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changed plugs, plug tubes, coils, have P0102, P1319, P1318, P1315, P1313 codes

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1999, 996,  117k miles


Due to leaking I recently changed my coolant reservoir tank, which involved disconnecting and re connecting 2 fuel lines..  Upon restarting the car I had a rough idle and CEL.  I purchased a $100b code reader, read a bunch of stuff online and decided to clean the MAF sensor, change the air filter, spark plugs, plug tubes and coils.    



upon today's startup I get an erratic/rough/low rpm idle, flashing CEL and the following codes:


P0102  mass air flow circuit low

P1319 misfire emission related

P1318  misfire cylinder 6 emission related

P1315 misfire cylinder 3 emission related

P1313 misfire cylinder 1 emission related


Somehow I went from a leaky tank to some bad stuff based on a do-it-myself moment.

I wonder if the coil packs might not be perfectly seated?

I'm thinking a new mass air flow sensor and all four O2 sensors need replacing??  

Please advise.


Hugo Kohl

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Please do not change anything else yet.

First does the car run (sound) normal or does it miss or backfire?

Those codes (except the MAF fault) are all misfires and can be due to a number of things especially after changing plugs.


What spark plugs did you use?

Did you properly torque all of the spark plugs? (also not over-torqued enough to crack the new spark plugs)

Double check the coil packs to see the electrical connectors are properly seated and also make sure the new coils were not overtightened and cracked.


Clear all the codes start the car and see what faults comes back.


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The car runs rough.  It feels and sounds like its not firing on all cylinders.  the rpm is low (400 rpm) and will stall if you let it.  There is a strong exhaust smell of un-burned gas.


codes are:

P0300  random multiple cylinder misfire

P0301  cylinder 1 misfire

P0303  cylinder 3 misfire 



I used Beru Ultra Spark Plug; 14FGR 6KQUs and torqued to 22 lbs as per instructions.  


ill double check the coil packs for proper seating on the plugs as well as  but at this point I don't think they are cracked as I installed those screws with locktite and firmly "snugged".



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I doubt that the fuel lines got any dirt in them but its hard to know unless the injectors can be diagnosed as clogged.  


My gut is improperly seated coils but Ill need to get it back up off the ground and broken down to reseat the #1 & #3 coils.  It smells, literally, like unburned gas is passing out the exhaust.  


I was also thinking of starting without the MAF connected.  I inspected around the MAF for possible air leaks but dont find any.  

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The codes are telling you exactly what is wrong - 1 and 3 misfires.  You can push the rubber boot up the wiring harness on the coils and make sure they are plugged in correctly.  They must firmly click into place and be fully seated in the coil connector.

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I removed, inspected and reinstalled the #'s 1 and 3 coils and also added fresh dialectic grease to the end of the boots.


 Its worth noting that I never felt a "click" seating any of the coils.  Upon close inspection, the contact between the coil and the spark plug is a coil push spring.  I measured the distance between the end of the spring and the plug and they do make contact.  The conductive grease should help insure proper conductivity.


 Upon re-start I did not re-install the mufflers.  I did however get a new set of error codes for the #4 & #6 cylinder misfires with a flashing cel.  


I then removed and reinstalled the #'s 4 & 6 coils and restarted and now get codes for the #'s 6 & 3 cylinders.


could these problems originate at the power supplies feeding the individual coils?




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Thanks for suggesting that.  I went back and checked them all, and the electrical connections to all six coils are properly made as far as I can tell; as in, the male and female ends are properly seated and the protective boot is in place.  In this last start-up the car idles properly for a few moments and then goes into a rough idle.  By that I mean you can hear the engine missing, rpm drops to the point where you have to play with the throttle to keep it running and you can smell unburned gas.  However, after another short interval the rpm rises to normal range (900 rpm) for a few seconds and then goes rough again and I get the flashing cell and error codes telling me about misfires.  My conclusion is that I've got bad electrical connections or bad coils somewhere.  Is there a way to do a simple diagnostic that can determine if a coil is bad?   What I'm down to trying is removing all the coils and plugs and testing the continuity with an ohm meter.  Loren suggested that there are any number of things that can cause a misfire after changing plugs but I'm running out of solutions to try.  Any advice is much appreciated.

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I haven't tried this yet.  Loren advises to stop changing things in a random way and that the MAF is not part of the curb idle and comes into play after 4000rpm.  I'm hoping for some step by step diagnostic procedure?

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  I just tried your suggestion..

I re seated the two coils that were giving misfire codes and restarted.  This time I have no codes but did have a low idle rpm and had to play with the throttle to keep it running.

After about 30 seconds of low rpm idle i disconnected the MAF.  The idle went frpm 600 rpm to 1400 but hen lowered to regular 800 with no misfires.  I repeated connecting and disconnecting MAF several times with identical results.  After 5 min of idling and revving engine I still get no codes.  Tomorrow am I'l reconnect the mufflers see what happens.  I did expect to get a MAF code but it was never disconnected for more than 30 sec at a time.


I appreciate the suggestion.  I'll keep you posted as info presents.  

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while reassembling the coil shield, then muffler on the passenger side of my car after changing spark plugs, tubes and coils I found this male plug dangling by itself in the passenger side of the engine compartment.  It is connected the the same bundle that the MAF sensor plug comes from.


After about 30 min of searching I cant find where it might go???

Any suggestions appreciated

IMG_2366 (1).JPG



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I had a bunch of misfire codes on all cylinders and flashing CEL after removing my air box and cleaning the engine. I unplugged the main wiring harness plugs in the passenger side of the engine compartment, blew the connections out with compressed air (in case I got some water in there somehow), plugged everything back together and everything is fine. May have been a fluke.

Sent from my iPhone using Tapatalk

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My car is now re-assembled and the misfire codes have been replaced with new codes:

P0102 MAF low voltage

P0112 Intake temperature sensor

P1319 misfire

P1318 Cyl 6 emission related

P1316 cyl emission related


The MAF code was due to my disconnecting the MAF sensor.  Upon startup I have a very low curb idle  Approx 600 rpm  If I disconnect the MAF the idle instantly rises to 1200 rpm and than drops to a normal 900 rpm.  There is no obvious un-burnt fuel smell like before  Even though the engine is idling very low, there seems to not be a misfire issue anymore.  


what diagnostic procedure or process should I follow now?

I was thinking about cleaning or replacing the "idle speed air control valve"

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Cleaning the idle stabilizer valve is good regardless. To test the MAF, you can use the Durametric or a regular multimeter to back probe the signal and see if you get ~1.1v with key ON engine OFF and ~1.3v at idle/680rpm.

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1999, 996, 140k


I started out changing a leaking coolant reservoir tank.

After completing this task I had misfire codes on all cylinders.  After changing the plugs, plug tubes and coils the misfire codes started "roaming" around.

After removing and re-seating the coils and their plugs several times the misfire codes went away and were replaced by intake temperature codes and roaming emission codes accompanied by a rough idle.  I cleaned the idle control valve and for now the car is running well with no codes.


I really enjoyed struggling my way through the exercise but have to wonder, Whats next?


being able to get some great suggestions and experienced information was a tremendous help.

Thanks Loren, Ahsai, brwilson, dbjoe996 for your guidance.


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