# Cylinder 1 and 4 misfire, no error code for O2 sensor, but reads 0v... please help



## dentate gyrus (Jun 6, 2007)

I have 2000 Jetta with AEG engine, 132K miles. It started misfires some time ago. It mostly happens at cold starts and sometimes when idling at normal operating temperature. I replaced coil, plugs wires, CTS, plugs 30K miles ago. Cleaned MAF sensor, replaced it with one from a car with no error codes. Replaced coil pack again, so it is brand new, but misfires continue. Here is log from VAG com. It did not throw O2 sensor code, but it does not register voltage. One thing that comes in my mined is that the car bruefly oveheated recently, as I flushed coolant and apparantly there was air bubble that I eventually got rid of and temperature went back to normal. I thought that might had killed CTS, but again, no error codes and it operating temp. is constantly 88.5 centergrade . 

I also noticed my mpg worsened. I was getting 400 miles from full tank (premium gas), 20% town, 80% highway. It is down to 310 miles. 

Thank you very much for your inputs. 




Adaptation Channel 001: 
Stored value 123 
Test value 125 
Idle Speed Adjustment 
790 /min Engine Speed (actual) 
760 /min Engine Speed (specified) 
A/C-Low A/C Readiness 
Compr.OFF A/C Compressor 

Saturday,28,January,2012,22:37:40:47635 
VCDS Version: Release 11.11.1 
Data version: 20111209 



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Address 01: Engine Labels: 06A-906-018-AEG.lbl 
Control Module Part Number: 06A 906 018 JJ 
Component and/or Version: 2.0l R4/2V MOTR HS V01 
Software Coding: 00031 
Work Shop Code: WSC 06442 
VCID: 73EB210F41AE08C 
6 Faults Found: 

16684 - Random/Multiple Cylinder Misfire Detected 
P0300 - 35-10 - - Intermittent 
16685 - Cylinder 1 
P0301 - 35-10 - Misfire Detected - Intermittent 
16688 - Cylinder 4 
P0304 - 35-10 - Misfire Detected - Intermittent 
16684 - Random/Multiple Cylinder Misfire Detected 
P0300 - 35-10 - - Intermittent 
16685 - Cylinder 1 
P0301 - 35-10 - Misfire Detected - Intermittent 
16688 - Cylinder 4 
P0304 - 35-10 - Misfire Detected - Intermittent 

Readiness: 0010 0001 
Saturday,28,January,2012,22:44:12:47635 
VCDS Version: Release 11.11.1 
Data version: 20111209 

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Saturday,28,January,2012,22:45:49 
VCDS Release 11.11.1: Generic OBD2 
Mode 1:Read Data 

06:Short Term Trim - Bank 1 0.0 % 
07:Long Term Trim - Bank 1 -0.8 % 
17:Throttle position sensor 3.1 % 
16:Mass Air Flow 3.47 g/s 

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TID 01 - Rich to lean sensor threshold voltage Test:0.445 V 
TID 02 - Lean to rich sensor threshold voltage Test:0.445 V 
TID 03 - Low sensor voltage for switch time calculation N/A 
TID 04 - High sensor voltage for switch time calculation N/A 
TID 05 - Rich to lean sensor switch time N/A 
TID 06 - Lean to rich sensor switch time N/A 
TID 07 - Minimum sensor voltage for test cycle Test:0.000 V - Min:0.000 V - Max:0.395 V 
TID 08 - Maximum sensor voltage for test cycle Test:0.000 V - Min:0.590 V - Max:1.070 V 
TID 09 - Time between sensor transitions Test:0.000 s - Min:0.040 s - Max:1.200 s 
TID 10 - Sensor period N/A


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## Anony00GT (Mar 6, 2002)

What kind of coil are you using? Given that it's intermittent on 1 and 4, I'm thinking coil. Are you using a genuine OE or aftermarket Bosch coil? Has the coil grounding TSB been properly performed (I believe it applies to the vehicle in question)? Are you sure you've got the correct spark plugs installed and the wires are good? 


You've got (a presumably legit) VCDS, use it properly. No need for generic OBDII functions here, all values can be read in measuring blocks and all tests performed in basic settings. 

