wrong, and also how to proceed.

Thanks.
 

tornadored7

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Location
GMTLand
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Golf MK3
The code is mentioned (but slightly hidden in the text);
Mechanic read VAG-COM fault codes as 00575:Intake Manifold Pressure -> 17-10:Control Difference Intermittent.
 
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Donny O.

Veteran Member
Joined
Jan 11, 2007
Location
Edgerton WI
TDI
96 Passat TDi
GoFaster said:
Step 2: Troubleshooting the "00575 Intake manifold pressure control difference" code

Usual symptoms: car temporarily runs OK after being started, but particularly in the higher gears, it loses power abruptly after a period of running under load. Power may or may not return temporarily by taking load off the engine and then resuming, and generally returns temporarily after switching off the ignition until the same load conditions occur again.
now this is exactly what my car started doing today....i've had it for 2 weeks. anyway should the check engine light be comming on if it's throwing the 00575 code? this happens at about 3000rpm in 4th gear but resets by turning off and on, but I get no check engine light. I have no way myself of checking the codes i would have to take it somewhere, but as i said i get no CE light when it happens. however I do ocasionaly get one on startup which I was told by the previous owner was jsut a common problem with the glow plug check, but they were jsut replaced.....no ill running when this happens.
 

rdkern

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Joined
May 21, 2004
Location
Humboldt Co CA
TDI
Passat 1997 silver (sold after 11 years), Jetta 2000 atlantic blue
Donny - check the "diagosing power loss" sticky. Really good read.
 

Donny O.

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Jan 11, 2007
Location
Edgerton WI
TDI
96 Passat TDi
rdkern said:
Donny - check the "diagosing power loss" sticky. Really good read.
that is what this thread is.....but it says you get a code, but I'm not getting a check engine light..
 

rdkern

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Joined
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Location
Humboldt Co CA
TDI
Passat 1997 silver (sold after 11 years), Jetta 2000 atlantic blue
A code will not always throw a CEL. Scan it to see if one's there.
 

Donny O.

Veteran Member
Joined
Jan 11, 2007
Location
Edgerton WI
TDI
96 Passat TDi
khb137 said:
I am have the same problem that you disscrib

did you find a fix

ken

khb137@msn.com
if you are refering to me then no. it has been a cold spell here the past few weeks(maybe part of the issue??) and didn't dare stand outside and work on the car. just don't get on it where it cuts off at and it has been fine!!
 

jim_arndt

Active member
Joined
Feb 9, 2007
Location
S. California
TDI
97 Passat TDI
A code will not always throw a CEL

rdkern said:
A code will not always throw a CEL. Scan it to see if one's there.
I confirmed this. I just bought a 97 Passat B4, the CEL light was on when I looked at it. I had the owner have the codes pulled, it came back with 00575. His mechanic cleared the codes and advised him to watch it.

I bought the car two weeks later, the CEL was not lit and the owner said he did not experience any loss of power.

Unfortunatly on my 60 mile drive home, I noticed a loss of power. Not being familiar with the car I wasn't exactly sure if this was normal or not. After a weeks worth of driving, it's clear it's entering limp mode.

My Vag-Com arrived today, this is what I got:


2 Faults Found:
00575 - Intake Manifold Pressure
17-00 - Control Difference

Time to start checking vacuum lines, and send Bruno to go collect from the previous owner.....
 

rdkern

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Joined
May 21, 2004
Location
Humboldt Co CA
TDI
Passat 1997 silver (sold after 11 years), Jetta 2000 atlantic blue
Congratulations on the B4. And on knowing what's probably wrong with it.

Take apart the ecu - (which chip do you have?) and replace that little chunk of hose in there. You're going to love it when it's "right".
 

Steve777

Veteran Member
Joined
Dec 1, 2003
Looking for a bit of help with the vag-com readings here...

Which measuring blocks are they speaking of when checking the injection quantity etc? When I go to the engine and measuring blocks they are empty. Do I enter in the number for the block I want?

