# Random/Multiple Cylinder Misfire Detected - MK4



## Erotas (Aug 23, 2003)

Getting the following errors lately.
16684
Random/Multiple Cylinder Misfire Detected
16687
Cyl.3 Misfire Detected 
16688
Cyl.4 Misfire Detected
I was getting the same as above before my last service and a Cyl.1 Misfire.
Had full service, changed spark plugs, ignition cables and changed the fuel filter, which was pretty clogged up (bloody australian fuel stations). 
What else should I look at? Change ignition coil?
Car has 128 000 miles on it.
I have done a search, but no answer to my above questions.
Any help will be appreciated.


----------



## FL 2.0L (Aug 1, 2002)

Which spark plugs did they use?


----------



## Erotas (Aug 23, 2003)

*Re: (FL 2.0L)*

Bosch, cant remember which though.
Normal ones I think.


----------



## FL 2.0L (Aug 1, 2002)

Search for the right plugs. Could be the coilpack, though.


----------



## TMTuned99.5Golf (Jan 27, 2004)

*Re: (FL 2.0L)*

check the plug wires, they tend to build up resistence and it might cause such a code to be thrown. otherwise just fouled plugs. my OEM plugs lasted about 136k, so might be yours.


----------



## vasillalov (Nov 5, 2003)

*Re: (Erotas)*


_Quote, originally posted by *Erotas* »_Bosch, cant remember which though.


There inlies your problem!
Here is a list of all MK4 spark plugs that I compiled a while back:








You should be running the NGK spark plugs as you most probably have an AEG engine code. 
BOSCH is crap anyway!


----------



## 97VWJett (May 17, 2003)

*Re: (vasillalov)*

I had a random misfire from a fouled plug. It was green and smelled like gas when I pulled it out. Replaced the plug and away I went.


----------



## kcn0113 (Jul 28, 2005)

*Re: (97VWJett)*

i had a really weird instance last night where my CEL started flashing...we scanned it and cylinders 3 and 4 were misfiring...it sucked, but after a little bit, i started it again and it didn't come back on







and today it's been running fine















my friend said it could be because of the damp weather (it was kinda rainy out)
it's a MkIV 2.0 with 39xxx miles. I just changed the oil and pollen filter and there's some other things associated with the 40,000 mile maintenance that i'll be doing. Changing the spark plugs will be on that list now for sure.
Just a quick question, it sucks because we (mkiv 2.0's) have to take the upper intake manifold off to change them. Is there a special tool you should use to get the back 2 hex nuts out?


----------



## at_the_speed_of_2.l0w (Jun 18, 2006)

*Re: (kcn0113)*

You don't really have to take off the intake to change plugs...I don't. It does make it easier. Just remember to check the plug gap. Don't just assume that the gap is correct. I have used Bosch "Silvers" in the past. Not too bad. No problems running or starting. NGK is the way to go though. The Bosch plugs won't cause your missfire (probably







). The coil pack is the most likely culprit here. Usually around $100...easy to replace.


----------



## atoson (Dec 29, 2002)

*Re: (at_the_speed_of_2.l0w)*

If it say's the misfire is from either 3 & 4 cyls then it would be a coil going bad. If it's just one of any cylinders then it could be multiple reasons. Right now I'm trying to figure out what 17978 P1570 "Control Module Locked" after a 16684 P0300 "Random Multiple Cyl Misfire" and P0304 "Cyl 4 Misfire Detected". Last year I replaced the coil and this year I just did the engine speed sensor on mi wife's NB AEG which also has 128K mi. Her car is guttless and misfire is very present during Idle. Anybody have suggestions?
Update:
Well it's a tear in number 4 cyl plug boot







did the water test and spark was arching to the cyl head. Fixed it with silicon and electrical tape till I get a new set of wires.










_Modified by atoson at 10:53 PM 4-14-2007_


----------



## elRey (May 15, 2001)

*Re: (vasillalov)*


_Quote, originally posted by *vasillalov* »_
There inlies your problem!
Here is a list of all MK4 spark plugs that I compiled a while back:








You should be running the NGK spark plugs as you most probably have an AEG engine code. 
BOSCH is crap anyway!


not to thread-jack but is spark choice dependant on ECU or mechanical engine? 
I.e. what would I run in a AZG engine being controlled by a AEG ECU? (say for a engine replacement, new engine in older car)?
Thanks,
Rey 


_Modified by elRey at 1:20 PM 2-18-2008_


----------

