WTF moment

[jjt]

49 minutes ago, NateB1583 said:

How do I check the catalytic converter? Is it something that can be cleaned or does it have to be replaced once it's plugged? Since I replaced the 02 sensor (Sensor 1 Bank 1) the check engine light has gone away and code cleared. I would still like to check it out if needed though. 

I would just bring it to a muffler shop to see if it is plugged and if it is then replace with aftermarket one.

[Doug_Scott]

You cannot service catalytic convertors, other than replacing.  If you can accelerate to redline at WOT then your convertors are not the issue.  When checking grounds, remove both ends of the cables and look for any bulges in the insulation near the ends.   If there are bulges, chances are very good that the wire inside is corroding.  The wire inside the cables are made up of copper clad in aluminum and the aluminum corrode worse than copper ever did.  Watch for white powder coming out where the insulation ends. 

My buddy ran his 2 year old low mileage 04 GMC through the touch less car wash and within 100 feet of leaving he got codes and crappy running.  He dropped it off at the dealer where he purchased it and they said it was O2 sensors and it would be something like $400.  He wasn't impressed.  He bought the truck there from the salesman I always use, so I called the salesman and suggested that he may want to intervene because I am coming up another new car or truck in the next couple of months.  My buddy got a call from the service manager telling him it was going to cost $100, the deductible on his extended warranty that he didn't have.  Ever since then I always clench when going through the car wash.  I think there is something that some O2 sensors just aren't happy with when they get that underchassis spray on hot exhaust.  I also think it is only on specific sensors that are assembled with some very minor defect that goes undetected until it gets hit with cold high pressure chassis spray. 

[Snowcamo]

I will do that after I run this tank out (shouldn't take long ;) ) Thank You

I can't speak on which is better. However I've had my share of mixing and hoping i could create some super cleaning mix. That left the engines idling like complete crap at times. So much so i thought I srewed the engine up. Then i got gas after the tank got low. IIRC what one does when adding a cleaner is creating a fuel that burns faster too much cleaner and there it goes.

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[riverbanks]

Reading back,the 02 code happened before the car wash,so the dealer cleared codes to turn off light, monitor did it's check,code came back,I would take a garden hose at home,and start spraying while it's idling,see if it can be duplicated

[NateB1583]

On 6/18/2019 at 1:02 PM, Doug_Scott said:

You cannot service catalytic convertors, other than replacing.  If you can accelerate to redline at WOT then your convertors are not the issue.  When checking grounds, remove both ends of the cables and look for any bulges in the insulation near the ends.   If there are bulges, chances are very good that the wire inside is corroding.  The wire inside the cables are made up of copper clad in aluminum and the aluminum corrode worse than copper ever did.  Watch for white powder coming out where the insulation ends. 

My buddy ran his 2 year old low mileage 04 GMC through the touch less car wash and within 100 feet of leaving he got codes and crappy running.  He dropped it off at the dealer where he purchased it and they said it was O2 sensors and it would be something like $400.  He wasn't impressed.  He bought the truck there from the salesman I always use, so I called the salesman and suggested that he may want to intervene because I am coming up another new car or truck in the next couple of months.  My buddy got a call from the service manager telling him it was going to cost $100, the deductible on his extended warranty that he didn't have.  Ever since then I always clench when going through the car wash.  I think there is something that some O2 sensors just aren't happy with when they get that underchassis spray on hot exhaust.  I also think it is only on specific sensors that are assembled with some very minor defect that goes undetected until it gets hit with cold high pressure chassis spray. 

I am able to redline when i get on it. I also inspected the ground wires and they looked pretty clean and they were tight. I did not yet but i intend to unhook them and clean everything with a wire brush and reinstall with some dielectric grease. It has been crappy raining all week so i did not get to the car wash to spray underneath yet but should be able to get that done tomorrow. Thank you for your help.

[NateB1583]

14 hours ago, riverbanks said:

Reading back,the 02 code happened before the car wash,so the dealer cleared codes to turn off light, monitor did it's check,code came back,I would take a garden hose at home,and start spraying while it's idling,see if it can be duplicated

Will be doing this tomorrow for sure. weather should be clear and i have the day off work

 

[NateB1583]

So after a few days of no lights and smooth running truck, i was on the highway on my way home yesterday and the check engine light came back on. Low speeds seems again to have a surge like a possible misfire. I got the codes checked again at AutoZone today on my way home and sure enough cylinder 6 is throwing a P0306 code and suggests "Replace valve springs". Is this diagnostic tool just throwing out idea's or is it reading something in the system that is diagnosing the valve spring specifically. Thinking i might replace the fuel injector regardless (cheap and relatively simple) and go from there. Also getting O2 sensor P015B codes for the Sensor 1 Bank 1 sensor that i just replaced. Does this mean plugged cat due to a possible history of misfires?

[Snowcamo]

So after a few days of no lights and smooth running truck, i was on the highway on my way home yesterday and the check engine light came back on. Low speeds seems again to have a surge like a possible misfire. I got the codes checked again at AutoZone today on my way home and sure enough cylinder 6 is throwing a P0306 code and suggests "Replace valve springs". Is this diagnostic tool just throwing out idea's or is it reading something in the system that is diagnosing the valve spring specifically. Thinking i might replace the fuel injector regardless (cheap and relatively simple) and go from there. Also getting O2 sensor P015B codes for the Sensor 1 Bank 1 sensor that i just replaced. Does this mean plugged cat due to a possible history of misfires?

