2000 5.3 liter Silverado runs rough until warmed up

[snowforfun4]

I just bought a 2000 Silverado with the 5.3l for a work truck. It has 150k miles and runs great after running for 2 minutes or so, but until it warms up a slight bit, it idles very rough and the RPMs fluctuate quite a bit. Any obvious things to check first?

 

[MH Hawker]

Re: 2000 5.3 liter Silverado runs rough until warmed up

Yes clean the MAF and run some sea foam in the gas

 

[Big Bubba]

Re: 2000 5.3 liter Silverado runs rough until warmed up

My question is, when was the last time the spark plugs, spark plug wires, and fuel filter been replaced on her? If it has not been done I would at least do the preventative maintenance on her just for piece of mine and it might run alot smoother. I had a 1999 Chevrolet Silverado with the 5.3 liter and I did the spark plug, spark plug wires change and made a world of difference for me. Is it missing or anything? One more thing, I would go to Advance Auto Parts and by a can of throttle body spray in a can and clean your throttle body really good and blow it off with compressed air. Your throttle body mounted on the intake body that has the air filter tube/snorkel hooked to it gets really carboned up inside of it and could cause it to run that way also. While your doing the spark plugs and spark plug wire replacement might as well give the throttle body a good cleaning also. That should square you away with the rough running in my opinion. One more thing, I keep thinking of more stuff after I hit the submit button, anyway, are you leaking any coolant around the plastic intake. If so, your going to have to replace it and that could be causing your issue. Pull the oil dipstick and see if any coolant is mixed in with the oil if it looks milky looking like a cup of coffee with alot of creamer in it then that could cause issues. And my final question is are you getting any service engine soon lights or Check engine light on the dash? If so, I would go to Advance Auto parts and get them to pull the code/codes for you so you know what it is causing the light to come on if it is comming on for you. Let us know what you find. I am very curious. On your throttle body, when you press the throttle with your foot, does it sometimes stick on you? On my 1999 Chevy Silverado, mine would stick on me when I went to press the throttle gas pedal with my foot and what causes that is the carbon build up on the throttle body butterfly. That carbon is kinda like a stciky substance when it gets on the throttle body butterfly and acts likes kinda like a glue to hold the butterfly in place and when you push the gas pedal with your foot it sticks on you and then releases. That is a sign your throttle body needs to be cleaned up to get the carbon buildup removed from it. I would check all of your vacuum lines for any cracks or lines that are rotten falling apart. One of my friends has a 2000 Chevrolet Blazer that was running a little rough and it had a rotten vacuum line and I found it and repalced it with a new one and she runs good to this day.

 

[snowforfun4]

Re: 2000 5.3 liter Silverado runs rough until warmed up

Yes clean the MAF and run some sea foam in the gas

Got call on the sea foam, keep moving the can around to get to stuff in the garage and did not even think to apply it to the truck.

 

[snowforfun4]

Re: 2000 5.3 liter Silverado runs rough until warmed up

My question is, when was the last time the spark plugs, spark plug wires, and fuel filter been replaced on her? If it has not been done I would at least do the preventative maintenance on her just for piece of mine and it might run alot smoother. I had a 1999 Chevrolet Silverado with the 5.3 liter and I did the spark plug, spark plug wires change and made a world of difference for me. Is it missing or anything? One more thing, I would go to Advance Auto Parts and by a can of throttle body spray in a can and clean your throttle body really good and blow it off with compressed air. Your throttle body mounted on the intake body that has the air filter tube/snorkel hooked to it gets really carboned up inside of it and could cause it to run that way also. While your doing the spark plugs and spark plug wire replacement might as well give the throttle body a good cleaning also. That should square you away with the rough running in my opinion. One more thing, I keep thinking of more stuff after I hit the submit button, anyway, are you leaking any coolant around the plastic intake. If so, your going to have to replace it and that could be causing your issue. Pull the oil dipstick and see if any coolant is mixed in with the oil if it looks milky looking like a cup of coffee with alot of creamer in it then that could cause issues. And my final question is are you getting any service engine soon lights or Check engine light on the dash? If so, I would go to Advance Auto parts and get them to pull the code/codes for you so you know what it is causing the light to come on if it is comming on for you. Let us know what you find. I am very curious. On your throttle body, when you press the throttle with your foot, does it sometimes stick on you? On my 1999 Chevy Silverado, mine would stick on me when I went to press the throttle gas pedal with my foot and what causes that is the carbon build up on the throttle body butterfly. That carbon is kinda like a stciky substance when it gets on the throttle body butterfly and acts likes kinda like a glue to hold the butterfly in place and when you push the gas pedal with your foot it sticks on you and then releases. That is a sign your throttle body needs to be cleaned up to get the carbon buildup removed from it. I would check all of your vacuum lines for any cracks or lines that are rotten falling apart. One of my friends has a 2000 Chevrolet Blazer that was running a little rough and it had a rotten vacuum line and I found it and repalced it with a new one and she runs good to this day.

The P/O took very good care of the truck so I would believe it had been plugs and wires were replaced at regular intervals, but you are correct, the only way to be sure is do it yourself.

Funny you mention the throttle sticking. It does and that was going to be the next thing I addressed after getting the startup smoothed out.

It is not throwing any codes so I think your suggestions should straighten it out pretty easily.

Once it warms up it even idles perfectly, that would not be the case with a vacuum leak would it?

