View Full Version : possioble bad fuel filter?

04-08-2013, 01:05 PM
Hey guys, aeb 99.5 1.8t.

Occassionally when driving for about 15-20minutes then idling (like at a long red light or to get food at a drive-thru) my car will begin to start shaking pretty hard and when I give the car gas it will sort of hestitate and not really move at what the indicated rpm's read, i'll also notice that when my car is fine on idle it reads at about 900 rpm and sits there, when its having issues (again after I've drove then idled for a few) it begins to bounce all over the place in the rpm's usually dipping to 800ish then back to 1000. This also happens if I'm just driving doing some errands.. like going to one store, in, out then another etc. I've found that if I'm idling if I just peridocially rev my engine to around 4k rpms it does not happen if I feel that I've been idling for awhile.

I asked a friend and he mentioned trying some fuel injection cleaner but I wanted to ask first. I honestly don't know when the last fuel filter change was so I thought maybe it could be that.. I've had the car for... about 6 oil changes at 4000 miles each.

On another note my car also rearly ever reaches operating tempature, could this have anything to do with it? I had a new coolant temp sensor put in (the one near the coolant flange) and nothing changed, the oil gets to about below half way and the same with coolant. My mechanic told me I probably need a thermostat last time he fixed some stuff.

04-08-2013, 01:11 PM
Then replace the thermostat. If your car never reaches operating temperature then you're going to be running way too rich. Get that fixed because as long as that known problem is lingering then you will never be able to track down other potential problems that have similar symptoms.

If you plan on keeping the car then replace the fuel filter anyway. It's about $20 bucks.

Do not waste time trying to unbolt the bracket that holds the filter. Being in CT I would bet money that the bolt will not come out cleanly. Just break the plastic filter holder near the bolt and swap the filter out. I wasted a lot of time in getting the proper socket for the bolt and it ended up just spinning and needing to be broken off.

04-08-2013, 03:29 PM
Yeah, if your thermostat is bad that would definitely be one cause as to your coolant gauge not displaying what you want.

Theoretically you are supposed to change the fuel filter every 15,000 miles, or so I've heard. First time I did it on my 99 prefacelift Q it took me no more than an hour and half. And I was able to do it without breaking anything. However, breaking that plastic holder would be fine I'm sure. Lot's of people do it that way. The filter is too jammed up in there for that plastic to actually do much holding.

04-09-2013, 03:18 PM
dont think just a fuel filter would be causing problems as significant as this

04-09-2013, 04:11 PM
what kind of gas milage are you getting?

04-09-2013, 08:28 PM
Gas gauge doesn't even work, I guesstimate with trip meter at 26 miles per gallon to be safe. ( i've already replaced this part once and it already broke again on me.)
Today I was in a contruction zone waiting to actually go and the car did its usual vibrations and stuff then it after about 2minutes of waiting (not driving at all just idling) it went away the rpm's didnt really change much at all either like it usually does. I drove home and it drove fine.. then I went to the gym and when I was on my way to work I noticed my CEL is on.. I would go scan it at joeshmoe autozone or napa but those code scanners don't work when you have a bad abs module..so I will need to find a vagcom, might I add today was the hottest day of the year so far in CT and the last time my car had a cel for what I believe the same problem was during the last hotter days in fall.

On to the whole thermostat thing, during the winter the coolant gauge NEVER moved up a notch (today it did, it gets about half way to the actual half way mark and stops). But during the winter I always had blazing hot heat when I turned it on after about 5minutes. I had the coolant temp sensor changed already by my mechanic.

I'm most likely buying a bunch of parts this week anyway front brakes, rotors, new dv (my car makes this sound.. http://www.youtube.com/watch?v=CNt7aO-rSoI) and mechanic said new dv is needed, fuel filter, fuel sending unit and the thermostat.. I know all these things are needed, sucks though I really can't keep up with this car. 145k miles, during the winter I replaced the coolant temp sensor, coolant flange, rear wheel bearings (awesome being in ct...), needed an alignment and my tie rod ends were frozen and those were the parts that were messed up, and a valve cover gasket. Some of this stuff I did myself but other things I couldn't.

I hear ya on fixing lingering problems, can't you already tell I have a few lol?

04-10-2013, 03:35 AM
26mpg to be safe??? wow, whats wrong with my car. i cant hit that on a good day.

04-10-2013, 06:17 AM
dont think just a fuel filter would be causing problems as significant as this

I've repaired cars that ran like absolute poop because of a bad fuel filter.

There was one case, and it was the worst one and there has been only one, where the gas tank was bad - full of rust. I replaced everything on this car, down to rebuilding the motor. Finally an old man said "Check out the gas tank." I pulled the top off and ran my finger around the edge and it was full of rust particles and sludge. Replaced it and it was like a new car.

Bad fuel tank/lines/filter can cause all kinds of problems and can be VERY hard to fix. That particular car had sat for years.

Good fuel flow is essential.

04-10-2013, 06:20 AM
26mpg to be safe??? wow, whats wrong with my car. i cant hit that on a good day.

lol u think thats good... try 36 mpg on a good day bone stock but cleanest engine in and out for sre no sludge what so ever fuel injector cleaned to the max and always v powerrr!!!! when i beat on it tho i got around 24-27mpg