Motor Firing On Half the Cylinders???
04-07-2010, 07:10 PM
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Motor Firing On Half the Cylinders???
Okay guys I am open for ideas. I have a 1999 C5 with an LS1 and its running on Cylinders 1,2,3,4 and not on 5,6,7,8. You can smell raw fuel and the car is running very rich. It sounds like there is a massive cam in it. I have changed the plugs and wires to see if that was the problem. I scanned it and I found out about the cylinders not firing. All the injectors are working and all of the coil packs are plugged in.
Im open for ideas and/or suggestions. Hopefully somebody on here has had this issue and knows how to resolve it. Thank you in advance.
Im open for ideas and/or suggestions. Hopefully somebody on here has had this issue and knows how to resolve it. Thank you in advance.
Last edited by JtothaP; 04-07-2010 at 08:58 PM.
04-07-2010, 11:46 PM
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Wounded Warrior Escort '11
Try the rear of the driver's side head. There are two wires there that ground the coil packs. If either of them is lose, you'll get the mis-fire
04-08-2010, 08:25 AM
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04-08-2010, 09:11 AM
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St. Jude Donor '08
Post your DTCs
04-08-2010, 10:43 AM
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Hum! this is a good one! If it were Cyl.s 1,3,5,7 and 2,4,6,8 I would say a harness or coil pack problem, but 1,2,3,4, that crosses harnesses soooo definately need more info.
04-08-2010, 10:48 AM
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04-08-2010, 11:35 AM
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It happened all of a sudden. I left my house to go to Sonic. It was a 30 MPH zone the whole way, maybe a mile or two. I pulled in the car was shaking badly. I killed it. It didnt want to crank up. Put some fuel in it and it cranked up but was still running like ****. Thats how it has been. I know the even cylinders are on the drivers side and the odd on the passenger side. I turned the cylinders off individually one by one. Cylinders 1,2,3,4 effected how the motor ran. Cylinders 5,6,7,8 did not have any effect on how the car ran. I checked all the injectors and they are all working as well.
04-08-2010, 11:47 AM
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It happened all of a sudden. I left my house to go to Sonic. It was a 30 MPH zone the whole way, maybe a mile or two. I pulled in the car was shaking badly. I killed it. It didnt want to crank up. Put some fuel in it and it cranked up but was still running like ****. Thats how it has been. I know the even cylinders are on the drivers side and the odd on the passenger side. I turned the cylinders off individually one by one. Cylinders 1,2,3,4 effected how the motor ran. Cylinders 5,6,7,8 did not have any effect on how the car ran. I checked all the injectors and they are all working as well.
Last edited by lucky131969; 04-08-2010 at 11:50 AM.
04-08-2010, 03:47 PM
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No codes no check engine light. I did it manually with the computer scan tool. 5,6,7,8 did not effect the motor or how it ran. I swapped some coil packs around and nada. Same issues same cylinders.
04-08-2010, 04:43 PM
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Burning Brakes
With Cylinders not firing, the check engine light should flash after a few cycles and you'll get either a multiple misfire code or a code ending in the cylinder number. I can't remember what number is was I think it was P300 for the multiple misfire.
No offense but do you know how to check the codes on the DIC? Make sure you check them as soon as the misfire happens.
No offense but do you know how to check the codes on the DIC? Make sure you check them as soon as the misfire happens.
04-08-2010, 04:59 PM
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CI 6,7,8,9,11 Vet
St. Jude Donor '08
This may sound very strange but,,you may have a broken valve spring. With no codes it running that crappy, that sounds just what I helped someone troubleshoot a few nights ago.
If you have access to a inferred thermometer measure the intake runner manifold runners where they enter each cylinder. If theres one of two that a LOT hotter than the others, that will be your broken valve spring. Or you could just pull the valve covers off and inspect. Heres a post that I was talking about that shows a broken spring:
http://forums.corvetteforum.com/c5-t...-sick-z06.html
If you have access to a inferred thermometer measure the intake runner manifold runners where they enter each cylinder. If theres one of two that a LOT hotter than the others, that will be your broken valve spring. Or you could just pull the valve covers off and inspect. Heres a post that I was talking about that shows a broken spring:
http://forums.corvetteforum.com/c5-t...-sick-z06.html
04-08-2010, 05:15 PM
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No offense take 03WhiteConv. It is not showing any codes or does it tell me anything out of the norm on the DIC. Thanks tho.
Bill Curlee, I also had some very good friends of mine over at EnglandGreen suggest this exact idea. Although it is a possibility I was just trying to troubleshoot everything possible before tearing into that bad boy. To me it sounded like it would be something simple. I may very well be mistaken.
Bill Curlee, I also had some very good friends of mine over at EnglandGreen suggest this exact idea. Although it is a possibility I was just trying to troubleshoot everything possible before tearing into that bad boy. To me it sounded like it would be something simple. I may very well be mistaken.
04-08-2010, 05:18 PM
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Tell Stephen and Jason to GET HOT troubleshooting your car!
Tell them Bill said HEY!
They should have a Inferred Temp sensor you can borrow!
BC
Tell them Bill said HEY!
They should have a Inferred Temp sensor you can borrow!
BC
04-08-2010, 05:26 PM
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Yeah when I had this problem I cruised down to their shop and they said change the plugs, wires and see if it helps. If it doesnt it may be a broken valve spring. They used thier Dr Stethescope to listen to the heads. There is a weird ticking noise coming from beneath the valve covers that they were unable to identify and havent heard before. They are both very great guys. I enjoy doing business with them and would refer them to anyone.
04-08-2010, 06:08 PM
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It really isn't running on half of the cylinders as much as it running on an air fuel mixture thats being seriously diluted with exhaust gasses.
You also have to consider that the cylinder /s that have the bad spring isn't firing at all.
BC
You also have to consider that the cylinder /s that have the bad spring isn't firing at all.
BC
