LT5 Misfiring at All Speeds

[Big D]

I got the swivel socket from NAPA and it works great getting the back two plugs out. It is easy with a swivel. Hope the plug is the problem.

I'm still chasing gremlins in mine. When I shoot back into the ECM, #6 injector pin is showing 86 k-ohms while the others are showing .97 - 1.0 m-ohms. Not sure if that makes a difference since I wasn't able to check to see if the injector is working; two person job and my assistant was working last weekend, one to turn over the car while I look down the injector housing to check for fuel spray.

Hopefully I will be able to check it this weekend.

By the way, anybody out there have a good schematic/diagram for the ECM, or know where I can get one? Would sure help in troubleshooting.

[XfireZ51]

Originally Posted by Big D

I got the swivel socket from NAPA and it works great getting the back two plugs out. It is easy with a swivel. Hope the plug is the problem.
I'm still chasing gremlins in mine. When I shoot back into the ECM, #6 injector pin is showing 86 k-ohms while the others are showing .97 - 1.0 m-ohms. Not sure if that makes a difference since I wasn't able to check to see if the injector is working; two person job and my assistant was working last weekend, one to turn over the car while I look down the injector housing to check for fuel spray. Hopefully I will be able to check it this weekend.
By the way, anybody out there have a good schematic/diagram for the ECM, or know where I can get one? Would sure help in troubleshooting.

Big D
69 L46/M21
90 ZR1

Not sure why you'd want a schematic. The pinouts are available in the FSM which I assume is what you really need.

[Johnny5]

My father changed the back 2 plugs the other day and it runs great now! Not a damn problem.....except my Bose radio, lol. Did you ever find out why your LT5 is missing? I am curious.

[Big D]

Originally Posted by Johnny5

my father changed the back 2 plugs the other day and it runs great now. Not a damn problem.....except my bose radio lol Did you ever find out why your lt5 is missing? I am curious

Nope, still chasing it. Haven't had a chance to get back to it because the Blazer decided it liked to shift into 4WD all by itself so I've been playing with that with my free time. Looks like a TCCM problem.

Still is pointing to the ECM with the big difference in resistance between #6 and the other 7 pins into the ECM. Not yet willing to shell out the $300 or more to experiment.

[Johnny5]

Originally Posted by Big D

Nope, still chasing it. Haven't had a chance to get back to it because the Blazer decided it liked to shift into 4WD all by itself so I've been playing with that with my free time. Looks like a TCCM problem.

Still is pointing to the ECM with the big difference in resistance between #6 and the other 7 pins into the ECM. Not yet willing to shell out the $300 or more to experiment.

My father owned a 96 jimmy and a 2000 jimmy and did all his work himself. PM me with your number and im sure he could point you in the right direction

[Big D]

With the schematic/diagram I can trace the circuit inside the ECM to see what controls the injector and if I find that the ECM is causing my problem I can hopefully determine if the internal circuit is replaceable or repairable. W/O the schematic/diagram I haven't a clue.

[XfireZ51]

Originally Posted by Big D

With the schematic/diagram I can trace the circuit inside the ECM to see what controls the injector and if I find that the ECM is causing my problem I can hopefully determine if the internal circuit is replaceable or repairable. W/O the schematic/diagram I haven't a clue.

Just my opinion, but you are quite a few steps from having the ECM as the culprit.

[tccrab]

Originally Posted by XfireZ51

Just my opinion, but you are quite a few steps from having the ECM as the culprit.

I agree. Try not to overthink this. Re-pin the connector with the pins I sent you.

It's not totally inconceivable that you might have a bad ECM, but you won't know for sure until you fix the pins first.

I made the same mistake. Took me over 3 years, more cash than I'll ever tell wifey about, untold stress and aggravation to finally nail it down. And truth be told, I'd likely never have found it if it wasn't for this Forum.

The Brotherhood of the Beast is alive and well.

'Crabs

[IMZZ]

Any luck? I finished my injector/plenum job. Everything came out OK. I just had to decide when to quit cleaning or fixing things. I wanted to be able to enjoy it this summer and remember that winter is coming.