SSclassic

ok guys dont beat me up to bad here,ive got an 88 monte ss with a 305 thats been converted to an 88-89 TPI.
i have an 88 harness & ECM (1227165) MAF used with an 89 intake/runners/plenum with a custom PROM (CS deleted)from Sinister Tech. Problem is injectors are flooding the cylinders to the point of hydrolock on prime cycle
,ive been through 2 oil/fuel changes,replaced a fuel rail,rebuit a fuel rail,2 sets of injectors,2 sets of plugs & checked the AFR twice. i have 46lbs of FP (walbro 255 pump)
injector pulse is strong & verified with noid light on all 4 connectors

With the ECM disconnected:
Injector ground wires do not have continuity to chassis ground.
All right side injectors grounds are connected to each other.
All left side injectors grounds are connected to each other.
Right and Left injector wires are not connected to each other.

With ECM connected:
All injector ground wires have continuity to chassis ground - (1.52 kOhm)
Right and Left injector wires are all connected to each other via ecm
tests look good
so ECM
i have 3 sets of injectors laying around. 1 set 88 IROC =4 leak & 4 good
1 set SOUTH BAY=wont open(have these installed now)
1 set 89 TA=look really rough,but i guess ill see what they do

SSclassic

UPDATE: each south bay injector will fire with a 9V battery

Vader

OK, we won't beat you up TOO badly...

The wiring seems correct. The injector ground from each bank connects to the ECM drivers at connectors C and D 14,15, and 16. It is the ECM which switches the injectors to ground to operate them. The 12V supply is present at the + side of the injectors whenever the ignition is on.

1.52kΩ does not constitute continuity. That is the normal resistance of the P-N junction of the injector driver transistor (Q1). When that transistor is biased on, the E-C resistance will be only a few ohms, not over 1,500.

It is likely that the injector driver is not firing, either due to lack of ignition reference pulses, dissatisfaction of any VATS programming left in the MEMCAL, or due to the ECM's injector output monitor (U12) detecting a shorted or open condition and refusing to fire the transistor. That last one is possible if injector impedance is incorrect or there is poor connection at the INJSENSE terminal at connector D9. There should be in the area of 2.5V at the E-SENSE input of U12 with everything connected for U12 to be satisfied.

SSclassic

thanks for the above average knowledge vader lol, my injectors ohmed at 19,and as far as the reference signal. i wouldnt have noid light pulses correct?
the ECM is from an 88 camaro that wasnt VATS equipped & i know that from the connector slots on ECM being empty.
so i guess with all that being said.....ECM is my problem?

Vader

If you are not reading pulses, it could be due to a missing reference signal. However, the basis of that reference is the pickup coil in the distributor, so if the spark plugs are firing, that rules out the front end of the reference pulse circuits.

If you can observe injector pulses on either a meter or a plug-in 'noid light the ECM is doing its job. The questions change completely if that is the situation.

Vader

I understand that the situation with the ECM and wire harness is that the '88 version had no VATS. However, if the MEMCAL was left with VATS programming and there are no wires to send the key pellet and VATS module signals to the ECM, there will be no injector pulses.

In other words, plug a 1989 MEMCAL into a 1988 vehicle - No injectors. There wouldn't even be wiring in place, let alone the necessary signals.

SSclassic

injector pulse is strong & verified with noid light on all 4 connectors on each side
& its a custom chip with vats disabled

Vader

So you get the light to operate when plugged into the injector harness. There's not much wrong then, unless the power source has a poor connection somewhere and will not carry the current of the injectors without significant voltage drop.