2003 Ta’Hoe—Fuel issues

[Jonesy92]

Awesome. I’ll do these, and report back.

 

[Fless]

Non-OE intakes and filters can dirty the MAF, more than the OE setup.

 

[Jonesy92]

As expected. I have not however, tested fuel pressure on the rail. My Original starter from 03 just went out this year. Completely rusted through, you could see the internals. Hell of a starter.
I am waiting on my pressure gauge to arrive.
Hopefully that MAF cleaning along with the TB will clear it up.

 

[OR VietVet]

When you check the fuel pressure, with the new gauge, I always like to have the longer line on it that allows you to bring out the back of the hood and tape to w/s to watch. Hopefully the MAF clean and TB clean will fix it.

I did replace my throttle body recently, just because. I still was not happy with the throttle response very slight lag. Ran fine but I am picky. I replaced this Accelerator Pedal Position Sensor and the lag is gone.

Without adjustable pedals: https://www.rockauto.com/en/moreinf...7DAc0taQ9e4s0mXPjcSUQdEJCYoqDprnPGgTpJBtagmDk

With adjustable pedals: https://www.rockauto.com/en/moreinf...7DAc0taQ9e4s0mXPjcSUQdEJCYoqDprnPGgTpJBtagmDk

 

[PNWYukon]

When you check the fuel pressure, with the new gauge, I always like to have the longer line on it that allows you to bring out the back of the hood and tape to w/s to watch. Hopefully the MAF clean and TB clean will fix it.

I did replace my throttle body recently, just because. I still was not happy with the throttle response very slight lag. Ran fine but I am picky. I replaced this Accelerator Pedal Position Sensor and the lag is gone.

In retrospect, do you think the problem was only the APP sensor?

 

[OR VietVet]

Very well could have been that but this was during the time that I was replacing parts, right and left, just so I could get my rig to as close as possible to completely dependable and I had no CEL. My tech friend, at the shop that I was doing most of the work at, suggested the APPS and that was an easy fix that did work. I was gonna replace the throttle body anyway, even if I did the APPS first and the lag went away.

 

[Jonesy92]

Reporting back today. Maf and
TB have been cleaned, tediously. Runs great now. But on cold start, under 40*, instantly kicks into REP mode. Clear the code(which is 4 codes. Bank 1 lean 3 times, and manufacture control malfunction). Started it today, and got Bank 1 lean 4 times. The same code repeated. I’ve checked fuel trim on both long and short term, and they’re in range with specs from GM. Any ideas?
I did also finally get the correct fuel pressure rail gauge, and have 53pounds at key on, and 56/55 at idle. Hard acceleration shows 64/65 pounds.

 

[Jonesy92]

If I remember correctly back when I bought this truck, I had a code for that. Something about accelerator pedal performance? I guess I’ll look into the APPS

 

[Fless]

Fuel pressure seems high when running. I think these like to run in the low 40s -- 43, 44 or so. Fuel pressure that's too high can cause issues, maybe not these, but...

KOEO specs for NBS V8 engines:
Non-Flex: 55 to 62 psi
Flex: 48 to 54 psi

 

[Jonesy92]

I would figure that specs would give or take a few psi into the mix given where it’s driven, etc. would that be correct?