2007 Chevrolet Suburban LTZ Rough Idle

Tiny
GUSTAFA75
  • MEMBER
  • 2007 CHEVROLET SUBURBAN
  • 5.3L
  • V8
  • 4WD
  • AUTOMATIC
  • 185,000 MILES
I am having an issue with my LTZ. When it is sitting idling it almost feels like a misfire, an engine stutter, or bad gas. When driving down the road I can feel it a little bit. Refilled gas tank and it still has same issue. Wife states that she feels as if it is sluggish while trying to accelerate. I noticed this a little but nothing to major. At first I thought that it might be an engine mount but when I place it into drive and press brake and gas it only slightly moves. It is not throwing any engine codes, but it does have "Service Suspension System" however that is due to most likely the module being bad because I replaced the compressor and it worked for around 20 minutes after installing. The next day it wouldn't work and I jumpered two wires at the relay and it was working. So I guess the question is:
1. Are the two related or could they be related?
2. Is there anything else that I can look at to determine issues with the idling?

I able to use most tools in the garage, since I was an electrician in the Air Force.

Thanks ahead of time.
Gus
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Sunday, April 26th, 2015 AT 12:23 PM

4 Replies

Tiny
HMAC300
  • EXPERT
Have a pro scan for codes for suspension problem it may be a sensor and jumping a relay isn't he correct thing to do unless you want to burn up a module. Check fuel pressure with a gauge auto parts rent it. Should be 50-60 psi key on engine off and hold for at least 5 minutes.
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Sunday, April 26th, 2015 AT 3:55 PM
Tiny
GUSTAFA75
  • MEMBER
Just an update.I listened to each injector and they are all working. I took the intake system apart and the filter was clean, the MAF does not look like there is any damage or anything that is visibly broken. I took the throttle body off and cleaned it. It had pretty thick build up on it so I got it completely clean. Cleaned as much of the actual intake as possible. I changed the throttle position sensor a while back. The Haynes manual says that there is a PCV sensor/valve, but when I went to the parts store (all 3 big ones) none of them had it and they said that it wasn't equipped with one? I read online that some of the lifters could be bad, but wouldn't have other issues?

Thanks,
Gus
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Sunday, April 26th, 2015 AT 3:57 PM
Tiny
GUSTAFA75
  • MEMBER
HMAC300,

Thanks for the quick reply. I did have the fuel/pump assembly just replaced last year, but I will check the pressure again. The idle is rough while it is sitting still, not just isolated to after start-up. I have a friend who is a Chevy Mechanic and he put his computer on it and said that the pump was kicking codes. I replaced the pump and it worked after the initial start, but after I shut it off and restarted it never worked again. What I jumped was the power/ground (relay up under the Master Brake Cylinder) for the pump solenoid for it to turn it on.

As far as the idle I forgot in my last post that the problem still exists after cleaning the throttle body.

Thanks,
Gus
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Sunday, April 26th, 2015 AT 4:13 PM
Tiny
HMAC300
  • EXPERT
Do what I said in first reply
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Sunday, April 26th, 2015 AT 5:01 PM

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