I'm running a 4bbl TBI with a Holley C950. The ECM refuses to run all 4 injectors. They are 95 #/hr, 4/1A injectors. The 4th injector on pin D16 does not work under any testing method. I scoped the injector leads and what I found doesn't quite look like a P&H driver. I rarely see P&H waveforms at work, so my ability to interpret what I'm seeing is not so good. What I'm seeing looks like a saturated injector wave to me... The second pic is what I'm seeing on the nonfunctional driver.

Those waveforms don't look all that good. And certainly not PnH. I have some around that I'll post later. Need to find them.

OK, picture is of a 3.5 msec PW of a TBI PnH injector. This is the voltage waveform.

The voltage is pulled to ground until the 4A peak is hit (about 1.3 msec). Then when the driver transitions to hold mode the voltage kicks back (50 V inductive spike) and settles to about 11 volts to hold at 1A.

When the driver shuts off there is another 50 V inductive kickback (right at the scope center line). The voltage then settles at about 14 volts. Which is the system voltage level.

RBob.

I'm so glad you jump in here I got to work this morning and pulled a couple screenshots from our waveform library. They all look just like the one you posted.

I don't understand how the C950 determines wether it's a P&H or saturated injector. There's no setting for it. I guess it's like throwing darts in the dark.

Anyway, with my current single T70 turbo system the last thing I need is an injector to stop working at WOT.

I'm about done dorking around with this Holley ECM. Mr RBob you will hear from me in a few weeks. I NEEEEED another EBL. My last EBL is still on the 4bbl TBI Weiand 142 engine combo...it's in a '93 Blazer now with a T56



the 4bbl TBI me and the Blazer guy made