Newbie: Running Questions

espensegal · August 18, 2008

Hello all,

I'm new here and look forward to the forums.

So I've searched for about an hour looking for my specific issue but haven't found anything. I'll give three scenarios that all exhibit similar symptoms of what I'll call "Lurching". It's not "surging" because the tach never really moves.

Scenario 1: The scenario is when I am rolling in "D" with foot barely on the throttle to maintain a walking pace (at around 1100 rpm) the truck sort of lurches repeatedly, but the revs don't seem to fluctuate. It will lurch evenly for as long as I hold the same throttle. Give it a little gas and the problem goes away. This lurch feels like my front wheels are a little oval.

Scenario 2: At highway speed, holding constantly at say +/-70mph there is the impression of the same lurching, but at highway speeds it's a little harder to percieve, but it's there. It's not as even as the lurching in Scenario 1, kind of a "random consistency". This lurch feels like a mild misfire.

Scenario 3: When coasting to a stop I feel the same lurching as Scenario 2, only it's easier to detect. Again, similar to a mild misfire.

This is a 2000 Sierra 1500, 5.3L, Auto, 25,000 miles, no mods, new plugs, wires, filters, spotless TB, 18-20mpg highway, no codes.

Hope someone can shed light on this. I'd prefer not to start the hunt-and-peck approach if someone's already been through this. Apologies if this is posted somewhere I missed.

DofD · August 18, 2008

Hi there and welcome to the forums!

Not being a mechanical expert in any way or form, I would venture a guess to a transmission issue or a computer issue dealing the transmission.

zxcv · August 18, 2008

maybe you shouldn't have bought the oval tires?

Lincoln30 · August 18, 2008

This is not a nice thought but your symptoms are the same as the symptoms I was having in my 99 just before the tranny needed a rebuild. The symptoms eventually progessed to a huge slip and then slam into gear...have yours checked before it gets to this point or you will also be rebuilding the ring and pinion gearset.

espensegal · August 19, 2008

maybe you shouldn't have bought the oval tires?

HA! What can I say, they were on sale. At the right speed with the right music the whole thing comes together.

This is not a nice thought but your symptoms are the same as the symptoms I was having in my 99 just before the tranny needed a rebuild. The symptoms eventually progessed to a huge slip and then slam into gear...have yours checked before it gets to this point or you will also be rebuilding the ring and pinion gearset.

OUCH! - The thing I hate about tranny shops is I always feel they're taking you to the cleaners. It's not like it's easy confirm their findings. I'll take it in for a checkup, but does this make sense at 25K miles or is it more time sensitive than use sensitive being that it's 8 years old?

bossier62guy · August 19, 2008

maybe you shouldn't have bought the oval tires?

HA! What can I say, they were on sale. At the right speed with the right music the whole thing comes together.

This is not a nice thought but your symptoms are the same as the symptoms I was having in my 99 just before the tranny needed a rebuild. The symptoms eventually progessed to a huge slip and then slam into gear...have yours checked before it gets to this point or you will also be rebuilding the ring and pinion gearset.

OUCH! - The thing I hate about tranny shops is I always feel they're taking you to the cleaners. It's not like it's easy confirm their findings. I'll take it in for a checkup, but does this make sense at 25K miles or is it more time sensitive than use sensitive being that it's 8 years old?

Are you certain the truck only has 25K miles on it?

Draenor · August 19, 2008

maybe you shouldn't have bought the oval tires?

HA! What can I say, they were on sale. At the right speed with the right music the whole thing comes together.

This is not a nice thought but your symptoms are the same as the symptoms I was having in my 99 just before the tranny needed a rebuild. The symptoms eventually progessed to a huge slip and then slam into gear...have yours checked before it gets to this point or you will also be rebuilding the ring and pinion gearset.

OUCH! - The thing I hate about tranny shops is I always feel they're taking you to the cleaners. It's not like it's easy confirm their findings. I'll take it in for a checkup, but does this make sense at 25K miles or is it more time sensitive than use sensitive being that it's 8 years old?

Are you certain the truck only has 25K miles on it?

Thats very, very low miles for that age of a truck. The cluster could of been replaced.

espensegal · August 19, 2008

Yes, by all indications. Carfax checks out, hourmeter checks out (~870 hours) and you could absolutely eat off the entire truck when I got it back in March; inside, underside and engine bay - totally mint.

I would think the computer would log the hours and miles, not the cluster itself - at least that's how it's been on other cars I've had with digital information. But there's no other indication of age more than what's on the odo.

bossier62guy · August 19, 2008

Yes, by all indications. Carfax checks out, hourmeter checks out (~870 hours) and you could absolutely eat off the entire truck when I got it back in March; inside, underside and engine bay - totally mint.

I would think the computer would log the hours and miles, not the cluster itself - at least that's how it's been on other cars I've had with digital information. But there's no other indication of age more than what's on the odo.

What a find....but the cluster is the only place that data is stored.

Lincoln30 · August 19, 2008

Yes, by all indications. Carfax checks out, hourmeter checks out (~870 hours) and you could absolutely eat off the entire truck when I got it back in March; inside, underside and engine bay - totally mint.

I would think the computer would log the hours and miles, not the cluster itself - at least that's how it's been on other cars I've had with digital information. But there's no other indication of age more than what's on the odo.

The trannys in these trucks are not known for being very durable but it shouldn't go out at 25K miles. We have no idea what kind of duty the truck has seen in the 25K miles? You can't judge mileage by looks as mine with 127K is clean enough to eat off of.

espensegal · August 19, 2008

What a find....but the cluster is the only place that data is stored.

Good to know - I've still got some learning to do with this truck. I've had a lot of cars and they're all as different as they are the same.

espensegal · August 19, 2008

You can't judge mileage by looks as mine with 127K is clean enough to eat off of.

Maybe in Texas! In New York all it takes is one winter!

I went through it inside out and (especially) under - I was suspicious, too. Even the undercarriage was mint, stickers and all - not a fleck of oxidation or wear. Strange but it's not the first time I've found a low mileage car. I bought a 1968 F-150 stepside from my first owner / neighbor with 70K on it - just hauled hay from one side of the yard to the other.

espensegal · August 19, 2008

Taking it in tomorrow for a diagnostic. I'll let you know what they find to close the thread.

Mike Diaz · August 23, 2008

Definitely let us know what you find. My truck does the same thing, only to a lesser extent. I'm going to try cleaning the diodes on the mass air flow sensor, since my truck only has 60k and wasn't showing any misfires on my Snap On scanner.