Any thoughts whats happening here?

[Charlescrown]

I'm starting to think ECU. I did another log today and watched the timing light at the same time. It is not affected by the engine temp but may be circuit board temp. The spark kept firing and the voltage didn't drop when it faltered. It didn't cut out but stumbled and the log showed the wideband go rich and the injector time sharply rise during that time. Will try another ECU tomorrow.

[Dylan]

Well worth a try but if it went rich and the pulse width increased sounds like it's been calculated?

[Charlescrown]

MMM. Now you got me. I'm not giving up on this one.

[Dylan]

I haven't viewed a log. If the voltage is fluctuating and it's going rich with the same target afr and you have unknown injector data. Maybe a possibility.

[antus]

Still try another 808 if you have one. When they do start failing they tend to do something like that. Whether the fault is input or output or cpu related. Super momentary glitches that cause a stall. But too quick or too catistrophic (cpu) to get a data frame that shows it.

[Holden202T]

I'm starting to think ECU. I did another log today and watched the timing light at the same time. It is not affected by the engine temp but may be circuit board temp. The spark kept firing and the voltage didn't drop when it faltered. It didn't cut out but stumbled and the log showed the wideband go rich and the injector time sharply rise during that time. Will try another ECU tomorrow.

got a log of this you can post up ?

[delcowizzid]

my old vn when turbo used to cut out in the middle of the same underground tunnel every morning like a timer was the chinese 2 bar map sensor that caused all my drama.later pulled it apart to find solid resin potting compound and when it warmed up it pulled one wire off the terminals inside that the plug plugs onto.

[Charlescrown]

Tried another ECU and it did exactly the same so I did some hard thinking about the tune. I have raised the VE figures up a bit in the very low RPM range. Even though it wasn't that low in revs I am sure the cells interpolate which may be causing it to run too lean when it seems to have it's little flutter and so far so good. The engine is like me old and tired so I figure there might not be optimum manifold vacuum and it jumps around a bit. Also going to make a small vacuum chamber to get a more stable map vacuum hoping it might help. Being TBI is not my idea of ideal particularly with big injectors probably having a lousy spray pattern at low speed pouring fuel onto the back of the throttle plate doesn't give a very even fuel distribution. Trying to keep the car as original as possible hence the reason I haven't gone to multipoint.

[Charlescrown]

Just went out a gave it a run and it looks like it was my lousy tuning. I followed the std VR tune with a lower VE at 400rpm but it looks like my engine likes to drop into the lower rpm area. Will post in a couple of days with an update.

[Charlescrown]

Finally discovered what was happening. Dylan pointed me in the right direction. I looked at the injector bias verses battery voltage as well as the actual injector duration and it was clear that if the voltage dropped the engine would likely flood so I started reducing the offsets and they are much lower than the original numbers I had there and now its fine. I still have a little voltage flutter from the alternator but will live with that for the moment.