i meant any* help would be greatly appreciated

 

Forget the cat's at this point in time, ...and stop guesstimating with changing parts out hoping for a fix!!! This motor needs to be diagnosed. Your changing of parts could of worsen your problem.

Time for you to connect a scan tool that reads data.

We need codes (if available)

We need fuel pressure readings at idle then at 2,000 rpm's.

Short term fuel trim (ST Fuel trim) - reading at idle and at 2,000 rpm's.

Long term fuel trim (LT Fuel trim) - reading at idle and at 2,000 rpm's.

O2 sensor readings on banks 1 and 2 - reading at idle and at 2,000 rpm's.

How many flip flops in voltages occur in 5 seconds with the O2 sensors at idle and at 2,000 rpm's?

MAF sensor readings at idle and at 2,000 rpm's.

I need TPS voltages / TPS percentages from idle to WOT (Wide Open Throttle) with the motor "not" running.

Then did you use "factory OEM" O2 sensors, ..or some aftermarket type sensors???

Report back once the data has been acquired, … once the data is posted, we will head in the right diagnostic direction.

 

good morning thanks for the reply rick! so my absolute throttle at idle not running is 29.0% and wot is 83.9 bare with me as i don't have much experience with the scan tool ive been trying to read up on it the past couple of days to help myself but these are the data logs i have
https://ibb.co/Hn4NSDY
https://ibb.co/5FwbcTy
https://ibb.co/ByqDJXP

 

i also had a p015b code

 

P015B Fault Symptoms :

1. Check engine light comes on
2. Engine stalling or misfiring
3. Engine performance issues …. You fall into this category with your Silverado
4. Car not starting

The solution:
Chevrolet P015B Possible Solution :
The crankshaft sensor signals the fuel injection computer or the ignition control when the cylinders are firing. This causes the ignition coil to provide a spark and the injector to inject fuel into each cylinder at the right time.

If either sensor isn't working correctly, the car will run rough and the engine will be less efficient.

In later car models, the car's computer can usually keep the vehicle running, but the engine warning light on the dashboard goes on to warn the driver.

Reason For P015B Code
The reason of P015B OBD-II Engine Trouble Code is Fuel Rail/System Pressure - Too High.
Parts or components should not be replaced with reference to only a P015B DTC.

That is why I'm asking for fuel pressure readings at idle and 2,000 rpm's, ...with that code, ...it now has become mandatory to know fuel pressure readings before we go farther.

 

I apologize Idk what pid to select for fuel pressure on my scanner

 

I didn’t see an exact pid that said fuel pressure so I’m at a loss on how to get that reading

 

i went back and found it!! https://ibb.co/Q8sKCQj

 

You have to tap into the fuel line mechanically (like a pressure tap, … same as a tire valve) to get a fuel reading.

Your fuel test port is on the right side (passenger side) of the motor near the rear, … just under the Vortec cover edge. Has a black looking tire valve cap. That is where the fuel pressure tap is.

The reason I ask for this method, I have to verify that the fuel pressure sensor is sending the same data as the mechanical fuel gauge is finding.

Need those readings.

 

so i just got done doing a fuel pressure test.. what a task rented a kit from autozone to find out the gauge didn't work then had to go buy one and i did the test and at start up it was at 50 psi then dropped to 40 at normal idle then i revved the engine to 2000 rpm and the needle didn't move

is a video of it

 

This is going to sound strange, … fuel pressure with the Key On, … Engine Off (KOEO) should be 55 to 62 psi. Closer to 55 psi.

When the motor starts and idles, the fuel pressure will drop about 7 to 8 psi. Usually in the mid 40's to 48 psi.

When you rap the motor, the fuel pressure will climb to near the KOEO original fuel pressure just for a moment. Maybe almost to the mid 50 fuel pressure range.

What's got me confused, … you claim you have a "rich condition" and a P015B code but your fuel pressure data that you stated are telling me you have a lower than normal fuel pressure condition with is a "leaner than normal" condition.

Does the mechanical fuel gauge pressures match the sensor data in the PCM???

Have you ever changed the fuel filter since owning this vehicle???

Does this vehicle have 72 or more thousand miles on the ODO?

 

Rick I appreciate all your input it’s been a big help so far! The log I sent you with fuel pressure matches at idle but with the rev to 2000 rpm it said it was 60psi on the data logger but on the pressure gauge I used it only moved up to maybe 45 psi max on the rev. I bought the truck with 70k miles and now has just over 100k I’ve never done the fuel filter as I read somewhere it’s all a part of the fuel pump? Correct me if I’m wrong please! That was my first idea when all this started to happen but with it being part of the fuel pump I didn’t really want to dig into that unless I was sure haha again thanks for everything!