TIA
 

caddy shack

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Joined
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Location
Milwaukie, Or.
TDI
81 rabbit pickup TDI Blue
good article

This sounds like the problem I am haveing except I have a p-box and .216 injectors and was wondering if thy could be senting me into limp mode. When I get on it it will boost up to 20-22 psi when it is cold after it warms up If I go over 15 it will go into limp mode and won,t go above 12.:confused:
 

jim_arndt

Active member
Joined
Feb 9, 2007
Location
S. California
TDI
97 Passat TDI
caddy shack said:
This sounds like the problem I am haveing except I have a p-box and .216 injectors and was wondering if thy could be senting me into limp mode. When I get on it it will boost up to 20-22 psi when it is cold after it warms up If I go over 15 it will go into limp mode and won,t go above 12.:confused:
Caddy_Shack, I was able to troubleshoot mine to a pinched ECU pressure hose. My VAG-COM really helped me diagnose this issue. I posted the results in the following thread:
http://forums.tdiclub.com/showthread.php?t=168848
 

vwcrewman

New member
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May 1, 2005
TDI
1996 passat wagon dark grey
Ok so where is the 5th injector on a 96 Tdi ? I am tired of codes and a constant check engine light.
 

jim_arndt

Active member
Joined
Feb 9, 2007
Location
S. California
TDI
97 Passat TDI
65535 and 00575

So I should of listened to rdkern and just replaced the little hose inside the ECU. Here are some tips to troubleshoot, this was from a 97 B4 Passat:

- Blowing into the ECU pressure hose will only tell you if you have a major leak, I had a minor leak and was not able to detect it by blowing into the hose.
- With a test pressure guage connected to the end of the ECU pressure hose, the ECU will hold a pressure of 12psi for at least 1 minute (I'm sure indefinately but thas is as long as I waited.) Before I changed my hose, I pumped up to 12 PSI and it would drop to 5psi and hold that pressure. I assumed that was normal and OK, it is not. I was able to test this with a pressure tester designed for an outboard engine gearcase.
- I got a CEL and 65535 immediately at startup. I was not able to clear the code with VAG-COM with the engine running and at idle, the code would immediately come back. With the engine not running, I was able to clear the code but it would come right back when I started.
- 00575 Limp mode was intermittant, it would usually engage on heavy accelluration on long slow climbs in warm weather.

Opening up the ECU and changing the hose was much easier than I expected, if your seeing the above symptoms just replace the hose. So long CEL and Limp mode, you won't be missed.

Thanks everyone for their advice, next time I'll just listen and just do the fix.
 

ryder006

Member
Joined
Nov 9, 2007
Location
Pa, USA
TDI
1996 Passat TDI, 1998 Jetta TDI
New B4 owner, having same problem when pulling inclines in 4th or 5th lose turbo/power. I have attempted to check fault codes(CEL not light), but unable to with two different OBD-II( Unitec & Snap-on). Also, have tried free version of VAG-COM. Get "linking error" with first two and " to many communiction errors to continue" on VAG-COM. CEL was out so replaced with new LED from Radio Shack. Works on sefl-test, but wondering if it is wrong size, causing communication error. Any way on to real problem, problem lose. It only happens when outside air temp is below 50F (above 50 you could put it to the floor and climb anything with no power lose), and happens exactly 5.5 seconds when pedal is mashed to the floor. If you count to 5 seconds and mostly let off pedal then mash it, repeating this, you can go all day without losing power. Without having fault code access, what are the logical steps to look at from t/s tree. Hopefully added info can narrow it down a bit. Any suggestions welcome. Thanks.
 

rdkern

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Joined
May 21, 2004
Location
Humboldt Co CA
TDI
Passat 1997 silver (sold after 11 years), Jetta 2000 atlantic blue
I'd guess the hose from the intercooler to the ecu, or the tube inside the ecu. It expects higher pressure, but you're losing enough between the ic and the map sensor, so it gives, most likely, a boost deviation code.
 

