Rough idle question, 2005 Passat TDI

thundershorts

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these are like most auto stats Tony, they're filled with wax which expands at a spec'd temp. I've seen quite a few fail both not opening or sticking open. this one in question probably was just fine.
 

thundershorts

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under the ambient conditions where you are, it won't get to 90c without putting it under load such as a long mountain climb.
 

abctdi

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The gage may say you are at 90c, but there is actually quite a range of temps that will do so.
 

lynnejohn

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Took another log tonight on a 16 mile round trip with a balmy and foggy 56F here in CT. Cruising speed 75. Within 238 seconds (I'm about 1 mile from the highway) it hit 90C. From there on it had steady points of 92.5, 93.7 and 94.5. After getting off the highway until I backed in and parked, it was again steady at 93.6. So I was not imagining the warmer air from the heater.
 

CharlieT

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Assuming you are reading data direct from VCDS or a scangauge, then this would suggest they did not fit the stock 89C thermostat, but a higher setpoint one, likely 95C.
What part # did the invoice show ?
 
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lynnejohn

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Assuming you are reading data direct from VCDS or a scangauge, then this would suggest they did not fit the stock 89C thermostat, but a higher setpoint one, likely 95C.
What part # did the invoice show ?
Part number 044-121-113 $51.90

So which set point is this one?
 

CharlieT

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That is the correct one, 87 Deg C setpoint.
So that does make me question why your coolant temps logged at 92-95 Deg C on a short run at low ambient temps (56F).
You also mentioned 93.6 Deg C when parked, in low ambient temps. That does not seem right.
I would keep an eye on it, especially when next summer comes.
 

lynnejohn

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When I say "parked", I meant that I had just driven about a mile from the highway at 35mph and backed in to the driveway. The final temp before I shut the engine off was the 93. It may cool down given more time idling but I'd have to check that. When it gets below 30F in the morning I'll do another log going to work to see how it does in the cold.
 

thundershorts

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coolant sensor is a possibility being faulty as well showing higher than actual.
 

2002tdi

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i have an update on my issue. i had the same thing happening. i pulled my intake off and it was almost completly plugged shut. cleaned it all out with a pressure washer at my work and acid. cleaned the EGR and the anti shudder valve with all the gaskets started it up and smoked like crazy for the first few minutes. i then took off the upper timing cover and started thinking maybe my cam timing was just off a little bit. turned it one way and it got worse. turned it the other way and tightened it back up again and it was perfect smooth idle and felt a lot better over all. power felt better over all and no smoke. now on a cold morning it will idle odd for about 5 seconds and then get super smooth. hope this helps you out.
 

lynnejohn

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i have an update on my issue. i had the same thing happening. i pulled my intake off and it was almost completly plugged shut. cleaned it all out with a pressure washer at my work and acid. cleaned the EGR and the anti shudder valve with all the gaskets started it up and smoked like crazy for the first few minutes. i then took off the upper timing cover and started thinking maybe my cam timing was just off a little bit. turned it one way and it got worse. turned it the other way and tightened it back up again and it was perfect smooth idle and felt a lot better over all. power felt better over all and no smoke. now on a cold morning it will idle odd for about 5 seconds and then get super smooth. hope this helps you out.
Wow so you finally got it. Is the cam timing you tweaked the same as torsion?

Good work.
 

2002tdi

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yes. there is a setting in vag com to check your idle quantity, but i have not had a chance to check it yet. it is going on about a month since i have done this and have not had any issues at all. even the other day when it was 18 deg. it fired right up and idled perfect after 5 seconds.
 

lynnejohn

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yes. there is a setting in vag com to check your idle quantity, but i have not had a chance to check it yet. it is going on about a month since i have done this and have not had any issues at all. even the other day when it was 18 deg. it fired right up and idled perfect after 5 seconds.
I wonder if I can set the torsion value without having to pull the upper timing cover?
Have you noticed any difference in mileage? I just don't see how the Passat's mileage can vary so much given they are all the same engine and tranny. I get an average of 36 with 38 on the highway and many here say they get over 40.
 

aja8888

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I wonder if I can set the torsion value without having to pull the upper timing cover?
Have you noticed any difference in mileage? I just don't see how the Passat's mileage can vary so much given they are all the same engine and tranny. I get an average of 36 with 38 on the highway and many here say they get over 40.
Wagons (04-05 Passat TDI) get less MPG on average than sedans. I had both.
 
