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Discussion Starter · #1 ·
My girlfriend is having a nervous breakdown! Her Jetta has recently developed a significant problem. Two things are happening together. One, even though it starts easily, the idle is terrible and things only smooth out when accelerating in gear or revving it up in neutral. At any cruise speed it seems to slightly buck and miss, much like the old cars did when a vacuum hose was off. Like I said, accelerating clears it up. It also appears the brake booster has quit working as it takes a lot of pedal pressure to stop the car. These two things happened simultaneously. When this first happened she took it to a nearby auto repair facility that took a lot of money, but did not fix the problem. She then took it to another with the same result.
Her last resort is to take it to a VW dealer that is a 100 mile drive and who knows what that will result in, cost-wise, however for $98 they will give a repair estimate.
Hopefully, I can glean some info here that might lead us to a simple fix. I have a cheapo code reader that that I know for sure works fine, but does not show any codes on the Jetta, even though I'm sure there are some in there as the CEL is on.
Any hints or advice would greatly be appreciated. My girlfriend would appreciate it even more than I would!
Thanks,
Deke
 

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Throw up the codes and I'm sure somebody on here would be able to tell you what they mean. Good luck.
Agreed, an autozone/advance auto scanner will read them.. They usually offer the code reading service free of charge.

Meanwhile for the hell of it, locate the MAF sensor and unplug it. See if the car runs better in idle.
 

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Discussion Starter · #4 ·
Agreed, an autozone/advance auto scanner will read them.. They usually offer the code reading service free of charge.

Meanwhile for the hell of it, locate the MAF sensor and unplug it. See if the car runs better in idle.
Thanks for the suggestion. First, there is no Autozone up here in NE Michigan. Probably the closest is about 90 miles. Can you possibly direct me to the MAF sensor or possibly supply a link to a photo? Would really appreciate it.
Meanwhile, I'll see what I can do to get the codes read. Without a brake booster it's chancy driving downstate.
Deke
 

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Thanks for the suggestion. First, there is no Autozone up here in NE Michigan. Probably the closest is about 90 miles. Can you possibly direct me to the MAF sensor or possibly supply a link to a photo? Would really appreciate it.
Meanwhile, I'll see what I can do to get the codes read. Without a brake booster it's chancy driving downstate.
Deke
I would worry about that brake booster first. But you can call up other auto parts stores even some shops are cool enough to give you the codes. I've seen some that charge like $10. Land vehicle Vehicle Engine Auto part Car
 

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Agreed, call around if you cant find any local chain stores that offer the service. But without codes, you're shooting in the dark. There's gotta be something near you right lol? O'riellys or something?

As for the brakes, check for fluid leakage at every wheel (with pressure on the brake pedal, car on or off)... And as you were, check the vacuum line to the brake booster. Could be alot of things though.. Bad master cylinder, bad booster, etc.
 

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Win for me. That's two agreed's from Chris! In a row! Man I'm on a roll.
Yes, yes you are lol. You may be the only person yet to figure out the procedure... Codes first!
 

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Discussion Starter · #9 ·
Thank you for the input and the photo. I'll try that this morning, once the temp gets above 4f. If removing that plug has a positive effect will it hurt anything to run the car for a couple hours? I currently have the car up on ramps and tried to find a vacuum line that might be disconnected, but even up on the ramps it's tough to see anything on the underside especially with the ground is covered with melting snow and mud. I talked to the VW dealer service manager in Bay City yesterday. They told me that they would run the codes, make a diagnosis, and give me an estimate of repairs if I can get it down there. I think we're going to give it a try and just leave it for the week. Once they give us the estimate we can decide whether to go with it or not and we can always go and pick it up. When I asked them about warranty of the repair they said 12,000 or 12 mo. Not bad if they actually fix what is wrong. The main concern right now is the brake booster. It has brakes, but it really takes some pressure. Almost 100 miles down there, but mostly low traffic and freeway. Even though the car has 184k miles, it's in nice shape and everything else is fine.
Thanks again,
Deke
 

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Well unplugging the sensor sends the ECU into ''stored fuel mapping'', which basically just means pre-set fueling (wont actually measure air). It'll run sorta crappy, but won't cause any harm to the vehicle.

If the car runs better with this unplugged, you have 1 of 2 problems (or both). First, the sensor is bad. Second, a vacuum leak, or again, both. So if the car does run better, get a propane torch and with JUST the gas turned on (no flame), run the fuel across all vacuum lines you can reach with the car running in idle. If you hear the motor start to rev up, you've found your vacuum leak. If no leak is found, you probably have a bad sensor.

I still think you may have a bad sensor because of your idling issues, in addition to your EPC light (traction control).

Note that unplugging this sensor WILL throw a code for it being faulty, so VW will automatically assume its bad.
 

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Discussion Starter · #11 ·
Well unplugging the sensor sends the ECU into ''stored fuel mapping'', which basically just means pre-set fueling (wont actually measure air). It'll run sorta crappy, but won't cause any harm to the vehicle.

If the car runs better with this unplugged, you have 1 of 2 problems (or both). First, the sensor is bad. Second, a vacuum leak, or again, both. So if the car does run better, get a propane torch and with JUST the gas turned on (no flame), run the fuel across all vacuum lines you can reach with the car running in idle. If you hear the motor start to rev up, you've found your vacuum leak. If no leak is found, you probably have a bad sensor.

