First timer

[rockola1971]

Yes I meant the electrode and the porcelain.

I had the injector code prior to replacing the injectors. Tested each connector with noid light all were pulsing. So I went with the injectors. But after when it still seemed to start stumbling under load I decided drive a while with a fuel pressure gauge on it. After about 30 mins pressure was slightly dropping while it sat took it on a drive and after about 10 minutes it started to see under 40psi on the gauge.

I’m gonna actually retest with a different gauge to make sure of accurate reading. I’m currently letting it sit so I can test pressure before koeo and with koeo so I can see if it rises in pressure. I’ll also be checking my intake for a possible crack or anything or anything with the IAC as the truck has a brand new MAF with less than 3k on it. Most things were replaced on this truck, engine, trans, ckp/cmp, ect, oil pressure, etc. So recently the only things that were being double checked IE injectors, FPR, and fuel filter are items I hadn’t replaced.

The truck never did the loss of power as I’m driving then cutting in and out of revving and having throttle response issues to where I had to go in and out of the throttle to keep it rolling. But even if I didn’t touch the throttle car would not die it would just not give any throttle response with accurate timing as if it had to get the pressure built up to even load the injectors possibly it was odd.

Id really like to see better close up pics of the plug. Different angles too. Did the pieces missing break off or were they melted off? I have to agree that the piston and cylinder walls need to be inspected with a borescope. Also need to make sure no spark plug debris are imbedded in exhaust/intake valve seats. Are you burning any oil?

 

[BigBackHoe]

Something else I just thought of before falling asleep. Is this a cable throttle? Or is it one of the oddball early electric throttle bodies? I think in 02 they tried something before the 03 ecm change.

Cable

 

[BigBackHoe]

TUNE:

This reminds me of spark and idle air control routines need adjusting in the controller. You said you did a tune, was it a mail order tune? What did he adjust in the controller?

When I did my cam I had to tune:

- Spark overspeed, & underspeed tables
- Idle Airflow Table for Park and gear
- And adjust the setscrew on my throttle body (not sure if you're cable or wire)

TIP: I also have a pretty mild cam as well. If these are not tuned properly the truck will stall when weather changes. Especially the Idle Airflow. If the temp, changes your truck won't run right till it's warmed up. If you replace injectors don't mess with the 24# ones they are REALLY close to the limit of their flow. Get the flex fuel injectors from the L59 motor. You can get them used fairly cheap. I spent $100 on 8 used ones. If you buy new they're the same price. You do have to do some spacing on the fuel rail but billet IAT sells the spacers and you can get the harness adapters on eBay.

What year is your vehicle?

PUMP:

37 PSI is lower than both flex fuel L59 (48PSI) and gasoline LM7 (58PSI) spec. Researching pressure regulators I see they do sell them that low for the 5.3L. If you're not careful you may have snagged one of those. Did you recently change the regulator? Otherwise likely a bad pump.

I had my junction block go out. It was TOTALLY random and would do odd stuff like that. You could probe it and it was fine... but it wasn't. There was a cracked trace inside the block for the pump. REALLY hard to diagnose and unfortunately, I destroyed the block confirming the problem. Probably only indicator externally was the fuel pump relay and fuse area was getting really hot.

Do you have a Wideband AFR meter? I monitored mine while the problem happened. It felt like a lean condition and I could quickly confirm that with the WB meter.

Loss of power makes me think it might be a lean condition.

FYI ~ fuel trims especially if your truck isn't well dialed in won't tell you much. I had a rich condition where the trims always reported lean from the PCM. Never did figure out why it did that. I had to re-baseline the PCM so I don't much trust the PCM unless I can confirm with my wideband now.. I also was told to turn of LTFT, not sure if you can turn of ONLY the STFT? I know software will allow it. I turned back on all my fuel trims once I got the VE table better calibrated.

So I believe it may be in the tune for the issue with the plug as I did tell the tuner it seemed to lean out under load at about 2500rpm.

I did get the flex fuel pressure regulator, the injectors are the multitec 2 style connectors. I do need to double check the ones I swapped in are Flexfuel ones. Even though I’m currently on 91. Would the difference in injectors be an issue?

Also I remembered another thing I had not replaced was the wires and coils. The issue could have began as less and advanced due to that cylinder the plug got destroyed in having a problem and it smelled Rich because one cylinder wasn’t firing at all. So raw fuel, the thing I’m wondering is. It never did the rev and lose connection to the pedal then going in and out the throttle inconsistently as well as being stuck in gear until I switched to the injectors I recently got. So I’m going to borescope the cylinder for any damage and then I’ll swap back my other injectors if it’s not destroyed in that cylinder and see what it ends up doing. Maybe clean IAC again for ***** and giggles

 

[BigBackHoe]

Id really like to see better close up pics of the plug. Different angles too. Did the pieces missing break off or were they melted off? I have to agree that the piston and cylinder walls need to be inspected with a borescope. Also need to make sure no spark plug debris are imbedded in exhaust/intake valve seats. Are you burning any oil?

I believe the pieces have either already came to pass, or I’m going to find them possible melted to the piston so when I borescope I’ll let you know and no it does not burn oil at all. Checked oil recently cause I was curious if it was low or something just as precaution I like to double check my fluids every few weeks.

 

[Hoesgottaeat2]

Don't starve that Hoe of fuel, because remember...Hoesgottaeat2

And welcome from NY!

 

[BigBackHoe]

For the one who asked to see more pics of the plug. I got you

 

[BigBackHoe]

Also, it just so coincidentally happens that a suburban came in with the same damn near issue. Now I know I need to see what the tuner turned off within the log. Cause for some reason never seeing a misfire and having a plug like that. Ain’t no got damn way that ***** didn’t wanna report a misfire. So I’ll be doing that today and also with the suburban, plugs wires and fuel filter and it ran great again.

 

[BigBackHoe]

And the suburban is as I said customer vehicle at work, the Tahoe is parked at home on timeout lmao

 

[Mudsport96]

So I believe it may be in the tune for the issue with the plug as I did tell the tuner it seemed to lean out under load at about 2500rpm.

I did get the flex fuel pressure regulator, the injectors are the multitec 2 style connectors. I do need to double check the ones I swapped in are Flexfuel ones. Even though I’m currently on 91. Would the difference in injectors be an issue?

Yes, because injectors are rated on how much they flow. So a flex injector is rated 33 to 36 pounds of fuel per hour at max flow. Because you need way more fuel when running e85 vs gasoline.
A standard 5.3 injector is like 22 to 25 pounds per hour.

Okay so the following times are made up to illustrate a point and not actually how long an injector would be open.

So if you had an original flex computer tuned for your setup, then changed injectors and ended up with some standard ones it is calculating fuel delivery wrong. It thinks I need to open the injectors for 1 second to get the right fuel because I have 33 pound injectors. But if you have 22 pound injectors it may need to have them open 1.5 seconds to get the right amount of fuel. So now it is lean until the short term fuel trims can adjust things ( something you said the tuner turned off). And long term trims are based off of short terms so they will absolutely never be correct and may get worse over time. AND if you try to run e85 you run a real risk of running out of injector flow.

 

[Matthew Jeschke]

If you can share your tune file (assume was done in HPT) I can take a look.

Fyi my misfire detection didn't work with aftermarket cam. Specifically P0300 random misfire. I tried like heck but couldn't calibrate it for the cam so I had to disable it. Not sure if any of that is reliable with an aftermarket cam.