hi guys girls and petrol sniffers alike,

im having some major problems with my audi 2003 1.8t cabriolet

it runs ok but has 7 fault codes, but idle its dog rough

i have a huge vacume on the engine oil cap when running

when the caps on the d.v hisses (not sure why ) and when its off the hissing stops on the dv valve

i have changed the coil packs plugs etc

it drives well but idle it almost knocks me out the seat with the rattle

here are my fault codes

17705 pressure drop between turbo and throttle valve
16684 random/multi cylinder mister
16685 cyl1 misfire
16688 cyl2 misfire
16686 cyl3 misfire
16687 cyl4 misfire
16683 boost pressure regulation

any ideas please id be extremly greatfull

 

My $0.02......

i have a huge vacume on the engine oil cap when running
- PCV valve may be done. These are known for getting clogged up due to crank case pressure. Also connected to a Suction Jet Pump which can cause issues as well.

when the caps on the d.v hisses (not sure why ) and when its off the hissing stops on the dv valve
-Buy a new Diverter Valve, it should not make any noise you'd be able to notice over the engines. I have a 2.7T with 2 DV's and they are silent until broken (unless changing gears @ high RPM's but that's a beautiful sound). Also check the vacuum lines attached and the various connections from that point.


it drives well but idle it almost knocks me out the seat with the rattle
- If you replaced spark plugs & coil packs, try seafoaming into the brake assist vacuum line into the PCV valve. Another culprit is the ICM sensors. Give your MAF a good cleaning as well, it wont hurt.

here are my fault codes

17705 pressure drop between turbo and throttle valve
16684 random/multi cylinder mister
16685 cyl1 misfire
16688 cyl2 misfire
16686 cyl3 misfire
16687 cyl4 misfire
16683 boost pressure regulation

These all look like the "codes" I get when I remove the brake assist vacuum line to add Seafoam into the intake. This is more a vacuum leak problem than an ignition one IMO.

 

hi thanks for a quick and in depth reply, im new to fixing cars etc but just gone and checked the dv, (its full of oily gunk) found replacement on line
how ever the pcv valve has been located but can some one check this is the correct part i need before i order it please


ill give the maf a clean tomorrow in day light

also what is sea spray and what does it do ?

once again thanks for your help

 

If your DV is full of gunk you most likely have a breather hose issue. What happens is the breather hose, pcv valve & suction jet pump get clogged, and this creates a vacuum in the crank case forcing oil into your intake system. This also most likely caused oil to leak from your valve cover as well.

These are all on ECS which some call "expensive" if it is too rich for your blood use it as a reference guide.

Seafoam (Sea Foam | How to Use Our Products) is a motor treatment additive. I induce it into my brake assist vacuum line to clean the hell out of valves, combustion chambers, pcv valves, anything it touches. It can also be added to fuel tanks to clean fuel systems as well. Just don't keep it in the petrol too long, make sure you burn the whole tank you added it to ASAP.

PCV Valve, also look at the suction jet pump
OEM / Performance Parts for Audi, BMW, Mercedes Benz, Mini, Porsche & Volkswagen - ECS Tuning

Breather Hose
Audi B5 A4 Quattro 1.8T > Engine > Emissions > Hoses > ES#5942 Crankcase Breather Hose Refresh Kit - 058198298

Diverter Valves
OEM / Performance Parts for Audi, BMW, Mercedes Benz, Mini, Porsche & Volkswagen - ECS Tuning

Valve Cover Gasket
OEM / Performance Parts for Audi, BMW, Mercedes Benz, Mini, Porsche & Volkswagen - ECS Tuning

 

cheers nice one, it dont seem to expensive, (expensive is taking car to garage to check it out and cant find the fault) ill change all these at once in case i ruin any , sea foam sounds good ill give that a shot as well before i change the parts, ill give a update when these ship to the uk and i fit them, thanks for your help on this :-)

 

If your in the U.K. you should be able to find some closer seller of Audi parts that is much cheaper than it would be for us in the U.S. I'd suggest starting with the PCV, Suction Jet Pump & DV valve. If the one time use clamps are still holding the hoses to the DV I'd remove them and replace with an updated adjustable hose clamp at the time of replacing DV.

If that doesn't cure it then change out the breather hose. If that doesn't cure it then.... sh*t!

 

Vacuum leaks are pandemic on these cars -- if a part is made of rubber, it is going to fail prematurely. Swap out all 3 or 4 (depending on 1.8T version) 3mm vacuum hoses, and inspect the big F connector at the back of the cylinder head. Pull your siphon pump and replace if clogged.

 

siphon pump ? whats that ? ill order some of this 3mm hose too

thanks

 

hi peoples,

just a quick update

i ordered the pcv and the new dv, as the other parts mentioned were ok

these were 38£ inc vat from audi

the car is now running as good as new

thanks every one who helped me on this bitch of a fault

here are the part numbers in case any one else needs them

pcv 035 103 245g
dv 06a 129 101 A but its now d in the end newer model

cheers

 

Good to hear it worked out! Keep us posted if it comes back.