N2OKX

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Joined
May 22, 2005
Location
Kentucky, Western
TDI
looking
This thread was very helpful, but it did not solve my problem. When I aquired the '98 Jetta, there were three trouble codes stored:
65535 Control module malfunctioning
01050 Glow plug monitoring
00575 Manifold absolute pressure control difference
All were listed as sproradic. When cleared, only the 65535 came back quickly. Thanks to some encouragement from Paramedic, it was the little tube inside the ECM. Only a pinhole leak, but sufficient to throw the code. Then I realized that the turbo was leaking oil through the seal/bearings into the intake for the engine. A new Borg Warner turbo from tdiparts fixed that. The glow plug code came back and it turned out to be as simple as needing one new glow plug.

Finally, I thought I was ready to sell the car. But taking the car on a trip brought back the 00575 code. When in third gear above 3,000 rpm and accelerating, it would go into limp mode. It behaved exactly as described in this thread and a few others that I checked. I had already replaced most of the hoses, but I rechecked my work and checked the various valves. I removed the snow screen. Cleaned the MAF. I had also checked some numbers shown by Vag-Com. Being relatively new to TDIs, I was not sure of the significance of anything. I figured my next step was to clean the intake manifold, but my EGR valve was fairly clean and I did not think it would clear the problem. I knew the fuel injection timing was on the edge of acceptability, so I confirmed that one more time and decided to attempt an adjustment. The timing belt had been changed 20,000 mi ago by a local shop. Apparently they had not set the timing or the system got out of spec. In any case, the timing needed to be advanced. I got it right in the middle of the Vag-Com graph (great program from Ross-Tech) and took it for a test drive.

Not really expecting a cure, I got the oil up to temperature and then put the pedal to the floor while in third gear. To my surprise, I had turbo boost all the way on up to near red line. I could not make it go into limp mode and there are no trouble codes stored.

So, my conclusion is that there is yet one more possible cause of the dreaded 00575 code. Check your fuel injection timing and get it in spec before messing with the other stuff. Had I done that first, I could have saved a lot of extra diagnostic time and head scratching. My thanks to all on this message board. This has got to be the best out there. Of course, diesel geeks are kind of special anyway. :)

Oh, the car is already sold. I put the buyer off telling him that it still had an issue that needed to be resolved. I could sell at least two more if I had them!

Windy Gregory
Vee Dub Motors, Kevil, KY
http://www.VWupdate.com
 

MTDiezel

Active member
Joined
Feb 13, 2007
Location
Bozeman, MT
TDI
1996 Passat
working through limp mode

I have a 96 passat sedan, and I've read this post thoroughly, as well as other posts related to low power. I've had a problem with limp mode since the day after I bought the car (didn't act that way when I bought it.) I've been getting the 00575 code, 17-10 so I replaced the red/blue/black hoses described as far as I know, the black hose from ECU to the manifold?, and the one from the n75. I replaced the red hose completely, and there was a splice in the blue hose that I hooked into with a new blue hose from the N75, (I blew into the lower section of the blue hose that seems impossible to replace, (but then again I'm fairly inexperienced with these cars) and it didn't seem like any air was getting through). I found a hole in the small black hose right off the EGR valve and I replaced that too. I was also getting the 65535 code, but didn't know what to do with it. After replacing the hoses, air filter, servicing a 7500 mile fuel filter I took it for a drive and still lost power in 4th @ approx. 3500 rpm. Checked the codes and got the same 00575 17-10 and 65535. Read some more and replaced the little black hose inside the ECU (the old one was blowing a little bit of oily goo out the out side). Drove. Same problem, but the 65535 code was gone. Now I've got the 00575 code with a 17-00 Control Difference, instead of the previous 17-10. Does that mean anything?
I guess I'll check the N75 next with a multimeter or via VAGCOM, and go on from there...I'll probably end up going through the whole process, but does anybody have any advice on where to go next, and where to pick up an N75?
Thanks
MTDiezel
 

TonyJetta

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Sep 15, 2005
Location
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TDI
'15 Jetta TDI SE / '06 Jetta TDI DSG Pkg0 / '96 Passat TDI
I would try a few cheap fixes and capturing some logs before condemning the N75, granted it only costs $50.

