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03 Silverado-- L0w Idle & Stalling

silver03ado

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silver03ado Enthusiast

silver03ado

Posted
Posted

2003 Silverado Ext Cab 5.3l engine

81K Miles

Stock configuration

 

In the last month, noticed that idle is lower than normal. In Park or Drive when stopped at a light, the idle gets pretty rough and stays around 300-400 or say and often stalls when turning a corner as well.

 

Always have the A/c on as I'm in Florida. At speeds of 15 MPH up to highway speeds, all is good. A/C blows cold and engine runs fine.

 

Stalling 10 times in 30 minutes, at red lights, etc isn't normal though. Last week, my battery died and with a boost I was back up, but while driving and slowing down for a stop sign or red light, the idle drops too low and she shuts off...

 

Finally, this past friday the battery was totally dead after testing it at the local Advance Auto Parts. Bought a new battery and she starts fine now, but still has the stalling & LOW RPM issue.

 

I metered the battery with the engine off, on (with A/c on & off)

Engine Off: 12.79 VDC

Engine ON/Ac Off: 13.67

Engine ON/Ac ON: 12.67

 

These tests though were done without giving any throttle. Please advise me as to what the possible cause is- if this is something you see all the time on this model. Like I said, I'm gonna bring it to check at the mechanic for codes, etc. I just like having an idea b4 going in. Basically, what can be done to raise the idle? I understand that its electronically controlled and I dont see any throttle cable...heheh

Anything I can check, clean, or test in this case...

 

Thanks and please advise.

redvett Senior Enthusiast

redvett

Posted
Posted

Clean the MAF with the correct cleaner and do the same with the IAC and the port. Carbon & varnish build up will cause poor idle. If after a cleanup you still have the problem have a tech check with a scanner. Engine hot in "D" IAC counts should be 15-30.

SinisterSS Enthusiast

SinisterSS

Posted
Posted

Beyond the cleaning above, check for an air leak from either a vacuum hose off or a loose clamp, etc. between the airfilter box and the throttlebody.

silver03ado Enthusiast

silver03ado

Posted
  • Author
Posted

thanks for the replies guys...new to the newer trucks...

 

How do I clean the MAF without messing it up? what exactly do I clean..those filaments? What type of cleaner? Etc?

 

Also, the Idle Air Controller...where is it? Searched all the posts here and googled it too- no pics. nothing came up and I dont know where to look/find the IAC.

 

For the IAC...what's the Correct Cleaner? And how do I go about cleaning it? Any pics or description of how to find it will be great.

 

 

Is the IAC underneath the plastic Vortec cover?

 

Please let me know - thanks in advance guys!

 

:devil:

SinisterSS Enthusiast

SinisterSS

Posted
Posted

Is your truck also hard to start, especially after the engine is warm? Check the fuel pressure at the fuel rail on the RH side of the engine. You may have a bad fuel pressure regulator (easy, 5-10 minute fix).

silver03ado Enthusiast

silver03ado

Posted
  • Author
Posted

thanks for the replies guys....

 

Just got back from the mechanic. He checked the truck with his computer/obd II machine and spent some good 15 minutes on it.

 

He said that its clean of codes. He told me he doesnt have the special machine needed, so he reccomended that as the first step I go to a place he reccomends that has this Computer Machine that "recalibrates" or flushes the computer. He said the idle may come up to normal after recalibrating.

 

He said thats step one- if that doesnt help I should come back..

 

What do you guys think? I'm here in FL...it's 11:25am and look fwd to hearing your responses so I can make a more informed decision.

 

Ever hear of such a thing? Computer Recalibration or Flush? Can it ruin anything...or only make good?

 

thanks in advance...

silver03ado Enthusiast

silver03ado

Posted
  • Author
Posted

oh boy! not happy to hear that...

 

I havent checked the pressure yet. What do I need to do to check fuel rail pressure? Any removal of plastic vortec cover .

 

its the 5.3l engine on a 2003 silverado.

 

What tool do i need to find/pickup to check the fuel pressure....

 

SINISTER- CAN you PM me yer phone # so i can talk to you for a few just so I know what im doing here...

Draenor Senior Enthusiast

Draenor

Posted
Posted
Clean the MAF with the correct cleaner and do the same with the IAC and the port. Carbon & varnish build up will cause poor idle. If after a cleanup you still have the problem have a tech check with a scanner. Engine hot in "D" IAC counts should be 15-30.

+1

Also I would clean out the throttle body.

Krambo Enthusiast

Krambo

Posted
Posted

Is there any way you can find someone with scanning software and do a basic scan? I would be interested in seeing what your fuel trims are. I think someone hit it by saying a leak past the MAF sensor. If your fuel trims are all over the place showing lean, it is a good indication you have a leak. Take some carb cleaner and spray down the intake past the MAF while the motor is running and see if there is a change in idle. If there is a noticeable change, good possibility you have a leak.

 

BTW, I woudld clean your TB really well and run some sea foam through your intake and another can through your fuel system. Next area would be your Fuel Pressure as someone mentioned.

silver03ado Enthusiast

silver03ado

Posted
  • Author
Posted

Can you guide me in how to get the seafoam Deep Creep Aerosol thru my throttle body.

 

1. If i completely take off air intake hose from TB, will it stall and check engine light will come on.

 

2. I have drive-by-wire...is it safe to use deep creep spray from Seafoam?

 

3. Anyone have a Real Picture of a 2003 silverado 5.3l engine bay they can make markings on to show where to disconnect or drill hole or do something to Properly inject seafoam without me causing any damage....

 

thanks

j.roffel Senior Enthusiast

j.roffel

Posted
Posted

DONT DRILL that comment scares me, as for seafoam, I've only used it with the crankcase and fuel lines, but napa or somewhere should be able to tell you exactly what to do, if the counterperson knows anything that is...

Norseman Senior Enthusiast

Norseman

Posted
Posted
Can you guide me in how to get the seafoam Deep Creep Aerosol thru my throttle body.

 

1. If i completely take off air intake hose from TB, will it stall and check engine light will come on.

 

2. I have drive-by-wire...is it safe to use deep creep spray from Seafoam?

 

3. Anyone have a Real Picture of a 2003 silverado 5.3l engine bay they can make markings on to show where to disconnect or drill hole or do something to Properly inject seafoam without me causing any damage....

 

thanks

Just disconnect the MAF sensor, then remove the intake tube from the TB.

Crank the truck (it should run maybe not real smooth but it will run) This might set a code just bring it to a part store to reset or let it reset on its own.

There is a small hole in the throttle plate spray it in there.

Load the engine up with the stuff and shut it off.

Hook every thing back up, wait about 10-15 min then crank it up and give it a ride.

GMTRUCKTECH Enthusiast

GMTRUCKTECH

Posted
Posted

Listen to me I hvae been fixing these trucks with this idle stumble and a/c inop since the electronic throttle body came out on the trucks. The throttle body actuator is binding up and causing the unstable idle. I have tried cleanig them and so on with no luck. Replace the throttle body and gasket and take it to the dealer and have them update the pcm to also improve the idle stability. Do this and all your worries will be gone!

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