calling all TPI guys-Flooding

[SSClassic]

i didnt check the voltage only used light,i did this test in the shop Manuel

i have power to 1 terminal on each connector
this is a very basic wiring system so i dont think i did anything incorrect,but apparently theres not supposed to be any power there with injectors unplugged?

 

[Wraith]

Basic wiring should be 12v present to injectors with ignition on and during cranking with the ECM providing the ground/switching for the injector circuit. The noid lights being a led would require less voltage to fire than an actual injector coil which may be giving you a false good.

 

[SSClassic]

Basic wiring should be 12v present to injectors with ignition on and during cranking with the ECM providing the ground/switching for the injector circuit. The noid lights being a led would require less voltage to fire than an actual injector coil which may be giving you a false good.

so at this point its almost safe to say an ECM failure?

 

[Wraith]

You may probe the power side and see if you have 12v with ignition on/under cranking as that would be separate from the ECM technically with the grounding of the injectors being handled by it. I thought it was the ECM from the start but I hate to diagnose over the internet.

 

[SSClassic]

i dont think i would have injector pulse if i didnt have power there,but if i can get my wife out in the garage to roll it over i can see if the voltage is legit.if i dont get close to 12v then im going to assume its ecm failure.if it does have strong voltage where do i look from there?

 

[Wraith]

The pulse only happens if they trigger to ground which is handled by the ECM, power is constant whether 12v or lower so the noid can read flash as triggered but still not have enough voltage to open the injector. I would guess weak voltage OR weak pull to ground from the ECM.

 

[SSClassic]

new ECM,new problem.
if i hold the throttle to floor it will run, but the drivers side is running very rich(black plugs) & exhaust manifold very hot,pass side is cold with wet plugs.note that i do still have the heat riser valve from the carb setup on the pass side!
my whole opinion on these tpi setups has changed.seems to be one thing after another

 

[SSClassic]

i found this on thirdgen.com
interesting however, tpi's from gm fire all 8 at once contrary to popular belief. The 2 fuses are for the load but the grounds for all 8 are common. Here's an excerpt from gm performance. I was always under the same impression untill I put on two noid lights on the oppisite banks.
"Most early EFI systems were batch-fire systems where the ECM fired all eight injectors simultaneously. Usually batch-fire systems fire the injectors once per engine revolution. This way, the injectors could be sized small enough to be more easily controlled at idle. Later, sequential EFI systems were refined to fire an injector a few degrees before the intake valve opened. Generally, sequential injection offers more precise fuel control at the price of increased complexity. But on production engines, the benefits are more in the area of emissions and driveability than in performance".