02 Chevy Silverado 5.3 liter jerking when accelerating

[Chevy9880]

I bought an 02 Chevy Silverado z71 two weeks ago.  Truck has a acceleration jerk at around 2000 rpms when cold. As it warms up it moves to 3000 then 4000 rpms. Sometimes will quit completely. I have replaced both upstream o2 sensors.  I also have codes for crankshaft sensor  confirmed. Also found that they unplugged the egr and removed wiring harness.  I plugged it off and no change. I have ordered a new crankshaft sensor but hesitant to replace due to possible relearn needed to start engine after replacement.  Any thoughts on why I'm having this issue? No misfire codes were present just too lean codes and crankshaft sensor. 

[Jsdirt]

Usually misfiring under load or acceleration is spark related, but also fuel starvation as well. If you're 100% sure the crank sensor is bad, replace it ... but this is one of those parts where I hesitate to buy it from any auto parts store chain, aside from maybe NAPA. As much as I hate GM, OE is the way to go here. It would appear they've successfully engineered them this way.

 

Replacing the crank sensor will not cause a no-start. It will keep the light on for a crank relearn needing to be done, and it will not accurately report which cylinder is misfiring, if one should occur.

[Chevy9880]

So this could be why I don't get misfire codes? Or could this be why its running bad? Due to engine timing and fuel delivery of the faulty sensor. Thanks for the advice. I've been scratching my head on this one. Makes a lot more sense now.

[Doug_Scott]

4 hours ago, Chevy9880 said:

So this could be why I don't get misfire codes? Or could this be why its running bad? Due to engine timing and fuel delivery of the faulty sensor. Thanks for the advice. I've been scratching my head on this one. Makes a lot more sense now.

I think you would still get the random misfire error code, just not the cylinder specific ones.  And are you saying the egr is still completely disabled? 

[Chevy9880]

Yes it is completely unhooked. The wiring harness is non existent.  I'm not getting any misfire codes. Hoping the crankshaft position sensor is the root of the problem or at least take care of most of my issue.

[riverbanks]

Code reader or scanner?and which code for crank sensor?and have you cleaned the MAF and throttle body?

[Chevy9880]

I cleaned maf. Read codes at advance auto.  Btw I changed the crankshaft position sensor and now it won't start.

[riverbanks]

Wiring issue at crank sensor?or what brand sensor?

[Chevy9880]

It's off brand but I already had it 9rdered before you said oe was the way to go.

Wiring looked okay plug is tight.

And there were 2 crankshaft sensor faults. Failure and confirmed.

[riverbanks]

At least you have the old one to put back in, when it rains it pours

[Chevy9880]

Yes that's the plan.  Starting from scratch . Putting old one back in tomorrow and going back through the basics.  Checking for vacuum leaks,coils, ect. 

[Chevy9880]

21 hours ago, Chevy9880 said:

Yes that's the plan.  Starting from scratch . Putting old one back in tomorrow and going back through the basics.  Checking for vacuum leaks,coils, ect. 

So we all get lucky sometimes right? I cleaned the old sensor and reinstalled.  Started right up. Took it for a test drive.  No hesitation or misfire.  Running like a top.  Who am I to judge. All I know is it's fixed and hopefully it doesn't act up again.

[riverbanks]

Nice,was the face filthy or wire connection?

[Chevy9880]

Not positive.  Just wiped it off and reinstalled.  Made sure it was plugged tight.  I was like a kid in a candy store when I took it out on the road.  A lot of power in those 5.3's.

[Jsdirt]

Gotta love electronics. No rhyme or reason to anything. People wonder why I miss the old days of carburetors and points! Problems were cut and dry, and ALWAYS fixable with basic hand tools, and little to ZERO money.

 

There's a possibility you had a pin fitment issue at the connector on the old one, and unplugging, and plugging it back in fixed the connection. Hopefully it remains fixed.

 

I like the 5.3 after 3k RPM. Before that, they're slugs, IMO - the old 80's 350's (tuned correctly) will stomp them off the line. I've owned many that would. In fact, our '86 Grand Marquis with the 302 / 5.0 will jump my Silverado off the line with ease, spinning 1 tire (the one-tire fire, lol) the whole way - 2.73 gears back there, too. The Silverado with 3.73's can't leave rubber from a dead stop unless there's sand, or rain. If they'd build these things with the torque of the 80's and the horsepower of today, I'd be a happy camper.