Engine miss

[DaveM]

I have this '87 GN here that belongs to a friend of mine. It has a miss under load. Direct scan shows the injector pulse width going to zero (from 15.9ish) just after the boost pw jumps from 0 to 65.6, 2500ish RPM. This is a repeatable miss loading the car against the brakes in the driveway, or taking off from a stop.
MAF, TPS ,O2 sensors are new and are responding.
Question... what in the ECU program can command the Injector pw to zero?
It seems to not like some input it is seeing.

 

[RmvBfrFlght]

There is a MPH fuel cutoff. Stock is 125 MPH, check the vehicle speed in the log as the VSS may be bad.

The only other one I know of is DFCO. Although, to enter this mode the vehicle needs to be moving, engine need to be above a set RPM, but most importantly, the TPS% needs to be very low. So I don't see occurring as the throttle is open.

RemoveBeforeFlight

 

[DaveM]

Update.
Unplugging the cam sensor after start-up got rid of the miss, batch fire mode right? Further investigation found a lot of vertical play in the cam sensor drive. Pulled it out and apart, added a shim to reduce the play and the miss is gone. There was about 3/16" up/down movement of the shaft. I think maybe there was a spring washer missing.
I suspect an improper cam signal, or lack thereof caused issues with injector pulse width.
Also, the split pin at the base of the drive holding the gear on was cracked and missing a piece.
Back on the road.

 

[DaySleeper]

So the cam sensor play was the problem? It hasn't come back?

 

[DaveM]

Correct. Runs just fine now.