1999 Silverado 5.3L V8 intermittent idle surge & rough idle
February 3rd, 2017, 1:19 PM
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1999 Silverado 5.3L V8 intermittent idle surge & rough idle
Problem vehicle, 1999 Chevrolet Silverado 1500 5.3L V8 2WD with 351,000mi.
I've read numerous threads on the rough idle cold start and the engine having some sort of intake leak and I don't believe I have this problem, but I could be wrong. I have sprayed carb cleaner all around the intake, throttle body and vacuum lines while it's idling rough and did not get an increase in rpm.
The problem started this summer (2016), I headed out for the morning and started my truck up only to find that is was idling rough and sputtering at low rpms when I would give it throttle to ease out of the driveway. Once I got going and got the rpms up a bit it ran fine. When I come to a stop light the engine will surge back and forth from a very low rpm to around 800-900rpms. It will still do this when I put it in neutral and take the load off the engine.
This would continue past the point when the engine got up to operating temperature and at some point everything would return to normal. This problem is more pronounced when the temperature is colder and takes longer to go away when it's cold, but I'm in Mississippi so we have summer in the winter quite often.
One other intermittent problem I've had since the day the fuel pump went out is it acts the fuel pump is loosing it's prime, meaning when I go to start the engine I have to spin it over for a few seconds before it will fire up and even then it will sputter a bit and catch up. The one time I almost never have this problem is when my truck has been sitting for a few days, which happens every week, it will start right up.
Here's everything that has been replaced or tried...
2004 - Original fuel pump went out. Replaced with O'Reilly house brand I think.
2004 - Changed fuel filter.
2004 - Installed Plugs and wires.
2008 - Changed O2 sensors (Bosch) and MAF sensor (Delphi).
2010 - Changed fuel filter.
Summer 2016 problem started.
2016 - Change fuel filter with AC Delco filter. No change to problem.
2016 - Changed fuel pressure regulator with BWD brand. No change to problem.
2016 - Installed AC Delco double platinum plugs (properly gapped) & AC Delco wires. No change to problem
2016 - Cleaned MAF and swapped MAF with wife's truck that uses the same MAF. No change to problem.
2017 - Cleaned idle air control valve. No changed to problem.
Here are the trouble codes that are present...
P0171 Fuel trim system lean bank 1
P0174 Fuel trim system lean bank 2
P0327 Knock sensor signal circuit front
P0332 Knock sensor signal circuit rear
I don't believe these are related to the issue I'm having cause the knock sensor codes have been present for the last 10 years. I know, I know but I'm dreading pulling the intake off.
These just popped up recently...
C0265 EBCM motor relay circuit
C0226 Left front wheel speed signal missing
C0222 Right front wheel speed signal missing
Now the odd thing is my wife's 2003 Yukon 5.3L V8 just started the same idling issue about a month ago, lucky me.
I've read numerous threads on the rough idle cold start and the engine having some sort of intake leak and I don't believe I have this problem, but I could be wrong. I have sprayed carb cleaner all around the intake, throttle body and vacuum lines while it's idling rough and did not get an increase in rpm.
The problem started this summer (2016), I headed out for the morning and started my truck up only to find that is was idling rough and sputtering at low rpms when I would give it throttle to ease out of the driveway. Once I got going and got the rpms up a bit it ran fine. When I come to a stop light the engine will surge back and forth from a very low rpm to around 800-900rpms. It will still do this when I put it in neutral and take the load off the engine.
This would continue past the point when the engine got up to operating temperature and at some point everything would return to normal. This problem is more pronounced when the temperature is colder and takes longer to go away when it's cold, but I'm in Mississippi so we have summer in the winter quite often.
One other intermittent problem I've had since the day the fuel pump went out is it acts the fuel pump is loosing it's prime, meaning when I go to start the engine I have to spin it over for a few seconds before it will fire up and even then it will sputter a bit and catch up. The one time I almost never have this problem is when my truck has been sitting for a few days, which happens every week, it will start right up.
Here's everything that has been replaced or tried...
2004 - Original fuel pump went out. Replaced with O'Reilly house brand I think.
2004 - Changed fuel filter.
2004 - Installed Plugs and wires.
2008 - Changed O2 sensors (Bosch) and MAF sensor (Delphi).
2010 - Changed fuel filter.
Summer 2016 problem started.
2016 - Change fuel filter with AC Delco filter. No change to problem.
2016 - Changed fuel pressure regulator with BWD brand. No change to problem.
2016 - Installed AC Delco double platinum plugs (properly gapped) & AC Delco wires. No change to problem
2016 - Cleaned MAF and swapped MAF with wife's truck that uses the same MAF. No change to problem.
2017 - Cleaned idle air control valve. No changed to problem.
Here are the trouble codes that are present...
P0171 Fuel trim system lean bank 1
P0174 Fuel trim system lean bank 2
P0327 Knock sensor signal circuit front
P0332 Knock sensor signal circuit rear
I don't believe these are related to the issue I'm having cause the knock sensor codes have been present for the last 10 years. I know, I know but I'm dreading pulling the intake off.
These just popped up recently...
C0265 EBCM motor relay circuit
C0226 Left front wheel speed signal missing
C0222 Right front wheel speed signal missing
Now the odd thing is my wife's 2003 Yukon 5.3L V8 just started the same idling issue about a month ago, lucky me.
