Questions about troubleshooting my 2003 V8 4.8 4X4 Silverado reg cab

[silenthunterstudios]

I fell into a great deal on a 03 Silverado, 4.8 V8 Vortec, after my accident. Family helped to get it roadworthy, and I lucked out. Had to buy parts, and get some work done by a family mechanic, but still came out not too bad. I've been driving this truck about a month, and it is far and above better than the 85 extended cab Toyota pickup I was driving before. I don't feel like a grizzly bear driving a Dodge Omni anymore (yep, had one of those too when I was about 17).

When I first drove it, it would idle at about 400-500 RPMs, and stall if you put it in Drive, or stopped at a light etc. Looked online, and found it was an easy fix, clean the throttle body. Man, I've never felt a truck get up on plane, like a speedboat, before. Got that fixed, ran like a charm. Gas guzzler like a wino with cheap strawberry ripple, but I thought that was because it's an 8 ft bed 4wd truck!

Check engine light came on, I took it to a local auto parts store and they came up with the PO332/P0332 code. Bad knock sensor. I haven't gotten around to getting them replaced yet, but I'm not done yet. I have noticed a bad shift from first to second, after doing some research, this is something common to this model (coming up on 80k, I've put about 2K on it in a month, 90 mile round trip to get to work and back). I have been religiously checking the oil, and found that it was a little low. I put about a quarter of a quart of Supertech 5W30 (5W30 is recommended) in to top it off, didn't overfill it. That was a couple weeks ago. My uncle had changed the oil, and used Valvoline 5W30 I believe. I did read that Supertech was crap (been putting it in all of my old jalopies up until now), that Supertech was fine and should prolong a vehicle's engine and that you should only use Mobil One, Valvoline, Quaker State etc. In the past few days, I've noticed that the oil pressure gauge, which idled around 40, and got as high as about 50-60 when reaching 2500-3300 rpms (highest I've gotten is 3500 RPMs when getting onto the highway, it hit about 4000 RPMs tonight which scared the crap out of me), is idling at about 25, and maxes out at about 45-50. I checked the oil last night, it was full, checked again tonight, and it is full. I had a Change Engine Oil warning come on the odometer since I've had it, I was told that was a bad code. I was able to reset it by turning the ignition to on, and feathering the accelerator three times. Got a Oil Setting reset message, and this was after the oil pressure gauge "issues".

Over the past couple weeks, I've noticed the engine continuously working harder to get speed. When I first started driving, I just had to barely touch the accelerator and she would take off. Now, she still gets up to speed quick, but needs a little more pressure on the gas. In the past few days, it seems like it's been working a lot harder, and while it isn't knocking, when I give it some gas on the highway (most of my daily commute is on major highways) it is a lot louder.

Since I've been driving, I've been driving junkers. Even though this truck is almost ten years old, it's the nicest truck I've ever owned. I know most forum members replies will be to get it checked out, but I am afraid of it blowing up on me in the interim. Internets research :foot: has revealed everything from blown head gaskets, to bad oil filters, to just needing to replace the oil sending unit. I thought the acceleration issues and poor MPG (about 15-17) were related to the knock sensors needing to be replaced. The hard shift from 1st to 2nd and the oil pressure has me really worried. I did read however that 20-25 is fine for about 2000-3000 rpms, with 6 (not 60) being ideal for idle.

Any thoughts are welcomed, this isn't WC though . Hoping I can drive it to our family mechanic, and possibly get the codes scanned and get some reset, and at least get a feel for what I need to have done, tomorrow. Going to need a ride to work if that's the case. Luckily, my mechanics shop is in the same commercial park as my fathers auto upholstery shop. About a 35 min trip, as opposed to a highway trip 45 miles to work, and then about an hour in bad traffic to my fathers shop, not knowing if I'll catch my mechanic before he closes up.

I thought deciding between a locking hard tonneau cover and just a tool box were gonna be a pain in the ass.

 

[beau5278]

Did your oil pressure go down after the oil change?5-30 is pretty light oil,that could cause the oil pressure to drop some but really 25lbs at idle isn't that bad.As far as the oil change indicator those are set at a certain interval to come on,possibly the oil got changed just before the light was ready to come on or something like that.

 

[78LilRed]

Going with a thicker oil would bring your oil pressure up but 25psi at idle is fine for 5-30, if you see it go below 15-20psi shut it off and get it towed otherwise drive as normal. For the 4l60e change fluid/filter and keep on driving it.

 

[gadgetgeek]

On Chevys the change oil light is on a timer (well, a bit more than that, it takes driving habits, RPM and a few other things into mind. If it happens again, just turn the key to on, and give the brake three good pumps to the floor (Its been a while, but I think that was the chevy re-set method, if not you can find it online easy enough, they are reset without tools, I know that) Then just keep track and do your normal 3000 mile, or whatever. They can go into a "safe" mode when the light has been on for a while, but the only time I'd seen that was a car that was 15000KM "over-due" (dumb-asses at the shop had never re-set it, just told the owner "don't worry about it, they all do that, it costs too much for the tool to reset it... dealer only... blah blah)
As for the sluggishness, I don't really know, but take another look at the throttle body, and see if its gunking up, that will tell you a few things. (also check the PCV valve, those die all the time, are cheap to replace and help maintain your crank-case gasses.
Head gasket will show up as either gunk in the rad, or foam in then engine. should be easy to spot.
Bad knock sensor will be throwing off your timing, which can make more noise, so getting that taken care of should help.
Hard shift, whats the condition of the transition fluid? it should look clear, red/pink and not stink. if it smells burnt, is brownish or at all cloudy, look into getting it flushed out. (if you have to go the drain and fill method, either do it a few times, just pulling the plug only drains about 30-50% of the oil.)
Its been a while since I was a grease monkey, but besides F350s, Chevy silverados of all years were possibly one of the most common trucks we worked on. The good news is that they are pretty robust, lots of them run around all the time with loads of problems, and many more are run hard and put away wet as it were. There will be a few things to work out for sure, but you should be alright.