William Parker

I am SURE I am beating a dead horse but need a little help. I have actually a suburban with the 5.3l and this keeps coming up. I've realized that using specific gas makes a world of difference so now I only use top tier gas and that helped for awhile. So I'm going to post what I've done so far and what my limited scan tool has given me and HIPEFULLY have some of you more knowledgeable folks give me a hand!
I cleaned the MAF, took off the TB and cleaned it (I did the relearn procedure after) I also put on a new TPS while I was at it, I also changed all 4 O2 sensors which, according to my scan tool are working perfectly. When I used 93 the MIL went off but as the tank gets down to about a quarter its come back. At 1 point it reset while I had it idling in the garage while I was checking the sensor test values.
So here is the freeze frame I got this last time and I'm HOPING someone will see something I dont that can lead to the problem. Btw I hear no hissing, and before I started using 93 I'd get a cloud of smoke on startup. Now it does it only intermittently.
FF
Fuel sys 1&2 closed loop
Calc load 67.1%
ECT 192 degrees
STFTB1 -0.8%
LTFTB1 6.3%
STFTB2 -0.8%
LTFTB2 5.5%
FUEL PRESSURE 44 PSI
MAP 22inHg
RPM 1481
SPEED 52 MPH
SPARK ADVANCE 18.0 DEGREES
IAT 75 F
MAF 5.23 LB/MIN
TPS 36.9%
RUN TIME 238 SEC
COMMAND EVAP 100%
FUEL LEVEL 39.6%
WARM UP DTC CLR 8
CLR DIST 99MILES
EVAP_VP -4.5 InH20
BARO 30 InHg
CAT TE 11 1168F
CAT TE21 1168F
ECU V9LTS 14.268V
LOAD VALUE 50.2%
EQ RATIO 0.999
REL TPS 22.4%
AMBIENT TEMP 64F
TPS B 36.9%
ACC PEDAL D 29.8%
ACC PEDAL E 14.5%
COMMAND TAC 32.5%.
On a side note the evap monitor was reading not ready fyi. PLEASE HELP

William Parker

Can ANYONE help? Its random itll pop on for a couple days then go off. I'm using top tier gas 93 octane to try and help clean it a bit. I've bought the injector cleaning tool and working on getting a new compressor to use it to flush it all out but the intermittent factor seems to NOT point to a vacuum leak. As I said the purge valve solenoid and all 4 O2 sensors I replaced, I also took off the TB and cleaned it real good and I replaced the TPS while I was at it but aside from my current plan to flush the top end of the fuel system I'm not sure if I am missing something? Pressure regulator? I cleaned the MAF using the right MAF cleaner too.

kevinkpk

Fuel pressure is low, rpm at 1481, what is the idle rpm?

William Parker

Idle usually runs around 600 or so. Think it may be the pressure regulator? Like an example would be it came on this morning, but by the time I went back out this afternoon it went off again (the MIL). And THANKS for responding I really appreciate the help.

KChevy75

Check your fuel pressure at the rail.

Fuel pressure with ignition on and engine not running should be 50 - 60 psi
Fuel pressure at idle should be 43 to 45 psi

Fuel pressure regulator is integral to the fuel pump so the fuel pump would need to be replaced if you determine your fuel pressure is too low.

Do you have the ability with your reader to show misfire information? If not, I recommend getting an inexpensive ELM327 adapter and the torque pro app from your app store and check misfire info. Another great little device that I discovered is the Autel/Hyper Tough HT200 bluetooth device available at Walmart for $50. It'll do the standard OBDII stuff but will also read all the modules in your vehicle. It'll also show misfire data.

KChevy75

Seems like a general GM bulletin but here's something: Clogged Fuel Injector Bulletin

Have your tried taking some brake or carb cleaner or starter spray various areas on the intake and intake manifold to try to locate a leak? Watch your long term fuel trim numbers while you are going this. If they drop, you've found the vacuum leak.

Jump to 10:53 to see the procedure to to locate the leaks.