2003 Oldsmobile Bravada Q&A

2003 Oldsmobile Bravada Question: I have a 2003 Olds Bravada AWD, I have a rough idle.

I have a misfire on Cylinder #2. I have changed the plugs, coil for that cylinder, and the fuel injector for that cylinder and it has not helped. Any help would be appreciated. -
Answer 1
maybe a intake manifold gasket.. is it the 4.3lt? if so they where known for intake leaks.. -
Comment 1
It is a 4.2l and it is only the number 2 cylinder. The IMG was changed when the new injector was put in. -
Comment 2
can you get to the injectors? if so might try renting a noid light from autoz, plug the injector wiring for that cylinder in to it,, start the engine, check to see if the injector is getting a signal -
Comment 3
I have spark in that cylinder, it runs fine off of idle, just a rough idle. I know that the 4.2l engines have trouble with valves and valve seats. I don't want to put any more money into it until I know what is wrong with it. -
Answer 2
Possibly a vacuum leak at the intake manifold. If you don't have axcess to a noid light as suggested, try this "listen" to the fuel injector. Using a mechanic's stethoscope (or use a long screw driver placing the handle end up to your ear place the metal tip end of the screwdriver against the body of the fuel injector), get a friend to crank over the engine while you "listen" to the fuel injector listen to each injector at the same point of the injector body. You should hear "click, click, click" as the injector is electrically opened and closed by the computer. If the injector is not being triggered you will not have fuel getting into the engine's cylinders. Disconnect the electrical connector at the fuel injector with the ignition key in the "on" position, (next position after the accessory position) you should have 12 volts at one of the two wires at the injector. This true for most vehicles but you need to consult a workshop manual for your vehicle to see that this is true for your vehicle. When the engine is running the second wire at the injector gets (triggered) grounded by the computer in your vehicle many times a second controlling exactly when and how much fuel gets injected into the engine. Listen to each injector at the same spot they should all sound the same not some dull some sharp. -
Comment 1
I have spark in that cylinder, it runs fine off of idle, just a rough idle. I know that the 4.2l engines have trouble with valves and valve seats. I don't want to put any more money into it until I know what is wrong with it. -