 

Bad news is the fuel filter is in the fuel pump assembly. Another dumb ass idea from GM with all the chitty fuels that America has.

Fuel pressure "should" increase about 7 psi or so when you "rap" the motor, if not, … the fuel pressure regulator (FPR) is not functioning properly. Under lower engine vacuum conditions, the fuel pressure will increase. If you have a vacuum hose on the fuel pressure regulator (FPR), disconnect it. Did the fuel pressure increase 5 to 7 pounds???

Shut off motor, monitor fuel pressure loss over a time period. After a minute or so, was the fuel pressure still in the 30 to 35 psi range??? If it dropped continuously / quickly after shut off the replace the fuel pressure regulator (FPR).

The fuel pressure specs I gave you are what is required to make the 5.3 run efficiently. If not, there are 2 areas, the regulator and or the fuel pump / filter systems.

 

this a 2013 5.3L engine then MY guess this is a flex fuel truck and the fuel pressure controller electronic adjusts the fuel pressure. 43PSI at idle on this is normal IMO.... on my 2000 5.3L it must be 53PSI because of the GM change on fuel delivery system to increase MPG and so that the fuel does not get higher in temps on your engine.

I would put back in the OEM tune . you have the Diablo tuner ... then see whats going on .. next you have any exhaust leaks ? if so any small leak will cause the O2 sensors to create a lean report to the PCM then the PCM will dump too much fuel into the engine ..check also for manifold bolts broken /gasket and the O2 sensors properly mounted .

if this continues you will have to buy new converters .. rich will overheat them and the internals will melt then a restricted exhaust .less power .

 

J I appreciate the reply I have already reinstalled the stock tune, it made it way worse I drove it for about 200 miles hoping it’d get better but never did. It’s actually just the regular 5.3 no flex fuel. Would a regular vacuum test show if the intake manifold is leaking? Or do I need to do the fog machine or carb cleaner method? Thanks again for your input!

 

if you had a intake manifold gasket leak this would throw lean codes . also the fuel trims would be 25 ..

you posted a rich condition so that would be -25 .. and as I stated any exhaust leak would create the rich condition because the O2 sensors would read too much air in the exhaust and then PCM would dump more fuel into the engine. O2 sensor not properly installed leak or the wires on the sensor got cut / messed with . check also for injector leak down test ..

post back how this is resolved ..

do not use any carb cleaner as this chemical damages wiring/plastic/rubber etc.. use a throttle body/or MAF cleaner chemical . carb cleaner is only for metal .. I when I was a stupid young guy used it on my 1967 442 .. had to replace the choke pull off diaphragm got damaged from the carb cleaner .. my family member owned a auto repair shop , who back then told me , only use it inside the carb not on the outside..

 

Can you modify specific fuel delivery values or is this general pre program software that you can't do chit to???

 

I think you can adjust a/f ratio in % not really sure what else you can do what would be a good handheld tool that could modify?

 

https://postimg.cc/mzP8CXYj
is this a good area to test vacuum pressure at? i started the truck and disconnected it and it a had a vacuum but i goto hook the vacuum tester up to it and pump it and nothing happens on the gauge

 

When you disconnect a vacuum control fuel pressure regulator, the fuel pressure should climb a few pounds.

If this condition does not occur, … the fuel pressure regulator must be replace with a factory OEM part. The fuel pressure regulator slightly increases fuel pressure as needed when the motor goes into a power mode by the reduction of engine vacuum.

 

So if I do a fuel pressure test and pull that vacuum hose that’s in the picture the fuel pressure should rise?

 

Yes, ...slightly rise maybe a few pounds.

If the fuel pressure needle does not move when disconnecting the vacuum fitting, check to see if you have "full" engine vacuum at the vacuum supply line.

If there isn't full engine vacuum, find the vacuum leak to atmosphere and repair as needed.

If full engine vacuum is present, ...replace fuel regulator with a "factory replacement". Don't be cheap, ...or you will pay the price in the long run.

 

Awesome thank you very much rick I’ll do this tonight when I get home I appreciate all your help!! You’ve been awesome! 10 thumbs up from me

 

stick a rubber hose in your ear and the other end put on around the exhaust manifold and also on the exhaust flanges/O2 sockets etc..

 

I’m at a total loss tonight spent all evening re doing fuel pressure test vacuum smoke test exhaust manifold 02 sensor leak checks and nothing.... I’m honestly puzzled and about to take it to the stealership and let them diagnose it... I want my tire shredding baby back lol

 

MAD,

Did the fuel pressures come in line with what I posted?
Did the fuel pressure slightly increase when you pulled the vacuum line?
Did you do what j cat recommended?

Also listen to j cat and his info also in addition to my input. Be patient!!! The both of us want you to stay out of the dealership or it will cost you a few weeks pay.