I still think you may have a bad sensor because of your idling issues, in addition to your EPC light (traction control).

Note that unplugging this sensor WILL throw a code for it being faulty, so VW will automatically assume its bad.
Hey, thanks for the great info. This morning when the temp got up to about a balmy 4f I went out and wiggled some hoses and connectors for one last look, then got in the car, turned the key and it started right up and ran perfectly! Brakes were good, idle was good, and after taking it for a short spin it ran just fine, even though the CEL was still on. We still had an appointment down in Bay City so we dook it the 100 miles down to the VW dealer and after filling them in on all the info we could think of we dropped it off so they can make an assessment to be picked up later.
Unfortunately the symptoms were no longer there so they were calling it an intermittent problem, but the codes should give them a history of what has happened.
I tried to disconnect the MAP sensor plug, but wasn't able to get it apart. Couldn't figure it out and being so cold my patience was in short supply.
Question: what relationship is there between the EPC and the traction control? It seems that when one comes on, the other comes on at the same time. Also, where is the EPC module located? Is it in an area where getting stuck in the snow can have an effect on it? I wouldn't think it would placed in a vulnerable position, but stranger things have happened.
Anyway, thanks for all the help so far. You're a great bunch.
Deke
NE Michigan
 

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This would be in Chris's ballpark. I'm still a n00b lol. But I'm gaining knowledge as I go. I hope you get this figured out. Seems like a real PIA.
 

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Hey, thanks for the great info. This morning when the temp got up to about a balmy 4f I went out and wiggled some hoses and connectors for one last look, then got in the car, turned the key and it started right up and ran perfectly! Brakes were good, idle was good, and after taking it for a short spin it ran just fine, even though the CEL was still on. We still had an appointment down in Bay City so we dook it the 100 miles down to the VW dealer and after filling them in on all the info we could think of we dropped it off so they can make an assessment to be picked up later.
Unfortunately the symptoms were no longer there so they were calling it an intermittent problem, but the codes should give them a history of what has happened.
I tried to disconnect the MAP sensor plug, but wasn't able to get it apart. Couldn't figure it out and being so cold my patience was in short supply.
Question: what relationship is there between the EPC and the traction control? It seems that when one comes on, the other comes on at the same time. Also, where is the EPC module located? Is it in an area where getting stuck in the snow can have an effect on it? I wouldn't think it would placed in a vulnerable position, but stranger things have happened.
Anyway, thanks for all the help so far. You're a great bunch.
Deke
NE Michigan
Glad to hear its back to normal!

EPC is actually part of traction control. It uses the electronic throttle body to close the throttle once slip is detected by wheel speed sensors. It's sort of tied into the same system that utilizes your anti-lock braking system to individually apply brake pressure on wheels spinning at different speeds (to keep you in a straight line). Snow and such can't really affect it, especially intermittantly. You may have just had a loose wire/plug somewhere, or perhaps one had a little corrosion that you knocked loose.

Post back up if you have these troubles again!
 

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Discussion Starter · #14 ·
Thanks for all who posted with help. A few days ago we drove the car 100 miles down to Thelen VW in Bay City. The car ran fine with no apparent troubles other than the CEL. We left it there with the agreement that they would run the codes and give an assessment of the damages. Well, the damages came to $1319.73 with no guarantee that it wouldn't be more. All parts would have to be ordered. Among the items they said need replacing are Secondary Air Pump, Vacuum Pump, O2 Sensor, and something to do with the Throttle Body. When I asked what the charge was for running the codes they said it was 2.5 hours and $242.40.
The car is 9 years old and 180k miles and I don't think it's worth repairing, but that is just cheapskate opinion. I just can't see pouring that much money into a car that isn't worth much more than the cost of the repair. Funny thing, it was running fine when we brought it in. I haven't told my girlfriend yet and I really feel bad for her as she does not have that kind of money to put into it. Somehow I doubt all these repairs are valid, but nothing much I can do right now as they have the car and won't release it until all the diagnosis money is paid up front.
It looks like it might be time for a FOR SALE sign. Anybody have any words to soften this up?
Deke
 

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Thats the thing about VW's thier exspensive to fix. I would say if you or your girlfriend aren't really into the euro scene and she just has it do drive as a daily driver maybe its time to let it go. Some people get lucky and get one that runs forever. I would say 180k is a good run on a 9 year old car (that might catch me some flak on here lol). Thats just my opinion. Sorry with the bad luck. Keep us updated on what you decide to do...
 

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Heh, you can do most of that **** yourself with basic tools and little knowledge. The oxygen sensor requires jacking up the car, unplugging the connector, unscrewing the old one and screwing in the new. Cake.

The throttle body itself prob needs replacement (the motor may be bad), also a plug and play type thing. Very simple, but can cost something like 400 bones for it.

SAI is the same thing as a vac pump, also can be expensive, but also totally useless. The only reason its there is to oxidize the catalytic converter for better emissions, more quickly. It's an emissions thing. If you dont have emissions inspection, dont even worry about it.

If you were to do this yourself you could probably get away with $600-$700 (Not including the SAI pump) in parts, max, and a couple hours of your time.

I can tell you because of the EPC light that the throttle body is prob legit, dunno bout the SAI (though common), dunno bout the oxygen sensor.

Which sensor did they say? Primary/secondary or upstream/downstream?

And ask them for the codes.
 
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