boggy idle...

[3THREE7]

So I've been having a boggy idle lately, as well as below average gas mileage, and after talking with a few people, I thought it would have been fixed w/ a simple change of the spark plugs. But unfortunately after doing so, my idle hasnt improved any, and neither has my gas mileage. I'm thinking it may be a vacuum leak, any way of checking this, and maybe a way to find where the leak is at? Also any other ideas as what the culprit may be? TIA

[3THREE7]

bump for some help

[Agent Orange]

i would start with all the visible vacuum lines coming off the intake manifold and fuel pressure regulator on the right side of the manifold. your best bet is to just check them all manually. if they look frayed, just replace them. i'd also check all your rubber turbo hoses for boost leaks just in case...

[Damon]

Might be your MAF peacing out.

[Brk4Euros]

Might be your MAF peacing out.

I would agree. Maybe just try cleaning it first with some 91% alcohol. Worked for me! :tup2:

[joe18tbo112]

quick check... works most of the time. let the car run at idle when it is running badly/rough/boggy. now unplug the maf and see if it gets better. if it does, replace the maf.

[3THREE7]

yeah i thought it might have been the maf, but it was replaced not too long ago. ill try to run it unplugged and maybe clean it and see how that goes. thanks for the responses

[3THREE7]

Ok, need some help again on this. Decided to replace the maf again(now on my 4th one). Replaced it w/ a bosch unit from ecs. The idle is noticeably smoother, but now it just slowly drops down then hesitates and goes back up. no more rough idle though. any other ideas as to what's going on? oh and my mpg has dropped about 1-2 miles per gallon ever since this problem arose.

+ rep points for some quick answers. need to get down to this before i drive down to socal next week.

[3THREE7]

bump

[idrivea2002golf]

replace the spark plugs for sure. and i would pull the injectors and let them soak in some rubbing alcohol, they may be plugged a little. beyond that i would look for loose vaccum lines and i would run a tank of HIGH octane fuel (in the 100s) and see if that cleans it out.

[Veedublin]

any codes? run a vag-com for any stored codes, vacuum leaks possibly, maf could be faulty.

[oc-audica]

maybe o2 sensors?

[MikekiM]

Sounds like a vacuum leak. Inspect your vac lines carefully. Squeeze them to reveal any hard brittle or cracked areas.

[joe18tbo112]

have you pulled the engine cover off? any codes? some common things are the pcv breather hose that connects to the side of the valve cover... that gets oil soaked and cracks. also there is another hose that comes off the bottom of the intake manifold that is hard to see but can collapse and cause that kind of problem. you can't really tell unless you touch it. where are you located?

[3THREE7]

ok maf was replaced a week ago since i thought that was the cause. and so were the spark plugs. smoother idle(not as rough as before) but the idle still slowly drops to just under 600 and "blips".

no access to a vag-com, but i went to autozone and the obd scanner says there aren't any codes. are there any codes a vag-com would read but a scanner wouldnt?

also kept searching around the tex and noticed people who had similar problems said they needed to get the coil pack wiring harness replaced due to brittle wires. so i inspected mine and everything seemed fine. i checked most of the vacuum lines that were visible and seemed ok. ill try to look for the one underneath the intak mani.

[GtIrOb01]

ok maf was replaced a week ago since i thought that was the cause. and so were the spark plugs. smoother idle(not as rough as before) but the idle still slowly drops to just under 600 and "blips".

no access to a vag-com, but i went to autozone and the obd scanner says there aren't any codes. are there any codes a vag-com would read but a scanner wouldnt?

also kept searching around the tex and noticed people who had similar problems said they needed to get the coil pack wiring harness replaced due to brittle wires. so i inspected mine and everything seemed fine. i checked most of the vacuum lines that were visible and seemed ok. ill try to look for the one underneath the intak mani.

I had a similar issue. Looked at all my boost/vac lines and found several problems. Once I repaired those... all problems went away. Sounds to me like you have a boost/vac leak somewhere. Be sure to also check the hoses to the DV.

[joe18tbo112]

if it's a vw specific code then a regular obd scanner wont pick it up... also if it's a pending code it might not pick it up.

[DTolo]

Do you have a K&N filter? Been re-charged lately? I've heard of similar problems coming from people over oiling thier K&Ns and further screwing up their MAF. Just an idea.

[idrivea2002golf]

maybe o2 sensors?

that's a good idea too. although they are expensive. i know that i replaced one of these on my buddies jeep and the rough idle disappeared.

[3THREE7]

reading up on the tex some more. could clogged pcv valve be the problem? noticed i'm getting a little oil sludge coming from the oil cap

[idrivea2002golf]

it's possible but i don't think it's that likely. your computer is having an issue with something. it sounds like there might be a connector off or a bad signal getting to the ECU. i don't know if you have any mods on the car but if you have changed anything (other than the MAF) that required changing the harness or the compressor piping then that is what is causing the issue.

try this just to humor me, it might work. put you key in the ignition and twist to right before is starts and leave it there. pop the hood get out and disconnect the negative terminal from the batter (10MM wrench) and let the car sit for about 15 minutes. reconnect the battery and go drive the car like you normally would and see if that helps. if it does it was your computer having an issue with a signal it got.

[3THREE7]

already reset the ecu when maf was replaced =/

[idrivea2002golf]

where are you located?? if you're close to mission viejo i can meet you somewhere and look at it.

[3THREE7]

norcal ;)







anyways, not having too much time to take care of things on my own i took it to tomas sport tuning up here(lots of recommendations came from the local vw groups here, and i can see why, great service). they took a look at the car and couldnt find any vacuum leaks, or even anything mechanical on that matter. they said its most likely a bad plug that connects to the maf. low readings even when the maf is completely brand new. and to cut to the chase, i remembered i used to have the split second boost controller when i first had the car, which splices into certain wires. maf included. i'll have to take a look at the old splicing since i took out the electronic boost controller when I got revo'd. I'm pretty sure that's the culprit now, and I'm hoping so since it won't really cost anything to fix :)