2014 5 3 engine issue

fsoria1315 · March 9, 2023

So I purchased a 2014 Chevy Silverado Z71 LTZ with the 5.3 with 141k miles. I've done tune up(Bosch double iridium plugs/ duralast wires), changed oil to royal purple, changed trans fluid with filter, changed transfer case fluid, has a rough country CAI, and have a diablo programmer.

I've noticed it consumes gas a lot average about 13.5MPG. Noticed at high RPMs when accelerating it pings and when I have AFM on and it switches from 4 to 8 cylinders it starts to detonate.

I've noticed the pinging happens with 87 tune or even stock tune. I've done fuel system cleaners and even used 91 octane with the same stock or 87 tune and issue still happens. I've been told it could be injector, fuel pressure regulator, or EGR value?

The truck drives pretty decent with normal driving besides the use of a lot of fuel averaging about 13 MPG. I've been told 16 to 17 should be normal?

Any help would be appreciated!

BO TIE 1 · March 9, 2023

Maybe try cleaning the MAF sensor. Seems like you've done everything else. Good luck.

fsoria1315 · March 9, 2023

5 hours ago, BO TIE 1 said:

Maybe try cleaning the MAF sensor. Seems like you've done everything else. Good luck.

Funny thing you say that. Took the truck on a 300+ mile trip and it broke down get shutting off. Had to tow it back home and come to find out the map sensor had a leaf inside of it causing it not to get a good reading. Cleaned it up and truck ran fine but issues with pinging and detonation still happens.

silveradosid · March 10, 2023

try some upper combustion cleaner

diyer2 · March 10, 2023

I always use OEM spark plugs and wires only. Look around this site and you will find this is recommended. Take it back to a stock tune.

BG 44K fuel system cleaner. Worth a try.

fsoria1315 · March 11, 2023

11 hours ago, diyer2 said:

I always use OEM spark plugs and wires only. Look around this site and you will find this is recommended. Take it back to a stock tune.

BG 44K fuel system cleaner. Worth a try.

I've done two Lucas fuel system cleaner the last few thousand miles. What are the stock plugs and wires? I purchased the plugs and wires from Autozone.

diyer2 · March 11, 2023

gmparts.com

plugs ACDelco Part # 41-168 GM Part # 19459511

wires

GM Part # 19431550

ACDelco Part # 19431550

GM Part # 19431551

ACDelco Part # 19431551

fsoria1315 · April 14, 2023

So I replaced the wires and plugs with the OEM ACDelco, issue still happening.

I took my truck over to a local mechanic I know and give them the issues I am having with my truck. They hooked up my truck to their scanner and saw the low-pressure fuel pump loses PSI at high RPM's. They recommended replacing it to see if they might fix the problem but said it might not also, it could be something small or something else not working correctly.

asilverblazer · April 14, 2023

The PCM may have been tuned by previous owner.

Have you tried running premium fuel?

Any other modifications to the truck?

Oversize tires, lift or leveling kit? Bigger tires and a lift would net fuel mileage similar to what you report.

Pinging and detonation are usually a timing problem, not a fueling issue. What PSI is the fuel pressure dropping to?

...maybe... the low pressure pump is starving the engine of fuel, causing a lean burn... which is hotter... leaving hot spots in the cylinder causing the problem... I would expect some codes though for all that.

fsoria1315 · April 14, 2023

1 hour ago, asilverblazer said:

The PCM may have been tuned by previous owner.

Have you tried running premium fuel?

Any other modifications to the truck?

Oversize tires, lift or leveling kit? Bigger tires and a lift would net fuel mileage similar to what you report.

Pinging and detonation are usually a timing problem, not a fueling issue. What PSI is the fuel pressure dropping to?

...maybe... the low pressure pump is starving the engine of fuel, causing a lean burn... which is hotter... leaving hot spots in the cylinder causing the problem... I would expect some codes though for all that.

I'm not sure, I bought the truck from an auction.

I have tried running different stations and premium, still happens.

When I got it, it had 31" tires and leveling kit rest was stock. Now I have 35" tires, 6" lift, exhaust, intake, and I have the diablo runner. Since these upgrades, my gas milage has dropped to high 10's/low 11's.

The mechanic said the PSI dropped to around 20-21 during high RPMs from the low-pressure pump in the rear. They said they recommend changing that because that is where it is dropping but also said it might not be the problem still could be something else.

The only code I had fault once before was a misfire in cylinder 7. A few times the check engine flashed for about 15 seconds and then shuts off.

asilverblazer · April 14, 2023

Assuming you don't have access to some quality scan tools to monitor live data, particularly fuel rail pressure from the high pressure pump and miss fire counts... My course of action below is easiest cheapest to more expensive harder...