MTDiezel said:
Same problem, but the 65535 code was gone. Now I've got the 00575 code with a 17-00 Control Difference, instead of the previous 17-10. Does that mean anything?
I had that one too...Does your wastegate move at all? More than likely you are going into overboost and the computer is responding with limp mode to protect the motor.
You need to connect a pressure source, while the motor is cold, to the wastegate actuator. Put about 4-7psi on it to see if the wastegate will move. If it does not move, it could be the actuator or the pivot rod through the turbo is rusted and won't move. If pressure to the actuator does not move the wastegate, try moving the actuator by hand or with a wrench. If not, spray penetrating (PB Blaster is good) oil on it and let it sit overnight, or as long as you can, then try moving it again. You may need a few applications before it comes free.

Also, double check hose routing to the N75. Check against Bently, under hood sticker, or the club site. Sorry, no link just yet.

MTDiezel said:
I guess I'll check the N75 next with a multimeter or via VAGCOM, and go on from there...I'll probably end up going through the whole process, but does anybody have any advice on where to go next, and where to pick up an N75?
Thanks
MTDiezel

Check the N75 with a multimeter. As long as you read <1k ohms, you should be fine. I just picked an arbitrary number. Too late & don't want to look just now. I'm sure someone else has measured & posted the resistance. If you read an open circuit, replace it.

Via vag-com, measure groups 10 & 11, log to file then graph in excel. I can't remember exactly, but when you graph, the field that is requested and actual pressure will be obvious.

Group 11 will give N75 duty cycle. It should vary with load. See some of these posts for reference.

HTH

Tony
 

MTDiezel

Active member
Joined
Feb 13, 2007
Location
Bozeman, MT
TDI
1996 Passat
Thanks Tony. I'll look into it and get back to you. Maybe a little help though, where is the wastegate actuator. Do you access it from under the car?

Thanks again-
 

TonyJetta

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Location
Tucson, Az
TDI
'15 Jetta TDI SE / '06 Jetta TDI DSG Pkg0 / '96 Passat TDI
MTDiezel said:
Maybe a little help though, where is the wastegate actuator. Do you access it from under the car?
The turbo hangs under the exhaust manifold in back of the engine - yes, you access it under the car - Up on a set of ramps is usually best.

This is a close up of it, from underneath:


Inside the turbo, this is the wastegate - flapper valve - that opens up to releive boost on the pressure side of the turbo.


BTW...you are likely to be better off with this in your own thread in the A3/B4 section. You'll get more attention which means more people can help.

Tony
 

likmywagon

Veteran Member
Joined
Feb 5, 2003
Location
Toronto, Ontario
TDI
95 Passat Wagon
This thread came up on a search for the word "Hissing" and it's got a lot of good information that I'll have to dig into a little further. One question I have and I can't find in the forums and I'm hoping someone here might know is what the source of a hissing under my dash might be. I have a boost gauge that I thought was the source of the noise but disconnecting it doesn't change the sound what so ever. The noise is an air rush noise that %100 tracks the boost on the gauge in duration and volume. As noted I disconnected the boost gauge line under the hood so that can be ruled out. What other system would deliver boost pressure to a point under the dash.
To complicate things I have a 95 TD Passat behind the firewall with a 98 Jetta AHU TDI engine under the hood. Lots of stuff in places where one wouldn't expect to find it on a normal TDI.

Thanks


Alex
 

MTDiezel

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Location
Bozeman, MT
TDI
1996 Passat
Sorry Alex, I'm still a newbie, wish I could help-


Tony, Thanks for the great information and pictures, that helps alot, (and I'm pretty sure I posted to this sticky on the A3/B4 forum, should I post a new thread there?)

