# Changed coil but still Misfiring on P0302 P0303



## MontoyaF1 (Apr 6, 2004)

*Solved! See last entry*
I've searched and read other threads and still I'm stumped. I have a MkIV GTI 2.0 (AEG) with NGK plugs and Neuspeed wires. I changed the plugs and wires about 25K ago.
*02/25* My car wouldn't start, then an hour later it did but had the following error codes: P0300, P0301, P0302, P0303, P0304, and P0322. The light went out on its own, but I changed the Engine Speed sensor anyway.
*02/29* I'm still getting P0301, P0302, P0303, P0304 and the car feels like it is missing. The Check Engine light would only seem to blink when I reached speeds higher than around 60, but usually at slower speeds it just stays lit continuously.
*04/07* Replaced the coil pack, then took the car out for a spin and the CEL started blinking when I accelerated quickly about a block from my house. I then had Autozone confirm the same four codes above, then had them clear the codes.
*04/08* The light came back on, but this time only cylinders #2 and #3 appeared, plus the random misfire (P0300).
I only have two problems to confess that might not have anything to do with my problem: 
1) While changing the coil I broke the stupid ribbed plastic hose coming out of the air injection pump, so I wrapped it with electrical tape. 
2) While installing the new ESS, I cracked the plastic connector in half while trying to get the harness to seat in the metal bracket. I just pushed it back together and the two parts seem to be in full contact.









_Modified by MontoyaF1 at 12:57 PM 4-14-2008_


_Modified by MontoyaF1 at 4:34 PM 9-7-2008_


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## MontoyaF1 (Apr 6, 2004)

*Re: Changed coil but still Misfiring on P0302 P0303 (MontoyaF1)*

Okay, I got codes for misfires on all four cylinders, so I've been driving it like a grandma and keeping it below 60 mph, so the CEL will not flash (therefore the light eventually went out on its own).
*04/10* I checked the plugs for cyl #1 and 4 and they still look rather good for 25K (but I don't know how to check the gap when they are the crossfire style plugs with four prongs).

Anybody have any ideas?


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## MontoyaF1 (Apr 6, 2004)

*Re: Changed coil but still Misfiring on P0302 P0303 (MontoyaF1)*

Bump.


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## gtdubber (Dec 3, 2004)

*Re: Changed coil but still Misfiring on P0302 P0303 (MontoyaF1)*

I've had nothing but problems with NGK (and Champion) plugs in my V-Dubs (Champion in almost everything), but it could just be me. 
When I had a similar problem, I had the wires in wrong order.







Make sure that they are full connected and in the correct firing order.


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## ps2375 (Aug 13, 2003)

*Re: Changed coil but still Misfiring on P0302 P0303 (MontoyaF1)*

get some diff plugs, a good single prong plug with have a good spark that can only jump to ONE electrode and not poss get divided between 4. Then you can mist your wires with some salty water, the salt helps the water conduct, and see if those are bad. While you're at it, mist the coil pak, it could be that too. Was the ciol new when you changed it?


_Modified by ps2375 at 4:59 PM 4-15-2008_


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## MontoyaF1 (Apr 6, 2004)

*Re: Changed coil but still Misfiring on P0302 P0303 (ps2375)*


_Quote, originally posted by *ps2375* »_get some diff plugs, a good single prong plug with have a good spark that can only jump to ONE electrode and not poss get divided between 4. Then you can mist your wires with some salty water, the salt helps the water conduct, and see if those are bad. While you're at it, mist the coil pak, it could be that too. Was the ciol new when you changed it?

Yes, it is a brand new coil pack that I just put in, and the car behaves exactly as it did before I installed it. I understand what you are saying about the 4-prong plug, but why would they work perfectly for two years, and then all at the same time begin misfiring on all four cylinders?


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## ps2375 (Aug 13, 2003)

*Re: Changed coil but still Misfiring on P0302 P0303 (MontoyaF1)*

then it's prolly not the plugs. But they are cheap to change to check. And it is real easy to mess up a wire(s) when you change plugs, so a spare set is good to have around.
Do you have access to Vag-Com, that is a much better way to check codes. Those generic OBDII scanners don't always tell the whole story.
Have you changed the fuel filter recently? This was posted recently. http://forums.vwvortex.com/zerothread?id=3791338 


_Modified by ps2375 at 5:33 PM 4-16-2008_


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## MontoyaF1 (Apr 6, 2004)

*Re: Changed coil but still Misfiring on P0302 P0303 (ps2375)*


_Quote, originally posted by *ps2375* »_Do you have access to Vag-Com, that is a much better way to check codes. Those generic OBDII scanners don't always tell the whole story. Have you changed the fuel filter recently? This was posted recently. 

Yeah, I've been using my friend's VAGCOM for the most recent code-checking. I will pick up a new fuel filter tonight. Thanks!


