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Do u notice a fuel smell? does your tahoe have a black intake manifold(plastic)?Do u notice a fuel smell? does your tahoe have a black intake manifold(plastic)?
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Misfires can also be caused by air flow issues and fuel supply issues. Have you had the vehicle scanned for OBD Trouble Codes to check this isn't a faulty sensor causing the problem. Check the fuel injectors are all firing correctly.
When was the engine last serviced? A dirty air filter can cause more issues than you would expect.
Hello, Your question lists codes p305p, and p305, which are not valid codes. Did you mean P0305? This is a diagnostic code referring to a misfire on cylinder #5. It looks like you've replaced parts that could be causing a misfire, but did not fix the problem.
A simple check to verify your misfire is not being caused by an ignition coil (the 4.8 liter engine has a coil-near-plug system, with one coil for each spark plug) is to swap the suspect coil (cylinder #5) with a coil from a different cylinder on your engine.
Cylinder #5 is the third one back from the front of the engine on the driver side of the engine. After you swap coils between a good cylinder and #5 cylinder, clear the codes and see if the misfire followed the coil- if a misfire code sets on the cylinder you moved the cylinder #5 coil to, you know the coil has a problem. That will at least help you rule out the remainder of the ignition system.
This is what all should be checked:
P0305 indicates the PCM has detected misfires on cylinder number five. Here are six common problems that may cause OBD trouble code P0305:
Fouled, cracked, worn or otherwise misfiring spark plug (Replaced)
Bad ignition wire - burnt, cracked, carbon tracked wire or plug boot (Replaced)
The aforementioned list covers the most common causes of P0305 in the order we feel is most likely to occur based on our past experiences. Certainly, each situation is different and there are other possible causes for cylinder misfires. Here are other causes we've seen (in no particular order).
Low fuel pressure
Leaking fuel pressure regulator
Poor fuel quality - water in gas tank
Uneven EGR flow caused by carbon build-up on engine with multiple EGR ports
loose or corroded fuel injector wiring
There seems to be a few things that have yet to be checked by your mechanic. I know it is frustrating when the OBDII codes don't point you directly to the problem. To be hones this is something that I can not solve from here. However I hope that with the above information you can get your misfire detected code to go away after the real problem is discovered.
misfire :-------- try checking your 02 sensors /fuel pump and filter. for 51 cylinder misfire :---
Change the coil. Period. Very easy to remove from the vehicle if it's a 4 cyl. Follow that spark plug wire from the spark plug to the other end. What it's attached to you should replace
for 54 cylinder 5 misfire :---First you have to eliminate the most obvious problems, like spark plug and spark plug wire. If you replace those and you still have a misfire, then it's a good idea to look for a vacuum leak in the intake manifold
How is the pressure in the fuel rail? a low pressure will cause erratic firing of the injectors - the further down the rail u get usually the worse the problem. If the fuel filter was not changed regularly or if the vehicle stood for a while, dirty fuel/standing fuel at some time in the recent past, this **** will accumulate in tyhe injectors. To avoid spending a loada cash, swap a few injectors around and see if the problem moves with the injector.
Do u notice a fuel smell? does your tahoe have a black intake manifold(plastic)?
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