missfiring doing my f*cking head in !!!!

[Jack111]

golf agu 1.8t last couple of days its started missing a little bit for a few seconds,but today on my way to work it was missing constantly its driving me mad scanned it has no fault codes /its fine on startup and idle but when you put it under load it missfires like mad can someone help

[jamie1989]

Ignition amp by the sounds of it. Famous AGU problem.
Youl find it on the airbox mate. About £60 with discount with ECP and a little over £100 with VW by memory.

[Dalo Harkin]

could be loads of things, cam position sensor (happened to me and luckily turned out to just be the wiring damaged as opposed to the sensor) easy to check and you can get used ones of ebay for about £12 delivered, I have one kicking around if you want one from me rather than ebay (PM me)

[jamie1989]

If camshaft sensor was foobared or wiring the car would run in limp at around 4psi constant it wouldnt miss either.
Ignition amp on AGU cause the car to miss BADLY under boost. I bet its the ignition amp buddy.

[xxChrisxx]

There really isn't enough information to make a conclusion, though the ignition amp is a prime suspect. So rather than pointlessly swapping parts, some investigation should be done first.

There is other useful information, is it smoking if so what colour and under what conditions?


You need to know if your misfire is a fueling, compression or ignition problem.

1. Locate the misfiring cylinder (if it is indeed just one).
2. Check the state of the plugs and the gaps (of all cylinders).
3. Perform a compression test on all cylinders. All cylinders should be around 11-13 bar and each within 0.5bar of each other.
4. With a long screwdriver, put the pointy end on the injector and the other to your ear. Check each injector is firing (to be honest if it's an AGU you'll hear the injectors ticking away without it, it's deafening under then bonnet).

All are cheap and quick to do, should take no more than an hour in good light. Also when following problems, always trace backwards from the issue.

As the most likely suspect is the ignition control module. You are best working back form there.
If it's just 1 cylinder, and the plug is good, swap over the coil. If the misfire jumps it's a dead coil. If it stays the same, the ignition amp is the next suspect.

[Jack111]

thanks guys great help put my mates ign amp on my car all is well again legends !!

[Wazzzer]

Unfortunately the AGU doesn't throw up many fault codes

[karls3abo]

Sorry to jump in in this thread.. But I have a similar problem. I have a misfire, cannot find why! My symptoms are...

When I pump the accellarator twice fairly fast it will misfire and the revs die then kick back in again. Also when At very low revs and slightly raising it up an letting it drop, I can hear a slight tapping noise coming from I think the rear or the engine, also I get a lot of white ish smoke out the back when i accelerate.

I have checked the packs and it doesn't appear to be them. I have also changed the plugs to (Boshe) ones as they were bad, oil, filter, an changed the ignition amp. I'm thinking maybe the crank sensor? Is there any noticeable thing I can tell from, if it is this?  No codes come up, I will get it conpression tested this week and make sure it's not that also.

Also mods on the car, k n n panel filter, forge cold side 007p with yellow spring, remap,
Also it only seems to boost until 14psi does this sound right,? i thought it should hold until around 18psi, before it had a baileys splitter valve which then the car would only hold until 12psi at a push.

Doing my head in!

[Jack111]

well i thought it was sorted put a new ign amp on and it sorted it for a day now its missing again same as before.
i also put new plugs in to rule them out can only be coil packs but i thought they are tough as hell on a agu

[topher]

could be the maf sensor, difficult to diagnose when its intermittent though unless you drive around with vagcom permanently logging