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## MontoyaF1 (Apr 6, 2004)

*Re: Changed coil but still Misfiring on P0302 P0303 (ps2375)*

Okay, I changed the fuel filter, but I'm still getting misfires


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## epjetta (Sep 19, 2006)

*Re: Changed coil but still Misfiring on P0302 P0303 (MontoyaF1)*

if the wires are 25k old i would say its time for a new set. sounds like bad wires to me.


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## MontoyaF1 (Apr 6, 2004)

*Re: Changed coil but still Misfiring on P0302 P0303 (epjetta)*


_Quote, originally posted by *epjetta* »_if the wires are 25k old i would say its time for a new set. sounds like bad wires to me.
 
Really? I appreciate all advice I can get, but I've never hear of wires going bad this soon, especially all four at the same time.
*Update:*
Still misfiring. I calculated my gas mileage over the past couple weeks and I'm getting about 29 mpg (mostly city driving, but I've been driving like a grandma).


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## Geesixty (Feb 8, 2000)

*Re: Changed coil but still Misfiring on P0302 P0303 (MontoyaF1)*


_Quote, originally posted by *MontoyaF1* »_ 
Really? I appreciate all advice I can get, but I've never hear of wires going bad this soon, especially all four at the same time.
*Update:*
Still misfiring. I calculated my gas mileage over the past couple weeks and I'm getting about 29 mpg (mostly city driving, but I've been driving like a grandma).

I had the same problem with my 99.5 2.0 AEG as well, although mine was ultimately the coil. Only thing(s) I can recommend would be to check the main fuel injection wiring harness for corrosion, and maybe replace the fuel pump relay ($10 bucks). Those are the only two things I can think would cause random misfires on all four cylinders.
I ended up replacing / repairing quite a few things on mine (plugs, wires, coil, vacuum lines, fuel pump relay, cam position sensor, cleaned MAF, Seafoam treatment).


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## VinnieGI1.8T2002 (Jan 1, 2002)

*Re: Changed coil but still Misfiring on P0302 P0303 (Geesixty)*

at night start you car and let it idle get a spray bottle filled with water and spary your wires and coil if you dont se lightening bolts the try swapping fuel injectors to see if the misfire travels then


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## macanic21 (Feb 20, 2007)

Did you replace the wires with VW ones from a dealer? If you didn't, DO IT!! I had this same problem with a 97. I put NAPA wires on it, it ran as bad if not worse, random/specific cyl. misfires. Everything was replaced except for the coil. We got wires from the dealership, put them on, ran like new again.


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## lmentop (Apr 10, 2005)

check the ground to the coil pack. there was a TSB about that wire being corroded. use a multimeter and check the resistance on the wire, it should be max 1.5 ohms over that and you could have corrosion problems.
check the wires between the connector for the coil pack and the ecu too. i was having a random misfire caused by that.


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## lmentop (Apr 10, 2005)

you can check your spark plug wires with a multimeter, specification is 4000 to 8000 ohms
you can check ignition from the ecu by doing the following:
pull the fuse for the fuel pump and check the voltage on the ignition coil connector between pin 2 and 4 while cranking the engine (4 is the one on the rounded side of the connector) it should be at least 11.5 volts. check it with a test light then to make sure it flickers. check pins 3 and 4 with a test light to see if it flickers.
you can check the resistance on each side of the coil pack, 1&4 and 2&3, should be 4000 to 6000 ohms at 68 degrees F.


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## VinnieGI1.8T2002 (Jan 1, 2002)

*Re: (lmentop)*


_Quote, originally posted by *lmentop* »_check the ground to the coil pack. there was a TSB about that wire being corroded. use a multimeter and check the resistance on the wire, it should be max 1.5 ohms over that and you could have corrosion problems.
check the wires between the connector for the coil pack and the ecu too. i was having a random misfire caused by that.


yeah good piont i forgot about that TSB


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## 02jetta2.slow (May 5, 2008)

*Re: Changed coil but still Misfiring on P0302 P0303 (MontoyaF1)*

maybe you have the same problem as me...check to make sure the injectors are all touching that air rail thingy...one of my injectors snapped off that rail and wasn't getting air. seems to run fine now, but may need to replace the injector since it's detached from the rail. not sure if they actually connect, or just hovers about the injector.


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## 02jetta2.slow (May 5, 2008)

*Re: Changed coil but still Misfiring on P0302 P0303 (MontoyaF1)*

also, the small vacuum line from the intake manifold has a hole in it, i'll need to replace that. Good Luck to ya


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## MontoyaF1 (Apr 6, 2004)

*Re: (lmentop)*


_Quote, originally posted by *lmentop* »_check the ground to the coil pack. there was a TSB about that wire being corroded. use a multimeter and check the resistance on the wire, it should be max 1.5 ohms over that and you could have corrosion problems.
check the wires between the connector for the coil pack and the ecu too. i was having a random misfire caused by that.