4 hours ago, fsoria1315 said:

When I got it, it had 31" tires and leveling kit rest was stock. Now I have 35" tires, 6" lift, exhaust, intake, and I have the diablo runner. Since these upgrades, my gas milage has dropped to high 10's/low 11's.

Lots of variables are being introduced... first, I would return to factory tune, then I would put the factory intake back on, a quality paper air filter and careful thorough cleaning of the mass air flow sensor. The intake probably came with a reusable filter that is oiled, it could have been over oiled and contaminated the sensor.

4 hours ago, fsoria1315 said:

The mechanic said the PSI dropped to around 20-21 during high RPMs from the low-pressure pump in the rear. They said they recommend changing that because that is where it is dropping but also said it might not be the problem still could be something else.

I would hold off on this until other issues are resolved and confirmed not to be a problem. Mostly, because this is difficult and expensive to repair. Unless further more detailed diagnostics can confirm a fueling issue at the injectors.

4 hours ago, fsoria1315 said:

The only code I had fault once before was a misfire in cylinder 7. A few times the check engine flashed for about 15 seconds and then shuts off.

This definitely needs addressed, whether its the root cause or a casualty. New AC Delco plugs would be a start, then AC Delco plug wires. If the miss fire persists, then start checking the coil and injector. An underperforming cylinder will lower fuel mileage. Unless a careful monitoring of all cylinder miss fire counts reveals a problem on all cylinders in which case I would skip back to the fuel pump.

fsoria1315 · April 16, 2023

On 4/14/2023 at 12:04 PM, asilverblazer said:

Assuming you don't have access to some quality scan tools to monitor live data, particularly fuel rail pressure from the high pressure pump and miss fire counts... My course of action below is easiest cheapest to more expensive harder...

Lots of variables are being introduced... first, I would return to factory tune, then I would put the factory intake back on, a quality paper air filter and careful thorough cleaning of the mass air flow sensor. The intake probably came with a reusable filter that is oiled, it could have been over oiled and contaminated the sensor.

I would hold off on this until other issues are resolved and confirmed not to be a problem. Mostly, because this is difficult and expensive to repair. Unless further more detailed diagnostics can confirm a fueling issue at the injectors.

This definitely needs addressed, whether its the root cause or a casualty. New AC Delco plugs would be a start, then AC Delco plug wires. If the miss fire persists, then start checking the coil and injector. An underperforming cylinder will lower fuel mileage. Unless a careful monitoring of all cylinder miss fire counts reveals a problem on all cylinders in which case I would skip back to the fuel pump.

I do have the Diablo programmer that allows me to see live data.

I did have this issue with the stock tune and the truck was completely stock except for leveling kit and 305/55/20 tires. I have taken the MAF sensor out and cleaned it with MAF cleaner. I do have all the new mods on the truck I listed above.

I do have brand new AC Delco plugs and wires.

BO TIE 1 · April 16, 2023

Have you used the Diablo to reset your tire sizes in the settings since you changed sizes?

fsoria1315 · April 17, 2023

7 hours ago, BO TIE 1 said:

Have you used the Diablo to reset your tire sizes in the settings since you changed sizes?

I have not, but the problem was an issue even before the tire change and extra mods.

asilverblazer · April 17, 2023

20 hours ago, fsoria1315 said:

I do have the Diablo programmer that allows me to see live data.

I did have this issue with the stock tune and the truck was completely stock except for leveling kit and 305/55/20 tires. I have taken the MAF sensor out and cleaned it with MAF cleaner. I do have all the new mods on the truck I listed above.

I do have brand new AC Delco plugs and wires.

So what do the miss fire counts and fuel trim look like?

Trying to determine if you have a cylinder 7 problem or an engine fueling problem.

Correcting for tire size will change your MPG, calculated or truck computer. The odometer is off so the miles driven is not correct.

Your 3 symptoms, pinging (pre-ignition combustion), detonation (post ignition combustion) and poor MPG's.

The poor MPG's may not be as bad as you are thinking based on the odometer being off.

How do you know you are getting detonation in V4 mode? The engine will have a different sound, compared to V8 mode, it will be more of a drone in V4 mode.

I think the pinging is still tune related. Since you have no way to confirm whether the factory tune is the 'factory' tune or not, it may need to be seen by a professional tuner to investigate further. Generically speaking, a tune is going to be more aggressive with timing, too much = pinging.

My recommendation at this point is to visit a reputable in person tuner. They would be able to determine if there is a tune problem and if not they would have the tools to better determine the problem.