PRO NEEDED: Electrical problem after head gasket replacement...

[pmpilot]

Ok. I'm getting pretty familiar with the 3.4 engine (98 Montana) after doing the intake gaskets in 05 and now the heads in 07. But, I just put the thing back together last week and she won't start. IMO I'm not getting spark. Here are the details:

1. Battery is good. Starter turns fine, compression "sounds" good.
2. I'm confident that I have the wiring harness rewired properly, with just a little question about one connection. There is a three pin connector that runs right out of the batter compartment with its own lead (not part of the wiring harness) that I am assuming plugs into the coils next to the five pin connector. I did the old felt tip pen thing over the connectors before I took them apart, but this connection was barely visible and it is the only one I question. Like I said, its on its own wire lead (only connection on that wire) with snaps built into it like it is meant to run by itself along the firewall.
3. When I run a spark test I get maybe one spark and then nothin' else. Its a week spark too. The plugs smell like fresh gas after cranking the engine, so I'm thinking its getting fuel and the spark is missing. I can clearly hear the fuel pump running when turning the ignition on (for a couple of seconds).
4. Here's the kicker. I had Bosch plugs in there before and bought new Bosch plugs in there when I redid the heads. They're platinum singles. Autozone had them listed as compatible but now I wonder. Wish I had put in the AC Delco just to ensure that this isn't an issue. I'm thinking that maybe the coils can't push enough current though them and that is the problem. I'm considering putting the old ones back in to check this theory but that's a 3 hour job from what I've read.

So here's where I need the professional help. I took the whole harness back off and removed the coil pack to make sure I've got it all wired right. I couldn't find another way of doing it so I put it back as is. I've jiggled each electrical connector while having someone else attempt a start to see if maybe there is a short or something with no luck. I'm a bit of a novice (learner) so the electrical stuff is new to me, but is there a way I can use an ohmeter to check these connections to find the problem? Is there any credence to my spark plug theory? That single wire running out of the battery compartment, is that supposed to be plugged into the coil pack or is that where my problem is?

Any ideas or help would be appreciated. I'm a little discouraged now after spending all this time replacing the head gaskets and now getting a new (probably self-induced) problem. Your help is much appreciated.

- Pete

[GTP Dad]

Pete, It sounds like you did everything right. I would check the grounds to make sure they are good especially the one to the ignition module. One problem may be the module itself. Sometimes if you overtighten them they will crack and then not work properly. That may be the only thing you need to check or change. Do a compression test on the cylinders that are easy to get to. By checking these you will be able to tell if the compression is good with actual numbers not just listening. This will also tell you if the timing is correct. Good Luck!

[pmpilot]

Thanks for the advise GPT Dad...

I dug out the ohmmeter and found power at all of the electrical connection on the wiring harness in one form or another. I'd get 12v (11.xx) at one connection and around 5v at the other.

I did finally get a computer code off of the OBDII tool!

P0122 Throttle/Petal Position Sensor/Switch A Circuit Low Input

Not sure where that is but I'm going to investigate that now...

[pmpilot]

Well, I finally made a breakthrough!

Turns out that the electrical connector for the coil pack at the 2 o'clock position comes from behind the engine (I lost this one somehow and found it after taking the harness back off for the second time), not the single line off the battery. Replaced the throttle position sensor and no bad codes. Started it up and everything sounded ok until...

It started knocking. And blowing white/grey smoke. Arrghhh...