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Discussion Starter · #1 ·
My mate has a 1.4 AHW (i think) mk4 golf. its done 77k and had a recent service and timing belt( not a water pump though) it starts fine but when driving has a misfire. He got an auto electrician to read the codes but said nothing came up. Any one got any ideas or know if this is a common fault.

Any helps appreciated
 

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Hi, there I too have a AHW coded 1.4 and have had the same problems. I sorted it out by cleaning the throttle body with carb cleaner.

The 1.4 has a common design fault, too much oil from the crankcase breather gets in the air filter housing covering the air filter with oil( not good) and then covering the throttle with oil causing it to stick and run rough. A good blast with carb clean should sort it out. It might be worth changing the spark plugs and air filter at the same time.Sorted mine out straight away.

check you coolant temp sender, does your gauge go up and down like a loose woman, this again is a common fault

To stop the problem happening again I fitted an oil catch tank to stop oil getting into the air filter housing or you could replace the crankcase breather as sometimes this fails.

hope this helps.
 

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Hi, there I too have a AHW coded 1.4 and have had the same problems. I sorted it out by cleaning the throttle body with carb cleaner.
I also have a 1.4 AHW engine and i'm getting the same missfiring issue. I want to clean the throtle body but have no idea where it is. Could you possibly point me in the right area of the engine?

Cheers!
 

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You'll have to take off the engine cover(has 1.4 16v on it) it's secured by 4 allen key bolts. once its off it gives you access to the screws on the air filter housing theres about seven or eight of them around the housing.A normal philips screwdriver will get them off. Disconnect the oil breather pipe which will be the large hose on the left going into the air filter housing.

lift off the top, be careful as the air filter will come with it, you don't want to drop it and pull away. As you look into the air filter housing to the right to will see the throttle housing with the butterfly halfway down.( big silver round thing)

Give it a good spray all around the edges of the butterfly and where it hinges. I wouldn't recommend using any rags to clean the oil/ crap out as fibres may drop down. I used my fingers to wipe away the oil etc ( make sure you wash your hands before u stick your hands in your pockets for your keys, leaves nasty marks on trousers!!)

I pushed one edge of the butterfly down so putting it in the open position and sprayed around the edge's. You will see a tide mark of oil, a bit like the tide mark on a bath, wipe the oil away with your fingers, this is what causes the butterfly to stick making the engine stall and misfire. Be careful not to get your fingers trapped as the butterfly is spring loaded!!.

On some carb cleaner instructions it says to leave the cleaner there to disolve the oil.

Once you've done all that replace the air filter, housing and breather pipe. You may find the air filter covered in oil. I would recommend changing, if it's really bad.

Start the engine, you may have to give it some throttle as it may stall or run rough for a short while maybe ten seconds or so. Loads of blue smoke will come out of the exhaust, this will quickly disappear so don't worry about it.

To stop it happening again you could buy an oil catch tank and divert the oil breather pipe into the catch tank.

I've had no problems with mine since doing this mod.It doesn't stall anymore and no misfiring.

My fuel consumption seemed to go up. I get about 48 to 50 mpg on a long run. 10ltrs to every 100 miles.
 

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Cleaned throttle body over the weekend. Took about 2 hours and 50 cotten buds. The dirt and grime was baked onto it. Could have spent longer but got bored. Might take it off the next time and give it a good clean.

Anyway the difference is massive. The car runs way better and even sounds better. No hesitation or stuttering. Even the jerk when you take your foot off the accelorator is nearly gone too. Would recommend everyone to clean theres. Thanks to Henry for the guide.
 

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Hi, I recently put my 1.4 16v AHW in for its 70k service and my mechanic said that the air filter etc was covered in oil and that he thought feul was getting into the oil. He thought that it may be due to a piston having over heated and going out of shape as the pressure was well down on the third piston. There is also a bit of a wobble when idling. Do you think this could the problem that you've described or a mixture of the two? Im currently trying to source a new engine but if its something as simple as cleaning it a bit, it would be a huge relief.

Cheers
 

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Discussion Starter · #9 ·
If your mechanic did a pressure test on the cylinders and the 3rd was off its probably bad as could be a worn piston ring or piston itself. If thats what it is you could source the parts yourself like the rings, head bolts gaskets and tools and a haynes manual you could probably sort it out for under ?100.
 

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If this works i shall personally kiss everyones feet!!!!

I have wanted to know why my car has been doing this for ages now and the gods have answered.

[:D] Posts like this make me proud to have a uk-mkivs sticker on the car
 

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Turned out to be a ignition coil it was getting very hot to touch after a minute or so.
I'm still getting a missfire after cleaning the trottle body. Although it's still there the car is running much better. Going into garage on Monday so gonna have them check the ignition coil.
 

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oil catch tank? Where do you get one please?

Ive got a k&n on mine and ive found that it gets a bit oily so would this oil catch tank work with that?

Oh and how much are they please?

I
 

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Discussion Starter · #15 ·
The 1.4s one of the more simpler mk4 engines to work on but changing a piston ring would be meduim-hard work. A basic explanation of work envolved is the head has to come off so timing will need to be reset, then the piston has to come out and rings changed with a piston ring compressor, new gaskets and head bolts fitted then put together with oil and water and belt retentioned and set. Have a look at a haynes manual for some more detail but if you were thinking of getting a new engine this must be a cheaper alternative if thats what is wrong.

Not a fault proof test but start the engine cold and let it run for a while checkin by touch the ignition coil. It should stay cool for this period but if it gets quite hot there could be a problem with the coil. vwspares.co.uk do them for ?54 which isnt too bad if that is the problem.

The k&n your using could be the problem getting the TB oily so a filter like green might help as they have the oil removed from them.
 

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Hi,

got mine off fleabay for about ?40.00. I diverted the oil breather pipe from the air filter housing using a hose i bought from a motor factors and ran the hose past the winscreen washer bottle and down into the void behind the offside headlamp. I adapted a bracket to hold the oil catch tank. The catch tank came with its own little filter to vent vapour into the air( to prevent back pressure building up) not too sure if this is legal but i have never failed my mot for it. You could run another pipe back into the air filter housing from the oil catch tank to overcome this.

The oil catch tank will collect oil vapour( you will be surprised how much oil there is) The only strange thing is I dont have to top up my oil level work that one out.

When i spoke to my Vw parts man at Jct600 in Wakefield he says it's a common fault in the Ahw engine and what sometimes works is replacing the oil breather on the rear of the engine ( black plastic block) it gets blocked and passes too much oil vapour into the air filter. In time it will fail again and do the same thing, so I've not bothered.

Do a search on ebay or Demon tweaks.

The difference after cleaning the throttle body is amazing and if anyone has a 1.4 16v AHW I would recommend doing that first before anything else.
 

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Oh Dear :(

Right i cleaned the throttle body the other day, Did it while on the car so didn't get underneath. It has been fine for the last few days nice and smooth. But then...

Today i started the car and the revs went to 2000 and would not come back down. so i put a little oil on the throttle spring and it got a bit better but still a bit slow anyone got any ideas??
 

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Although I've not had any misfiring definitely an erratic idle , also have a coolant temp gauge that spends most of it's time stuck at bottom end (left side) and then every now and then shows in the middle , could this also be a cause of the erratic idle problem as well as the air filter / oil situation ?
 
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