Fuel filter and fuel pressure regulator

[mbagge01]

I have a 2005 S4 B6 avant with 99,000 miles and been having high long term fuel trims (~ 14) and getting p1127 and p1129 codes after performing maintenance such as a new fuel filter, new coils and spark plugs. My question about the fuel filter (3 prong) is that from what I read, it also has the fuel pressure regulator within it because I cannot find a FPR on the fuel rail in the engine. If this is true, even though the fuel filter is new, could the FPR be bad inside it and causing extra fuel to leak through leading to both banks being rich (prior to maintenance fuel trims where fine). I had sprayed to original MAF with MAF cleaner which I thought could have damaged the MAF sensor for which I just put a new MAF in but still the furl trim problems. Short term trims are fine. The fuel pump also makes a winning noise and I cannot remember if it did that before changing the fuel filter but I know that a clogged fuel filter could cause fuel pump noises but fuel pumps in general will create a noise anyway. One thing that has not been done yet is changing out the oxygen sensors but I would not expect both sensors to go out at the same time causing both banks to go rich so I am looking at parts that can affect both banks. I also did the check for vacuum leak trick with carburetor cleaner and did not find any change in idle. Any thoughts?

[blocke]

Could you have put the lines into the wrong spots on the filter? Dunno if that's possible just trying to eliminate simple stuff. Have you swapped on a known good filter and re-tested?

[mbagge01]

It only connects up one way for the 3 connectors so I am not concerned about the connection. I would have to buy another new filter to test it this one is bad. My understanding is that if the filter portion of it was bad, I would have lower fuel pressure and be getting running issues due to that and not a fuel rich trim issue. I would be interested to know what I would expect symptom wise if the fuel regulator portion of it was not working right. My assumption would be that extra fuel would get by and that could cause a fuel rich situation?

[evolution2147]

Did you use the correct spark plugs? Also did you use the correct coil part number? I would assume it is a problem with one of those instead of a fuel issue. I'm not sure about the s4 models but I know in my rs4 vcds will tell me the fuel pressure and it gives me an actual value compared to an expected value. I would imagine there has to me at least one pressure sensor on the s4 models. But I would assume it to be a plug/coil issue.

[mbagge01]

Plugs and coils are all genuine OEM for the car.

[httuner]

Scan it with Vag-Com to see if you are able to identify any codes; If you ain't got O2 sensor codes, your O2 sensors aren't bad. I hate to tell you but your FUEL pump is on its way out. Same thing happened to me, I replaced my fuel filter about a good year ago, before the new fuel filter, my car made no hissing/whinning noise from the fuel pump/filter area. It was quiet, but I replaced the fuel filter and all a sudden its making all sorts of hissing noises. Didn't bother me at first, I figure it was normal and just drove anyways. At idle it was a little louder but once you get going, I couldn't hear it.

Well, turns out my fuel pump failed this last winter and my car sat all winter, I was surprise that the fuel pump even lasted nearly a year before it finally gave out. The symptoms I was getting was random misfires, sometimes turning the car off and turning it back on got rid of the misfires and it ran fine. Well at the end of the day it turns out a fuel pump that is going to fail causes all sorts of symptoms. The hissing and whinning noise you hear now, are its warning signs to let you know it needs to be replaced.

Cheapest place I found the pump for was 299.99 @ europaparts.com_ I replaced mine and no more misfires, no more troubles, engine runs strong and no more noises.

Goodluck brother and yes the fuel filter does have the FPR built inside; Check your ohms(resistance) reading on your injectors, not sure what the specs should be but thats somewhere to start.

[mbagge01]

I would expect that if the fuel pump was going out, I would have low fuel pressure and a lean issue, not a fuel rich issue. I am not getting any O2 codes, just fuel rich codes multiplicative on both banks. I am thinking of trying another fuel filter to see if that does anything. The filter that the audi dealership gave me said Hengst on the side and I have been reading mixed reviews that some said this is aftermarket and others say that Kayser is the appropriate OEM filter. Does anyone know if this is true because some have said that the aftermarket filters can cause problems.

[SprintBlueWorld]

When I did my 3 prong fuel filter for my 08 I know it wasn't exactly the same, it was updated. There was a different, I believe higher, BAR value on it. Did you get the latest and greatest revision T coils? Got the car stock and never had vcds but prior to doing fuel filter and tuneup I did intake spacers and had a lot of carbon buildup.Thinking back I attribute this to a combination of the, non updated parts and possibly bad fuel from previous owner.