Car started running rich and miss firing

[Darkness]

Use the EFILive scan tool to do the Cylinder Balance test.

Then you may also want to do a compression/leakdown test.

The cylinder balance test is not very consistent because the idle is bouncing up and down when rough. As for the compression test I'm doing it tomorrow.

[Darkness]

I got a code P0200 "Injector Circuit Malfunction"

Anybody know what this is?

[joecar]

P0200 = PCM detected incorrect voltage on injector driver circuit(s) for 5 seconds or longer.

[joecar]

Check the INJ fuse (and find the cause if it's popped);
Check for voltage at each injector connector;
Check for pulsing/"blinking" voltage with engine cranking,
if not, then check for short or open.

You have either:
a. one or more electrically open injector(s);
b. one or more injector circuit(s) that are open or shorted (to either ground, or to voltage, or to each other);
c. one or more bad injector connectors and/or harness connectors;
d. one or more failed injector driver(s) in the PCM;
e. a bad ground somewhere;
f. a bad connection to the INJ fuse, or the INJ fuse is blown (see "shorted" in b. above).

[Darkness]

Check the INJ fuse (and find the cause if it's popped);
Check for voltage at each injector connector;
Check for pulsing/"blinking" voltage with engine cranking,
if not, then check for short or open.

You have either:
a. one or more electrically open injector(s);
b. one or more injector circuit(s) that are open or shorted (to either ground, or to voltage, or to each other);
c. one or more bad injector connectors and/or harness connectors;
d. one or more failed injector driver(s) in the PCM;
e. a bad ground somewhere;
f. a bad connection to the INJ fuse, or the INJ fuse is blown (see "shorted" in b. above).

Thanks, I'll look it up. Would this be the cause for this whole problem?

How do I check the blinking voltage? Sorry for the dumb questions

[joecar]

How do I check the blinking voltage? Sorry for the dumb questions

Darkness,

Not dumb... it would be dumb to not know AND not ask...

Can use a LED voltage probe (looks like a pointy screwdriver with red and green LEDs inside the handle, and a long wire lead off the handle to a crocodile clip... green lights up on positive voltage, red lights up on negative voltage; available at parts stores for $20), connect across injector harness connector, flashes as engine cranks...

Or can use injector connector test light (plugs into injector harness connector and flashes while engine is cranking; some parts stores have these, you need the GM variant, these are more expensive and less verstile than LED voltage probe)...

Or can borrow a scopemeter (will show a squarewave) if you know the right person...

May be able to use a DMM, but it's more difficult... you'll see a varying DC voltage while engine cranks, may be able to see an AC voltage... some DMM's have a Hz function, gives a reading matching RPM / 2.

You'll need a DMM to check for injector resistance and wire continuity anyway.

Goto www.ls2.com and look at their forum's diagnostic sections (courtesy of Elmer, good job )... they have diagnostic proceedures for just about any DTC... if you can't find it, I'll try to find it... it's sectioned by year/make/model, but most of these have the same exact diagnostic procedure.

Cheers
Joe