# mk4 2.0 misfiring cylinder 2 and 3. . .



## normlhero (Aug 6, 2008)

1999 mk4 Jetta, AeG engine code. Misfiring in cylinders 2 and 3. Just replaced spark plugs and wires. Could it be the injectors, can anyone help me out?


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## Jay-Bee (Sep 22, 2007)

AEB is a 1.8T, AEG is your 2.0 engine code...

How many miles on it? I would look at the coilpack before the injectors.

You using OEM plugs and wires?


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## normlhero (Aug 6, 2008)

Yes, AEG, about 120,000 miles. Would the coilpack only make it misfire on two cylinders? This happened almost overnight. The motor runs, at lower RPM's but seems to get better when revved higher. OEM plugs and wires.


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## x85golf (Jan 13, 2009)

a faulty coil pack will give you bad ignition had my 99.5 aeg go misfire on me a couple times because of it also your camshaft positioning senor will make it misfire as well hope it helps you out :thumbs up: .


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## dkfackler (Feb 8, 2010)

Scan and post codes, please. 

This could be the dreaded coil ground problem, but we can't do anything but guess without a scan.


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## normlhero (Aug 6, 2008)

I'll get some codes up today. Appreciate the help so far.


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## normlhero (Aug 6, 2008)

Alright, scanned for codes. 7 codes showed up. Random/multiple cylinder misfire, cylinder 3 misfire, cylinder 2 misfire, Ecu Fault showed up with 00001, and o2 sensor circuit bank 1 sensor 2. 

My buddy says replace the o2 sensor, my dad says injectors, my girlfriend just wants it fixed.


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## FL 2.0L (Aug 1, 2002)

Check that coilpack.


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## Jay-Bee (Sep 22, 2007)

Fix or replace the coilpack, o2 sensor is bugging out because it's seeing a super rich exhaust from fuel not being burnt.

Some people have removed them and checked for cracks and used JB weld... if you can't pinpoint anything just replace it.

I highly highly doubt it's an injector issue, you would see a code for that like short to ground or something.


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## normlhero (Aug 6, 2008)

Appreciate the input fellas, I'll be looking for a new coilpack most likely.


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## normlhero (Aug 6, 2008)

Put some fuel injector cleaner in it, runs better, and check engine light went off.


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## Jay-Bee (Sep 22, 2007)

normlhero said:


> Put some fuel injector cleaner in it, runs better, and check engine light went off.


That's only a band-aid.

Does this seem to happen more often if it's wet out?


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## normlhero (Aug 6, 2008)

I'm going to get her to replace the o2 sensor, and I'm going to take a look at the coil pack. Hopefully I can get it figured out.


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## normlhero (Aug 6, 2008)

I just don't see the coil pack being bad, then put fuel injector cleaner in it, then have the coil pack work fine for the time being. I'd see that being true for the oxygen sensor maybe, and the injectors. I'm going to keep an eye on it, change the o2 sensor as soon as possible, and hopefully that will fix the problems, but for now it's running great, and she can get back and forth to work. Again I appreciate the help guys.


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## SqueaksPwnz (Oct 20, 2008)

Didn't want to start a new thread so I figured I'd post here. I'm having the same issue but the thing is i've replaced plugs, plug wires, coil pack, vacuum lines, put a used fuel pressure regulator in and a new fuel pump and it's still sputtering really bad. I had someone read the codes and it said misfire in cylinders 2 and 3. I really honestly cannot think of anything else to change I also replaced my MAF back in april and my crank shaft position sensor and put my stock air box back on the other night


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## FL 2.0L (Aug 1, 2002)

Brand new coil pack?


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## blackandblue01 (Nov 26, 2009)

Jay-Bee said:


> That's only a band-aid.
> 
> Does this seem to happen more often if it's wet out?




mine sputters when its wet out.. after a heavy rain.. ive been wondering what it was, also my secondary air injection code was thrown.. could these go hand in hand?


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## normlhero (Aug 6, 2008)

We replaced the coil pack. No more misfiring.


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## dubmandon (Jan 30, 2011)

Hello, I know I'm posting to an old thread but it needs to be quoted that on these AEG motors there are two very important maintenance steps that need to be accomplished that almost everyone does not follow.
First and very crucial is to change your fuel filter. This is the # 2 reason people bring their dubs to me to be fixed. It;s easy to replace your self and the filter can be purchased everywhere for under 20 bucks. The Repair manual states the filter needs to be changed every 20,000. but thats for the people who follow the 91 octane fuel suggestion in the owners manual. For everyone else change it at no longer than 15 thousand. Cheap -dirty fuel clogs these filters.

Second is to change the timing belt. I would recommend that if you have little mechanical ability to take it to a shop or friend you know can do the job. It's not hard, just a bit technical and if you miss a step the timing will so off you will loose yourself in it fast.

AEG coils don't go out nearly as often as the 1.8T plug coils so I would worry about that last. 

AEG motors are practically indestructible if you keep the oil and all filters clean and use the recommended 91 octane fuel suggested.


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## 2kJetta86 (Mar 6, 2011)

*same issue*

just got the car a few days ago, went through state inspection without any issues but as soon as i washed my car today my engine light came on, code reads misfire in cylinder 2 and 3 ... i read someone asking if this issue was when it was wet out, is this something i should genuinely worry about or is it a BS code because of water somewhere it shouldnt be?


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## FL 2.0L (Aug 1, 2002)

Water where it shouldn't be, but because a part is failing. Take a look at your coilpack. Remember that 2-3 and 1-4 are paired, I believe.


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## dubmandon (Jan 30, 2011)

2kJetta86 said:


> just got the car a few days ago, went through state inspection without any issues but as soon as i washed my car today my engine light came on, code reads misfire in cylinder 2 and 3 ... i read someone asking if this issue was when it was wet out, is this something i should genuinely worry about or is it a BS code because of water somewhere it shouldnt be?


 
I'm guessing they were worried about the moisture affecting the vehicles electric system. 

All warning lights are not BS they only light up when something is wrong. Have you had the coils tested?


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## customgp (Sep 4, 2011)

*Cylinder4 Misfire*

Code= P0304
cylinder 4 misfire, got it scanned, 
car is a 2L 1999.5 jetta. anybody help me out?!


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## trekvw (Sep 5, 2011)

Check your ground connections. One you may not think of is your ECU. The ECU connects to ground via the mount, pull it out and clean/sand the contacts apply some antiseize compound and throw it all back together. Just did this to MK3 GTi and fixed it right up.

Good Luck!


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## jrock750 (Mar 26, 2006)

Dubmandon I've never heard of having to change the fuel filter that often. After i read this I went down to my manual, I have 2000 jetta AEG 2.0 and mine says that the fuel filter does not have to be serviced for the life of the vehicle. Then I checked my bentley manual and it said the same thing.


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## ace00dog (May 30, 2008)

*how is my old ride doing*

hey bud its me erik i sold you the mk2 jetta wonderin if you still had it ? could you send a pic if yes thanks man:snowcool: check out november issue of eurotuner i held my boy build that gti .


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