[doctorona]

Hey Gang,
My Mom's car has a rough idle when starting up after its been sitting for a while.
Basically if it has sat for a few days, the symptoms are this..

Turn key to the on position.
Wait a few seconds and then turn key to start car.
Car starts up good.. about 7 seconds or so afterwards the idle goes down very low, motor shakes from low idle like it's going to die, get a couple "pops" from the exhaust, and then the idle goes up to normal.

This seems like it's only on start up after a few days... after it's warmed up, it doesn't happen.
Fuel is 100 octane and fresh.
Any ideas on what could be the cause of this?

Thanks again!

Rob

 

[jetfuel]

...last service done?...plugs?...air filter?....but the 100 octane has me wondering...is it LL 100 octane?

Jetfuel...just to start...

 

[jimvw57]

Leaking Injectors??

 

[smark]

How many miles on the vehicle. Might be bad plugs, dirty fuel injectors. 100 octane fuel?

Something wrong with a start up sensor. For the fuel injectors, when the vehicle is started cold. Since modern cars don’t have chokes anymore. The cars computer not sending out the right information.

 

[doctorona]

Thank you all for the replies!... and my apology on the octane level, it is 92 octane, not 100
I'm going to do a minor tune up at Christmas time ( new plugs, oil change, filters ).
The car has 58,000 and is driven rarely.
Would an OBD2 show these codes you speak of?
Sounds like injector issues/start up sensor area..

Thanks!
Rob

 

[jwight]

Check for the dreaded P030x code - x being the cylinder that may be misfiring. Usually a symptom of a burned valve.

 

[Miss Mercedes]

Check for the dreaded P030x code - x being the cylinder that may be misfiring. Usually a symptom of a burned valve.

P030x can also be caused by a bad plug, a bad coil, or even poor compression on that cylinder too.

 

[doctorona]

Thanks again Gang...
I'll check the compression and buy a OBD code reader to see what's going on.
Hopefully it's just a fouled plug!

Rob

 

[doctorona]

Update:
Bought a OBD2 code reader.. good news, no codes.
The cars been actually running really good with no issues.