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engine speed hunting at hot idle
Posted: Tue Jun 24, 2008 1:16 am
by eastavin
2007 model, auto. With a hot engine (a/c off) at idle I can watch the tach move between 800 and 1000 rpm every 15 seconds or so like someone throwing a switch. Is this normal in a vibe/matrix? I am used to a rock steady idle unless there is a vacuum problem of some kind with my GM cars. Is there anything to check for that might provide a clue if I hook up my neighbours live engine data reader?
Re: engine speed hunting at hot idle (eastavin)
Posted: Tue Jun 24, 2008 1:18 am
by joatmon
I wonder if it might be the engine cooling fan cycling on and off. When the fan comes on, it puts a little more load on the engine, and the computer will kick up the RPMs a little to compensatewelcome to genvibe!
Re: engine speed hunting at hot idle (joatmon)
Posted: Tue Jun 24, 2008 4:43 am
by zionzr2
Quote, originally posted by joatmon »I wonder if it might be the engine cooling fan cycling on and off. When the fan comes on, it puts a little more load on the engine, and the computer will kick up the RPMs a little to compensatewelcome to genvibe!That would be my thought as well!
Re: engine speed hunting at hot idle (eastavin)
Posted: Tue Jun 24, 2008 1:08 pm
by ajconover
I find I get a bit of idle speed fluctuation as well, especially when stopped in hot weather and sitting in drive. I also find the idle a bit rough with the Vibe in gear, so if I'm stopped at a longer light, I generally shift into neutral, which seems to smooth out the idle.
Re: engine speed hunting at hot idle (ajconover)
Posted: Fri Jun 27, 2008 5:31 am
by Lancer
You all have automatics, right?