2000 5.3 Rough Idle

hendo6479 · April 23, 2009

Hi,

My 2000 Gmc sierra, 5.3 Idles like garbage. Worse when it's warm. The only code that came up on the snap-on scanner was a fuel pump code. Changed the pump. Worked better but not perfect, for a day. Fuel psi is right at 63. Checked regulator, intake for leaks. Cleaned MAF and it helped but after a couple of days, the same. Put a new MAF on. A bit more power but still not helping. New plugs, wires and fuel filter already there. Throttle plate is cleaned and shiny. Have the latest engine mgmt. updates as well. Now I'm leaning toward a dirty or slightly malfunctioning EGR. As well, no codes coming up.

Anyone want to tackle this one???

Thanks..

bill190 · April 24, 2009

Have you replaced the fuel filter?

Does it idle better when you step on the accelerator just a little?

If yes, have you checked the Idle Air Control Valve (IAC) and PCV valve?

233monte · April 24, 2009

Any scanner readings? fuel trims @ idle and at cruise, O2s.

jbordi · April 24, 2009

My want to check the EVAP vent solenoid. There are known to be a problem when dust clogs them. Mine was giving me idle problems w\o any codes. There is service bulletin out for this.

hendo6479 · April 27, 2009

Have you replaced the fuel filter?

Does it idle better when you step on the accelerator just a little?

If yes, have you checked the Idle Air Control Valve (IAC) and PCV valve?

New fuel filter and rough running doesn't smooth out till past 1500rpm

Thanks

hendo6479 · April 27, 2009

Any scanner readings? fuel trims @ idle and at cruise, O2s.

O2 readings fluctuating but within spec. Didn't check the others. My mechanic buddy was in a hurry...

Thanks

hendo6479 · April 27, 2009

My want to check the EVAP vent solenoid. There are known to be a problem when dust clogs them. Mine was giving me idle problems w\o any codes. There is service bulletin out for this.

Okay, thanks. Was thinking about taking it to the dealer as they probably have better diagnosing equip. I'm sure they will look for it.

rodram · April 28, 2009

I have had rough idle or stutter issues on two different trucks.... and where there are no codes to indicate the source of problem, it has ended up being faulty injectors on the fuel injection system

hendo6479 · April 28, 2009

I have had rough idle or stutter issues on two different trucks.... and where there are no codes to indicate the source of problem, it has ended up being faulty injectors on the fuel injection system

Took it to the dealer yesterday... they couldn't find anything other than dirty injectors causing erradic misfiring. 150 bucks to purge and clean intake and plenum. Not all that bad, considering the shop rates up here now. It's like up to $108/hour now. Yikes

Thanks for the reply

BH

ScottyBoy · April 28, 2009

I have had rough idle or stutter issues on two different trucks.... and where there are no codes to indicate the source of problem, it has ended up being faulty injectors on the fuel injection system

Took it to the dealer yesterday... they couldn't find anything other than dirty injectors causing erradic misfiring. 150 bucks to purge and clean intake and plenum. Not all that bad, considering the shop rates up here now. It's like up to $108/hour now. Yikes

Thanks for the reply

BH

Thats too bad that the dealer is collecting over $100 an hour on the mechanic's labor, but only paying the mechanic chump change for his labor. On top of that, most of the technicians have to supply all their own tools. Thats why I don't work in a car stereo/alarm shop anymore. They were making anywhere from $50-$120 an hour off of my labor, but only paying my $13 an hour. It would take me about 30mins or so to install a radio, and they would charge the customer $45, yet I'd only get $6.50 of that $45 and I have to supply my own tools and everything, so how is that fair? I made more money charging friends and others 20 bucks to install a stereo in my driveway. The same goes for alarms. I made a deal with many friends and coworkers of mine over the years. What I'd tell them was "You pick out the alarm system you want and get a price quote, and I bet I can get the same alarm off the internet AND install it for about half of that quote." Only two or three times was my "half price deal" not worth doing it, every other time, I still made $$ off the deal.

hendo6479 · May 3, 2009

My want to check the EVAP vent solenoid. There are known to be a problem when dust clogs them. Mine was giving me idle problems w\o any codes. There is service bulletin out for this.

What is the fix and where is it located....I want to try that. Nothing else is working. My EGR is reading .73 volts at idle. Should it be closer to .5v?

Thanks

hendo6479 · May 3, 2009

Have you replaced the fuel filter?

Does it idle better when you step on the accelerator just a little?

If yes, have you checked the Idle Air Control Valve (IAC) and PCV valve?

Yes all that is done... It doesn't smooth out til past 1500rpm

thanks

hendo6479 · May 3, 2009

I have had rough idle or stutter issues on two different trucks.... and where there are no codes to indicate the source of problem, it has ended up being faulty injectors on the fuel injection system

Took it to the dealer yesterday... they couldn't find anything other than dirty injectors causing erradic misfiring. 150 bucks to purge and clean intake and plenum. Not all that bad, considering the shop rates up here now. It's like up to $108/hour now. Yikes

Thanks for the reply

BH

Got it back fr. the dealer Still same problem. They purged the fuel rail with injector clean. Cleaned plenum and intake. Still not helping

popps · May 3, 2009

Ill take a shot at it. I have a nissan 240sx also. Had a rough idle too on most days, and got worse over time. Changed the plugs,cap,rotor, wires, air cleaner ,pcv valve, cleaned iac valve and still no change. I finally replaced the adjuster for one of the timing chains because there was too much slack in one of the chains causing the erratic idle. Fixed the problem. I'm not familiar with the 5.3 but maybe this could be a cause, also depends on how many miles you have on your truck. I used to be a trans mechanic and was for years.... just tryin to help.