GTI rough below 2k-rpm

[javalin]

Hiya all,

I've a 8v AGG GTI.  Runs really well (sounds very smooth) above 2k rpm but the idle is a little lumpy and the pull off is inconsistant - i.e. you're never sure how much RPM to put on so when you lift the clutch the car will pull off.  Most sensible things changed (plugs, wires, dizzy cap & arm, temp sensors, relays etc).  As far as I know its a standard cam.

Should add that its rough but I don't think its a mis-fire as such - well not that rough.

I know it can behave (aka run super smooth) at idle and have torque to pull off at idle - because occasionally it does work.  Only differences I can see is its sometimes better when the air is damp and dense, and if its been run, stopped and restarted then used again.

Any idea's?

James

[axewielder]

hello fellow shire dweller, i have similar lumpy idle on my ADY (pretty much identical)
one thing to do if you havnt is the coil and this is probably my next attempt to get it solved
good luck finding the fault, im just happy its not cutting out anymore so im not too desperate to get this sorted
+ have you had it on vagcom?

[javalin]

yeah have vcds (new name) no error codes.  Thanks,

James

[Christo77]

Hi..you mention air quality, at a guess what's the condition of the air filter?  and then the MAF sensor..even the old classic a dirty gunked up throttle body internal..?

Christo

[javalin]

air filter is a k&n panel filter.  Its not been cleaned since I had it - a bit oily maybe.  The Throttle body is a good plan - i'd wondered about that.  MAF is clean - i've checked it recently.

Cheers,

James

[Christo77]

If it was me i'd replace the air filter and done with it!  and if it was me i'd replace the fuel filter as well..but that's just me!
Get that throttle body internal nice and shiny clean both sides of the butterfly valve..and check the main air intake concertina tube for cracks as well as other vacuum lines..


Christo

[boneybradley]

It does sound throttle body related...as the butterfly wont be able to close meaning the engine gets air when it doesn't need/ expect it!
the other thing i recommend is cleaning all the breather hoses out 

[javalin]

Hiya

OK.  The throttle butterfly is clean.  The engine breathers are clean.  The intake hoses are ok as far as I can tell.

I'll get an new air filter for it and see. Fingers crossed for a cheap and easy fix.

If not maybe i'll whip the throttle body off and see if anything to be seen in that.

James

[javalin]

Update - put new paper air filter in it on Tuesday - seems much happier.  Time will tell I guess.  I've ordered a cleaning kit for the K&N filter too.

The fuel filter was changes last year too.

Cheers,

James