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boop
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42 Posts
Discussion Starter #1
2003 Beetle 2.0L
automatic
89'000 mi.

I am having a very upsetting experience with my Beetle — it is randomly and intermittently misfiring and nobody can figure out why.

The problem started about 2 months ago; i was just driving along, maybe 35 mph, and suddenly the engine sort of surged and my CEL started blinking. Within a moment or two the engine returned to normal and the light went off, but i took it immediately to my normal shop. They said they saw a misfire on cylinder 1, but couldn't replicate the problem and had no explanation for why it occurred. So i took it back, and then it happened again. I took it to them again, same exact thing, they said there's nothing to do but keep driving it and see what happens.

After that, the same thing continued to happen, maybe once a week or so. The light always returned to normal after a minute. Because i was going out of town, i decided to be extra careful and take it to the dealer. They said the same thing as the last place — couldn't replicate, all tests passed, just keep driving it.

That went on for another week or two. Then today it got really bad. I was going about 35 again, but slowing to enter a turning lane, and right then it started happening again, but this time it continued — it was vibrating very noticeably for several moments and the light did not go off. I pulled over and let it idle for another minute or so, still vibrating, still blinking. Finally i turned it off. I waited 5 minutes, then turned it back on — no more light, no more vibration.

Because of how bad it was this time, though, i took it back to my normal place again. They said the computer shows misfire on cylinder 1 AND 3, and also multiple misfire, but once again they can't replicate the problem and all tests passed.

Nobody will tell me anything except to just keep driving it, they don't want to speculate and they don't want to do anything else until they can get it to happen as they're looking at it.

I get that problems can be hard to diagnose without seeing them (i work with computers and it's very similar), but this is making me extremely anxious about driving my car. I wouldn't mind having some more invasive/expensive tests done, if it will help solve it, but they just say there's nothing else they can do.

I don't know what to expect from here, i guess i'm just looking for someone to speculate about how screwed i probably am, to confirm/deny whether i'm risking serious damage by continuing to drive it, and to share any similar experiences.

Cheers
 

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13,860 Posts
Well, seeing how you are an IT guy; you KNOW how important it is to have the right tools for the job, right? Stop relying on others to diagnose your problems; get your own VW compatible scan tool! To diagnose things successfully, you need full control of your testing and troubleshooting process (a scan tool, is pretty much required these days to work t on these cars).... especially intermittent issues, which you can't always replicate for your repair shop to see. VW compatible scan tools: On the low end there is the Vgate vs450 for $50 on Amazon or go FULL Geek out, with the high end VW factory level, Ross Tech VCDS software/cable system! With your IT background; you will appreciate, this tool and will have tons of fun, delving into the software, hardware VW has built into these marvels of German engineering!

On the 2.0l, you have: the plugs, wires, and the coil to deals with. Any of those components could be failing intermittently.

1. Plug Wires test with a vom and inspect for physical damage: replace if they fail testing or are damaged.

2. Coil pack commonly has cracks on the back of the plastic case; many members spray it with water, as the engine is running and if that affects how it runs, it is probably grounding out. Replace.

3. Spark plugs: pull them and see what they look like, look for damage or cracked porcelain etc. replace if needed.

4. There was a tech bulletin on grounding wire for the coil, that caused issues for some cars. Required running new coil ground wire under the battery tray and that fixed the intermittent misfire problems.

5. After checking all of the above; if it doesn't reveal anything... you, might do some traditional retesting of the following things:

A. cylinder Compression
B. Fuel pump pressure

For correct testing procedures; check out these free service manuals: http://workshop-manuals.com/volkswagen/
 

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boop
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42 Posts
Discussion Starter #3
WelL,Seeing how you are an IT guy; you KNOW how important it is to have the right tools for the Job, right? Stop relying on others to diagnose your problems; get your own VW compatible scan tool.! To diagnose thing successfully, you need full control of your testing and troubleshooting process ( a scan tool, is pretty much required these days to work t on these cars).... Especially intermittent issues, which you can' always replicate for your repair shop.
I'm not a guy. There is a history of codes stored in the computer, isn't there? I assume that is where the codes they already found came from. Will getting my own scan tool to use give me different results from what they're seeing, or are you speaking generally?

