07 Silverado Classic runs poorly at cold start and has multiple DTCs

Tiny
SHADOWEN1
  • MEMBER
  • 2007 CHEVROLET SILVERADO
  • 5.3L
  • V8
  • 4WD
  • AUTOMATIC
  • 62,000 MILES
I'm in need of some help with this one. A while back I started pulling some DTCs. A P071 bank 1 lean and P075 bank 2 rich at the same time. Then maybe a day later it would reverse with bank 1 rich and bank 2 lean. Now when I start it cold it hesitates and sputters like it is only running on a few cylinders untill I give it a little throttle and then it comes back to life and runs pretty much normal. If I don't give it any gas it will die. The exaust right at start up smells very rich, almost like its flooded. At first it was only only once in a while but, now it is at every cold start. Now in the last few days I started gettin a P2A01 and P2A04 HO2S performance Banks 1 & 2 sensor 2 with a genaric code 1400. What do you think is going on And what do I need to do to fix it? Thanks so much.
Thursday, January 23rd, 2014 AT 6:25 PM

13 Replies

Tiny
SATURNTECH9
  • MECHANIC
  • 30,869 POSTS
The first thing I would do is unhook your vacuum line from your fuel pressure regulator see if there is fuel in line or on the nipple. Also have you looked for vacuum leaks or checked actual fuel pressure?Or see if your fuel pressure regulator holds vacuum?
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Thursday, January 23rd, 2014 AT 8:02 PM
Tiny
SHADOWEN1
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I will be checking for vacuum leaks this weekend. I have not checked the fuel pressure as of yet. I was figureing that as long as it was actually running pretty well once it was warmed up that was not a very likely suspect. As for the regulator, these are built in to the feul pump in the tank and not too easy to check. I still have a few steps I know of to troubleshoot but, I was just hopping to get it narrowed down a little or maybe I might just be missing something. Thanks.
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Thursday, January 23rd, 2014 AT 9:18 PM
Tiny
SATURNTECH9
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I was thinking of the earlier pressure regulators on those. But check the fuel pressure and check for vacuum leaks.
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Thursday, January 23rd, 2014 AT 9:26 PM
Tiny
SHADOWEN1
  • MEMBER
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Just as a quick update. I tested for vacuum leaks and found none. I also checked my codes again and am still pulling the same P1400 code but, now it is telling me I am running rich on both banks instead of rich on one of them and lean on the other. It is no longer giving me a code for the secondary after CAT O2 sensor but I know that one only shows up if it fails a certain amount of times in a row. Keep Calm and Troubleshoot On!
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Saturday, January 25th, 2014 AT 12:01 PM
Tiny
SATURNTECH9
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So whats the actual fuel pressure?How did you check for vacuum leaks?
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Saturday, January 25th, 2014 AT 4:22 PM
Tiny
SHADOWEN1
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  • 15 POSTS
Ok, as for the vacuum I started off the old fasioned was with a light, can of carburator cleaner and some patience. After that of cource I hooked up the vacuum guage. At idle it is at about 19 inches. And at 1000 - 2000 rpm it is at about 21 inches. When you quick rev it up to 2500 rpm and back to idle it will drop down to 5 and climb quickly up to about 25 then back to 19. This all seems just about the way it is supposed to be. The only hicup it had during the vacuum test was when we reved it up to 2500 a few times it started to stutter for a few seconds and smoke. Then it cleared up and ran normal.
The fuel pressure was 58 switched and between 59 to 60 at idle and other rpms. With a cold start it was at 58 when first switched on and while it was caughing and sputtering it bounced pretty wildly between 56 and 62. As soon as it started running normaly it settled down right where it was before at 59 to 60.
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Sunday, January 26th, 2014 AT 7:05 PM
Tiny
SATURNTECH9
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There many different ways to do a vacuum leak check you can spray around looking for a drop rise or stumble at idle. Watch the front o2 sensors reading for a spike while spraying around xarb spray at idle. But its better to do that while watching the short term fuel trims for spike. The fuel trims have a faster update rate then the front o2 sensors. The best way to check for a vacuum leak is to inject smoke into the brake booster vacuum hose. Then look for smoke leaking you have to block off the throttle body first.
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Sunday, January 26th, 2014 AT 8:46 PM
Tiny
SHADOWEN1
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  • 15 POSTS
Do you think I still need to look for vacuum leaks? The readings I got were just about perfect so, I was figuring I was pretty good in that arena.
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Sunday, January 26th, 2014 AT 10:03 PM
Tiny
SATURNTECH9
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What are the exact code numbers you have Right now?I have a search data base to type them into I found?
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Monday, January 27th, 2014 AT 3:01 PM
Tiny
SHADOWEN1
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Sorry I did not get back to you yesterday, I was on duty. The codes I have right now are:

P0175 - System too rich Bank 2
P0172 - system too rich Bank 1
P1400 - Cold Start Emission Reduction Control System
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Tuesday, January 28th, 2014 AT 6:13 PM
Tiny
SATURNTECH9
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I posted what I found there talking about cleaning the injectors by running the engine with a pressurized canister with cleaning solution in it.
Image (Click to make bigger)
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Tuesday, January 28th, 2014 AT 6:53 PM
Tiny
SHADOWEN1
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Where and how do you hook up the canister? Or would you need a special adapter to put it pre fuel rail in the fuel line?
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Tuesday, January 28th, 2014 AT 7:08 PM
Tiny
SATURNTECH9
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You have to unhook the fuel line cap off the fuel rail nipple where the line hooks to the rail. Then hook the pressurized canister up where you check for fuel pressure. Then you have to pull the fuel pump fuse. It would be cheaper to pay someone to do it betime you buy the canister adapters etc.
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Tuesday, January 28th, 2014 AT 7:54 PM

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