Volkswagen Passat Forum banner
1 - 20 of 21 Posts

·
Registered
2002 Volkswagen Passat 1.8T
Joined
·
42 Posts
Discussion Starter · #1 ·
Hi everyone,

I'm having a P0441 on my 2002 Passat B5. I replaced the purge valve with a new Bosch one and after erasing all codes, the code came back a month later. The car is also vibrating heavily when idling in Drive or Reverse, but not while driving or while in Park or Neutral. Fuel efficiency is reduced by 10-20%.
I couldn't find any obvious vacuum leaks but I also wouldn't know where to look exactly. I inspected the area around the N80 purge valve and section jet pump because I didn't know any better...
Any ideas what could be causing the vibration/code?
 

·
Registered
Joined
·
28,620 Posts
The purge valve needs enough vacuum to actually pull fumes from the charcoal canister. A vacuum leak at the engine could cause the code, but should also set a lean code. Did the mpg drop occur at the same time as the P0441 or was there a difference in the weather?
Do you have VCDS? If so, check the fuel trims. A vacuum leak should not cause low mpg in general, but if it's low vacuum due to another issue (low compression, timing off), it will cause mpg drop and engine vibrations.
Here is the simple 4 vacuum hose replacement DIY. You can use it to check your car.
I don't have a diagram of the rest of the system, which is everything else on the intake side of the engine.
 

·
Registered
2002 Volkswagen Passat 1.8T
Joined
·
42 Posts
Discussion Starter · #3 ·
Vibrations, low MPG and P0441 all came at the same time (engine code slightly delayed, but maybe that was the time it took to set the code?). No significant difference in weather.

I had the car parked on the road for about two weeks. When I drove it again, I suddenly had the strong vibrations and low MPG. I was wondering if an animal could have chewed through one of the hoses?

I don't have VCDS but I'll inspect the 4 thin vacuum hoses for any leaks this weekend. Thank you for the help already and any other ideas are appreciated.
 

·
Registered
Joined
·
28,620 Posts
If you have a source of pressurized air, a boost leak detector might help. They are pretty easy to build.
Here is the link, but no pictures:
 

·
Registered
2002 Volkswagen Passat 1.8T
Joined
·
42 Posts
Discussion Starter · #5 ·
I made an interesting observation today. I checked all the thin vacuum lines and they look fine. I took out my suction jet pump and replaced it with a spare one I had lying around. Suddenly, the rough idle was much better. I drove around for 15 minutes and already thought I had fixed it. Went for a walk and when I started the car again, the rough idle was back. Was i hallucinating or could the p0441 be related to the suction jet pump?

I'll try the boost leak detector but it'll have to wait until next weekend. I need to get a source of pressurized air and do some reading...
 

·
Registered
Joined
·
28,620 Posts
A broken suction jet would be an issue, but not a working one. Perhaps the PCV valve is stuck open as it's upstream of the SJ. Swapping the SJ might have knocked the PCV loose enough to close for a minute. Try plugging the hose on either end of the SJ and see if the idle improves.
 

·
Registered
2002 Volkswagen Passat 1.8T
Joined
·
42 Posts
Discussion Starter · #7 ·
I went down there again and checked that the PCV valve is working properly. It wasn't stuck, there was just a bunch of liquid (oil?) in the T-adapter that holds the PCV valve.

I still need to plug the hoses on either end of the SJ to check if the idle improves and I haven't built the boost leak detector yet... I do hear a hissing sound from the sujction jet pump area though. Is anything else in that area that is prone to leaking or breaking?
 

·
Moderator/Administrator
Joined
·
25,593 Posts

·
Registered
2002 Volkswagen Passat 1.8T
Joined
·
42 Posts
Discussion Starter · #10 ·
I still have no air compressor so no leak detector yet...

However, i sprayed some starter fluid around the suction jet valve and and the secondary air injection valve. Idling speed did not change but the check engine light was immediately off when I went back into the car! Am I right in inferring that the vacuum leak is somewhere in that area?

I then noticed some loose hose clamps on the line from the N80 to intake manifold, and replaced them. Car is still idling really roughly though so I suspect there is more. When I recently replaced some hoses i ran out of small hose clamps to tighten the F-shaped hose in the picture shown below. A mechanic told me that's probably fine and not every hose needs a tight hose clamp. But i recently learned that that hose connects to the vacuum reservoir so this might be the source of my leak?

Tool Font Wood Office supplies Musical instrument accessory
 

·
Registered
Joined
·
7,098 Posts
Don't know where you're at on this, but have you checked the oil dipstick? 1.8's the dipstick is all plastic and they tend get very brittle and crack where it attaches to the engine block.
 

·
Registered
2002 Volkswagen Passat 1.8T
Joined
·
42 Posts
Discussion Starter · #14 ·
i just pulled the dipstick out and plugged the hole with a rubber cork. Unfortunately no luck and i still have the really rough idle. Sounds like I'll need to drive the car like this to Thanksgiving.