1. Plug Wires test with a vom and inspect for physical damage replace if fails testing or damaged
2. Coil pack commonly has cracks on the back of the plastic case; many members spray it with water, as the engine is running and if that affects how it runs, it is probably grounding out. Replace.
3. Plugs, pull them and see what they look like, look for damage or cracked porcelain etc.
4. There was a tech bulletin on grounding for the coil, that caused issues for some cars. Required running new coil ground wire under the battery tray and that fixed intermittent misfire problems.
The plugs, plug wires, coils, and ignition wires (i assume those are the same as the coil wires?) were all replaced about 2 years ago (also due to a misfire, now that i think of it). Both shops did mention doing the water-spray test on the coils this time around and said it passed with no issues. I think they checked the plugs too but i'll have to confirm.

The other things i am definitely not able to do myself, lol
 

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Well, do you want to fix it yourself or keep taking it to a shop, that cannot or is unwilling to diagnose, troubleshoot and fix the problem? :confused:

If you can't see the codes yourself; then you don't know what is going on, right?

The parts; being replaced two years ago, doesn't mean that they haven't failed within that time...

So, we are here to help you but you need to decide, how you want to proceed with your problem, without a scan tool.... you are essentially flying blind. Help us; to help, you! :) Get a VW scanner; scan it and post up the codes, that you find... we will go from there.

We can help walk you through troubleshooting processes and procedures, but you need to get some tools... like the scanner and be willing to get your hands dirty! :D

What say you and do you want to fix your car or take it back to a shop? :confused:

As you are experiencing; many times, you have to fix things yourself... to fix it right, especially with intermittent issues. As the old saying goes: "if you want something done right; do it yourself!"... are you ready? Let's fix this thing! :)
 

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My '03 vert has the 2.0 engine. I was having the same problem. I replaced the temp sensor, plugs and wires and used dielectric on both ends of the plug wires and still had the same problems. I changed the fuel filter and drained the old filter and it was half full of water. It appears that every time I went around a curve some water came out of the filter and caused the motor to act up as it went through the injectors. It's been 12 months and no more problems. I also run some Chevron Techron injector and premium fuel every third tank.
 

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Certified Arcade Tech
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416 Posts
Hi.

Right now you have general information about the misfire. The auto parts scan tools only report back with generic OBD2 systems error codes.

If you have a laptop, you can get a cable and software to connect it to the car's computer and see more of the information that each computer in the car has. (Yep, more then one control module in these cars...in fact SEVERAL!)

Here's how we figured out our #3 misfire. Pulled the plastic engine cover. That way we can see all the nifty parts.

Use a spray bottle with both a stream and a mist function. If you have the car parked in a garage with some good air flow it helps. You really want to try this when it's "darkish" to see the next part.

With the engine idling give the front of the engine where the spark plugs are a good misting down. The idea is to kinda reproduce the morning 'dew' that coats the parts.

Have a helper do the following CAREFULLY!!! Put the car into gear and set the brake, and have the helper mash the foot on the brake. This can be dangerous to do. With the engine under a slight load--you're listening and looking for electrical arcs. You will know when you see the arc--looks like a mini lightning bolt. And the arc has a "SNAP/CRACK" sound when it does it.

The trick is not to drown the engine. Just to give it a nice moist coating and get it under slight load. If it starts to flash the code, and you can catch this in the act? You'll know what part needs to be replaced.

You'll also need the spray function for the coil pack. It's under the small air pump on top of the engine. The spray lets you get the coil pack damp without pulling the air pump off.

I suspect you may have a crack in the coil pack, or one of the spark "towers"

If this does not yield results, then we can move along to other possible issues with the fuel system and other such things that can cause the misfire.

Let us know how you make out, and be careful when doing the above test(s)

S-
 

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My '03 vert has the 2.0 engine. I was having the same problem. I replaced the temp sensor, plugs and wires and used dielectric on both ends of the plug wires and still had the same problems. I changed the fuel filter and drained the old filter and it was half full of water. It appears that every time I went around a curve some water came out of the filter and caused the motor to act up as it went through the injectors. It's been 12 months and no more problems. I also run some Chevron Techron injector and premium fuel every third tank.
"Premium" fuel won't help in this case, so you're just wasting money you could be spending on a product which will actually address the problem.

