p0300 misfire HELP!!!
p0300 misfire HELP!!! Well I've been getting this code ever since I installed my new motor. It usually does it around 2k while i'm crusing. I've searched and saw it might be my MAF but I dont know how to test this. I unplugged it while it was running and logging with HP Tuners and notice little to no change in my RPM. Only thing it did was throw a MAF low circuit or something like that code. The car doesnt idle or run rough so I'm lost. If it was the MAF wouldnt it be throwing a code. The only real reason I think that's it is because i blew the old motor by driving through somewhat deep water and hydrolocked the motor, possibly messing up the MAF at the same time. Any idea?
Last edited by 99LS6SS; Sep 21, 2010 at 07:21 PM.
I realize it's a misfire code. If I didnt know that I would have asked what the code ment. What I'm saying is why would I have a misfire code being thrown, but really can't tell a difference in the way the car runs? Motor has right at 10K miles on it, almost every sensor on the motor is new with the exception of the MAF and O2's. Injectors and coils are stock. I read the first part of the link you showed me. I figured I would be able to feel whats interupting the crank signal. I cleared the codes and am going to drive the car to work tonight. I'll see what codes are on it in the morning
If your not going to read the diagnostics for the code how do you plan on isolating the problem? Guessing and throwing parts on cars is the easy part. You came on here asking a question, here is the answer.
Ok I've read the diagnostics and it says obstructions in the intake tract can cause it. Irratic road conditions or constant vibration can cause it. Bad fuel filter can cause it. Also misaligned belts and pullies. I drove the car last night and it did it again. Cruising at 2k in 5th gear, tps within 1%, not under load, the mil started to flash, stopped flashing for a little bit and started flashing again, stopped for a little bit, and did it again. Only thing that comes to mind would be fuel related, misaligned belts and pullies, or excesive vibration from something else. I just don't know why it only does this at 2k in 5th gear not under load. This things been a pain since the new motor
Another thing I noticed last night and it only does it when it rains. I get a grinding sound or vibration from the front of my car and it goes with the RPMs so it's just not a constant sound, I can hear it start to die off when I let off the gas.
Just got back from work, drove the car to work and the SES light flashed (p0300) and drove it home and it flashed. I'm stumped. Car seems to me to be running fine. Wasnt raining today so I didnt have the gurgle/grinding vibrating sound. I'm lost here. Guess I can spray ether or starting fluid around the intake and see if i'm getting vaccum leaks. Another thing. I tapped on the MAF as the car was running and the car didnt run any different. I was watching with HP Tuners on my laptop as I did this and I didnt have any change in RPM and I couldnt hear any changes. Might also take my alternator in and have it checked. Maybe when my other motor blew from all of the water, the water could have damaged the alternator? It was around 6-8 inches of water.
Last edited by 99LS6SS; Sep 17, 2010 at 07:49 AM.
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Even though the PCM only sets a Random misfire code if you log misfire history on all cylinders you can isolate which cylinder it is. Then first check would be to look for a cracked spark plug or bad wire. After that if you don't find anything you could try swapping the ignition coil and injector and see if the problem follows to the other cylinder you switched with.
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Verdad Gallardo Go to my web site and download the misfire.cfg file and open that in the scanner.
Right click the name on the page and save it, don't try to open it from there.
http://ls1tuningguide.com/files/free...s/cfgfiles.php
Right click the name on the page and save it, don't try to open it from there.
http://ls1tuningguide.com/files/free...s/cfgfiles.php
I right clicked and saved target as to my desktop. Tried extracting it and it turns it from an HTML to a .zip, then tried to extract it again and it didnt do anything
With a cam swap, a new motor the PCM needs to re-learn the new engine confiuration related to mis-fires.
Here, read this:
http://www.seattleautomotive.com/ckpdoc.htm
Also, I found I needed to desensitise the misfire diag tables.
I ended up doubling the valuves in the various 6 tables also.
Hope this helps!
Here, read this:
http://www.seattleautomotive.com/ckpdoc.htm
Also, I found I needed to desensitise the misfire diag tables.
I ended up doubling the valuves in the various 6 tables also.
Hope this helps!
Alright thanks I'll check it out when I'm near a computer. I'm almost certain I've narrowed to my alternator. It would explain the gurgling grinding sound when the bottom of the car gets wet (rain or car wash). And I've noticed on the gauge when I first fire the car up it runs at 15volts or so and after about 10 mins it drops to 13 and below. I think a bearing could be going out in it from the puddle i drove the car through. Either way I'll hve it checked next week and hopefully find out that's my problem I've been chasing
Alright well I put the new knock sensor in that i've been needing to get in and it fixed my p0327 or whatever the code is. Opened the misfire.cfg and made two separate logs. First log about 1/3-1/2 way through i start getting misfire on #1 and #6 what looks like pretty bad. I dont get the misfire at WOT, only while I'm cruising. On the second file, I start getting it on #1 and #6 again, and then I start getting it on every cylinder but not nearly as bad as 1 and 6. I really dont feel the car run any differently is what stumps me. Maybe someone can take a look at the files I posted and see something Im missing.
Also why wouldnt I be getting a p0301 and p0306 insted of p0300? I didnt get my alternator tested because I figure if it actually is the alternator it would have the same amount of misfire on all cylinders and not only two cylinders.
The cylinder specific codes will only set when it has a set amount of misfires detected in a certain time frame. Not sure what the exact numbers are but its very common to only have a P0300 code stored.
I tried the CASE learn and nothing happened. Fuel didnt cut off. IDK. Now it says my other knock sensor is bad. Looks like I will be tearing it apart for a third time!
