Possessed truck please help

Wmfmike3 · February 5, 2020

I have a horrible 08 silverado 1500. Bought used with 121k miles. Power steering pump was a little week. 2 weeks after buying it I got a p0420. Replaced with after market cats and o2 sensors. Next day p0420 codes came back.... Lots more of them too p069e p2272 p0157 started notice it stumbling at stop lights and then would get p0420 p0430. Next the service 4 wheel drive lights would come on randomly on dry pavement on the Hwy. Sometimes I'll park turn the key and nothing happens...turn the key again and the clocks and temp control reset but starts Now I just started getting a misfire (still fine when on hwy) and these codes p0161 p0056 brought it to the dealer and they said I had a grounded 02 wire which I did. And is now fixed.... Really don't think an o2 wire would do all this questioning the dealers diagnosis and now lol I just got a flashing cel but only for a second and won't leave a code and my stabilitrak comes on intermittently but only in park. Oh and my after market cats pass on my obd reader except today bank 2x1 and 2x2 both read 0 other side read how it should. Any advice would be great. I now have 137k miles and would love a few more

Edited February 5, 2020 by Wmfmike3
Misspelled a few words

swathdiver · February 5, 2020

12 hours ago, Wmfmike3 said:

I have a horrible 08 silverado 1500. Bought used with 121k miles. Power steering pump was a little week. 2 weeks after buying it I got a p0420. Replaced with after market cats and o2 sensors. Next day p0420 codes came back.... Lots more of them too p069e p2272 p0157 started notice it stumbling at stop lights and then would get p0420 p0430. Next the service 4 wheel drive lights would come on randomly on dry pavement on the Hwy. Sometimes I'll park turn the key and nothing happens...turn the key again and the clocks and temp control reset but starts Now I just started getting a misfire (still fine when on hwy) and these codes p0161 p0056 brought it to the dealer and they said I had a grounded 02 wire which I did. And is now fixed.... Really don't think an o2 wire would do all this questioning the dealers diagnosis and now lol I just got a flashing cel but only for a second and won't leave a code and my stabilitrak comes on intermittently but only in park. Oh and my after market cats pass on my obd reader except today bank 2x1 and 2x2 both read 0 other side read how it should. Any advice would be great. I now have 137k miles and would love a few more

Cheap Chicom cats rarely last more than a year. It is not unusual for a new cat to throw a code within the first 100 miles or so after installation. I replaced my cats and y-pipe with Magnaflow about two years ago and am good.

Ok, all the codes up there seem to be related to O2 sensors, several and not one right? If the wiring all the way to the ECM is good and hasn't been eaten by mice or chafed away, I would say it's time for a new ECM. If you had codes from other places, I would say the problem was battery/battery cables and grounds related.

Flashing CEL is usually a misfire, not good. Could be a collapsed lifter causing a misfire.

If you do have a problem with your engine, it can take out your cats, even those new ones. If you like this truck and want to keep, and save money working on it, get a Tech-2. It's the most important tool in your box, more than the wrench, and will quickly pay for itself. They run about $350 delivered on ebay. This is the tool the dealerships will use to work on your truck.

Wmfmike3 · February 5, 2020

Well what's really strange is the traction control and stabilitrak say they have turned off or needs to be serviced. it will misfire. say my trucks at 10.5 volts no battery light and then it will bump up to 14v after about 15 min. Other times I start the truck and it stays at 14.

The cats, after replacement of the whole y pipe everything new o2 sensors..... It gave me signals both cats had failed.... Mind you this only happens if I've been driving a bit and come to a stop light. After stopped about 15-30 seconds my truck shudders and would throw cat codes. If I give any gas at all...ie 50 extra rpm no cat codes and since stabilitrak and traction and service 4x4 I haven't thrown a cat code only o2 sensor codes and bank 2x1 and 2x2 are at 0. And I cant find a broken wire anywhere. Also strange, I don't get cat codes and they are all on the same side.

Flashing cel also is intermittent because on the Hwy it runs great. Thanks for your help on this.... Honestly is stressing the hell out of me since the dealership wouldn't help and other shops just tell me that they just don't understand

swathdiver · February 5, 2020

7 minutes ago, Wmfmike3 said:

Well what's really strange is the traction control and stabilitrak say they have turned off or needs to be serviced. it will misfire.

That's normal when there's a misfire.

7 minutes ago, Wmfmike3 said:

say my trucks at 10.5 volts no battery light and then it will bump up to 14v after about 15 min. Other times I start the truck and it stays at 14.

Look up RVC and EPM, the computer controls the output of the alternator, uses it like a smart charger to extend the life of the alternator and battery. However, a bad cell in a battery or one near worn out, can wreak all kinds of havoc with the electrical system. If the battery is more than a couple years old, replace it. Quite often fellas will start getting all kinds of errors, warning lights, stuff cutting in and out and it turns out to be the battery most of the time. The other times it is corroded cables or grounds.

10 minutes ago, Wmfmike3 said:

The cats, after replacement of the whole y pipe everything new o2 sensors..... It gave me signals both cats had failed.... Mind you this only happens if I've been driving a bit and come to a stop light. After stopped about 15-30 seconds my truck shudders and would throw cat codes. If I give any gas at all...ie 50 extra rpm no cat codes and since stabilitrak and traction and service 4x4 I haven't thrown a cat code only o2 sensor codes and bank 2x1 and 2x2 are at 0. And I cant find a broken wire anywhere. Also strange, I don't get cat codes and they are all on the same side.

Only use GM OE or ACDelco parts. The computer system doesn't take kindly to aftermarket parts, especially O2 sensors for some reason. If you are getting codes on one side, swap the sensors and see if the problem changes sides or remains.