Also, there's a much better way to verify the MAF. Get on the road, run to the redline and have a friend watch the VCDS readout, what is the MAF reading at high RPM under heavy load (g/s)? 

Given that all codes are intermittent, clear the codes, then run the readiness script with VCDS. What codes, if any, come back?


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## dentate gyrus (Jun 6, 2007)

Thank you for the reply. The coil is no-name new coil from ebay. Probably Chinese made. The coil I had before came from GAP, soem asian made coil. I had exact same simptoms on that previous coil. What do you mean properly grounded? I thought it receovbes -12V trough 4 pin connector, I don't see saparate ground wire.


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## Anony00GT (Mar 6, 2002)

Search for the coil ground TSB. It basically involves running a new ground for the coil. 

Also, get that made-in-China coil out of there, replace it with a good one. IIRC, that TSB (or another TSB) also addresses the issue of aftermarket coils being problematic.


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## dentate gyrus (Jun 6, 2007)

I ran separate ground wire from the coil to the battery, but it did not change anything. Moreover, it developed persistent misfire in cylinder 3. I pulled the plugs this morning and replaced them with Bosch cooper plugs, the only match that was available in local Autozone. (The ones I pulled were NGK BKUR6ET plugs which I replaced 30+K miles ago, when I bought the car). The picture below shows one from cyl. 3. It was wet and full of crud or some caked substance. 











The one from cyl 4. had crud but looked dry and light grey: 










Cyl 1 and 2 looked as normal plugs should look: 











There are no more misfires (for now), which makes plugs the culprit. But it brings another question: what made cyl 3 plug wet? Could it be oil escaping past the the piston ring, or it gould be leaky guide seal for a intake or exhaust valve guide? I should probably run compression test. Do you think if there is as bad piston ring, there should be loss of compression? The engine looses about quart of oil per 1000 miles; but I was told it is usual for AEG engines built in 99-00. BTW, tha car has 133L miles on it and I fill strictly with premium grade fuel.


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## Anony00GT (Mar 6, 2002)

Check the coil and wires. Insufficient spark caused insufficient combustion, fouling the plugs like that.


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## squabeggz (Feb 20, 2009)

^^^ This...and get that aftermarket coil OUT! please


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## Anony00GT (Mar 6, 2002)

dentate gyrus said:


> There are no more misfires (for now), which makes plugs the culprit. But it brings another question: what made cyl 3 plug wet? Could it be oil escaping past the the piston ring, or it gould be leaky guide seal for a intake or exhaust valve guide? I should probably run compression test. Do you think if there is as bad piston ring, there should be loss of compression? The engine looses about quart of oil per 1000 miles; but I was told it is usual for AEG engines built in 99-00. BTW, tha car has 133L miles on it and I fill strictly with premium grade fuel.


 Missed this part at the bottom on my last reply. The wetness is fuel and the black is carbon buildup. The plugs were the cause of the misfire, however the fouled plugs are but a symptom of the root problem. Replacing the plugs is only a temporary band-aid. Get that cheap coil out of there and install a good one, and make sure you've got good quality ignition wires as well. You should be OK with the Bosch plugs, as long as they've got the same 3-electrode tip as the original NGK's...I don't know part numbers offhand. 

I doubt you've got a piston ring problem. 1qt/1000mi on any engine at 130k miles is acceptable, even normal. I don't see a problem there.


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## dentate gyrus (Jun 6, 2007)

I am going to orderthese parts; I have replaced bunch of stuff with Meyle brand parts in past and I am happy with quality of Meyle. Wonder if anyone has installed Meyle coil 

http://www.autohausaz.com/search/pr...pcfe55&[email protected]&[email protected] GL&year=2000&[email protected] Parts&[email protected] Coil

and these wires from bosch:

http://www.autohausaz.com/search/pr...pcfe55&[email protected]&[email protected] GL&year=2000&[email protected] Parts&[email protected] Plug Wire Set


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## Anony00GT (Mar 6, 2002)

Links don't work.

Meyle coils that I've seen lately are made-in-China junk. Get a Bosch, Beru, or OE coil. Bosch wires are good.


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