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Discussion Starter #1 (Edited)
So I don't often see CELs on my car. I've only ever seen two other untill yesterday.

After popping the VAG-COM onto the car I came up with two throw codes.

16855 - Vehicle speed sensor, implausible signal... intermittent

&

17544 - Long term fuel trim add. fuel (bank 1) system too lean

Hmmm... the first one doesn't bother ne too much because I was going 900 mph and the ECU just didn't understand that. :p

But the lean system is not great. I'm thinking vaccume leak somewhere.

Any ideas?
 

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Discussion Starter #2
Man, 23 viewings and no one has any insight for me? :confused: :(

Rusty are you out there?
 

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Maybe if people wouldn't clutter up the Garage with "where can I buy HID" posts, I might have seen this sooner...

So what are your fuel trims - block 032? You've probably got some kind of vac leak somewhere. Process of elimination - have fun... ;) Although it would have to be pretty f*n' major leak to make your LTFTs throw a code - they'd have to be over +20%. That big of a leak shouldn't be too hard to find.

Gee, if you were going to be there for the GTG this weekend, we could look at it together... :heart:
 

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Discussion Starter #5
Dave, I'm not sure why I didn't think of that sooner. Thanks. I think... :)

I looked at the fuel trims block Rusty before I cleared the codes. It was showing -7%, so I'm a little lost on that one. I was sure I would find a large number on the positive side, but that wasn't the case. Since throwing the CEL I haven't had it come back on. It's only been two days, but if it was a major issue I would have seen it back on by now. Right? The only recent change was my CAI system. I'll look it over and see if there isn't something wrong with it somewhere, but all that stuff is before the MAFS and wouldn't constitute a "leak" to cause a CEL. Maybe unfiltered air getting in, but not a leak of un-metered air.

Another freaky thing happened a day after the CEL came on. I pulled into my favorite gas station that sells 93 octane gas and after filling the tank, the car would not start. As if it was out of fuel or fuse 28 had been pulled. It cranked and cranked an only when I pushed down on the gas pedal did I get any kind of starting response. It did finally start and sputter to life, but only after a few tense moments. It finally settled down and returned to normal. While that was going on the vacume level in the manifold was reading about 10 in/mg. That's a bit higher than normal. I usually see about 15 or 16 in/mg durning idle. Like I said, it eventually settle back into it's normal state of opperation. The only thing I can think of was that I was actually running on fumes as I pulled into the gas station. But the gauge was reading just at the edge of the red makers. And I could only pump 11.3 gallons of gas into the tank. The darn thing will hold 13 if you fill it completely. So I'm not sure what the heck that was. It was a seriously hot day. About 92 degrees for the end on May in Denver is hot! Maybe it just didn't care for that. Hmmmm... I can't wait for a really hot day then if that's what it was. :rolleye:

The other thing I was thinking about is this, and it kind of relates to me missing out on track day, again... I haven't really driven the car hard for a long, long time. It's a known fact that the 1.8T cyclinder head is a great place for corbon deposits to collect and gather in larger quantities. And I haven't run any BG's 44K through the system in a while. Maybe I have a some carbon deposits that are causing issues from within??

Unfortunately I will have to miss out on the gathering this coming weekend, yet again because my wife said yes to some friends that have a family farm in South West Nebraska. It's a great time out there with lots to do. The kids and I have been working on some Estes rockets that we plan to launch out there. We'll have the use of a couple of Honda Rubicon 4 wheelers to track them down. So I'll get a little bit of a motorsport fix, I guess. But on the way out there I plan on "blowing out" the Passats "nose" on the highway. I plan on bringing the VAG-COM. With that much flat, empty, open road to travel, I'm sure I can do a couple of hard pulls and not get into trouble. But my total vehicle wieght will be heavier than normal. Lots of people and stuff in the car.

Sorry for the ramble, just thinking out loud I guess.

Thanks for the help! :D
 

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Discussion Starter #6
Oh, BTW, where can a person get HIDs from??? :p
 

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Chas: the fuel issue might be the result of your charcoal canister being full from overflow gas . . . . there was a recent thread on AW regarding that causing an EVAP system fault which would make the car extremely hard to start.

Dave
 

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Discussion Starter #8
I'll look into the evap system as well on the VAG-COM. There are a few tests I can run on it to make sure everything 100%. Hell, I'd take 98% at this point...
 

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Yeah, if your LTFT's (field 2 in block 032) were -7%, then there's no way you are running too lean. Must have been some kind of peculiar burp. Sounds like Dave has your gas-station problem covered. :thumbup:
 

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Chas said:
While that was going on the vacume level in the manifold was reading about 10 in/mg. That's a bit higher than normal. I usually see about 15 or 16 in/mg durning idle. Like I said, it eventually settle back into it's normal state of opperation. :D
I see closer to 18-20 in/hg which I think is normal for 1.8T. Was the -7% block 032 the first or second field?
 

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scotty_passat said:
but chas is at high-altitude, right?
Yes, excellent point. I forgot he and Rusty are the mountain men. At 5-6,000 feet 15-16 is about all you'd see.
 

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Discussion Starter #13
Yeah, I'm sitting at about 5400 ft above sea level. So 15 in/mg is about right for me. Then again the gauge isn't all that accurate either. But it's with-in 1 in/mg and the same with boost I would bet.

