LB7: Need help/opinions

[Kappa9012]

Have a friend with an 03 lb7 at 178k miles. Truck has always been kept stock no tunes what so ever, and he's a freak about maintaining his truck.

He's got a slight engine rpm surge at idle. it runs fine off idle and it does get slightly worse as the engine warms up. No visible smoke from the exhaust and I don't hear anything odd from the engine.

I logged it for a bit and right away noticed an injector is going bad. The #4 injector is running about a -3.25 at idle while the rest are holding pretty tight around 0-.5. I didn't get desired vs. actual rail, but I was watching the regulator and it's swinging between between 34-39%.

I'm going to start with the bad injector, but any other ideas? Trying to figure out if that bad injector would be causing the rough idle or if something else is going on?

Also forgot it's the original injectors.

 

[Fastorange]

it could also be a bad regulator

 

[Kappa9012]

That's originally what I thought, I can't believe I didn't look at rail pressure...

 

[mrbonklavy]

brother had similar problem with his '03, injectors fixed the problem, surprised he got 178k on originals, good luck!

 

[Kappa9012]

lol that's what I told him... I thought about recommending all 8 based on the 178k on the clock, but given his other balance rates, I gave him the option and told him that he will likely be eating the labor again if another one goes out.

 

[Kappa9012]

glanced over the log again and noticed he had a p1093 Fuel rail pressure low during enrichment period logged... Thoughts?

 

[bml2200]

Your bike is slow

 

[bml2200]

Also would love some 1/2 love, trying to got -5s

 

[MACKIN]

Myself I'd run some fuel additive and see what happens. Then I'd consider running some GM injector cleaner.

 

[jraymer]

-3.25 isn't that bad. I would think regulator.

 

[Kappa9012]

BML2200 suck it B!tch.... lets race, ohh wait... n/m