Misfires on 1, 3, 5, 7 cylinders

Tiny
WYOPOKES
  • MEMBER
  • 2004 CHEVROLET SILVERADO
  • V8
  • 4WD
  • AUTOMATIC
  • 21,000 MILES
My truck recently had a misfires on 1 and 7 cylinders. I tried to clean the injectors with a fuel injection machine, but that did not work, so I replaced the two injectors and the plugs for those two cylinders. It worked for about 30 minutes and started to run really bad. It turned the engine light back on so I scanned it and it said that I had random misfires on 1, 3, 5, and 7 cylinders. I really do not know what else to do. The converter seems to be alright. The mass airflow sensor was changed out and that did not help, and there are no head gasket leaks.
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Tuesday, February 12th, 2008 AT 2:29 PM

26 Replies

Tiny
BLACKOP555
  • EXPERT
Hello,

It sounds like you have a shorted injector on 3 or 5, can you please use this guide to confirm? Also please check the injector fuse Inj2 in the underhood fuse panel.

https://www.2carpros.com/articles/how-to-test-a-fuel-injector

and

https://www.2carpros.com/articles/how-to-check-a-car-fuse

Here are the engine wiring diagrams so you can see how the system works.

Check out the diagrams (Below). Let us know what happens and please upload pictures or videos of the problem.

Cheers
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Tuesday, February 12th, 2008 AT 4:40 PM
Tiny
ROSIE0288
  • MEMBER
Thanks for this post! I found my injector shorted which popped the inj2 fuse. I got a new one for $78.00 and put it back together all fixed! I love this site.
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Wednesday, March 5th, 2008 AT 8:35 PM
Tiny
BRONCBUSTER35
  • MEMBER
  • 2004 CHEVROLET SILVERADO
  • 101,000 MILES
I have a 2004 chevy 5.3t ext. Cab 4x4. I am getting a number 7 misfire code. I changed the Coil on cylinders 3 and 7.3 cleared up, and 7 is still misfiring. Could it be an injector vs. An elect. Prob?
Any help would be greatly appreciated?

Thanks
Cole
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Monday, September 17th, 2018 AT 2:09 PM (Merged)
Tiny
WRENCHTECH
  • EXPERT
It certainly could. Try moving the plug and wire around too. Examine the plug closely for a crack in the porcelain.
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Monday, September 17th, 2018 AT 2:09 PM (Merged)
Tiny
BRONCBUSTER35
  • MEMBER
I forgot to mention, I have also already changed the plugs and wires. I rechecked the codes this afternoon, and now it is throwing a "Multiple Random Misfire" Code.
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Monday, September 17th, 2018 AT 2:09 PM (Merged)
Tiny
CHEVYFORLIFE
  • EXPERT
Try and spray the intake down with water. You could have a intake leak from the gaskets get warped. Does it do it more hot or cold?
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Monday, September 17th, 2018 AT 2:09 PM (Merged)
Tiny
BRONCBUSTER35
  • MEMBER
It does it all the time. Unless I hold it to the woodwork. Then it runs like a top.
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Monday, September 17th, 2018 AT 2:09 PM (Merged)
Tiny
TXFIREFIGHTER
  • MEMBER
  • 2004 CHEVROLET SILVERADO
  • V8
  • 2WD
  • AUTOMATIC
  • 34,000 MILES
I have a 2004 silverado 1500 5.3L that I took to the dealership I purchased it at to have it checked. It was ideling very rough. When they ran diagnostics on it, it came back with P0300 code and missfire counts on cylinders 1, 3, 5, 7. (The entire left bank) Cylinder 1 had 40,000 missfires and they intermittenly decreased to 16,000 on cylinder 7.

This thing idles rough, at road speeds it's fine.
I took the throttle body off and cleaned it really well, checked for vaccum leaks on the intake manifold. No problems I could find there. Spark pllugs are all good.

The service techincian had no clue what to do with it.
I searched on the net and found that this is becoming a problem with this motor, but no one seems to be able to figure out how to fix it.

You guys have any clues?
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Monday, September 17th, 2018 AT 2:09 PM (Merged)
Tiny
BRIAN 1
  • MEMBER
I've had this problem before, try this info:Check Engine Light with a P0300 due to 2 - 4 cylinders misfiring on the same bank of the engine. DTCs P0171, P0172, P0174 or P0175 may also set for the misfiring bank.

