Car issues

Funkmasterr · Post by **Funkmasterr** » March 14, 2007, 10:51 am

So I am having troubles with my car.... again. I have an Audi A4. I figured I would just post the issue here before I bring it into the shop to see if anyone has any ideas on what it may be.

The issue has been getting progressively worse with more symptoms. First the car was not driving as smoothly (seems to jerk a bit at lower speeds), the gas mileage has gotten to be terrible, and the check engine light came on.

After a while of all that happening, now a something new has started happening - about once a day I will be driving and all of the sudden the RPM's will drop like 1k real quick and pop back up. After this happens the "EPC" light comes on on my dash, and the car idles higher than it should (at around 1200 rpm's instead of 800.)

If this happens when I am driving down the freeway, the rpm's just drop down, the light comes on and everything continues as usual. However, if it happens when I am going really slow, or stopped (has only happened once) the car stalls, but will start back up.

I think this is about all the info I can provide, any ideas would be appreciated - thanks.

Boogahz · Post by **Boogahz** » March 14, 2007, 10:53 am

Sounds similar to issues with a car I used to have. I was also smelling something like gasoline when the car was running. It turned out to be some hoses that needed to be replaced, and all was fine after it was fixed. Mine never got to the point where it was actually stalling though.

Funkmasterr · Post by **Funkmasterr** » March 14, 2007, 11:09 am

Boogahz wrote:Sounds similar to issues with a car I used to have. I was also smelling something like gasoline when the car was running. It turned out to be some hoses that needed to be replaced, and all was fine after it was fixed. Mine never got to the point where it was actually stalling though.

I do get the gas smelling deal too (very faint). Interesting, sure would be awesome if it was something that simple!

Kluden · Post by **Kluden** » March 14, 2007, 12:58 pm

its really not that simple, but, what it sounds to me is:

1. Fuel pressure is off. Either fuel pump is malfunctioning, hose(s) lines have an issue (hole), and the pressure is not there (ie, fuel leaks out instead of making it to the injectors).

2. Oxygen sensor is mucked up somewhere, and is causing your car to run "rich", so you have fuel backfiring and giving off the fuel smell.

Basicly, its a sensor problem. The sensor sends the signal to the computer that you are running "rich or lean", the computer adjusts, the RPM's go out of whack, then back to normal as it adjust back. Oxygen sensors can seriously screw up how an engine runs when they are faulty or dirty.

3. It could also be something as simple as your battery not providing the proper voltage to the monitoring system, or your alternator having a debunked voltage regulator, etc as well.

Either or, its a relatively cheap fix. I say relative, because in a Yugo car, it would be 200 bucks, in an audi, probably 450. Most money is going to be put towards "diagnostic time".

My money is on oxygen sensor(s). Please to be letting us know what it is when you get it back!

Boogahz · Post by **Boogahz** » March 14, 2007, 1:01 pm

Yeah, I went into the repair situation thinking it was my fuel pump on my Town Car, but I lucked out on it just being the hoses. Total cost of repairs was around $120.

Funkmasterr · Post by **Funkmasterr** » March 14, 2007, 2:07 pm

Yeah I will let you guys know when I find out. I called the dealership a week or so ago and asked about the O2 sensors because I thought that might be the issue, and they said I have two - each one would be 350 dollars each parts and labor.... ridiculous.

Sendarie · Post by **Sendarie** » March 14, 2007, 3:20 pm

Thats textbook O2 sensor failure symptoms.

You do have 2 O2 sensors if your car is 96 or newer aka OBDII iirc, but only one matters.
The front aka precat O2 sensor relays a/f ratio to your computer and adjusts air/fuel/timing constantly. The rear one only indicates if your cat is working properly (postcat O2 sensor). The ONLY thing this going bad can do is throw a code and cause the check engine light to come on.

Additional but much much less likely of a possibility is 1. clogged or old fuel filter 2. vacuum leaks 3. maf going out (very unlikely).

I would place bets your front O2 is fucked.

Funkmasterr · Post by **Funkmasterr** » March 14, 2007, 3:38 pm

Cool, if it's only one of the sensors then that won't be too bad. I am almost tempted to just bring it in and ask them to replace the front O2 sensor instead of having them hook it up to the computer and charge me for that, then probably try and feed me some bullshit about something else I should replace.

Boogahz · Post by **Boogahz** » March 14, 2007, 3:46 pm

Funkmasterr wrote:Cool, if it's only one of the sensors then that won't be too bad. I am almost tempted to just bring it in and ask them to replace the front O2 sensor instead of having them hook it up to the computer and charge me for that, then probably try and feed me some bullshit about something else I should replace.

um, I would still have them check. What happens when you spend the 350 to replace one sensor and it does nothing to fix the problem?

Funkmasterr · Post by **Funkmasterr** » March 14, 2007, 3:52 pm

Boogahz wrote:
Funkmasterr wrote:Cool, if it's only one of the sensors then that won't be too bad. I am almost tempted to just bring it in and ask them to replace the front O2 sensor instead of having them hook it up to the computer and charge me for that, then probably try and feed me some bullshit about something else I should replace.

um, I would still have them check. What happens when you spend the 350 to replace one sensor and it does nothing to fix the problem?

