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HELP/Misfire codes

14K views 42 replies 6 participants last post by  jasonm4 
#1 ·
Ok heres the problem im having: I am supercharged but i dont have the charger in at this time, but im throwing a mutiple/random misfire code and one day it also threw a cylinder 3 misfire code. So i changed all my plugs and replaced the coil pack for cylinder 3, but the code came back, the mutiple/ random misfire code and the misfire for cylinder 3 didnt come back yet. Anyone has any idea what this problem could be, and when i pulled my injectors i couldnt smell gas on the plugs so i dont think its a leaky injector.
 
#2 ·
Have you tried maybe swapping #3 injector with another cylinder's injector? It's also possible that the injector is not pulsing/opening. You may want to stick a screwdriver up to #3 injector and feel for injector clicking. The only other aspect I can think of at the moment is maybe the ignitor is failing or has failed. I would verify you actually have spark on that cylinder. Pull off the plug wire and see if you have spark or use a cheap spark tester.
 
#3 ·
what was the gap of your plugs? plug gap i have seen cause it, as well as a bad injector. try swapping coil and plugs from another set, see if it still misfires on cyl 3. that would eliminate the coil/plug. Do you have aftermarket injectors?
 
#5 ·
My plugs are gapped at .023-.025, and i do have denso 550cc injectors. The code i pulled up for the cylinder 3 came up only once but the random/mutiple misfire code always seems to come up after clearing. I already swapped out brand new plugs and replaced the coil pack on cylinder 3 but still getting the misfire code.
 
#8 ·
Do you have one primary oxygen sensor on each side of the motor? Because aftermarket headers sometimes u can only put them on one side
 
#12 ·
I have the tokensolutions O2 delete but my 2 left over I had to to put on one runner on the header. My car had random misfire codes and I had to weld new bung on other side of the header
 
#14 · (Edited)
Absolutely. even a pin hole in the cord set would be enough to ground your spark. I bet if you turned out the lights and took a look at night, you can see it getting grounded. There should be no imperfections in the wires, so since you see an issue with 2 of the 5 wires, then I would replace all 6(others are same age and probably on verge of cracking.). Those cords should be smooth and flexible.
 
#16 ·
sure, I couldnt feel my misfires for a while untill I would set cruise or level out my foot on the pedal and then I would just barely feel it.
 
#19 ·
I had a little piece of plastic break off my coil pack where the wire cover would connect. The piece was to clip the wire down on the coil causing a bad connection. I ended up with new Coil pack even though it still worked.. kinda.
 
#21 ·
UPDATE: I changed all my plugs and gapped them properly, replaced all 3 coil packs and all of the plug wires and the random misfire codes are still appearing. One time and only one time the code said it was a misfire in cylinder number 3, but now thats not showing up only the random cylinder misfire code. I think from reading some of the other posts the only thing thats left for me to check would be the injectors. If thats all thats left how do i check the injectors?
 
#22 · (Edited)
You're better off pulling the injectors and have em cleaned and tested. In the mean time, you can verify they are getting a signal to open or trying to open by using a long flat blade screwdriver and listen for the clicking. Another thing you can do is shut off the engine, wait 5 minutes and then pull a few plugs to see if you can smell raw gas(ie leaky injector). The only other reasons why you might be getting misfire codes could be the ECU or more likely, the ignitor may be failing.
 
#23 ·
Update: I just changed my ignitor and the random misfire code still shows up, so far ive replaced all the plugs, wires, coil packs and the ignitor so is the injectors the only thing besides the ECU left that would cause this code? And if i need to pull my injectors is there a DIY step by step with pixs on how to do it, i tried a search but came up empty. Only step by step without pixs any suggestions?
 
#24 ·
Its very possible if you havent changed your VVTI oil control valve at all that could be causing this. I had random misfire codes until i swapped my ocv out. I would do that before pulling the injectors, how is it running atm?
 
#27 ·
Not really sure how the oil control valve would cause a misfire code, so that's a new one for me. Even the diagnostic mentions nothing about misfires and the OCV that I can see. Since you have new plugs, wires, coils, and ignitor, its safe to say you don't have a spark issue unless there is a problem with the plugs that were put in. You can always put a guage on the banjo bolt where the gas feed is from the fuel pump and see if your injector(mainly #3 or #4) is leaky. System pressure should stay at same psi(43 I believe) for at least 5 minutes. Check the FSM as well. The OCV can be pulled and checked. It is only a valve that switches state and allows oil to flow or not to flow. In most cases, a bad OCV would give you poor idle almost to the point of stalling.
 
#28 ·
When my OCV went bad my TRAC OFF was flashing which is a misfire, i drove it to autozone got the code read and long list of probable causes and VVTI OCV was #1 on the list. This may not be you problem but its good to change it, i also noticed they changed part no. on the VVTI OCV so they may have made changes to it to make it last longer.

http://my.is/forums/f115/vvti-ocv-install-430720/
 
#35 ·
Ok so heres yet another update: Today i went to start my car and when it started it ran really rough, then the trac and CEL came on. I pulled up the codes and the ramdom misfire code showed up again no suprise there, but i also got these three other codes misfire cylinder 1,4, and 5. I already changed everything i can think of besides the injectors what else could cause this problem!
 
#36 ·
Have you done any testing on the oil control valve as we talked about before? Since your ignition components are all new and I take it as the spark plugs are gapped right, it could very well be the injectors. Other than that, you may want to verify the new plug wire set is firmly locked into the coil packs, unless you are sure that is ok. This may be off the wall, but you may want to check your plug wells for condensation or debris. I wouldn't think it would be an ECM issue. To sum it up, you have new plugs, wire set, coil packs, ignitor, and the misfires are still occurring, correct?
 
#37 ·
I havent done the testing on the oil control valve just yet, i just have to take it out and apply 12volts to it correct? And watch to see if it moves? Is it possible for those cylinders to act up out of the blue like that? That was the first time i seen those codes pop up! I changed all those things you mentioned and they are still showing up.
 
#43 ·
To be honest. I didn't really think it was going to be the OCV. Even though it may sounds like a fuel delivery issue since ALL of your ignition components have been replaced, I would't rule out a loose connection or a vacuum hose connection. Take a look at this download and it will show you the common troubleshooting flow chart for P0301 codes.

http://my.is/forums/f87/new-01-05-is300-diagnostic-manual-download-435089/
 
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