Give us some more run time man before you buy any parts. Likely due to the injector cleaner in regards to the misfire history

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[NateB1583]

Just now, Snowcamo said:

Give us some more run time man before you buy any parts. Likely due to the injector cleaner in regards to the misfire history

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Gotcha. So no emergency? I was just worried about causing damage by running it with misfires. If it is not an emergency I can give it another week and another fresh tank of gas with some different fuel system cleaner. 

[Snowcamo]

Gotcha. So no emergency? I was just worried about causing damage by running it with misfires. If it is not an emergency I can give it another week and another fresh tank of gas with some different fuel system cleaner. 

I see I miss read that if it is misfiring then I would start by checking the plugs. Very well could have broke something loose in the injector hope that's not the case. If I'm reading correctly you're saying that it's running a lot better with the new fresh tank of gas but you still have a misfire correct? Sorry trying to read while driving home from work sure. I'll check back later.

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[NateB1583]

I

2 minutes ago, Snowcamo said:

I see I miss read that if it is misfiring then I would start by checking the plugs. Very well could have broke something loose in the injector hope that's not the case. If I'm reading correctly you're saying that it's running a lot better with the new fresh tank of gas but you still have a misfire correct? Sorry trying to read while driving home from work sure. I'll check back later.

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I just replaced plugs and wires after the problem started last week. Since then, I am reading a lot of people online saying they can't run anything but AC Delco on their GM's because they get misfire's and unsteady idle. This has me considering replacing them again but with AC Delco this time. I don't recall which plugs I bought but they were the more expensive ones at Oreilly. It is definitely running better than when the problem first started though. At first it was misfiring to the point I though I was going to nuke it if i drove it and check engine light was flashing along with stablilitrack and traction control lights on. I was able to get it smoothed out and check engine cleared for a few days but now check engine is back but solid instead of blinking, and still running much better with a slightly noticeable misfire at low rpm's. 

[Jsdirt]

I run NGKs in everything - motorcycles, lawn equipment, truck, etc.. - the Iridiums are exactly the same as what GM put in my '07 with an AC Delco label on it. That said, these days misfires are rarely caused by ignition problems.

 

The computer isn't smart enough to diagnose a misfire due to a busted valve spring. A misfire can be caused by alot of things - ignition, vacuum leaks, compression, valve train, or cam problems, fuel injectors, bad fuel, etc.. You'll need to do a compression test, plus a RUNNING compression test to find a busted spring - they can be tricky to find. With the year model truck that you have, a broken spring, or bad AFM lifter are very high possibilities. #6 is an AFM cylinder, if I remember right. Check out this page for tips on running compression tests: https://support.alldata.com/article/tech-tip/running-compression-tests

 

I would perform an injector drop test using a bi-directional scan tool before wasting money on an injector you probably don't need. Doubt there's anything "breaking up" in the fuel system, unless that truck sat parked with 10% ethanol gas in it for 5 or more years, or something was dumped in the tank. Fuel is very clean these days. Only way crap will get in there is from dirty gas cans, gas cap off in dusty areas (or mud, or rain), or sabotage.

 

EDIT: I forgot to ask an extremely important question. Is that a Direct Injection (DI) fuel system on that? I forget what year GM came out with that. Lots of problems with intake valve coking on those.

[Jsdirt]

59 minutes ago, NateB1583 said:

Gotcha. So no emergency? I was just worried about causing damage by running it with misfires. If it is not an emergency I can give it another week and another fresh tank of gas with some different fuel system cleaner. 

If the misfire is bad enough (and there is raw fuel being pumped through the cylinder(s) ), it will melt down your catalytic converter(s). A blinking check engine light is an indicator of a cat-melting misfire. 

 

If you live where there is no emission testing, this isn't a huge deal, since you can eliminate, or punch through them if desired.

[Snowcamo]

I
I just replaced plugs and wires after the problem started last week. Since then, I am reading a lot of people online saying they can't run anything but AC Delco on their GM's because they get misfire's and unsteady idle. This has me considering replacing them again but with AC Delco this time. I don't recall which plugs I bought but they were the more expensive ones at Oreilly. It is definitely running better than when the problem first started though. At first it was misfiring to the point I though I was going to nuke it if i drove it and check engine light was flashing along with stablilitrack and traction control lights on. I was able to get it smoothed out and check engine cleared for a few days but now check engine is back but solid instead of blinking, and still running much better with a slightly noticeable misfire at low rpm's. 

Ah makes sense now. I run denso iridium plugs and wires, tho it shouldnt matter if the plugs are gapped correctly. But Denso are better quality. Lot of senerios being tossed around. The last one about the cat melting goes along with my first post in reguards to a faster burning fuel as it is also has more heat in the combustion process. However even though you changed plugs it wouldn't hurt to check #6s condition and plug gap.

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[NateB1583]

On 6/18/2019 at 11:11 AM, MaverickZ71 said:

Use a couple of bottles of Chevron Techron Fuel System cleaner (not fuel injection cleaner, that they also sell) once in a while.  It's available at WalMart and auto supply stores.  The Owner's Manual says to use GM Fuel System Treatment PLUS at each oil change if you need to.  The GM stuff is the Chevron Techron Fuel System Cleaner, same bottle, but with a GM label on it.  

So i went to Walmart Friday to pick some of this stuff up. As soon as i saw it i recognized it. This is the stuff i bought buy one get one at the auto store. I ended up getting some Lucas brand deep clean fuel system cleaner.