Jonathan Jackson

Hello all. New here. Would greatly appreciate some fellow opinions ideas of what in the hell could be the problem with my truck.. I bought a 00 silverado.. 5.3 ext cab 4x4 vortec. Ran like crap since day one..

The truck is idling rough extreme, surging idle, sometimes to the point of stalling.. Cranks right up though without problems. It stumbles super bad from 0-60.. City driving is hell.. It just doesnt have the power it should.. Truck has 252,000 miles. Note: it runs GREAT when its cold in the morning till 10_15 min. Its at 210 and sluggish again.

I have replaced SO FAR..
Spark plugs. Wires. Coil packs.
Fuel pressure regulator.
Camshaft & crankshaft sensor.
Air filter. New air box.
fuel filter
Motor flushed changed oil twice
seafoam'd vacuum system
Four new 02 sensors..
throttle position sensor
fuel pump replaced 35,000 miles ago

Engine throwing stored code p0300
pending code bank 2 sensor lean...

Somebody please help me out. Itd be greatly appreciated!


I've replaced everything i can think of...

oilcanhenry

Have you done a wet/dry compression test yet?

What's your fuel pressure like?

Might also be having fuel injection issues.

I'd do a dry than wet cylinder compression test first.

Jonathan Jackson

Heres what my code reader is saying...
i dont fully understand the fuel trim situation..

oilcanhenry

Your scanner doesn't store driving TMS codes as in a set of lines? I still recommend a full compression test. If you need help on that I can tell you how its done or you can view it on YouTube.

Gumby22

I agree compression or vacuum testing should be done, but you said you didn’t understand fuel trim, so here’s what it means.

Fuel trim is the PCM’s response to O2 sensor data. The amount of fuel per combustion cycle is either increased or decreased by changing the injector pulse width (amount of time the fuel injector is opened).

SHRTFT = Short term fuel trim - direct response to changing data from the upstream (pre-cat) O2 sensor.
LONGFT = Long term fuel trim - adjustment of fuel over the course of the drive - resets every ignition cycle.

The numbers refer to either one bank in general or a specific sensor.

1 = bank 1 as a whole
2 = bank 2 as a whole
11 = bank 1 sensor 1 (driver side upstream)
12 = bank 1 sensor 2 (driver downstream)
21 = bank 2 sensor 1 (passenger upstream)
22 = bank 2 sensor 2 (passenger downstream)

Ideally the fuel trim stays at or near zero but -10% to +10% is considered normal. Your bank 2 short term shows the fuel trim is pegged at +99% - either the signal circuit is shorted to ground or there’s a significant air leak that’s only affecting bank 2. The intake manifold gasket is about the only thing it could be, based on your description of the issue.

That being said, leaks at the exhaust manifold can cause false O2 sensor readings, but it’s not typically enough to peg the fuel trim positive like that.

Gumby22

Actually, I’m going to correct myself - another possibility for bank 2 fuel trim being pegged is if the injectors aren’t pulsing correctly or aren’t pulsing at all.

In the underhood fuse block, fuse INJ B (15A) supplies power to the bank 2 injectors. If it’s good, turn the key on, engine off and check for battery voltage on the pink wire of one of the injectors (can be unplugged or back probed).

If no or low voltage is present, turn the key off, unplug one injector, remove the fuse and check continuity between the fuse block and the injector - anything more than 0.2 ohms is reason to consider damage to the power circuit. Also wiggle test the harness to check for an intermittent open.

If battery voltage is present, you’ll want to check for continuity between the injectors and the PCM. The easiest way is with a noid light and a helper to crank the engine. A regular test light will work, but instead of pulsing it will just glow dimly.

Jonathan Jackson

Hey man, most definitely appreciate the response.. and the information. I'm still at the same issue, only to now have transmission or torque converter problems.. but most definitely will be looking into that intake manifold gasket.. as well as injectors.. what's your opinion on Amazon injectors? Such as the four holes instead of two? I'd love to replace all right with ac delcos.. but at 84$ a piece.. that's just an expensive fix right now..

Gumby22

I wouldn’t bother with the transmission at this point - the transmission depends on a smoothly operating engine in order to work correctly, and given the issues you describe, the trans may only be responding due to the engine problems.

I’m not sure which injectors you’re looking at on Amazon but, my general opinion on aftermarket parts is there’s no reason not to use them so long as they meet the OEM standards and are correct for the application.

Aftermarket brands I trust and have used on customer cars without issue are SMP, Delphi and GB Re-Manufacturing.

That said, there are A LOT of cheap knockoff injectors (and parts in general) on Amazon - oftentimes the pictures are stock photos and unrepresentative of the actual part being sold, so I’d caution you to carefully research any products you’re considering before buying them. Amazon does pretty well with returns, but the inconvenience of having to deal with that is one reason why I don’t personally buy a lot of specific parts off the internet.

chem_man

Go to rockauto.com and you will see that ACDelco fuel injectors are a little less expensive ($68.79 each) than what you saw on Amazon. Stay away from the unbelievably low priced fuel injectors that sell in mutipacks for less than the cost of a single decent (ACDelco, Delphi, SMP) fuel injector. I've never had any experience with the GB Remanufactured fuel injectors. Also, stay away from ebay fuel injectors unless you absolutely know what you are purchasing. Lots of counterfeit parts on ebay (and Amazon, but to a lesser extent)..

Gumby22

I’ve found GB is a good source for older vehicles. A couple years ago I was replacing all the injectors on a 1995 Lincoln town car and GB had all 8 available whereas I could only get 1 or 2 from aftermarket manufacturers.

At the same time I’m limited on sources for customer cars - for reasons already stated, my boss doesn’t like sourcing parts online unless absolutely necessary.

I’ve only installed a few of their injectors in the past few years but so far so good - no problems. Typically I only need one or two at a time - the most recent example is I recently replaced the head gaskets on a 2006 equinox and one of the injector nozzles broke while I was attempting to remove it.

There’s quite a bit of debate on auto forums about the difference between “rebuilt” vs “remanufactured” and while there’s technically different definitions for those terms, my position is as long as it works like it’s supposed to, who cares what they call it.