Cylinder 5 misfire

Asked by Lisa Dec 15, 2016 at 07:25 AM about the 1998 Chevrolet C/K 1500 Silverado Extended Cab Stepside 4WD

Question type: Maintenance & Repair

What would cause a Constant misfire code my valves are
good and it doesn't smell like antifreeze the plug is dry can
someone help me please

6 Answers

224,145

P0305 CHEVROLET - Cylinder 5 Misfire Detected.... Possible causes - Faulty spark plug 5 - Clogged or faulty fuel injector 5 - Faulty ignition coil 5 - Fuel injector 5 harness is open or shorted - Fuel injector 5 circuit poor electrical connection - Ignition coil 5 harness is open or shorted - Ignition coil 5 circuit poor electrical connection - Insufficient cylinder 5 compression - Incorrect fuel pressure - Intake air leak... The P0305 code means that the cylinder 5 is misfiring or is randomly misfiring. Start by checking for intake leaks an if no leaks are found the next step is to replace the spark plugs on cylinder 5. If the problem persist more tests needs to be done to diagnose problem.

25 people found this helpful.
380

I don’t know if you ever found the problem.”, but it’s your fuel pressure regular under the upper intake plenum. It leaks raw fuel straight to a port that drains into cylinder 5. Makes for rough idle and bad exhaust smell. Should cost you about $75 to fix if you do yourself for the regulator and upper plenum gasket kit. Not too difficult, just take careful notes on what bolts come out of where in the plenum.

31 people found this helpful.
140

Is this also true for 2011 Chevy Silverado, cause I swapped coil, wire, fuel injector, new plug, checked voltage on harness and on the OBD reader show the misfire count and is always cylinder 5 there is always a misfire it never fires by the way the count goes up so quickly. Thanks

14 people found this helpful.
200

Replace power booster check valve #5 cylinder supplies vacuum for the brakes works every time

20 people found this helpful.
140

This is going to be a long story, and hope that this helps someone. I know unfortunately engines can have same symptoms and different solutions but it’s worth it if it helps anyone. So 6 days ago my husband totaled our 02 Chevy blazer( tree fell in the road) and we were on the search for another way to go. Found a 99 Tahoe with a 5.7L engine. This thing ran so beautifully, not a tick, not a rattle, not a noise out of place. For 5 days we almost couldn’t believe we had found a used 99 model car that ran so smoothly. We had to rewire our boat trailer lights and afterwards decided to test the Tahoe out on pulling the boat. We got to probably the smallest hill we have here in our county and this thing started shaking like crazy, and skipping, and felt like it was going to stall out and then the dreaded check engine light came on. We could let off the gas and give it time to adjust and would run beautiful. Came to another hill and it started acted crazy again wasn’t even sure we would make it up the hill. We got the Tahoe and boat back home and hooked out scanner to it and it said cylinder #5 misfire. We popped the hood to investigate and see if we could see anything and the only thing we could see that would cause any trouble whatsoever was for whatever reason the air filter had been removed from the truck, so I came in here to read and see if anyone else had this problem and saw that a lot of people have this problem but very few actually get resolved and the ones that do are never the same, so of course I was not having high hopes that this would be an easy fix on this vehicle we have owned for 6 days. I knew the truck had to have a filter so I went to the parts house and bought one and went a head and bought a fuel filter and fuel pressure regulator because someone cured there’s with one it was worth a shot. So he drove the Tahoe to work and when he got home said that now it was acting that way on every hill without the boat. So we installed the air filter and decided to just drive it around the block to just see if there was any change and lo and behold we cannot make the Tahoe misfire or act crazy. We were definitely sceptical so I said hook the boat up and let’s see, so we hooked up the boat and go up the same hill as last night and she runs beautifully, so we decided to go to one of the biggest hills we have around here and came to a dead stop at the bottom of the hill and hit the accelerator waiting for the shaking and loss of power and the dreaded light but instead she climbed that hill like that boat was not even back there. No hesitation no shaking no misfire no stalling no light. A $20 air filter was all we needed to stop the craziness. So if your vehicle runs great until it’s under pressure and gives a cylinder #5 misfire I would start with your air filter first.

14 people found this helpful.

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