5.3L Surging

[Mo Mason]

I have a 2000 Silverado 4X4 Z71 5.3L that surges between 40-50 mph. The tach fluctuates 50-100 rpms. I can hear the engine surging it is very noticeable, nothing imagined. At highway speed 70-80 mph there is NO surging. I can smoke the tires off the line, no problem. Even get second gear scratch sometimes, no problem. But just trying to hold a steady 45 mph and it surges up and down. I have replaced the fuel pump and fuel filter. Put a pressure gauge on it and it goes to 50 psi and holds there, at idle. Any ideas appreciated.

 

MO

[Zed71]

I have a 2000 Silverado 4X4 Z71 5.3L that surges between 40-50 mph. The tach fluctuates 50-100 rpms. I can hear the engine surging it is very noticeable, nothing imagined. At highway speed 70-80 mph there is NO surging. I can smoke the tires off the line, no problem. Even get second gear scratch sometimes, no problem. But just trying to hold a steady 45 mph and it surges up and down. I have replaced the fuel pump and fuel filter. Put a pressure gauge on it and it goes to 50 psi and holds there, at idle. Any ideas appreciated.

 

MO

 

 

Dude I hate to say this but is sounds mechanical.

 

Hopefully it's just an accessory on the engine (alternator, power steering, a/c compressor I'd replace the belt tensioner anyways as it's $30 but can cost $1000's if it goes) that is going, and possibly causing resistance on the drive belts, but if it's not that then check your transfer case, and transmission for fluid quality, and levels. If not the fluids, your tranny / transfercase may need servicing.

 

Just my .02 aswell, and I am NOT a mechanic.

[BRZ71]

Could be intake gasket

[Mo Mason]

Thanks for replying guys, I certainly appreciate it.

 

Reese

[GRB60]

If it's running at only about 1200-1300 RPMs I know what you're feeling. I think it's related to the engine speed. Kick it down a gear and it stops, right?

 

I don't think there's anything wrong. It seems to be a trait of the vehicle.

[Mo Mason]

If it's running at only about 1200-1300 RPMs I know what you're feeling. I think it's related to the engine speed. Kick it down a gear and it stops, right?

 

I don't think there's anything wrong. It seems to be a trait of the vehicle.

 

No, it doesn't stop! I can kick it down to 3rd and it still does it. It even does it with the cruise control set. There is definitely something wrong. Surging or hunting or whatever you call it, is not normal. Understand that I do not have to really pay attention to notice it. It is fluctuating 200-300 rpms at times. At first I thought it to be a fuel problem but I am starting to think it may be transmission related. Hep me fellars, hep me!

 

Reese

 

[AcetyleneDreams]

I had a 2000 4.8L and I had a similar problem and it turned out to be the torque converter. At 40 mph to about 45 mph, the engine would surge (to use your term) and a scratching noice was noticeable. This only happened at 40 - 45, and it was happening the day I drove it off the lot new. Needless to say, I took it back after about a week and had it checked. The tech told me it was the torque converter making all the noise, so I said...ok...and left it be. I never had a problem with it, and I just never drove at 40 - 45. Not that I would ever speed.

[Mo Mason]

I don't have the scratchy noise, but you are right on I think. So you just lived with it? Not sure I can do that as it is irritating as he**. But actually I never have liked going 40-45 mph anyway. I just wish I knew for sure before tearing in to it. Is anything for sure? Thanks for your input AD it's greatly appreciated.

 

Reese

[AcetyleneDreams]

Sure thing. Yeah...I just lived with it. I fugured that if it broke, it was under warranty, so it was all gravy. But I never had a single problem out of it. the tech I talked to about it said he was surprised too, so he took another new one off the lot (in 2000) and drove it...same thing. So I don't guess it's going to cause you a problem mechanically, but emotionally it will. Just do 50 everywhere and you're golden. : )

 

Regards,

 

Ben