FIRING ORDER needed for TGP 3.1L code for 3900

[Guest]

Struggling to get the 3900 started. I need to confirm I have the plug wires connected properly starting from the dual plug end of the ignition module. It shouldn't matter what position they are in on the same coil since the plugs fire in pairs. Please be specific because it's not in the standard vehicle.

My problem so far is a crank without run. I was able to get it to run twice briefly using starter fluid which indicates to me that it's not getting enough fuel. It ran erratically though. I'm not going to use the starter fluid again because I know it's dangerous and I did get a reversion. My pump is working, I have power to the injectors and obviously I have spark so the problem appears to be between fuel quantity and possible timing inaccuracy due to a sensor being out of wack and causing a problem.

[IsaacHayes]

SFI motors fire 1,2,3,4,5,6 IIRC. No idea how the 3.1l fires. 1,3,5 are on the "backside" with 1 being by the alternator, and 5 being by the throttle. 2,4,6 are on the front side with 2 being by the water pump, 6 by the throttle.

As far as the coil packs, I assume it's the same as other SFI motors. Coils:
(Pulleys) 52 36 41 (throttle body)

EDIT: Read your thread on pennock's. You can use the 3900 MAP sensor if you didn't know that. Not sure why you need to run vacuum tube to the MAP unless you are using the old style...

[Joseph Upson]

SFI motors fire 1,2,3,4,5,6 IIRC. No idea how the 3.1l fires. 1,3,5 are on the "backside" with 1 being by the alternator, and 5 being by the throttle. 2,4,6 are on the front side with 2 being by the water pump, 6 by the throttle.

As far as the coil packs, I assume it's the same as other SFI motors. Coils:
(Pulleys) 52 36 41 (throttle body)

EDIT: Read your thread on pennock's. You can use the 3900 MAP sensor if you didn't know that. Not sure why you need to run vacuum tube to the MAP unless you are using the old style...

Thank you kind sir, I have it backwards according to your discription, I have the plugs wired as follows:

facing the front of the engine looking at the pulleys with the alternator on the left bank with cylinders 135, 1 just below the alternator, I have coils arranged in this order moving front to back with the coil plug terminals down low or on the left side close to the plugs on the head and the coil body next to the manifold and the end of the ignition module with two plugs closest to the alternator, 1-4, 3-6, 2-5.

Or just as you see in the picture to make it easier. Am I correct that I have the wires crossed up although they are disconnected now?

I also no longer have any spark for some reason which is why I haven't had any further attempts from the engine to run.

[1988GTU]

Make sure you know that the coils are mounted up top on a SFI and down by the front exhaust manifold for the MPFI. So I think you're fine for the location of the plug wires.

[IsaacHayes]

The MPFI has the coilpacks rotated 180* down there from what the SFI motors have on top of of the rear/left valve cover.

EDIT: The #s I gave are if the coils look like this: Yours sounds like you have them turned 180*.

[Joseph Upson]

Make sure you know that the coils are mounted up top on a SFI and down by the front exhaust manifold for the MPFI. So I think you're fine for the location of the plug wires.

That doesn't help me as far as a confirmation, I don't have an actual 3.1 and high and low mounting positions don't orient me as to wire location since in both locations the outer coils can be swapped around. I don't know if I have the assembly turned around or not since I mounted the assembly to the 3900s mounting plate and the 3900s coils do not look anything like the older style. Thanks for effort though.

[1988GTU]

That how they are numbered and 123456 is the firing order.

[Joseph Upson]

The MPFI has the coilpacks rotated 180* down there from what the SFI motors have on top of of the rear/left valve cover.

Okay now you're really confusing me, when addressing engine left and right I always orient myself to the engine facing from bellhousing end to front end true left and right with odd on the right and even on the left.

So did I botch the firing order according to the picture? I'm using 8F code so it's not SFI. The best comparison would be where 1-4 is relative to the ignition module end with the large plug and crank sensor plug, that way no matter how it's turned I would get it right.

[1988GTU]

146325

[Joseph Upson]

That how they are numbered and 123456 is the firing order.

Okay, I had it correct and apparently there is an ignition problem developing while it was running a little and now not at all.

[1988GTU]

facing the front of the engine looking at the pulleys with the alternator on the left bank with cylinders 135, 1 just below the alternator, I have coils arranged in this order moving front to back with the coil plug terminals down low or on the left side close to the plugs on the head and the coil body next to the manifold and the end of the ignition module with two plugs closest to the alternator, 1-4, 3-6, 2-5.

146325

That is how the plug wires are placed.

I think you had the 63 in the wrong order.

[IsaacHayes]

Heh, that picture helped explain it better than a thousand words.

[Joseph Upson]

That is how the plug wires are placed.

I think you had the 63 in the wrong order.

No, I have 63 in the middle, the picture of the coil firing is not what was on the car today, that was off to the side to help diagnose a no spark condition which I have again today for some strange reason using the module that was firing in the picture.

EDIT: Read your thread on pennock's. You can use the 3900 MAP sensor if you didn't know that. Not sure why you need to run vacuum tube to the MAP unless you are using the old style...

I'm running 8F code requiring a 2 Bar MAP, I had a vacuum pump on the sensor to help simulate a closed throttle condition while figuring out what to do about not having a vacuum line fitting.

[IsaacHayes]

Ah, I totally forgot you had those turbos on there haha. Did you know you can get a 2bar MAP thats the same style as the 3900 from those boosted ecotech cobalts I believe? Probably not worth the effort or cost, but would be clean factory looking.

[ForcedFirebird]

A 3bar GM MAP is available from DIYAutotune for $40 IIRC. They also have "The MAP-Daddy" 4bar for $65 (yes that's really what they call it). But I'm unfimiliar with GM tuning and don't know if you could tune for a larger one.