What will help is a bottle of gas line dryer (usually some sort of alcohol) for a few bucks a bottle. One popular brand is "Sta-Bil Iso-Heet Fuel System Anit-Freeze". This is especially helpful in colder climates where any water in the fuel system will freeze, causing a no start until warmer weather condition, which is a huge inconvenience if spring is months away. Put that in every third tank along with the minimum octane fuel VW recommends for your engine and you won't have any water accumulating in your fuel system.

The bigger question in my mind is why is water getting in there in the first place. Most gasoline where I live contains a small percentage of ethanol, which will do the very same thing as gas line dryer. I'm going to guess the gas where you are either doesn't contain ethanol, or the station you're using has a lot of water in the gas (so much that the usual ethanol can't absorb it all). You might consider a different gas station.
 

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"Premium" fuel won't help in this case, so you're just wasting money you could be spending on a product which will actually address the problem.

What will help is a bottle of gas line dryer (usually some sort of alcohol) for a few bucks a bottle. One popular brand is "Sta-Bil Iso-Heet Fuel System Anit-Freeze". This is especially helpful in colder climates where any water in the fuel system will freeze, causing a no start until warmer weather condition, which is a huge inconvenience if spring is months away. Put that in every third tank along with the minimum octane fuel VW recommends for your engine and you won't have any water accumulating in your fuel system.

The bigger question in my mind is why is water getting in there in the first place. Most gasoline where I live contains a small percentage of ethanol, which will do the very same thing as gas line dryer. I'm going to guess the gas where you are either doesn't contain ethanol, or the station you're using has a lot of water in the gas (so much that the usual ethanol can't absorb it all). You might consider a different gas station.
The car was a garage queen with only 49k on the clock for a 10 year old car. Not too sure of it's history but it now has a good home. The filter was half full of water and driving it hard some water would get into the injectors. The premium gas in our area (BP white gas) has no ethanol in it. Seems that is some of the problem with cars that weren't driven much.
 

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True. If a car isn't driven much, water in the gas can separate if the gas has no ethanol in it. This is definitely a bad thing. Gasoline can do nasty things if kept in a stored car for too long. Products like "Sta-bil" are designed for just this sort of situation. Among other things, it will remove water to prevent corrosion, which is a very bad thing to have in your fuel system.
 

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boop
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42 Posts
Discussion Starter #11
Sorry for not replying to this sooner, i didn't get any update notifications for some reason.

Right now you have general information about the misfire. The auto parts scan tools only report back with generic OBD2 systems error codes.

If you have a laptop, you can get a cable and software to connect it to the car's computer and see more of the information that each computer in the car has. (Yep, more then one control module in these cars...in fact SEVERAL!)
I don't know if my normal shop has a Volkswagen-specific scan tool, but i'm sure the dealer does, and it didn't seem to help them much. I assume the 50$ tool mentioned above doesn't handle the VW codes, just the generic ones?

I looked into the PC tools but they are all extraordinarily expensive, Windows-only, or (usually) both.

With the engine idling give the front of the engine where the spark plugs are a good misting down.
What does this test, exactly? The spark plugs themselves?

You'll also need the spray function for the coil pack. It's under the small air pump on top of the engine. The spray lets you get the coil pack damp without pulling the air pump off.
Both of the places i've had look at it have done the spray test on the coil packs, neither of them found any trouble.

Since my last post i started having problems with the battery draining. In addition to replacing the battery they found that the fuel-pump relay was malfunctioning, and replaced that. I was hoping that maybe that was related to the misfires, but apparently not; happened again today.

I had also been having a drainage problem (apparently clogged moon-roof drain hoses, now fixed) which was leaking water into the driver's-side foot well. Misfires started within a month or two of noticing that, i suppose it could be that water got into the electrical bits somewhere.

I really like my car, but Jesus Christ it's a lot of trouble.
 
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