My check engine light has been on for a while, it kept coming on and off, on and off, then all of a sudden it just stays on, and If i step on it it starts to blink on and off. Also my ABS and BRAKE lights came on. The ABS light stays on, and the BRAKE light keeps blinking on and off. I pulled the codes, and everytime after I clear them I get the same codes back:

16684 - Random/Multiple Cylinder Misfire Detected
............P0300 - 35-00 - -
16688 - Cylinder 4: Misfire Detected
............P0304 - 35-00 - -
18014 - Rough Road/Engine Torque Signal from ABS: Electrical Malfunction
............P1606 - 35-00 - -

I've chenged the coils, spark plug cables and spark plugs. I also changed the brakes on all 4 wheels. Evertthing is the same, I still get the same codes over and over. Any suggestions as to what might be cusing this? Could that malfunction from the ABS module be causing the engine to missfire? I did a search on the forum and it seems that most people would that code got their ABS module replaced, but what about the missfire that keeps coming back. What could be causing that?

 

For starters, it is always a good idea to post more specifics on your car - year, engine, transmission, etc.

Regarding the misfire and the flashing CEL, one possibility would be a bad power output stage. They are a bit different on the different engine choices, so it's hard to say.

 

From the Bentley Manual for 18014:



Signal for rough road recognition from ABS/EDL control module, checking




Note:








The ABS/EDL control module generates the rough road signal if it recognizes wheel spin on a wheel. The Engine Control Module (ECM) switches off the misfire recognition once the rough road signal is recognized by the ECM.








The rough road signal should only be checked if the malfunction (P1606) 18014 "Rough Road Spec Engine Torque ABS-ECU/Electrical Malfunction" is stored in the DTC memory. It is possible that the malfunction "Misfiring" is also stored in DTC memory, however this is then a sequence error and should be ignored.








The wiring and the rough road signal are monitored by the ECM.

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Test conditions








Control module coding OK Page 01-103 .




Test sequence







-
Connect VAG1598/31 test box to wiring harness for engine control module. Do not connect to engine control module itself Page 24-20 .







-
Check wire from test box socket 74 to ABS Control Module according to wiring diagram for short circuit or open circuit.



Electrical Wiring Diagrams, Troubleshooting & Component Locations




If no malfunction is detected:







-
Replace ABS control module.




If, after the ABS control module has been replaced the malfunction appears again:







-
Replace Engine Control Module (ECM) Page 24-24 . [/align]

 

P0304 seems to be the only one with any value and possible a bad spark plus or coil pack/wire,

P0300 is telling you about P0304 sits only doing what its supposed to do which theoretically isn't a problem

P1606 simply means you lost traction at one time ( bit of offroading) or taking corners a little too fastso also not realy a problem

 

I'm sorry I forgot to mention. This is a 99 Audi A6 Quatro, no Traction Control. The Bently says that the missfire should be ingnored. It's funny though because the engine does feel like it's missfiring when accelerating. I just don't know wthat else to check that would possible cause missfire on cylinder 4.