VW TDI forum, Audi, Porsche, and Chevy Cruze Diesel forum banner

1 - 14 of 14 Posts

·
Registered
Joined
·
18 Posts
Discussion Starter #1
Please help solve my problem?
I have a 2004 passat bhw 2.0 liter diesel automatic tiptronic .
I have about 150,000 miles on this car currently.
What appears to be happening is that the engine is bucking just as the temperature gauge is getting into the normal operating range .
No check engine lights on or message center notes .
But i can drive through the bucking and the car has plenty of power .
I eventually it goes away . I had the recall glow plugs changed and two reflashes performed.
About three months ago i replaced the oil pump balance module assembly to gear drive , timing belt , and water pump .
Cleaned carbon out of the intake manifold assembly , cleaned out the intercooler and intake piping ,and trans fluid and filter
at that point the car ran awsome with no issues .
I replaced the coolant temp sensor about 5 months ago .
I also recently replaced the maf sensor and the fuel filter this week .
What was a very fuel efficient and fun car is turning into a money pit . The dealer would not guarantee that they could find the issue causing this . I guess i am not realy sure if this is fuel related , engine controls or early stages of transmission problems . Any help from the veterans out there would greatly be appreciated / i am getting very frustrated ...................
 

·
Super Moderator
Joined
·
23,902 Posts
moved to mk4 section.

My best guess, you have a small boost leak that is showing up only sometimes. Don't know why it would go away. The rubber intercooler hoses like to rub through on the ground cable, just loosen and move the cable out of the way. Could be another prob but doing a boost leak check is free if you DIY. See FAQ for some tips. Beyond that, check the low power FAQ article and see if you can monitor the sensors and spot something out of the ordinary. Maybe something is causing the timing to go off.

When you say no message center notes, you mean no codes are stored in the car's memory? There can be error codes w/o check engine light.
 

·
Registered
Joined
·
18 Posts
Discussion Starter #3
2004 bhw passat bucking

I glanced at all of the intercooler hoses this weekend . The area by the ground on the right side looks ok . This turbo outlet seems extremely loose in the turbo outlet bore even with the retainers installed is this normal ?
The seals all seem to be in good condition . I need to do the pressurized boost leak check to verify sealing at all of the joints . I stopped at advanced auto to do a quick memory scan and they did not show any stored faults with their scanner . Every time i drive this thing the temp gauge gets to operating temperature then about 2 minutes later it starts bucking under slight acceleration or it goes away in about 2 minutes . At that point it runs perfectly fine . Until the temperature cools off and goes back through same temperature cycle . I wish that i had a diagonistic tool to read what all of the sensors are doing at the time of the event , it seems that something is loosing a signal or getting an incorrect value possibly. What is strange to me is how well it runs at any time other than in this temperature window .
It feels like the old style igniton module when they would overheat and the board would breakdown and buck like crazy . Any common problems with engine sensors throwing eracting readings or intermitant signals ? When you say timing which are you refering ? I am still a diesel newbee with the tdi. Could this possibly be an issue with the ecm ? Anybody out there a vw tdi driveability expert ? All input is greatly appreciated
 

·
Super Moderator
Joined
·
23,902 Posts
see if changing gears manually makes any difference, turbo hose may have some play but as long as not oily around it, it's not leaking. Boost leak is just a guess and should be more consistent.

No common engine sensor probs, most common probs are torque converter, abs pump, worn camshaft, and the biggie, the oil pump/balance shaft module. If you want to diagnose yourself, get a ross tech VCDS to log all the sensors. You'll be able to read sensors. Prob not bad injector harness although it happens.

Prob not problem with ECM but it can get waterlogged if it rains and your drain plugs are clogged, trans control module is under pass seat, if your carpet is wet it means you have a leak and it'll get damaged.

It's pretty rare for a car to buck just before fully warm and then be fine for the rest of the trip.
 

·
Registered
Joined
·
18 Posts
Discussion Starter #5
2004 bhw passat bucking

I will try the manual shifting to see if there is a change .


What type of symptoms are related to torque converter issues ?
I would that trans issues would be more cosistant and not go away ?
I assume that any codes can be read through the under dash diagnostics ?

The worn camshaft would probably run poor all of the time ?

Thanks
 

·
Registered
Joined
·
18 Posts
Discussion Starter #7
2004 bhw passat bucking

I do not have acess to a ross tech vcds but today I hooked up a obd 2 scanner to look at some of the sensors. The O2 sensor seemed to be jumping all over the place. When the bucking started it appeared to be lean. Still no codes at this time. So at this point I am thinking possibly a O2 sensor faulty or erattic. So with the recommendation of some of the calibrators at work I disconnected it and drove at low speeds to see if this was causing the bucking but it still did it. At this point I am thinking that the O2 is ok and something else is causing a lean condition.

It seems to be getting worse today than ever. When the O2 was disconnected and driving the vehicle the vehicle set a preliminary code of P0201 injector circuit malfunction cylinder #1. I am now thinking is the injector coil bad setting the code? Any idea what the resistance values should be for these coils? From what I have read that injector replacement is not a simple task on these engines. I am also reading about cam lobes wearing out but from what I saw it was just on lifter lobes.

Any thoughts?
I was thinking about just changing the #1 injector and driving to see if this fixes the problem?
Thanks
 

·
Super Moderator
Joined
·
23,902 Posts
Since o2 sensor doesn't adjust mixture, only EGR, it's probably not the problem.

My suggestion: get the VCDS and do some logging before you get a headache from worrying and changing stuff that may not be bad. Don't know resistance for the coils, sorry. Could just be wiring.
 

·
Premium Member
Joined
·
44 Posts
My car does the same, there is a slight hesitation or bucking as the OP originally stated under part throttle. I have a worn lower intercooler hose that goes to the intercooler from the lower underbody interconnect tube. My tools should be here soon then I will check it out. It is very strange to me as well, as it only happens under part throttle and I don't have any codes being thrown. Somewhat of a miss it feels like to me.
 

·
Super Moderator
Joined
·
9,231 Posts
VAG Error Code: 16585

EOBD II Error Code: P0201

Fault Location:
Injector 1 (N30) - Circuit Malfunction/Open Circuit

Possible Cause:
Malfunction Indicator Lamp (MIL)(K83) active.
Lack/Loss of Power.
The engine may be harder to start.
Engine hesitation.

Wiring/Connector(s).
Injector 1 (N30).
Engine Control Module (ECM).

Possible Solutions:
Check/Replace all faulty Wiring/Connector(s).
Read Measuring Value Blocks (MVB).
Low side signal current < 2.1 A.

When is the code detected?:
The P0201 is set if the Engine Control Module (ECM) is detects a low or high voltage drop or resistance at the injector 1.

Description:
Engine Control Module (ECM) checks the injectors circuit resistance and monitors the voltage drop during normal operation. The Engine Control Module (ECM) will trigger the P0201 code when the resistance or voltage drop at the injector 1 is out of specifications.

As taken from my new Free EOBD II Error Codes software
 
1 - 14 of 14 Posts
Top