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03 Grand Am GT will not start


lucky131969
11-29-2007, 09:12 AM
Engine rotates, but will not fire. Battery is strong. PCM is not throwing any codes. Here's what I've done soo far:

Fuel pressure at the rail is good=57 psi (no bleed down), Spark at plugs is good. MAP sensor reads normal for altitute, IAT and ECT temp read good, Throttle pos sensor good, Check for 12 volts at fuel injector harness(good), intake and exhaust is free of obstruction.

I'm at a loss here. I did not check the crank sensor output, but I wouldn't think the spark plugs would be firing if the crank sensor had no out put. The car literally ran one day, and not the next. I'm leaning toward the PCM because I've got fuel, and spark, but I suspect the PCM is not allowing the injectors to operate.

xeroinfinity
11-29-2007, 06:35 PM
Welcome to AF.

What engine, the 3.4 ??

Get a Noid light and test the injectors for pulse.

Also are your spark plugs & or wires old or New ?
Old fauled out plugs will give you problems when the temps drop or if they get flooded with fuel.

lucky131969
12-11-2007, 02:45 PM
Welcome to AF.

What engine, the 3.4 ??

Get a Noid light and test the injectors for pulse.

Also are your spark plugs & or wires old or New ?
Old fauled out plugs will give you problems when the temps drop or if they get flooded with fuel.

The injectors are not firing at all. This car is in a shop right now, and they cannot figure it out. I took it to a shop because I did not have a tech II, and could not look at the BCM and theft deterrent system.

So far, they have replaced the ignition module and PCM. The only way the car runs is if they do an injector balance test, which forces the fuel injector s on. If the car sits in the shop overnight, it will fire up, but if it sits in the cold overnight, it won't fire. So, it sounds temperature related, but these guys have had the car for two weeks, and can't find the problem. GM mechs are involved, and are scratching their heads.

xeroinfinity
12-11-2007, 05:45 PM
Well, looks like they need an upgrade, cause the PCM would be the Last thing I replaced! :shakehead

Sounds like a crank or cam sensor problem.....

Good Luck!

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