Recommendation/Instructions:
If the published misfire diagnostic does not isolate the cause, perform the following suggestions as necessary:

Perform a fuel injector balance test for all 8 cylinders. If a fuel injector concern exists, it is possible to misfuel an entire bank of the engine, causing multiple cylinders on the same bank to misfire even though the root cause is a single fuel injector.
Inspect O2 sensor connections on the misfiring bank for corrosion or water intrusion. If water intrusion is found on the right bank, it may be due to the AC Evaporator Condensation dripping onto the O2 sensor harness. If this condition is found, reposition and shield the harness to prevent a repeat concern and repair the connections.
Check for excessive exhaust backpressure using the restricted exhaust diagnosis from SI.
Swap the Position 1 O2 sensors side to side to see if the misfires move to the other bank of the engine. If so, replace the O2 sensor. Also perform an exhaust back pressure test on that bank, a plugged cat converter can cause this also. Post back with what you find.
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Monday, September 17th, 2018 AT 2:09 PM (Merged)
Tiny
TXFIREFIGHTER
  • MEMBER
Ok, Did like you said, started by flipping the o2 sensors. Bingo! New O2 sensor and bam. Problem fixed! Thanks!
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Monday, September 17th, 2018 AT 2:09 PM (Merged)
Tiny
JAY05
  • MEMBER
  • 2002 CHEVROLET SILVERADO
  • V8
  • 4WD
  • AUTOMATIC
  • 221,000 MILES
I have a 2002 chevy Silverado 1500HD 4x4 with the 6 Lt Vortec engine and auto tranny. Problem is that I also have a milit cylinder misfire. It idles rough and looses quite a bit of power when climbing hills. I have hooked up the diagnostic scope at chevy and have identified the misfire but am unable to pinpoint the problem. Have changed the plugs, wires, air filter, fuel filter, tested for sufficient fuel pressure(good), checked for borken wires going to the coil leads on the valve covers. I have come up empty handed. What else could the problem be. I have 221000 Kms on the truck, and it just started this about 8 months ago, I just can't find the problem. Can you help?
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Monday, September 17th, 2018 AT 2:09 PM (Merged)
Tiny
DENNYP
  • EXPERT
Check the MAF sensor. It could be giving incorrect readings under load.
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Monday, September 17th, 2018 AT 2:10 PM (Merged)
Tiny
JAY05
  • MEMBER
Thanks for the reply. I forgot to add that I did check the MAF sensor, and there was some loose ducting there. I repaired it, but the problem still persits. It there a way of checking the MAF sensor itself. No codes are present for the MAF so I presume it is OK.
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Monday, September 17th, 2018 AT 2:10 PM (Merged)
Tiny
DENNYP
  • EXPERT
You will need a scan to to read the data stream from the MAF sensor. You will need to monitor the readings to see if the airflow readings correspond to the throttle position and engine load.
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Monday, September 17th, 2018 AT 2:10 PM (Merged)
Tiny
CHEVYCOLE
  • MEMBER
I'm having the same problem, have yyou determined the cause?
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Monday, September 17th, 2018 AT 2:10 PM (Merged)
Tiny
HENDRICKS
  • MEMBER
  • 2002 CHEVROLET SILVERADO
2002 Chevy Silverado, Automatic,
My truck, during cold weather only, gives me a cylinder misfire code. When I first start my truck it will rev high and then the rpms will drop, then it will begin surging. Sometimes the rpms will drop too low and the engine will turn off. After it idles for a while the surging is not so bad. But when I put it into to drive it will slowly accelerate on its own. After the truck has been running/driven the engine will stop surging and the check engine light turns off. Again, this only happens in cold weather. I have replaced the spark plugs and wires. And the fuel pump is new.
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Monday, September 17th, 2018 AT 2:10 PM (Merged)
Tiny
DENNYP
  • EXPERT
Check the intake manifold gaskets for a leak when cold. You can do this by spraying carb cleaner around the gaskets with the engine running. If it boggs down when you spray an area, you have a leak.
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Monday, September 17th, 2018 AT 2:10 PM (Merged)
Tiny
PROBLEMAUTO
  • MEMBER
  • 2000 CHEVROLET SILVERADO
  • V8
  • 4WD
  • AUTOMATIC
  • 18,000 MILES
You responded to a question I had a few days ago on this same problem. Fuel pressure at the fuel rail is 50 to 55 lbs. There is no fuel in the vacuum line going to the fuel pressure regulator. Do you have any more suggestions? Respond to problem.
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Monday, September 17th, 2018 AT 2:15 PM (Merged)
Tiny
JACOBANDNICKOLAS
  • EXPERT
Hi:
I did not respond the last time. However, when you remove the vacuum line from the regulator, does the fuel pressure increase? Also, can you let me know what is going on so I can better help?

Joe
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Monday, September 17th, 2018 AT 2:15 PM (Merged)
Tiny
PROBLEMAUTO
  • MEMBER
Hi Joe, I appreciate your int rest in my problem. The original question was a 2000 Chevrolet Silverado check engine light was on. The code was multiple engine misfires. Installed new wires plugs and fuel filter' cleared the code and run it. Light came back on with cylinder seven misfire. It has a real light miss at idle. I checked the fuel pressure at the fuel rail and it was 50 lbs. The fuel pressure increases to 55 to 60 lbs. I switched around coils and it still codes cylinder seven misfire. If you have any suggestions please reply. Thank you.
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Monday, September 17th, 2018 AT 2:15 PM (Merged)

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