2003 Silverado 1500hd 6.0 hard start.

[riverbanks]

So,lean,I think your pressure is low,but gauge, maybe?and first start is open loop,later on is closed loop,a sensor is sending bad info,c.t.s stuck lean?map gone dumb?

[duhzombie]

So,lean,I think your pressure is low,but gauge, maybe?and first start is open loop,later on is closed loop,a sensor is sending bad info,c.t.s stuck lean?map gone dumb?

Maybe the map that I haven’t changed. I did swap out an entire intake though just to make sure my intake/throttle body wasn’t at fault (didn’t buy a new intake had a spare laying around from a swap).


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[riverbanks]

A look with a scanner would be nice,unless you have a spare map

[riverbanks]

Still thinking,in the back of my mind,I am suspicious of a leaking injector (s)do you think,use a screwdriver to ear and other end on each injector,listen to them all,see if click is equal,or pull plugs,look for a wet or black one, just typing out loud,the bulb above my head is dim,but lit,lol

[duhzombie]

A look with a scanner would be nice,unless you have a spare map

I’ll check once I get back home on my scanner. I think I can check the map in it.


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[duhzombie]

Still thinking,in the back of my mind,I am suspicious of a leaking injector (s)do you think,use a screwdriver to ear and other end on each injector,listen to them all,see if click is equal,or pull plugs,look for a wet or black one, just typing out loud,the bulb above my head is dim,but lit,lol

Yeah I’ll check that on my break in a min. I thought injectors as well but didn’t want to go out and just throw parts at it especially injectors haha they’re pricey. They all look good and seemed to no leak when I had the rail off and them hooked up to pressurize them. I’ll check the spark plugs for wetness though.


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[duhzombie]

So I was able to get some reading from my scanner. I’m not great at reading the data but I got a some pictures while running the data so maybe something will stick out.

 

 

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[riverbanks]

Bank 2 running rich.799,watch bank 2 sensor 1, see how low it goes, hoping below .45,and bank 2 sensor 2 is reading low,lack of o2,least now you only have to pull plugs on that side,might have a bad spray pattern on one

[riverbanks]

I wrote that backwards on b2sensor2,lean,not lacking 02,do you have a leak in exhaust on that side, before cat

[duhzombie]

So that’s the passenger side right?


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[riverbanks]

Yep, remember perfect is .45 on b1s1,b2s1,a little below,a little above,back and forth,5 times a second,or as fast as the scanner can display

[duhzombie]

So while checking the o2 reading I noticed that the truck has the hard start when the fuel system is in open loop. Every time it’s closed it starts fine. Checking the plugs and injectors now.


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[duhzombie]

Here’s a video of the live data I get from the O2

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[CamGTP]

Hold on a minute guys, the o2 sensors have a range they are going to be in. You can't take a freeze frame picture and say something is bad without seeing the live data from it.

 

On the 2 upstream primary o2 sensor, they have one objective and that is to keep fueling around stoich. In numbers terms, stoich is .450mv. The o2 sensors will show it switching lean and rich of stoich to keep fueling in line. You would want to watch the sensor movement and the fuel trims. Seeing the sensors drop and rise from .100 to .900 mv is good and exactly how you want them to operate.

 

 

The freeze frame shots showed the long term trims at less than 5%, which is perfectly fine for a good running engine.

 

The rear o2 sensors will tend to stay in the 500-700 range once the exhaust is fully heated up because they are only there to monitor the cat converter. When a cat goes bad the rear o2 sensor will stray from there values and could even start switching like the upstream o2 sensors because the insides of the cat are not doing it's job anymore.

 

 

 

Also, all engines start in open loop. The time it takes to switch to closed loop depends on coolant temp and a delay. If the engine was already completely up to temp, it would start and should immediately enter closed loop. A cold engine won't enter closed loop until engine temps are generally over 130 degrees.

[duhzombie]

Hold on a minute guys, the o2 sensors have a range they are going to be in. You can't take a freeze frame picture and say something is bad without seeing the live data from it.
 
On the 2 upstream primary o2 sensor, they have one objective and that is to keep fueling around stoich. In numbers terms, stoich is .450mv. The o2 sensors will show it switching lean and rich of stoich to keep fueling in line. You would want to watch the sensor movement and the fuel trims. Seeing the sensors drop and rise from .100 to .900 mv is good and exactly how you want them to operate.
 
 
The freeze frame shots showed the long term trims at less than 5%, which is perfectly fine for a good running engine.
 
The rear o2 sensors will tend to stay in the 500-700 range once the exhaust is fully heated up because they are only there to monitor the cat converter. When a cat goes bad the rear o2 sensor will stray from there values and could even start switching like the upstream o2 sensors because the insides of the cat are not doing it's job anymore.
 
 
 
Also, all engines start in open loop. The time it takes to switch to closed loop depends on coolant temp and a delay. If the engine was already completely up to temp, it would start and should immediately enter closed loop. A cold engine won't enter closed loop until engine temps are generally over 130 degrees.

Hmm damn idk then. It does seem to run great but on my way home just now I did get the p300 misfire flashing on the dash when around 70mph first time this has happened since the hard start issue started.


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