P0300 Random Misfires but it only does it at certain times????
08-23-2005, 07:13 PM
#1
P0300 Random Misfires but it only does it at certain times????
I changed out the torque converter in my truck last week and now I have random misfires. I have cleaned the MAF and that didnt help. I changed out the spark plugs and that didnt help either. I put some injector cleaner in it and so far nothing has changed. I took it to the Chevy dealer and they put it on their machine and all it told them was that my truck ahd random misfires adn they couldnt pin point a cylinder. What it does is when I brake stall it the stall only goes up to 2500 where it should be close to 3200 since its a 3400 stall. When I left off the brake and punch it it will cut out and pop and back fire all the way through first gear and I don try it any further through second. Now if I punch it from like a 35 roll and it drops down into the higher rpms it wont cut out and run fine and pull hard to the shift point and pull hard through 2nd but through second it may have a couple of little backfires or misfires whatever you want ot call it. When this is happening the power is greatly reduced but when it clears up it runs like normal. When Im not flooring it it drives fine and the tc locks up and everything. The battery was dead on the truck due to sitting for about a week so i didnt disconnect the battery when I did the transmission stuff. I dont know if sometihn was damaged or what. Could it be a fuse of some sort? If so where and which one? Any help would be greatly appreciated. The fuel pressure is fine too the fuel pressure gauge shows 58 at WOT.
Last edited by 1slow01Z71; 08-23-2005 at 07:22 PM.
08-23-2005, 07:54 PM
#2
Just took the ground off the battery and let it sit for about 30min and went out and ran it and that didnt change anything so Im back to square one. I f I keep driving it will it eventually set a hard code that will stay in the pcm and keep the ses light on? When its misfiring and all the ses light flashed for about 10 seconds and then goes back off.
08-23-2005, 09:05 PM
#5
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well maybe just maybe you broke a spark plug kinda cracked it., next is how many miles on the truck? Have you ever had your injectors cleaned by a professional?
08-23-2005, 09:19 PM
#6
I really dont see how I cracked a plug since all teh work was done under the truck only filled the tranny with fluid and the engine with oil sonce I did an oil change at the same time. 165,000 on it. To my knowledge they have never been professionally cleaned just few bottles of injector cleaner.
08-23-2005, 09:35 PM
#7
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I have heard of missfire codes being set because of the new torque converter, but it sounds like you really have a misfire, I did a search I found some posted talking about misfires with new torque converters, but this is the only one I can find.CLicky Clicky I'll go do some more digging.
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08-23-2005, 09:42 PM
#8
Yeah I have heard of that too but I actually have misfires though. There is no doubt about it. Maybe I should replace the crankshaft sensor. I was told that might be the problem I just dont understand why everything was perfect then after the transmision stuff it is acting up. It must have been because Mjhoward touched my truck he is always messing his stuff up. 
Thanks for letting me use your lift Mark it was a life saver. 
Could have been cause there was alot of that going on LOL.
Thanks for letting me use your lift Mark it was a life saver. Could have been cause there was alot of that going on LOL.
08-23-2005, 10:43 PM
#9
If youve got backfiring chances are it really isnt firing correctly. have you checked spark on the cylinder that is doing it, if its a spuradic misfire on differentcylinders I would look at the electrical system that controls the coils.
If you have to hook up a timing light to each plug wire and try and get it to misfire.
Also the converter probably isnt locking with that code.
If you have to hook up a timing light to each plug wire and try and get it to misfire.
Also the converter probably isnt locking with that code.
