coils are not firing...need help

[ivorton74]

so I talked to my buddy today and he says that he went through the wiring and checked everything and the pcm is not letting the coils for cylinders 2,4,6 and 8 fire. could this have anything to do with the pcm reflash or could the pcm be messed up somehow? everything else is fine....the other coils and injectors etc are working as they should.

[Wasted Income]

Make sure the coil connector for that bank is plugged in...and make sure it's getting power. Nothing in the flash would cause this.

[ivorton74]

its all plugged in and getting power but just not firing

[BenStark]

If it's only 2/4/6/8 I highly doubt it's the flash. You either have a bad ecu (bad transistors/connections) or bad wiring.

Stupid checks: Swap the 1/3/5/7 and the 2/4/6/8 coils see if the problem persist, or if it swaps sides. If you can get your hands on an o-scope check the signal wire into the coil. If you're losing 1/2 the motor I feel like it has to be at the distribution block.

[BR3W CITY]

corrupted injector drivers can cause random ass problems, especially if the ecm was flashed to a non-standard driver.

You could also have a physical restriction in the rail, but its tough to get one that locks up one whole bank.


From the blue connector:

4 LT GRN/BLK 1745 Fuel Injector 2 Control
44 LT BLU/BLK 844 Fuel Injector 4 Control
37 YEL/BLK 846 Fuel Injector 6 Control
77 DK BLU/WHT 878 Fuel Injector 8 Control

[Wasted Income]

What is a non-standard driver, and how do you flash one in?

[BR3W CITY]

Originally Posted by Wasted Income

What is a non-standard driver, and how do you flash one in?

Two separate thoughts, muddle together lol.

The injector driver is the part of the PCM that controls injector pulse. The PCM is setup to control a certain impedance of injectors, but aftermarket "Boxes" and wiring can be hooked up. IF you hook up a set of injectors in the wrong impedance, you can fry the PCM board (internal short).

The other half was supposed to be; was different injector scaling flashed in?


Thanks for keeping me honest Wasted.

[ivorton74]

Yea my buddy said that driver is whats not letting the coil fire...i emailed brendan and he replied...heres the reply....

make sure o2 sensors are not crossed up. 4 wires going to each sensor (check connector for the o2, harness side.) Should be a purple wire in the bunch, drivers side should be purple white stripe, passenger side solid purple no stripe. If these were backward, it could have fouled the spark plugs causing a miss on one side of the motor once the fuel trims went crazy. If they are backward, you will have to reset fuel trim with scanner, or unplug pcm for a few hours...

[BR3W CITY]

You can unplug both 02's and the MAF and force OLSD, which tries to command straight off the VE table with no other inputs. Don't drive it like that on a stock tune, but you can try it, to see if bypassing the 02's helps you. I don't see how the 02's would stop a whole bank from firing, but you can try.

You can also try grounding the case of the pcm straight to the block/heads to see if you have any of the internal grounds fried. Injectors fire off of Ground on these motors, and have a constant +12v supply iirc.

[ivorton74]

thanks guys...ill let him know what u guys suggested and see what he finds

[Wasted Income]

Originally Posted by BR3W CITY

Two separate thoughts, muddle together lol.

The injector driver is the part of the PCM that controls injector pulse. The PCM is setup to control a certain impedance of injectors, but aftermarket "Boxes" and wiring can be hooked up. IF you hook up a set of injectors in the wrong impedance, you can fry the PCM board (internal short).

The other half was supposed to be; was different injector scaling flashed in?


Thanks for keeping me honest Wasted.

Haha, ok. Was wondering if I'd missed something in my 10 years of tuning GM ECUs

[ivorton74]

Well turns out there was a loose ground wire....the coils are all firing now but the MAF sensor is dead so have to get a new one

[dman1982]

Originally Posted by ivorton74

Well turns out there was a loose ground wire....the coils are all firing now but the MAF sensor is dead so have to get a new one

i believe i read somewhere on here someone else having a issue with the maf sensor as well, did you check both grounds on the back of the motor? not saying it'll fix it but worth a shot

[ivorton74]

Yeah all the grounds are good.