Well that was from the dealership, I just called the guy I usually bring my car to and he told me that it would run about $150 so I think I'm gonna go for it. The reason for this being that hooking my car up to the computer immediately costs $150 dollars.

Boogahz · Post by **Boogahz** » March 14, 2007, 3:57 pm

Funkmasterr wrote:
Boogahz wrote:
Funkmasterr wrote:Cool, if it's only one of the sensors then that won't be too bad. I am almost tempted to just bring it in and ask them to replace the front O2 sensor instead of having them hook it up to the computer and charge me for that, then probably try and feed me some bullshit about something else I should replace.

um, I would still have them check. What happens when you spend the 350 to replace one sensor and it does nothing to fix the problem?
Well that was from the dealership, I just called the guy I usually bring my car to and he told me that it would run about $150 so I think I'm gonna go for it. The reason for this being that hooking my car up to the computer immediately costs $150 dollars.

That's shitty, most places around here will waive the cost of hooking it up since that's going to confirm why the error is there in the first place. I guess there are no real honest mechanics up there that would prefer doing it right to testing out multiple repairs to see what fixes it

Funkmasterr · Post by **Funkmasterr** » March 14, 2007, 4:14 pm

For the most part, at least from what I have experienced and heard from other people, you hit the nail on the head.

Kluden · Post by **Kluden** » March 15, 2007, 8:53 am

If you are mechanically inclined, you could do it yourself. O2 sensors screw in like spark plugs, so its not overly difficult.

Also, sometimes new sensors don't fix the problem...wierd, but it has happened to friends of mine before. Put new 02 sensor in, doesn't fix the problem...clean old O2 sensor, put old one back in, works fine again.

Toothbrush and rubbing alcohol are the high power cleaning tools.

Also, new O2 sensors are expensive. I'd bet for an Audi your looking at $100 to $150 for a new intake side sensor.

So in all honesty, if that garage is going to replace it for $150, I'd have him do it, because that's cheaper than the part, or damn close to it.

Sendarie · Post by **Sendarie** » March 15, 2007, 11:18 am

Yeah O2 sensor swapping is relatively easy but a bit more of a pain on a turbocharged vehicle (if yours is turbo that is) due to higher exhaust temps they tend to get stuck in there more than the NA versions. I highly advice getting an O2 sensor socket it has a cutout for the wire so you dont screw anything up.

You'll also need some way of loosening it, I usually heat it up a bit with a torch and do the old 1/2 turn left 1/4 turn right, rinse repeat so you dont fuck up any threads.

Funkmasterr · Post by **Funkmasterr** » April 6, 2007, 7:12 pm

Well, I brought the car in last week. They had to replace the O2 sensor and the Engine speed sensor, and all was well... For one day.

The next day I was stopped at a light and the engine started rumbling. It was to the point that the car was lightly shaking with it.. I was only a mile away from home and drove it back and parked it... I am gonna bring it back in on Monday to see what it's gonna be next.

Kluden · Post by **Kluden** » April 9, 2007, 9:55 am

have them check your emissions. Perhaps your catalytic converter is all banged up, and is forking with your back pressure.

Is it "herky jerky" now? Like, maybe its rough getting upto a certain speed, but once there, it runs better? or perhaps, it runs fine at a certain RPM, in any gear? Either of these symptoms, I would check the exhaust...starting at the cat.

Funkmasterr · Post by **Funkmasterr** » April 9, 2007, 12:44 pm

Interesting.. I am going to bring it in today - at lower rpm's, especially idling it jerks to the point that the car is wobbling. It did get better at higher rpm's (acceleration sucks major ass, too) but not totally better.

I am just trying to decide if I should have it towed there or drive it there.. IF it is something thats going to be major $ I won't be fixing it right now and my triple A won't tow it out of the same place I have it towed to.. thats why I am debating.

Kluden · Post by **Kluden** » April 9, 2007, 12:55 pm

Just drive it, and get the tow if you need it. If the car stalls out, then it could be a power issue, again, test that alternator/battery/starter...that test is free. If there is a short somewhere, its going to sap power, and fuck up your engine running properly.

But if the car is shuddering, but seems to get better at higher RPM's, I may change my vote to an exhaust issue. A new catalytic converter is best purchased and installed at a shitty muffler shop, ie Midas or something. They have to be broken for them to be replaced...US law and shit.

I think the test for a bad cat is smacking it with the butt of a screwdriver, and listening for all the rattling pieces...if you hear them shaking around, your cat is shot. An emissions test should show a catalytic problem as well, along with any fuel mixture issues.

Funkmasterr · Post by **Funkmasterr** » April 9, 2007, 4:21 pm

Brought it in - it's the coils apparently.. One is bad and one is going in and out.

Another $210

Boogahz · Post by **Boogahz** » April 9, 2007, 5:27 pm

It's still cheaper than getting a new car

Funkmasterr · Post by **Funkmasterr** » April 9, 2007, 6:11 pm

Well I just got back from picking it up and one the positive side it seems a lot faster then I remember it being

Kluden · Post by **Kluden** » April 10, 2007, 2:03 pm

Glad I was wrong, new cats are more than that.

You need to be pimping that garage you goto to everyone out there near you. Those are outstanding prices on work that is usually much higher.