wrote:
> We have a 1999 Isuzu Rodeo 4 cylinder 2.2 SUV with about 96K miles on
> it. The car has always ran fine but recently it began to idle rough. The
> check engine light has been coming and and going off for several months
> now, Other than the rough idle, it runs fine. We have changed the spark
> plugs and spark plug wires within the last few weeks but it still idles
> rough. Any ideas would be appreciated.
>
> Doug and Patty

At the least you need to see what code(s) are stored in the ECM. They
may lead directly to a faulty component or just direct you generally
towards areas to test. The best case would be if you had an individual
cylinder misfire code (P0301 to P0304); then you could isolate that
cylinder and test spark, compression and fuel delivery. Many causes of
a rough idle symptom will either send unburned gas into the catalytic
converter and lead to it's early demise or result in lean operating
conditions that are damaging to your engine. In all cases, a rough
idle results in degraded fuel economy.

Your problem could be as cheap as a leaking PVC hose and as expensive
as a cracked cylinder head.

Toyota MDT in MO