*Update:* Just swapped the MAF and still having problems, so I will check this wire as you suggested.


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## MontoyaF1 (Apr 6, 2004)

*Re: (MontoyaF1)*

*Update:*
My mechanic said that the coolant sensor was bad and replaced it, but that didn't take care of the misfire.
My mechanic said the TSB on the corroded wire was not for the 2.0, but he checked it and it was fine.
I swapped the Neuspeed sparkplug wires that I had on the car for a set of brand new OEM ones--still misfires.
I had my mechanic clean the injectors and it still misfires. It is extremely intermittant. Only does it once every few days.


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## tdmtown (Jul 15, 2008)

*Re: (MontoyaF1)*

I'm having the EXACT same problems.
I replaced the wires, plugs, used coil pack, fuel filter.
Still having issues.
Relented and took it to a mechanic
He said there was a million codes, reset it, and told me i had to drive it until the CEL comes on again and bring it back.
Picked it up and took it for a ride, got the CEL to flash, but not stay on, and dropped it off again.
Hopefully they can pull a code.
Anybody know how to change the injectors? or could point me to a reference source?
will give updates.


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## digraph (Jul 23, 1999)

*Re: (MontoyaF1)*

Did he clean the injectors by taking them off of the car, or just running a solvent through the fuel system?
Did you replace the important vacuum hoses?


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## MontoyaF1 (Apr 6, 2004)

*Re: (digraph)*


_Quote, originally posted by *digraph* »_Did he clean the injectors by taking them off of the car, or just running a solvent through the fuel system?
Did you replace the important vacuum hoses?


He used a solvent. I decided to do an experiment by going back to the last thing I messed with before all these problems started:
I switched the Crankshaft Position Sensor back to the old one, cleared the code, ran a few errands (about 6 miles in total). When I came out of Caribou the car wouldn't start.
So the car didn't misfire, but I was forced to put the damaged CPS back in just to get the car to work. This, of course, doesn't prove it is the CPS because the problem is sporadic, so it might be coincidence that it didn't misfire using the old CPS


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## mk2.slow (Oct 17, 2003)

*Re: Changed coil but still Misfiring on P0302 P0303 (MontoyaF1)*

You haven't mentioned the cap and rotor. Use Bosch only!


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## tdmtown (Jul 15, 2008)

*Re: Changed coil but still Misfiring on P0302 P0303 (mk2.slow)*

ummmmmm..............
thanks for the thought, but these don't have a "cap and rotor"(?)
i got mine back from the shop, they changed a couple vacuum lines and it ran great for a couple of days. Then back to crap.
Brought it back in.
They say i should replace the coil pack with a new one(i had put in a used one, which kicked out the same codes....)
So now my NEW new coil pack is in and it runs great........for now.
keeping fingers crossed.


_Modified by tdmtown at 6:35 PM 7/24/2008_


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## 97VWJett (May 17, 2003)

*Re: Changed coil but still Misfiring on P0302 P0303 (tdmtown)*

Check your mechanical timing. Check your intake manifold gaskets. Since the latest round of problems are near each other could be an intake manifold leak. Check compression.
Are there any pending codes for P0422? Have you seen this code at all with P0301, P0302, P0303, or P0304?


_Modified by 97VWJett at 11:09 PM 7-24-2008_


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## tdmtown (Jul 15, 2008)

*Re: Changed coil but still Misfiring on P0302 P0303 (97VWJett)*

Thanks, and not 100% sure, but again, don't think these have mechanical timing.
(mine doesn't....AVH engine)
Sensor on the crank and an all electronic/ECU based ignition.
No distributor, no distributor cap, no rotor..........
i don't think i had any 422 codes.
At this point, i can't imagine my issue is compression, it's probably too dramatic a transition from running well to running bad to be a ring or head gasket.
So far i'm back at 100%, 2 days strong......


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## 97VWJett (May 17, 2003)

*Re: Changed coil but still Misfiring on P0302 P0303 (tdmtown)*

Sorry I didn't see at the bottom that it was running better with the new coil.


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## MontoyaF1 (Apr 6, 2004)

*Re: Changed coil but still Misfiring on P0302 P0303 (MontoyaF1)*

Problem solved. My mechanic told me that if the crankshaft position sensor that I installed (aka engine speed sensor) was not pushed in deep enough it could cause a misfire. He suggested getting a piece of wood and a hammer and tapping the thing in deeper.
There wasn't enough room to use the hammer effectively, so I took a screwdriver with a squared-off shaft and with a strong, prying motion I forced the ESS farther in, then tighted the hex bolt that holds it in. It is now a week and a half later and I don't have any more misfire codes. Thanks for everyone's help!


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## FL 2.0L (Aug 1, 2002)

Wow. I think that's a new one. Too far in and it makes contact with the flywheel, no? Let us know if it continues to run problem free.


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