firing order, '94 Grand Am

I have a question about my sisters 1994 Grand Am with the 3.1L V-6. What is the proper firing order for the spark plugs? My chiltons guide says one thing, but the way it was wired when it came back from the shop was completely different!

It was recently in for service for an ongoing misfiring problem. They recommended taking it to a dealer to have a new computer put in, (the shop said they couldn't "flash it" without it being in the car?).

The new computer went in but the problem remained, sort of. It felt like bad timing. Not wanting to pay a dealer to mess with it, (I generally don't trust them, many bad experiences) I thought I would take a look myself. I found the wiring was different than my manual, so I took notes on where everything was and rearranged it according to the book. Now it will not start (not suprising) but before I go further I was wondering if anyone had any insight, or at least the proper firing order!
:banghead:


For more history read on, though I am not sure it matters. The problem developed a few years after we got the car. the engine ran roughly, at idle and at speed. My mother hesitated to take it for service but finally took it to a dealership several times, and each time they claimed to fix it, but the problem would return. It gets worse in hot weather, and at times feels like only a few cylinders are firing. If the engine is stopped and restarted, sometimes it would run fine, especially if it wasn't to hot. Recently we took it to a "reputable" shop, and they said the ignition is fine, but not all the injectors are firing, and it is a problem with the computer (specifically they said, "first we found the #5 injector not firing, then the #2). We took it to a dealer to have the computer replaced, and now the engine still idles roughly, though it feels different than before. oh, and the spark plug wires were different than in my chiltons guide. Help!

Okay, I have achived some insight into the situation.
the Chilton's guide lables the cylinders as such:

rear of engine

2 4 6

1 3 5

front of engine

with the number one cylinder on the left of the front of the engine,
the plugs were wired as such

rear of engine

1 3 5

2 4 6

front of engine

with the number one cylinder on the left of the REAR of the engine. Is this a misprint on Chiltons part? am I reading it wrong? Help!

(according to the guide, the firing order is 1,2,3,4,5,6 )

Look on your rad support there should be an emissions label and sometimes they will show the plug wires and where they go.

I want you to know not all dealers are bad, you found one did you try another??

The rear bank has numbers 1 3 5.
The front bank has 2 4 6.

The first cylinder on your left facing the engine is number 2 in the front and number 1 in the rear.

thank you for the reply, I guess my book is wrong, :(
Maybe you can answer another question, are the symptoms I described, (no power, rough idle,) possibly caused by a leaking intake gasket? I have heard this is a problem on this car. I am pretty sure it isn't leaking coolent, but maybe it is allowing air into the into the mainfold resulting in a low vacuum condition. can I test for this? again, any help is appreiciated.

Yes it is possible for a gasket to go bad causing your problem. But I would think that you would get a higher idle with a vaccum leak after the MAF sensor. Have you replaced your gas filter lately. Low fuel pressure or low volume would cause a power loss. Dirty injectors could also do it. The list of possbilities is long for a rough idle and low power. I would go after a fuel pressure problem first.

The guy at the shop said, "first the #5 injector wasn't firing, then the #2," they checked for carbon in the fuel rail and clogged injectors, found neither, and recommended replacing the computer, which hasn't helped. I was wondering if a bad sensor such as MAF would cause the computer to mess up. Either that or the 02 sensor, but don't they check that durring tune-ups? Or wouldn't the computer throw up an error?

How did they test for the injectors causing your problem??

Computers are stupid!!! if your MAF sensor is reading and moving the computer will think it is working right but that doesn't mean it is measuring the air right!! We have a major problem with MAF sensors and KN air filters the oil charge gets on the fine wire sensor and the sensor can't read the Proper amount of air entering the engine. BUt a bad or skewed MAF will give you a hesitation not a misfire.

The way it work the crank sensor determines what cylinder is where it sends this signal to the ignition module which fires the injector and plugs and also sends the signal to the PCM.

Is there a way to test the crank sensor(s) (there are two, one mounted in the block and one near the flywheel.) And would a problem with one of them cause a miss-fire of this nature.

Also, in asking my sister about previous problems with the car, apperently a rat had nested and torn up some wires in the car. Could this be the problem? (and unfound short) I would assume it could be, how much to test the harness, or replace it outright?

Yes the rat could be the cause of your problems. I would suspect the rat ate some of your injector wires. For some reason rats like the pink injector wires (must be the taste). You might have to lift your upper plenum off and look at the wirng close. Also are you sure the aprk plug wires are good? Take a water hose to the engine soak the wires down and brake torque the engine and see if it breaks up.

Their is no real easy way to test the crank sensors. Usually I use a scanner and see what is happening. The one on the block is called the 24X sensor and the one the is the 3X sensor. Usually if one is bad it would cause a no start condition. And you can't forget about the cam sensor mounted on the top on the block.

I have seen several 24X crank sensors with melted wirng harness, they are routed near the rear exhausrt manifold and if they come loose they will melt, but that again causes a no start.

One clue I just noticed is that you say the problem is there at idle with no load on the engine usually that is an indication of a fuel or injector problem.

First, thank you for your help.

I will take a look at the injector wires if the mechanic dosn't fix it. One question, What do you mean by:

Take a water hose to the engine soak the wires down and brake torque the engine and see if it breaks up.

Exactly what am I looking for?