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johnboy00

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I can get just under 42mpg consistently in my wagon, at 70mph. With winter fuel, it drops by about 2-4 mpgs.
 

aja8888

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What mpg did your wagon get on the highway at say 70?
Mostly around 35 - 36 MPG @ 70 - 75 MPH. Lots of trips on highways in Texas, Oklahoma and Louisiana. A/C on 98% of time. 17" wheels and wide tires. With the sedan, we averaged 42+ on trips. That Passat had 16" wheels.
 

lynnejohn

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Ok we have a 40mpg wagon, a 35-36 with AC Wagon and my wagon at 36 avg commute (32miles each way @ 70-75). 4 mpg is a pretty significant increase and I'm throwing the wheel size out as I have 16's on now with snows but had 17's during the summer with no difference.
This must be the question you need to answer to get into the secret Passat club (only those knowing how to get 40mpg out of the wagon are allowed in..)
 

blu_jet_92

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OK sorry to butt in here.... but i have another 04 Passat (my dads) with a REALLY bad idle.... interesting thing is..... I have a fault code telling me it has misfired. and this literally happened overnight. one day its all good and dandy, the next it's HORRIBLE. from your experience, where should i start? I've read this whole thread, and really haven't come up with anything....

EDIT:


16685 - Cylinder 1
P0301 - 000 - Misfire Detected
Freeze Frame:
RPM: 819 /min
Torque: 74.0 Nm
Speed: 0.0 km/h
Load: 0.0 %
Voltage: 13.53 V
Inj. Quantity: 2.96 mg/str
Temperature: 56.7°C
(no units): 0.0

Tonight I've changed the fuel filter, checked the intake manifold, banged on the EGR valve, tried running without MAF,....

Few more notes: The injection quantities for cylinders 2,3,and 4 are around -1.5... cylinder 1 is stuck at +2.99.... im thinking plugged injector?

Torsion value is at -.5kW

EDIT 2:

Also i should add... it is always rough. NEVER stops being rough. at full temp, it's just as rough as when it's cold.
 
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lynnejohn

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OK sorry to butt in here.... but i have another 04 Passat (my dads) with a REALLY bad idle.... interesting thing is..... I have a fault code telling me it has misfired. and this literally happened overnight. one day its all good and dandy, the next it's HORRIBLE. from your experience, where should i start? I've read this whole thread, and really haven't come up with anything....

EDIT:


16685 - Cylinder 1
P0301 - 000 - Misfire Detected
Freeze Frame:
RPM: 819 /min
Torque: 74.0 Nm
Speed: 0.0 km/h
Load: 0.0 %
Voltage: 13.53 V
Inj. Quantity: 2.96 mg/str
Temperature: 56.7°C
(no units): 0.0

Tonight I've changed the fuel filter, checked the intake manifold, banged on the EGR valve, tried running without MAF,....

Few more notes: The injection quantities for cylinders 2,3,and 4 are around -1.5... cylinder 1 is stuck at +2.99.... im thinking plugged injector?

Torsion value is at -.5kW

EDIT 2:

Also i should add... it is always rough. NEVER stops being rough. at full temp, it's just as rough as when it's cold.
You are in a completely different territory from the issues you have seen in this thread. When the problem comes on so suddenly and it is consistent, you should be able to track it faster. That said your going to need someone close to Guru status to figure out if a injector went bad or some sensor/wiring is getting flaky. Could you get any help from the folks that did you mods?

John C.
 

blu_jet_92

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You are in a completely different territory from the issues you have seen in this thread. When the problem comes on so suddenly and it is consistent, you should be able to track it faster. That said your going to need someone close to Guru status to figure out if a injector went bad or some sensor/wiring is getting flaky. Could you get any help from the folks that did you mods?

John C.

This is on my dad's passat, not my 01 Jetta, but i found the problem....

 

lynnejohn

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Wow,
That gremlin must have been working pretty hard to unscrew it that far. Were there any marks on the underside of the valve cover from that?
 

johnboy00

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This must be the question you need to answer to get into the secret Passat club (only those knowing how to get 40mpg out of the wagon are allowed in..)

I don't know any secrets but I have to ask: With your 32 mi commute, how much is not highway? That makes a huge difference. I'm about 8 miles from the highway, and the only way I can get a full tank anywhere near 42mpgs is to drive almost 100% highway. Like Ma to MD or to Lake placid and back.

