Misfiring help???

My brother in laws daughter has a 99 grand am. sorry but i dont know the engine that it has but it is running like crap and we checked the codes and it has multiple cylinder missfire and injector circuit open.. soo he took it to a mechanic and they changed the plugs the cover that connecets to the plugs and the coil packs and that fixed noting. Now they say its the injectors but that there is no way to test them and i always thought that could check them with a olm meter?? so my question is does anyone have any thoughts and if it would be injectors they dont look like it would be the hardest thing to change unless you need to plug into the ecu or any special tools needed?
any info would be helpfull thanks he doesnt want to waste anymore money letting someone else just take stabs in the dark

And the traction control off light is on.. and i think its a 3.4 if that sounds right.. and also how do you know if it has EGR

If your engine have several injector, just compare the resistance of each injector. they should be fairly close.

Also, as for the traction control, if the PCM detect serious issues it will turn it off.

The traction control require that the engine work correctly, also the abs need to be sane too (it use the abs data)

find EL diagram so you can ohm your injectors at the 10way injector connector. This way you don't have to remove upper plenum to gain access to injector's male terminals. If I can remember corectly injectors should be around 12.6 ohm. Ohm them all and find odd ball.

ludermn, your first post has your answer as to what the misfire was from, open circuit injector, not uncommon with these.

Ok, the 4 cyl is easier to test than the v6. The v6 you can test them from the large harnesss connector by the alternator.
If you follow each set of injector wires back to the large injector harness connector, you can test each one without removing the intake.
The EGR is on the drivers side of the engine, on top of the intake, and Im sure this 99 has one. So the resistance should be between 11.4-12.6 Ohms for the 4 cyl and the V6.
If it does not have an EGR then the resistance would be between 1.95-2.3 Ohms.

On the traction light, you'll need to have it scanned with an ABS capable scan tool. THough it could be the trac switch on the dash by the radio faulty.. :dunno:

Hope that helps