Hello again folks.

The other thread was getting long and I've narrowed things down a bit (I think!).
I put a new engine, CPS, and spark plugs in my car and now have a miss once the car's warmed up.
The engine is an 92 B230FT with Bosch LH2.4 ignition.

Here's the problem:
When the car's warmed up (and not before), it will miss more and more frequently as time goes by. Seems to be on one cylinder at a time, but pulling injectors resulted in a loss of power and change in idle on disconnection and reconnection for all cylinders.
It will miss at idle and under partial load, but improves(misses less frequently, or less noticeably) with increased throttle.
It will not miss at idle in N or P - but it also won't idle below 1000rpm. I fixed my intake leaks, and I don't think that's the problem now.

I found the RSR pigtail was pretty trashed today, after replacing the RSR with a junkyard unit. I spliced in some longer wires and reattached the individual bullet connectors. This made no difference.
I put in a new power stage connector. This made no difference.
Put in the coil from my 244DL - This made no difference.

Disconnected the knock sensor... A-HA! THIS MADE A DIFFERENCE. It happens much less frequently. Instead of missing 10 times in thirty seconds, it barely misses - but still does it.
Idles lower, but still not at the proper idle.

I did not install a new timing belt, nor check the timing when installing the new engine, in the name of timeliness - but wait! This was happening with the old engine and its timing belt as well.

I could not find a distributor cap, rotor, or ECU at the JY today. There's this very consistent pattern of someone (or someones) using a crowbar to trash 740's interiors to remove relays and ECUs. My car has a 560 CA EGR and Cold Start Injector ECU. The fuel pumps have come on as prime/running and also as always on in kp2. I think there is a fault in the fuel pump circuit and maybe that makes other failures inside the ECU more likely. Maybe...

I did swap in used parts, but I think it's highly unlikely that I would get the exact same failure mode from different parts, even if they weren't good.
The miss is very brief and it responded to the knock sensor changing the timing - I think it's a good assumption that it's a spark related problem.

So.. how about a checklist?

Coil - swapped, no change
plugs - new
wires - old but serviceable
Cap/rotor - older, but cleaned, and less worn than others I've had installed
CPS - new
Power Stage - swapped used, no effect
Coolant temp sensor - resistance consistent with old ECT
O2 sensor - old, but voltage sweeps

ECU....? Fuel pump circuit is flakey...

Ignition control module? EZK? ??? I know nothing about this.


There are no hot, cold, or otherwise start/restart issues. The car doesn't outright die.

Will the car increase the idle to avoid a miss at idle? Or can self-adjusted timing increase the idle?

Feel free to post more items or questions and I'll hit it in checklist form.

I'm supposed to move 400 miles north Tuesday... Doesn't leave much time for shipping or scrounging for parts.
I need to check the timing and would love to try a different ECU/EZK unit.

EDIT: I think I am going to go try to pull another EZK Ignition control unit tomorrow. The LH fuel units seem to be always missing in the junkyards, but maybe they overlooked the less demanded EZK unit. I really don't know what else to do now, besides put it on craigslist and hope some tuner wants it. Or to let it sit for months, resurrect it this summer, and then sell it or drive it till it dies.

Happy Bricking!
--
1990 740 Turbo, on its way to stock specs, maybe beyond