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1997 chevy 1500 4.3l misfire codes, running rich


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revolute
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Jun 3, 2012, 11:08 PM

Post #1 of 11 (2909 views)
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1997 chevy 1500 4.3l misfire codes, running rich Sign In

I have a 97 chevy 1500 with 4.3l. 350000 miles on it. It runs like poop. It idles rough, and is very sluggish when accelerated unless i put alot of gas into it. Pretty much typical running rich symptoms. Ive changed plugs, wires, rotor, cap, and air filter, and fuel filter. Ive cleaned the maf sensor-no difference. Ive tested the hz load on the maf and it fluctuates a good bit even in just idol. The numbers are jumpy...possibly bad? Ive sprayed carb cleaner looking for vacuum leaks but came up with no leaks.


I bit the bullet and got a scan tool with live data stream. It comes up with 0300, 0102, 0172, and 0175.

Ive looked at the live data but im not really sure what this engine should read normally like timing, and o2 sensor specs. This info or where to find this info is what i need the most right now. Ive searched google but came up with nothing as far as how to interpret the info coming from the scan.

Some other things i need to check is my cat converter and fuel pressure. I really dont wanna spend a ton of money fixing parts that have nothing wrong with them which is why i bought the scan tool.

I need to get this thing fixed because ill be using it for my new job and ill need the best mpg's i can get.

Any help would be great. Thanks.



More info...I pulled my cat off to see if it was clogged up. It wasn't.
In fact i could see right through it and see that it was in fact hollow. So my thinking is that the downwind o2 sensor is picking up the unburnt

exhaust and changing the way the engine is running. Does this make sense?
Im pretty desperate to figure this out. Please help.



(This post was edited by Double J on Jun 4, 2012, 12:11 AM)


Hammer Time
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Jun 4, 2012, 6:08 AM

Post #2 of 11 (2841 views)
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Re: 1997 chevy 1500 4.3l misfire codes, running rich [In reply to] Sign In

No, the cat and downstream sensor have nothing to do with the way it's running. You have a rich condition and a MAF code so that's where I would be starting. There is something wrong with the MAF circuit.




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Tom Greenleaf
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Jun 4, 2012, 6:45 AM

Post #3 of 11 (2836 views)
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Re: 1997 chevy 1500 4.3l misfire codes, running rich [In reply to] Sign In

revolute: 350,000 miles! Do you have a good history on what has been done with hard mechanical/wearing drivetrain everything on this? If original engine if known and so on.

A truly hollow cat converter!? Wouldn't be surprised if some place sells them to appear real.

What did old plugs look like compared to each other? For the moment I'm not so concerned with codes but the miles unless a typo I would be concerned about general mechanical condition of this engine. Compression ok? Does or did it burn oil? Oil pressure quick to come up to spec and so on.

Would hate to hear of anyone losing new employment over being late or a no show because of a vehicle and can happen to any at any mileage but this is pushing it IMO,

T
_________________________________________
Long retired now


Discretesignals
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Jun 4, 2012, 8:22 PM

Post #4 of 11 (2809 views)
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Re: 1997 chevy 1500 4.3l misfire codes, running rich [In reply to] Sign In


Quote
0172, and 0175


Unplug the MAF sensor and see if your richness goes away.

Look at your fuel trim. Long and short term. What are they reading at idle with the engine warmed up?





Since we volunteer our time and knowledge, we ask for you to please follow up when a problem is resolved.

(This post was edited by Discretesignals on Jun 4, 2012, 8:23 PM)


revolute
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Jun 4, 2012, 9:40 PM

Post #5 of 11 (2796 views)
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Re: 1997 chevy 1500 4.3l misfire codes, running rich [In reply to] Sign In


In Reply To
revolute: 350,000 miles! Do you have a good history on what has been done with hard mechanical/wearing drivetrain everything on this? If original engine if known and so on.


A truly hollow cat converter!? Wouldn't be surprised if some place sells them to appear real.

What did old plugs look like compared to each other? For the moment I'm not so concerned with codes but the miles unless a typo I would be concerned about general mechanical condition of this engine. Compression ok? Does or did it burn oil? Oil pressure quick to come up to spec and so on.

Would hate to hear of anyone losing new employment over being late or a no show because of a vehicle and can happen to any at any mileage but this is pushing it IMO,

T

No clue whats been done to it. It was pretty much given to me so i cant really complain.

I pulled out one plug that was throwing off 0306, so the #6 plug and it had lots of black carbon but was still firing. Last time i changed them, it did nothing for engine performance.
Dont know about compression because i havent checked it... yet. It does leak and/or burn oil.
My oil pressure used to sit around 40 at idle in gear and hit 60 at hwy speeds. I think i may have over filled it or something. Now it goes to 15 at idle in gear and 40 at hwy speeds. Not sure what the specs are.



revolute
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Jun 4, 2012, 9:43 PM

Post #6 of 11 (2795 views)
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Re: 1997 chevy 1500 4.3l misfire codes, running rich [In reply to] Sign In

Ive unplugged the maf but it didnt change anything. short fuel trim readings are -30% and long term is -18% and goes up when i hit the gas.


Discretesignals
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Jun 4, 2012, 9:53 PM

Post #7 of 11 (2791 views)
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Re: 1997 chevy 1500 4.3l misfire codes, running rich [In reply to] Sign In

With fuel trims like that you definitely have a rich condition.

Got a feeling you have a problem under the intake. Leaking fuel pressure regulator or injector itself. Your going to have to remove the plastic upper intake and then pressurize the fuel system by turning the key on to see what is leaking under there after putting the fuel pipe back on the top of the injector. Should be pretty obvious.





Since we volunteer our time and knowledge, we ask for you to please follow up when a problem is resolved.

(This post was edited by Discretesignals on Jun 4, 2012, 9:57 PM)


revolute
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Jun 4, 2012, 9:56 PM

Post #8 of 11 (2781 views)
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Re: 1997 chevy 1500 4.3l misfire codes, running rich [In reply to] Sign In


In Reply To
With fuel trims like that you definitely have a rich condition.

Got a feeling you have a problem under the intake. Leaking fuel pressure regulator or injector itself. Your going to have to remove the plastic upper intake and then pressurize the fuel system by turning the key on to see what is leaking under there. Should be pretty obvious.


Thanks. I will check that and also check my fuel pressure from the pump if i need to.



Discretesignals
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Jun 4, 2012, 9:59 PM

Post #9 of 11 (2777 views)
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Re: 1997 chevy 1500 4.3l misfire codes, running rich [In reply to] Sign In

You can also remove the throttle body and then use a flashlight and small mirror to see under there.





Since we volunteer our time and knowledge, we ask for you to please follow up when a problem is resolved.


nickwarner
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Jun 5, 2012, 6:19 PM

Post #10 of 11 (2760 views)
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Re: 1997 chevy 1500 4.3l misfire codes, running rich [In reply to] Sign In

If you want an idea how to interpret your data streams go on YouTube and look for ScannerDanner. the guy is a tech instructor and has some great videos. He gets very technical and can be hard to follow as a novice but well worth watching to pick up some knowledge.


Discretesignals
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Jun 5, 2012, 6:26 PM

Post #11 of 11 (2758 views)
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Re: 1997 chevy 1500 4.3l misfire codes, running rich [In reply to] Sign In

He's my hero....

Nick, you bought his E book yet?





Since we volunteer our time and knowledge, we ask for you to please follow up when a problem is resolved.




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