07 suburban 5.3L misfire and white/grey smoke

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Leadfoot31
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Joined: Fri Dec 13, 2013 4:32 am

Re: 07 suburban 5.3L misfire and white/grey smoke

Unread post by Leadfoot31 » Mon Dec 16, 2013 12:04 pm

I have heard of leak down test before. How would I do that test? And would u no what the compression normally would be for the cylinders.

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carriedi
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Joined: Wed Apr 10, 2013 12:42 pm

Re: 07 suburban 5.3L misfire and white/grey smoke

Unread post by carriedi » Mon Dec 16, 2013 3:06 pm

to do a leakdown test you would need a compressed air supply and a leakdown gauge. it is simply two gauges that measure how much air you put in and how much air escapes.

just do a compression test for the bank that's not firing correctly. if all four cylinders are comparable they should be ok. If one or two seem different you may have to do the other side to get your relative normal compression. Look for the cylinder that's different. (especially #7 if that is a continuous misfire) If everything looks ok maybe it's an injector not firing enough fuel. Spark, compression and fuel all have to work together to make the cylinder run correctly. Check all three.

If you have a scanner available check your O2 sensors and also look at the misfire counter to see what cylinders are misfiring and how much they are misfiring.
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Leadfoot31
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Joined: Fri Dec 13, 2013 4:32 am

Re: 07 suburban 5.3L misfire and white/grey smoke

Unread post by Leadfoot31 » Sun Dec 22, 2013 1:34 pm

sorry took so long to reply I took it to dealer and they told me it was a bad cam and need to replace lifters also. I don't think that this is the problem I had a bad cam in another truck and it wouldn't even run. Unless when it first started I herd a clank noise and truck stated to jerk alittle then this problem with the misfire started. when I drive it now it hesitates alittle but still runs. I don't think this motor is a dohc motor is it??? if not why would it only misfire on one side and not the other? I should have truck back next week an ill check the o2 sensor before cat and after to see what the readings are . thanks for the repost I appreciate all the help.

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carriedi
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Re: 07 suburban 5.3L misfire and white/grey smoke

Unread post by carriedi » Sun Dec 22, 2013 5:19 pm

It is possible that you have a bad cam but I would do more research to verify that. It would seem difficult that only the one bank would be bad. You need to hook up a scanner and graph the misfire counter and see what cylinders are missing and how much they are missing. can you list all the codes that your engine has had? and does both of your O2 sensors go below .2V and above.8V back and fourth? One test you can do yourself is to switch the two front O2 sensors and see if the miss goes to the other side. (unless your cat is plugged from the bad O2)
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Guest

Re: 07 suburban 5.3L misfire and white/grey smoke

Unread post by Guest » Fri Aug 19, 2016 1:18 pm

Leadfoot31 wrote:
> sorry took so long to reply I took it to dealer and they told me it was a
> bad cam and need to replace lifters also. I don't think that this is the
> problem I had a bad cam in another truck and it wouldn't even run. Unless
> when it first started I herd a clank noise and truck stated to jerk alittle
> then this problem with the misfire started. when I drive it now it
> hesitates alittle but still runs. I don't think this motor is a dohc motor
> is it??? if not why would it only misfire on one side and not the other? I
> should have truck back next week an ill check the o2 sensor before cat and
> after to see what the readings are . thanks for the repost I appreciate all
> the help.

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carriedi
Posts: 2573
Joined: Wed Apr 10, 2013 12:42 pm

Re: 07 suburban 5.3L misfire and white/grey smoke

Unread post by carriedi » Sun Aug 21, 2016 5:09 am

can you give me a list of any and all the codes you have had on this vehicle since experiencing this problem? Have you had a scanner hooked up and watch the misfire counter? Any cat codes? Any cam codes?

While the dealer recommended cam and lifters, and this engine does have many cam and lifter issues, it is unusual that only one bank is affected. And every cylinder on that bank. but, stranger things have happened. If they have looked and tested things on this engine and this is their conclusion I would let them repair your vehicle. I don't have the vehicle in front of me to make to make any tests to confirm or disagree their conclusion. It's just odd that only all the bad parts are on one side of the engine. I would look at other things that would only affect one side.

to do cam and lifters on your engine is a major repair. The heads have to be removed to change the lifters. when doing these repairs make sure they replace the oil screen for the cam actuator. They plug up and cause low oil pressure to the oiling system.
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Tim

Re: 07 suburban 5.3L misfire and white/grey smoke

Unread post by Tim » Thu Jan 04, 2018 11:16 pm

Has anyone had a solution to the misfiire on #7 cylinder? I’m having the same exact problem!

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