I noticed that the thick tube going into the intake manifold looks pretty bad at the highlighted connector in the attached pic. What does this tube do?
Tire Automotive tire Tread Motor vehicle Automotive design
 

·
Registered
2002 Volkswagen Passat 1.8T
Joined
·
42 Posts
Discussion Starter · #15 ·
I have a feeling it must be related to the PCV system though. When I open the oil filler cap, i feel a strong pulsating pressure coming out. I just don't know where to start looking. I recently put in a new crankcase breather hose valve set...
 

·
Registered
Joined
·
7,098 Posts
I recently put in a new dipstick but it fits pretty badly and slips out all the time. This can cause a vacuum leak?
Sure can.
There should be an O-ring around the bottom of the dipstick tube. I can't remember for sure, but somewhere on the dipstick tube isn't there an attachment point to secure it into the engine block?
Thought it had a small screw that secured it to the intake manifold. I'm not 1.8 guy and it's been a number of years since I've worked on one.

That large dia hose is for the turbo intercooler intake air. I've only actually touched a couple of 1.8s in all my years but the few I have seen are loose at that connection.
That won't cause you the problem you're having though.

There should be no pressure at the oil filler cap. That means you have a major vacuum leak somewhere or your piston rings are completely shot. (not likely)
There are a few hose connections underneath the intake manifold behind the dipstick, have you checked those out. Again, those hoses get brittle and crack or get soaked with oil and swell up causing leaks, which in turn will cause major vacuum leaks.

The old school vacuum leak detector trick is to start the engine and spray some type of flammable liquid around any of the vacuum hoses. I personally wouldn't use starter fluid - it's a little too volatile.
Something like WD-40 works good. The engine RPM will increase if it gets sucked in but won't start anything on fire.
 

·
Registered
2002 Volkswagen Passat 1.8T
Joined
·
42 Posts
Discussion Starter · #17 ·
I will try the WD-40, thanks for the tip. Otherwise, I will drive down to Maryland for this weekend, so if anybody knows a knowledgeable VW mechanic there, I could see if they have time to check it out. As @AndreasPassat said, it's probably a major vacuum leak that an experienced mechanic can spot in 5 minutes...
 

·
Moderator/Administrator
Joined
·
25,593 Posts
Where in MD? I am 30 mins north of Baltimore. I have spare parts and hoses. PM me if you want to possibly meet up.

By the way that big hose you circled is the intercooler to throttle body hose. They all end up looking like that with no ill effect.

Try clamping the line from the intake manifold to the "T" at the PCV valve and see if idle improves. A PCV, or bleeder valve as is it supposed to be called, can partially open or even partial close because the little plate in the middle that closes can become dislodged and sit off to the side in the housing. I had that happen years ago to me.

Also there are lines over top of the airbox and check valves can develop a leak.
 

·
Moderator/Administrator
Joined
·
25,593 Posts
It was nice meeting you today.

For everyone:
1. Vibration in "D" or "R" is most likely motor/snub mounts. When he put it in drive, the engine easily rose 1-2 inches.
2. He mentioned that on cold starts, the engine ran rough and it was loud. I let him listen to mine on a cold start and the engine sounded the same, but my SAIP was much quieter. I recently replaced my SAIP hoses because one had a tear in it. So much that it eventually triggered a P0411 code. Amazon.com: GooDeal 2pcs Secondary Air Pump Connector Hose Kit for VW Passat B5 Skoda 1.8T : Automotive
3. Engine idled smoothly. Pulled the oil cap and it bobbled around on it while idling. Same as mine.
4. Could use a new serpentine belt but not a cause for any current issues.
5. I couldn't detect any leaks anywhere from a cursory inspection of the hoses and check valves.

I did recommend he get a scan tool. VCDS lite or something more portable like the Torque app with a bluetooth dongle . OBDeleven if going advanced.
Torque will allow real time sensor reading like O2, AIT, MAF, MAP, fuel trims, etc.

An adapter like this: https://www.amazon.com/Scanner-Vehicle-Adapter-Wireless-Diagnostic/dp/B076FRK5BT/ref=sr_1_9?keywords=ELM327+bluetooth+adapter&qid=1637954273&qsid=130-0665014-8607909&s=automotive&sr=1-9&sres=B074DWH8JR,B01HXGX8V6,B01C3HAHCS,B06Y5ZGN7L,B01MAURDGG,B076FRK5BT,B07P7HJ4M3,B07CP5ZJVQ,B08HRR1QMH,B08L7XYTMK,B07Z65HX5X,B005NLQAHS,B011NSX27A,B073XKQQQW,B07Z46L5FG,B07MQ8GHG3,B07JFRFJG6,B07L4926C1,B078K54MT5,B082SMZTFL&srpt=VEHICLE_SCAN_TOOL

Various links for fuel trim, Evap, engine mounts, etc. below
Fuel Trim Info - Ross-Tech Wiki
Here's How A Volkswagen/Audi EVAP System Works
B5_Motor_Mount_DIY.pdf
Motor Mount Install WriteUp - incld Front Snub
1.8T Motor Mount DIY
 
  • Like
Reactions: PZ and mstein
1 - 20 of 21 Posts
Top