You say you're speed is between 70 and 75, that's a big range. How many times do you throttle up and down from one speed to another? I would guess that if you're in traffic that results in a lot of speed changes over 30 miles, fuel economy will be effected significantly.

I also believe that warm up time to best economy is also a lot longer than you might realize. For instance, I drove 6 mi to the highway yesterday afternoon, got up to speed and immediately reset the trip computer. Fuel economy (per computer) indicated about 36 mpgs. Slowly, over the next 12 miles, the indicated fuel economy went up to over 40mpgs. Yes I know these numbers are not absolutely accurate but they are in a relative sense. What this tells me (I think) is that even after the 6 mi drive to the highway, the car was still not warmed up fully. Over the next 12 miles or so, if finally became fully warm and I saw the indicated mpgs increase. BTW, I'm in Ma and it was about 32-35 degrees yesterday, so not extremely cold.

I will periodically do a mpg check by filling up right before getting on the highway before a long trip 100+ miles each way. I'll drive with the cruise control set for 70 and check fuel economy when I return. I've never seen the fuel economy less than 41 doing this. On the other and my average fuel economy is only about 34 in the summer and 31 in the winter over the last year.

Finally, I do think I looked at my torsion value once, but I never set it and don't remember what is is.. I did not have Vagcom when I did my BSM. I am now coming up on another timing belt change and will check it before and afterwards.
 

lynnejohn

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I don't know any secrets but I have to ask: With your 32 mi commute, how much is not highway? That makes a huge difference. I'm about 8 miles from the highway, and the only way I can get a full tank anywhere near 42mpgs is to drive almost 100% highway. Like Ma to MD or to Lake placid and back.

You say you're speed is between 70 and 75, that's a big range. How many times do you throttle up and down from one speed to another? I would guess that if you're in traffic that results in a lot of speed changes over 30 miles, fuel economy will be effected significantly.

I also believe that warm up time to best economy is also a lot longer than you might realize. For instance, I drove 6 mi to the highway yesterday afternoon, got up to speed and immediately reset the trip computer. Fuel economy (per computer) indicated about 36 mpgs. Slowly, over the next 12 miles, the indicated fuel economy went up to over 40mpgs. Yes I know these numbers are not absolutely accurate but they are in a relative sense. What this tells me (I think) is that even after the 6 mi drive to the highway, the car was still not warmed up fully. Over the next 12 miles or so, if finally became fully warm and I saw the indicated mpgs increase. BTW, I'm in Ma and it was about 32-35 degrees yesterday, so not extremely cold.

I will periodically do a mpg check by filling up right before getting on the highway before a long trip 100+ miles each way. I'll drive with the cruise control set for 70 and check fuel economy when I return. I've never seen the fuel economy less than 41 doing this. On the other and my average fuel economy is only about 34 in the summer and 31 in the winter over the last year.

Finally, I do think I looked at my torsion value once, but I never set it and don't remember what is is.. I did not have Vagcom when I did my BSM. I am now coming up on another timing belt change and will check it before and afterwards.
To get to the highway in the morning is about 2 miles of 40mph zone through 5-6 lights. Once on the highway I'm just north of Hartford so the first highway miles are 20mph until I reach the other side of Hartford.

You are correct that the speed varies from 65 - 80 in the fast lane with a lot of traffic. Once you get about 15 miles south of Hartford the traffic will break up enough where I can do a steady 74. Mind you at any time there could be someone not wishing to leave the fast lane and doing a steady 60. As the traffic flows around the vehicle speed can vary a bit as you jockey for position.

So you are correct that the commute is not a steady speed the whole way and that may be a good part of the reason for my mileage (Yes I have checked the torsion value.) It is just my impression that I have read the 04-05 Passat's wagons mpg reading from high 20's to low 40's. That is a huge difference and I just want to make sure I've covered the critical bases so that I'm getting the best mileage I can given my commute.
 

johnboy00

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I've got a few pretty good baseline so even though I virtually never (once a year maybe) drive a full tank to the point when I can get 40 + mpg, I can always go back to a baseline to see if my overall fuel economy has deteriorated.

I know exactly how you feel. I had a 03 Mercedees diesel Sprinter van for a couple of years. Many would claim that they could get up to 27mpgs while I never saw anything north of 21 or 22 mpgs.
 
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