Cylinder 2 & 3 Misfire Detected (P0302 & P0303)

elmicko

Cylinder 2 & 3 Misfire Detected (P0302 & P0303)

Lads, hoping someone may be able to tell me that I'm not in for a huge bill but give it to me straight! Any advice is appreciated as I'm a complete noob and have to make a call on whether to keep the car or not.

Quick context:
I left my car in for a valet and everything was fine. When I left the valet place it felt like I had no power; almost like if you try to start in third or even fifth gear. The car was very sluggish and shuddering at low speed but wasn't too bad at medium speed (50Km/h+). I don't suspect the valet guys did, or could even do, anything that may have caused this (open to correction on this).

I have a bluetooth OBDII adapter and hooked it up and got the codes below. I watched a few videos on youtube and did a bit of research (I need to respect those of you that may give reading time to this). I am hoping that it could be something as simple as spark plugs but I think that the fact that multiple cylinders are misfiring may mean something more serious and this is essentially what I'm seeking advice on, i.e. does the sudden misfiring of both cylinders 2 & 3 signify anything?

Potentially key piece of information:
There is a 'burning' smell - (not what I'd call a rotten eggs smell, which I believe may indicate a catalytic converter)

Make/Model:
2002 VOLKSWAGEN PASSAT (3B3) 1.6 Petrol (1595cc 102hp)
I've had it 5 years and it has been for the most part absolutely perfect.
http://engine-codes.com/p0303.html
P0302 - Cylinder 2 Misfire Detected
P0303 - Cylinder 3 Misfire Detected
- Faulty spark plug 3
- Clogged or faulty fuel injector 3
- Faulty ignition coil 3
- Fuel injector 3 harness is open or shorted
- Fuel injector 3 circuit poor electrical connection
- Ignition coil 3 harness is open or shorted
- Ignition coil 3 circuit poor electrical connection
- Insufficient cylinder 3 compression
- Incorrect fuel pressure
- Intake air leak

My intention is to bring it to a garage but that will have to be Monday. I would like to bring it to my usual garage, which is somewhat inconveniently located a good distance away, but I fear driving unnecessarily on it may cause serious damage.

Again, any advice greatly appreciated. Happy to provide any more information.

jimgoose

Valeted, eh? Wasn't there a recall in America at least on those 3B3s about coilpacks? They seem to be somewhat intolerant of water. That's not a big deal to sort, but driving it with a bad misfire can damage the cat.

my3cents

I bet the plugs have never been changed, take at least number 3 plug and one other out and take a look. Most plugs will work even if not in great condition so the one that is missing and giving that fault will probably be very obvious if its just a plug problem.

pablo128

Coil most likely. Put a new set of plugs in while you're at it. Coils are cheap enough for those.

PADRAIC.M

Did they wash the engine bay? If so there is probably water on plugs/coil pack area.

elmicko

Thanks all for the response.

From my limited searching (and knowledge) I was thinking it may be the ignition coil but didn't (and still don't) want to be that guy going to a garage telling them I know what's best, just enough to not get ripped off. I checked out Micksgarage and coils only seem to cost ~50 quid. Is it a big job to get this done, say if I was getting a full service?

About the valet, and this part is curious, I didn't think they could have even done anything to have an effect on the engine. The car was running perfect going in. I'm not looking for a fall guy but as @jimgoose & @padraic.m have alluded to, water on the ignition coil/plugs area could have caused the problem; if so, is it possible to resolve the problem without replacing the coil or would they be spent?

my3cents

I've had a similar set of codes and found it was just the plugs. You couldn't miss the fact that the ones that were missfiring were totally warn out. No spark means a load of other things aren't going to return a good signal to the control unit so you will see more than just the bad plug error msg.

If you haven't changed the plugs in 5 years then they probably all need replacing anyway, if the problem persists then move on to the coilpacks.

No garage should get upset and try ripping you off if you change your own plugs.

The problem with water mixed in with high voltage is that once the electricity has found a route to earth (the metal of the engine) through the water it can keep following the same path even once the water has dried out. The same process can break down insulation so it no longer works. Probably best replacing the coil packs if they are damaged but start with the plugs.

wandererz

Had a similar problem on a BMW previously.

Firstly, check that the connectors are seated properly.

Secondly, Why don't you try replacing the spark plugs yourself?
It's the quickest and cheapest way to check yourself (without experience).

You will just need two spark plugs and a spark plug socket + socket wrench. Cylinders 2&3 should be the two middle ones in a 4 cylinder vehicle.

It could also be the coils that are gone. This would be more costly than the spark plugs but shouldn't be a crazy amount.

Check prices on micksgarage.ie or mister-auto.

But i would start with spark plugs first. Order all 4 or however many is required for your vehicle. Your local motor factors should be able to supply this.

If that doesn't resolve it then order the 2 coils.

St. Leibowitz

I had a 2002 Skoda Octavia petrol. A coil failed, and was replaced. Shortly afterwards, a second coil failed, so the remaining three were replaced. No issues afterwards. Symptoms were very similar to what you describe.

At the time, a web search indicated that there was a bad batch of coils in VAG 2002 models.

Waterson

It would be an idea to check the security of the HT leads for cylinders 2 and 3 first. Unlikely that water has ingressed into the spark plug wells, more likely that the coil pack is at fault. It is a waste spark design system on these engines, cylinders 2 and 3 share an ignition coil. Perhaps some water/steam ingressed it during the valet. A simple cylinder drop test will confirm this to be the case very quickly and a replacement coil can be sourced cheaply enough.

elmicko

Quick update:

Dropped car to garage near work on Monday lunchtime and I still don't have it back as they are very busy; frustrating but hey. I had to hound them and finally got speaking to 'the boss' who assures me it will be sorted by Wednesday evening.

They are telling me that I shouldn't replace the plugs as they are what I believe were described as long life or platinum plugs - frankly I have no idea and would really appreciate confirmation that this is correct.

Next they are telling me that because of the make/model it's tricky to replace the coils as they sit under a manifold and that on my make/model you can't replace individual coils, you need to do the whole bank of them. Also all the leads will also need replacing.

I tend to believe the guys and have given them the benefit of the doubt, however I probably wouldn't be posting this if there wasn't an element of doubt! So, it would be great to get confirmation.

jimgoose

Yes, that sounds about right. Long-life platinum or iridium plugs are fairly common these days, replacing HT leads is a good idea, they're cheap, and componentry being buried under a load of gubbins is getting frustratingly common too.

thomas anderson.

All that sounds about right

Waterson

It sounds like they may be throwing parts at the problem. If they replace both coils, all HT leads and clean up the irridium plugs, (at your expense) thats pretty much the whole secondary side of the igniton system replaced so they are bound to fix the problem, rather than focussing in on the actual component at fault. Sorry but that approach, in these financially constrained times, irritates me.

elmicko

Cheers for the reply Waterson. If you don't know much about cars (I don't), you have to take a leap of faith with a garage. I would have liked to have gone to my usual garage but it's no longer convenient in terms of location due to where I live. I could have gone to a big name garage but it wasn't feasible financially.

As an update, I got the car back and they have resolved the issue, i.e. the cylinders are no longer misfiring. I haven't got the sheet in front of me but essentially they did what they said they would, i.e. cleaned the plugs and replaced the coil pack and plugs. It cost me €225 all up. Part of me doesn't want to know how much I should have been charged.

I asked if the valet could have caused the problem and the guys in the garage said it was most likely not the cause as there was no sign of water.

Thanks again to all that replied.

biko

Not a DIY effort, moved out from DIY forum.