 

[snowforfun4]

Re: 2000 5.3 liter Silverado runs rough until warmed up

Good call on the sea foam, I keep moving the can around to get to stuff in the garage and did not even think to apply it to the truck. Thanks for the suggestion.

Edit spelling

 

[bruceb58]

Re: 2000 5.3 liter Silverado runs rough until warmed up

Don't use sea foam on any engine that has O2 sensors.

Although I kinda doubt its the plugs, they did change the plugs designated for that engine and the gap.

Clean the MAF with MAF cleaner. I had issues with a dirty MAF. It was worse when it was cold but affected the vehicle even when it warmed up.

 

[agallant80]

Re: 2000 5.3 liter Silverado runs rough until warmed up

Same thing happend to my old Silverado. It was the ignition control module located under the distributer cab. I was skeptical about it, changed the cap, plugs wires etc. It all had no effect until I changed that module. It cost about $45.

 

[snowforfun4]

Re: 2000 5.3 liter Silverado runs rough until warmed up

Same thing happend to my old Silverado. It was the ignition control module located under the distributer cab. I was skeptical about it, changed the cap, plugs wires etc. It all had no effect until I changed that module. It cost about $45.

Thanks for the tip. I am still working on the other suggestions and will try this if it does not improve.

 

[rogerwa]

Re: 2000 5.3 liter Silverado runs rough until warmed up

My 2004 suburban with the 5.3l had the same type of symptoms. Ended up being the intake manifold gasket.. Mine occured at ~50K miles.

 

[MTboatguy]

Re: 2000 5.3 liter Silverado runs rough until warmed up

Make sure and test your O2 sensors to see if they have thrown any codes that are stored in the ECU, if they are not heating up correctly when you first start it, they can cause it to run rough until it is warmed up.

 

[bruceb58]

Re: 2000 5.3 liter Silverado runs rough until warmed up

Make sure and test your O2 sensors to see if they have thrown any codes that are stored in the ECU, if they are not heating up correctly when you first start it, they can cause it to run rough until it is warmed up.

I would think you would have a CEL if that happened. My Lexus had a bad heater on one of its O2 sensors and set the CEL.

 

[MTboatguy]

Re: 2000 5.3 liter Silverado runs rough until warmed up

I would think you would have a CEL if that happened. My Lexus had a bad heater on one of its O2 sensors and set the CEL.

Not always, my jeeps that I have owned, did not always throw codes that activated the CEL, they would be in the process of failing, but not throw a CEL light, the ECU in the cars now a days and for about the last 10 years will store Pending codes, which means a component is getting ready to fail, or may be at a low voltage level due to fatigue, but not activate the CEL light. Both my OBDII meter as well as my computer interface will warn you of impending problems as well as any problems that have occurred but is not activating the CEL.

 

[bruceb58]

Re: 2000 5.3 liter Silverado runs rough until warmed up

Yes, there are certain codes that won't trigger a CEL but the O2 codes are supposed to always set them once the sensor goes out of spec.

I think the heater code only occurs if its an open or a short.

I use the AutoEnginuity tool. http://www.autoenginuity.com/

 

[MTboatguy]

Re: 2000 5.3 liter Silverado runs rough until warmed up

Yes, there are certain codes that won't trigger a CEL but the O2 codes are supposed to always set them.

I think the heater code only occurs if its an open or a short.

Not always Bruce, there are certain low voltage codes that will not trigger a CEL on non-CA cars.

I use a Snap On, tuning system for my laptop and it is amazing what you can find out.

 

[bruceb58]

Re: 2000 5.3 liter Silverado runs rough until warmed up

Not always Bruce, there are certain low voltage codes that will not trigger a CEL on non-CA cars.

Talking about O2 codes only.
here is an example of the low voltage O2 sensor code that sets the CEL(MIL).

OBD-II Trouble Code: P0131 Oxygen O2 Sensor Low Voltage (Bank1, Sensor1)

None of the SnapOn OBDII tools hold a candle to the AutoEnginuity one unless you go to their very high Verdict systems.

 

[MTboatguy]

Re: 2000 5.3 liter Silverado runs rough until warmed up

None of the SnapOn OBDII tools hold a candle to the AutoEnginuity one unless you go to their very high Verdict systems.

Well Bruce, with the amount of money and training I have on these systems now, I do beg to differ, but hey what ever works for you is a good thing, I know what works for me. I am using the exact same system that they use at the local dealerships. By the way, I am very familiar with the O2 codes

 

[CharlieB]

Re: 2000 5.3 liter Silverado runs rough until warmed up

Don't use sea foam on any engine that has O2 sensors.

Bruce,

Wife and Dau's Astro vans have about a 28 gal tank. I've ran a can of SeaFoam thru both of them every 2 or 3 years, haven't had a problem, yet.

Our Blazer and my S-10 are only 18 gal, no prob there either, yet.

Should I be worried, or switch to Chev Techtron, or comparable?

 

[bruceb58]

Re: 2000 5.3 liter Silverado runs rough until warmed up

Well, you are dumping oil through your fuel system. Sea Foam claims it is ok but of course they would say its ok. Chev Techron is a WAY better fuel system cleaner than the 30% Naptha that is in sea foam.

Every 2 or 3 years is not very often. I would be more concerned if you were doing it more often than that or dumping it down the intake or through a vacuum line like I have seen some people do.

 

[dockwrecker]

Re: 2000 5.3 liter Silverado runs rough until warmed up

My 5.3 showed lean condition codes when my intake manifold warped.
The intake manifold is a very common problem with the 5.3.