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'03 Avalanche problems

First, the codes:

P0101 - P0101 MAF or VAF Circuit Range/Performance Problem P0300 - Random/Multiple Cylinder Misfire Detected P0576 - Shift Solenoid B Performance or Stuck Off

The symptoms:

Rough idle, very little power.

What happened:

I was driving at highway speeds yesterday with no issues. After a stop light, I noticed a slower than normal acceleration. About 10 miles later I came to a small hill, nothing large, just an overpass. The truck began to decelerate and MIL began flashing. I took the next exit and barely made it up the ramp, engine running very rough and very little power. I stopped the truck and shut off the motor. I checked the fluid levels and all was fine. I restarted the truck and decided to drive 1/4 mile to a relatives home.

I returned today and retrieved the codes listed above. I then cleared the codes and restarted the truck. It was still running rough. I only got the first 2 codes and no flashing MIL. I then drove down the drive and got no additional codes. I then drove it down the short road to a small incline which was too much for it to overcome and caused the light to begin flashing again. By small, I mean the intersection was raised about 3 feet higher than the road I was on. This 3 foot rise is over a length of 10-12 feet. I then got the last code again.

I don't even know where to begin with this. Fuel filter, fuel pump, computer, sensor? A year ago I would have just taken it to a shop and asked them to fix it. Unfortunately, it's now my grocery money that I have to work with. Ant ideas or similar experiences? Thank you so much.

Reply to
James Horn
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Those codes and symptoms could be the intake gaskets......seen this before.

Reply to
Augustus

Well a bad MAF/VAF signal can cause the symptoms your seeing.

Does your scan tool allow you to read live data? If so I would look at the MAF/VAF signal and see what you have in relation to the TPS signals.

Reply to
Steve W.

If you want to save money and work on your vehicle yourself, you will need a

2003 GM Avalanche service manual.

There are all sorts of sensors which need to be tested with a multimeter. The Factory manual tells what to test, how to test, and what readings a good sensor would show as opposed to a sensor which needs replacement.

Without testing these things, you are just guessing. Then wind up replacing parts which don't need replacing.

(When all else fails, read the instructions...)

Reply to
Bill

The last time I experienced your symptoms, one of my plug wires had burnt through. I doubt that's your problem, but they always say check the easy things first ;)

Reply to
80 Knight

Is there a quick easy way to check this? Ha-ha, nothing is really quick and easy I suppose.

Thanks

Reply to
James Horn

Unfortunately my scanner only reads and clears codes. I do have software for my laptop that will do this, But I don't have a cable.

Reply to
James Horn

That is an excellent idea. I will look into it today.

Thanks

Reply to
James Horn

I did look at them, even in the dark looking for arcs. They all appear to be good, I replaced them all at just under 100,000 miles, it's at 109,000 now so they should be good, but you never know. I did get random misfires which led me to believe it's something before we get to that point.

Thanks

Reply to
James Horn

Hess Gas?

Reply to
Bill

Ha-ha, no. Speedway. I filled up earlier in the week and used 3/4 of it before the problem developed. I am going to change the filter tomorrow, can't hurt.

Reply to
James Horn

I know it is a PITA, but if you still have your old ones, maybe a temp swap out for a no cost test. ??

Reply to
Meebers

That certainly can't hurt. I'm not going anywhere anyway.

Reply to
James Horn

On Sun, 07 Jun 2009 22:41:31 -0400, James Horn fired up the etcha-a-sketch and scratched out:

Seen the other posts too.

Some guesses - fuel injectors? Cat clogged? O2 sensor(s)?

What do you have the 1500 or the 2500? Any mods?

Reply to
PerfectReign

Can a clogged Cat cause an engine to run rough??

Reply to
Tim

In a Heartbeat!

Reply to
Bill

Are you sure?

I have seen a lot of clogged cats, and even stuffed a few potatoes over the years, but I have never seen an exhaust restriction cause an engine to run rough.

Reply to
Tim

Simple test, remove it and see.

Reply to
Bill

Simpler test, take any vehicle running well, and stuff a potato in the exhaust, see if it runs rough.

Reply to
Tim

Hi,

It's a 1500 5.3 all stock. I put the old plug wires back on this afternoon and got the same results. Your guesses sound progressively less expensive, an O2 sensor would thrill me.

Would a bad injector cause the random misfires? Wouldn't a code come up for any of those issues?

It does still have the original exhaust system, I've never had one last this long actually. Is there an inexpensive way to determine if it's the Cat?

Thanks for your input, you guys are great!

Reply to
James Horn

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