The -7% was the second field alright.

That's what I was thinking too Rusty, just some stupid hickup in the system. The speed sensor showing an "implausible signal" would probably go hand in hand with the too lean code now that I think about it.

I'll keep an eye on everything as I drive the car this weekend. I'm betting that nothing else shows up.

Right now the car is running very strong. It has a tank full of 93 octane gas with BGs 44K and a sump full of fresh new Mobile 1 15/50 for summer time use. I bought the new larger VW oil filter this time around to see if there is any difference in the long run use of it compaired to my stock pile of Wix 51333 filters. The guy at the VW parts counter said that the new design VW filter uses a check valve so that the oil in the upper part of the engine doesn't drain back down. So there are no dry starts. The Wix filter is slightly larger than the VW offering, we'll see. Hmmm...
 

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^^^^ most oil filters have an antidrainback valve and a bypass valve. I bet your 51333 has em already.
 

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Discussion Starter #15
Well the stupid CEL is back on and it's showing itself out to be the same 17544 code LTFT too lean in bank #1. :(

But no other codes this time. Block 032 is showing the second field to be -4.7 this time.

And the dumb problem of the car being hard to start only after re-fueling is still with me. I've tried a couple different times to just leave the gas cap off for a few minutes to see if I can replicate the problem, but no such luck. It only happens when I get gas.

All the info about the Evap system I have checked on or run the tests that I could. No such luck on that front as the VAG-COM says everything is fine.

Any clues to these issues? I've looked for vacumn leaks in all the usual AEB spots only to find a big 'ole bag of nothing. Could a dirty MAF sensor cause this code? I didn't think so, but in doing some research someone raised that point. I'm just thinking out loud here.

HELP!!!
 

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Chas said:
Well the stupid CEL is back on and it's showing itself out to be the same 17544 code LTFT too lean in bank #1. :(

But no other codes this time. Block 032 is showing the second field to be -4.7 this time.

And the dumb problem of the car being hard to start only after re-fueling is still with me. I've tried a couple different times to just leave the gas cap off for a few minutes to see if I can replicate the problem, but no such luck. It only happens when I get gas.
More thinking out loud. The lean code with the block 032, field 2 at -4.7 makes no sense, so there must be an intermittent lean condition sufficient to throw the lean code but not enough to change the trim. Also, whatever is causing the lean condition isn't throwing a code on it's own like an intermittent bad MAF signal. Could you have an intermittent big vac leak? Vac leaks themselves don't throw a code. I'll give this more thought........
 

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Discussion Starter #17 (Edited)
Well if I had a big, intermittant vac leak that would probably mean I would also have a big boost leak. Boost is fine I am seeing a peak of 18 psi just as always. If I had a big leak I'm sure I wouldn't see that high of a spike.

Also, I just ran the VAG-COM again to look at things. Block 032 showed 2.3 in field number one and -6.7% in field number two.
(edit for the negetive sign I forgot)

I cleared the CEL and did a TB adaption. I also did a gas tank leak test and that showed itself to be fine. I'm a little lost on this one right now. I think I'l clean the MAF sensor just for kicks. I haven't done that in a couple of years. It something I try not to mess with.
 

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Chas said:
Well if I had a big, intermittant vac leak that would probably mean I would also have a big boost leak. Boost is fine I am seeing a peak of 18 psi just as always. If I had a big leak I'm sure I wouldn't see that high of a spike.

Also, I just ran the VAG-COM again to look at things. Block 032 showed 2.3 in field number one and 6.7% in field number two.

I cleared the CEL and did a TB adaption. I also did a gas tank leak test and that showed itself to be fine. I'm a little lost on this one right now. I think I'l clean the MAF sensor just for kicks. I haven't done that in a couple of years. It something I try not to mess with.
If block 032, F2 moved from -4.7 to +6.7, something is causing it to turn lean, but not off the chart, yet. MAF could be going and reduced readings are leaning it up, with an intermittent burp making it show really lean. Next vagcom some block 003 MAF readings. See what they are at idle after warmed up and do a 3rd gear WOT run and see what kind of numbers you get.

With the most recent info you posted on the fuel trims moving, I'd definitely suspect the MAF sensor. Get the readings even before the cleaning so you know where you're starting from. Cleaning probably only helps about 50% of the time.
 

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Discussion Starter #19
Great info, but I mistyped the most important number. It's -6.7% not 6.7%. That kind of changes things, doesn't it? :whistle:
 

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Chas, I don't think I have any real help necessarily but more or less a couple observations.
I've thrown the speed sensor twice. Both times were on days above 95. I know a couple times last week, it was up over 100.
Also, my car does not like those high temps. It runs alot crappier. I think I would be the only one to notice because I'm so in tune with my car :biglaugh: It seems sluggish and hesitant. Only in high temps though.
I was throwing the large vac leak code for about a week, cleared it every time (I think you were with me) and that's it. I've not seen a code in about 8mo.
I've also filled up there in the last week twice with no issues. Just a random thought as to where I'd start looking is my fuel filter and fuel pump. I do plan on changing my fuel filter maybe this weekend and clean my air filtering system.
Anyway, just a couple notes that may or may not help as we have the same car in the same place (oh, and I get the same vac readings at idle)
 
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