2017 issues

[YJSONLY]

Long story short:

New vehicle to me 2017 suburban 5.3 had 37,000 miles.

 

Vehicle had rough idle and would miss. Took to dealer they replaced motor mounts some tsb about them under powertrain warranty.

 

At 39,000 miles and a week-10 days or so later (when I drove it not wife). Popped up cold start error code. Took to dealer told I need 2 new injectors and 3 fuel rail parts. I paid for all these. Thanks GM for a wonderful fuel design by the way. [emoji849].

Picked up car didn’t make it a half mile had to turn back light came on. Fuel trim code.

 

For a solid week at dealer. I was told the car on build up on piston was built up and damaged spark plug... needed to clean carbon off which they done. To then had to order 2 more injectors because the ones they replaced where bad out of the box......

 

So now my question is. Should the rpm gauge at idle be consistent? See video.

 

 

And what really happened after they replaced the injectors to have to replace the injectors again that would give a fuel trim code?

[Black02Silverado]

Yes that is normal for the rpm.  Well if the injectors they installed were not calibrated correctly then they would throw a trim code.

[YJSONLY]

Yes that is normal for the rpm.  Well if the injectors they installed were not calibrated correctly then they would throw a trim code.

They say they did the re cal. They thought that was the issue when I took back the same day. Then they said/did the other stuff. (Carbon build up on piston/hitting spark plug electrode and cleaned the deposit 2-3 times). But still was throwing trim code. And then they had to order 2 new replacement injectors.


So to be clear it is normal for the rpm to bounce like that under idle with or without the ACs on?

[Black02Silverado]

1 hour ago, YJSONLY said:

 

They say they did the re cal. They thought that was the issue when I took back the same day. Then they said/did the other stuff. (Carbon build up on piston/hitting spark plug electrode and cleaned the deposit 2-3 times). But still was throwing trim code. And then they had to order 2 new replacement injectors.


So to be clear it is normal for the rpm to bounce like that under idle with or without the ACs on?

Yes it is normal for the rpm to move like in your video.

[YJSONLY]

Yes it is normal for the rpm to move like in your video.

Thank you.

[Doug_Scott]

The easy way to decarbon the engine is to simply go to the closest highway on ramp and from a dead stop floor it and hold it there till you hit speed limit.  Watch the crap come out the exhaust.  Do it a couple of times to get it all. 

If the idle is too rough you will get a code thrown for excessive misfires. 

[Colossus]

I also recommend running some BG44K and if needed, having a EPR service done.  I like the idea of running the hell out of it like the post above this, but sadly that's not going to get much done, it'll do some but not the good chunk of it.

 

DI Engines are a whole new animal when it comes to carbon mitigation.

 

https://www.bgprod.com/catalog/engine/bg-epr-engine-performance-restoration/

 

 

 

 

[YJSONLY]

I also recommend running some BG44K and if needed, having a EPR service done.  I like the idea of running the hell out of it like the post above this, but sadly that's not going to get much done, it'll do some but not the good chunk of it.
 
DI Engines are a whole new animal when it comes to carbon mitigation.
 
https://www.bgprod.com/catalog/engine/bg-epr-engine-performance-restoration/
 
 
 
 

Is this something I can do myself. Doesn’t look like any shops near me

[Doug_Scott]

Never been a fan of these "cleaners".  The big difference in how direct injection has changed the carbon world is back in the intake ports.  Moving the fuel injection into the cylinder removed the wash down effect of spraying fuel ahead of the intake valve, helping wash the oil misting off the valve stem.  The pcv system pulls oil vapour from the crankcase and dumps it back into the intake.  Oil does not vaporize in the air stream and hits the stem and back of the intake valve head.  Injected fuel used to help a bit to wash some of it off.  Not any more. 

Using an oil trap on the pcv line will help alleviate the oil from hitting the intake in the first place.  You would be surprised at how quickly it can gather a cup of oil. 

Misting water into the intake AFTER the MAF sensor will remove carbon from top of piston.  I find it hard to believe your engine managed to get enough carbon like they described in the first place. Your truck has high mileage for its age.  40,000 miles is usually over 3 years, your truck is probably half that age.  That means a lot of highway mileage, not the traditional carbon build up driving. 

[YJSONLY]

Never been a fan of these "cleaners".  The big difference in how direct injection has changed the carbon world is back in the intake ports.  Moving the fuel injection into the cylinder removed the wash down effect of spraying fuel ahead of the intake valve, helping wash the oil misting off the valve stem.  The pcv system pulls oil vapour from the crankcase and dumps it back into the intake.  Oil does not vaporize in the air stream and hits the stem and back of the intake valve head.  Injected fuel used to help a bit to wash some of it off.  Not any more. 
Using an oil trap on the pcv line will help alleviate the oil from hitting the intake in the first place.  You would be surprised at how quickly it can gather a cup of oil. 
Misting water into the intake AFTER the MAF sensor will remove carbon from top of piston.  I find it hard to believe your engine managed to get enough carbon like they described in the first place. Your truck has high mileage for its age.  40,000 miles is usually over 3 years, your truck is probably half that age.  That means a lot of highway mileage, not the traditional carbon build up driving. 

It was a rental car I do know that.

[Doug_Scott]

3 hours ago, YJSONLY said:

 

It was a rental car I do know that.

 

You may want to ask your salesman to get you a service history on it.  Rentals where I am typically appear with 30,000 km on them, and usually being in service for 12 months.  They are usually a good deal if you get a dealer that gets a load of them at a time.  We don't generally ever see trucks though.  My brother in law has bought a couple of those cars when his daughters got drivers licenses.  Paid about half price for a current model year(just) Impala a few years ago.  Paid $16.5k for a car that listed for $32k 11 months earlier.  Car had 28,000 km on it. 

[YJSONLY]

So I drove this vehicle some more. And I know there is something going on. No lights or anything. But you can sit there and it will run fine for a few seconds or so then rpms fall and you can hear/feel a miss or something happening.

[Doug_Scott]

Get the service history for it.  You need to see if there has been a history of repairs or reports of rough running.  I can tell you that without trouble codes being set they will correctly tell you the engine is running within specs.  I would suggest that until it sets a code just stop staring at it. Keep in mind that if you disconnect the battery you will lose some of the learned "adjustments" in the ECM.  The ECM will relearn based upon your driving habits. 

[YJSONLY]

Get the service history for it.  You need to see if there has been a history of repairs or reports of rough running.  I can tell you that without trouble codes being set they will correctly tell you the engine is running within specs.  I would suggest that until it sets a code just stop staring at it. Keep in mind that if you disconnect the battery you will lose some of the learned "adjustments" in the ECM.  The ECM will relearn based upon your driving habits. 

Besides me with the rough running there is no others. Sitting at s red light it’s normal for a a few secs of miss/rough running??? Same time rpms dip....