Just another nugget, took the car in for timing belt replacement before a long trip(have a few mileage discrepancies from previous owner, so I thought I would just have it done...prevention etc...and due to poor planning on my part and a bit of trepidation I thought I'd pay this one time for the dealer to change it out...). The dealer didn't get the parts in time, so had to use different car for road trip. Anyway I asked the dealer to check the wastegate operation, and he said it did not work at all, and on test drive they were getting a "back boost". I told him what I knew regarding overboost and limp mode, but he disagreed and said it was some sort of back pressure problem. He then said he could diagnose the lack of boost problem, but would need to replace wastegate first (as that is where they start their diagnostic procedure), at a cost of $800. I told him I would need to save some cash and bring it in later, but wanted to see if I could do it myself, with some help from you guys.

I'll check the wastegate myself first with the procedures you suggested Tony. Any thoughts on the validity of the dealer's statements?

Thanks
 
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TonyJetta

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Joined
Sep 15, 2005
Location
Tucson, Az
TDI
'15 Jetta TDI SE / '06 Jetta TDI DSG Pkg0 / '96 Passat TDI
MTDiezel said:
Tony, Thanks for the great information and pictures, that helps alot, (and I'm pretty sure I posted to this sticky on the A3/B4 forum, should I post a new thread there?)
Glad to help!

Starting a new thread is the best way to go. Mostly because the information is specific to your symptoms. The sticky's are usually a collection of common or generic symptoms.

MTDiezel said:
...took the car in for timing belt replacement before a long trip(have a few mileage discrepancies from previous owner, so I thought I would just have it done...prevention etc...and due to poor planning on my part and a bit of trepidation I thought I'd pay this one time for the dealer to change it out...)...
Run away from the dealer! Find a guru or TDI shop near you...even if you have to drive a few hundred miles and stay overnight! It's worth NOT having the aggravation of a botched timing belt. Most dealers don't replace the stretch bolts (1-time use) and don't replace the rollers (they're fine :eek:)!

MTDiezel said:
Anyway I asked the dealer to check the wastegate operation, and he said it did not work at all, and on test drive they were getting a "back boost"...He then said he could diagnose the lack of boost problem, but would need to replace wastegate first (as that is where they start their diagnostic procedure), at a cost of $800. I told him I would need to save some cash and bring it in later, but wanted to see if I could do it myself, with some help from you guys.
He wants to throw parts at it, at your expense! "Back Boost?" Is that where the turbo sucks? ;):D New term to me. Sounds like they are making it up.

MTDiezel said:
I'll check the wastegate myself first with the procedures you suggested Tony. Any thoughts on the validity of the dealer's statements?
Buy some PB blaster and soak the wastegate lever (that penetrates through the exhaust flange) and let it sit overnight. Oh, and do this on a
cool or cold engine - potential safety issue w/ hot exhaust and lubricant.

See above regarding dealer's comments:rolleyes:

HTH

Tony
 

MTDiezel

Active member
Joined
Feb 13, 2007
Location
Bozeman, MT
TDI
1996 Passat
Thanks Tony, I'll start a new post soon if things don't work out.

Checked the wastegate today with a bike pump on the blue hose (that's where it goes?...) A friend worked the pump while I watched the actuator and it seemed to move relatively easily, although I'm not sure the exact pressure....but it seemed to work fairly smoothly both ways. Guess the dealer was just lying to me, or didn't care....good to know now. I also changed the old blue hose out with a new silicone one while I was down there.

So now I guess I'm on to checking the N75. I'll look myself as well, but how do you check the resistance? I've got a regular multimeter (not digital), should it be more than 1k ohm, or less?

What's after the N75?

BTW....since the timing belt has been replaced by the dealer, should I be concerned about the stretch bolts?

Thanks again-
 

TonyJetta

Top Post Dawg
Joined
Sep 15, 2005
Location
Tucson, Az
TDI
'15 Jetta TDI SE / '06 Jetta TDI DSG Pkg0 / '96 Passat TDI
If the wastegate is moving, it's probably fine.

N75 resistance...Not sure, haven't had time to measure mine. But, look for the extremes: should not be an open circuit and should not be <10 ohms.

Ran out of time, otherwise, I'd post some pics. Try replacing the vacuum line inside the ECU. Common boost control problem. Replaced mine last december as it was gooey.

Tony
 
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