2001 Jimmy - trouble getting engine started and acceleration?
The starter cranks the engine, but the motor does not turn over, esp. in the morning. It takes about 12 times with the starter before the engine fires up. It takes fewer times as the day goes on. Also acceleration is almost non-existent. The starter is new, the battery is new, the spark plugs are fine, the fuel pump and filter were replaced twice just 7 months ago, the mass air flow filter is fine, the catalytic converter is fine...I have had the fuel injection system cleaned a couple of times. Any helpful suggestions on what might be the problem? Thanks.
YA ..2009-07-17T09:29:11Z
Favorite Answer
Get a stoich meter gauge and hook it up to the O2 sensor wire, etc. Then you'll be able to tell if it's running too rich or too lean. A way to check the MAF sensor is to just unplug it. If it runs better (although it will stumble a bit because it initializes a "limp home" mode), then try using some MAF cleaner or contact cleaner on the sensor itself. Or then replace with new. Check the TPS (throttle position sensor). Loosen it up and manually turn it back and forth to see if it helps smooth out the engine. If it does, then good chance it's bad. In a worse case the actual onboard computer is shot. To check O2 sensors, put a multimeter on them. Here's how.
Connect the voltmeter leads to the feedback wire and ground terminals on the O2 sensor.
Set the voltmeter dial or option to the millivolt option on your voltmeter.
Start your vehicle. Run it at idle until it warms up to normal operating temperature. Your oxygen sensor will not give you a proper reading unless you are running the vehicle at normal operating temperature.
Check the voltmeter. It should fluctuate and then settle at 150 millivolts. Rev the engine (or have an assistant rev the engine). The voltmeter reading should drop momentarily while the throttle opens. Then, as the throttle closes, the meter should read slightly higher than 150 millivolts. It should then return to the 150-millivolt reading.