Which engine do you have? In your glovebox is your RPO Sheet, look for LY5, LC9, LMG, LY2, L76, etc.

Do you have a scan tool or OBDII Bluetooth adapter? It would be helpful to see your Fuel Trims. The Tech-2 can also see and graph them.

Wmfmike3 · February 6, 2020

Here's a couple pics. Wondering if it could be the coolant temp sensor or tps.... Coolant sensor reading online sounds like it causes many of the issues but not all of them. Just strange because my o2s on bank 2 are usually 0 but just now 2x2 is pinned at max. Also just got a p0300. Multiple random cylinders misfiring (first misfire code) and at idle should my tps be reading 20%? And unfortunately that sheet wasnt in my glove box so im unsure of motor. Its a 5.3l

swathdiver · February 6, 2020

3 hours ago, Wmfmike3 said:

Here's a couple pics. Wondering if it could be the coolant temp sensor or tps.... Coolant sensor reading online sounds like it causes many of the issues but not all of them. Just strange because my o2s on bank 2 are usually 0 but just now 2x2 is pinned at max. Also just got a p0300. Multiple random cylinders misfiring (first misfire code) and at idle should my tps be reading 20%? And unfortunately that sheet wasnt in my glove box so im unsure of motor. Its a 5.3l

Check the 8th digit of your VIN, it will be J for LY5, 3 for LC9 or 0 for LMG. The latter two are FlexFuel engines and are always measuring the alcohol content of your fuel and compensating for that. Sometimes the system gets out of whack and has to be reset.

Can you graph the O2 Sensors? The upstream sensors should move up and down from 200-900 or maybe 200-700 pretty steadily once warmed up and at a steady speed. The downstream sensors should be rather steady and not move around so much. If they do move around a lot, that particular catalytic converter is no longer doing its job.

Also run a graph or get the percentages of the LTFTs, the Long Term Fuel Trims for each bank. Would like to see what they are at idle once warmed up.

Is that the Torque or Dash Command app? I have little experience with both, very little!

Edited February 6, 2020 by swathdiver

Wmfmike3 · February 6, 2020

My 8th letter is an m and my 7th letter is a 3.

I am using torque and it doesn't have long term fuel trims but I did the best I could to graph what you asked for I can also do individual graphs for each bank too. This is warmed up and no sputtering or traction or stabilitrak messages. Also I noticed on a short drive.... Stabilitrak and traction lights only come on for 5-10 min upon start up. Sometimes will continue when at a stop light but still seems totally fine while driving

swathdiver · February 6, 2020

1 hour ago, Wmfmike3 said:

My 8th letter is an m and my 7th letter is a 3.

I am using torque and it doesn't have long term fuel trims but I did the best I could to graph what you asked for I can also do individual graphs for each bank too. This is warmed up and no sputtering or traction or stabilitrak messages. Also I noticed on a short drive.... Stabilitrak and traction lights only come on for 5-10 min upon start up. Sometimes will continue when at a stop light but still seems totally fine while driving

Hmm, you should be able to pull up the LTFTs, you have one STFT there in the photo. Anyhow, when the truck is running, what are O2 1x1 and 2x1 doing? Looking for data on upstream O2 sensors. Are they constantly moving up and down?

Now for the downstream sensors, they should be more steady, O2 1x2 and 2x2 I think they'll be.

Now with the misfires, can it tell you which cylinders and how often? How about the knock sensors?

The 8th letter is an M? That would be an LH6 and to my knowledge was only used in vans or something other than the pickups and wagons. Anyhow, see if you can check the alcohol content of the fuel too.

Edited February 6, 2020 by swathdiver

Wmfmike3 · February 6, 2020

Misfire code says random and multiple cylinders but won't do individual cylinders... I'm guessing bank 2 and I can't remember if thats odd or even cylinders. And I cant find the lifts anywhere just short term. This pic is warm at about 2000 rpm going down the hwy

I can't check alcohol levels either.... I think k it's time for a better reader. Also i had 1extra oem o2 sensor that I'm going to put in 2x2 at lunch

swathdiver · February 6, 2020

3 hours ago, Wmfmike3 said:

Misfire code says random and multiple cylinders but won't do individual cylinders... I'm guessing bank 2 and I can't remember if thats odd or even cylinders. And I cant find the lifts anywhere just short term. This pic is warm at about 2000 rpm going down the hwy

I can't check alcohol levels either.... I think k it's time for a better reader. Also i had 1extra oem o2 sensor that I'm going to put in 2x2 at lunch

From the limited amount of time I spent with Torque Pro, you can download set ups for your truck type or configure your own if you the PIDs. I think I used the GMT800 profile for mine but I bought it for my daughter and her car, I use the Tech-2. I was able to pull up the alcohol content and fuel trims using Dash Command.

Ok, well, your downstream O2 sensor on the passenger side is dead, not reading. Are these ACDelco sensors? Upstream sensors are 12583804/213-3866 and downstream or rear sensors are 12609457/213-4229. Can you swap them to the other side? With a proper scan tool or the app set up right, you should be able to see the misfire count on each individual cylinder.

Your driver's side O2 sensors appear to be operating perfectly. Your Short Term Fuel Trims on the driver's side might be alluding to something being amiss, like a vacuum leak. Your TPS being at 20% is also not right, should be 2%-7% or so but may be compensating for an error and since there are no codes for it, something to keep an eye on.

If you cannot get Torque Pro set up, try Dash Command and download those configurations for our trucks. Try talking to Ken KBusKill over at the TahoeYukon Forum. Those guys know more about these Bluetooth apps then I do. We'll also get more help over there, seems the fellas here are busy elsewhere these last few days.