I'm bringing a 1990 740 GL out of hibernation after 16 months. It's up and running, although there's a 3-2-1 diagnostic code indicating no signal to the cold start injector valve. Once engine is at operating temp, computer is able to hold idle steady at 750 rpm, no idle hunt after cold start. I haven't traced CSI wire to ECU yet, but it's now developed a serious hesitation during acceleration from stop or after a turn if throttle is advanced too quickly. A very smooth, slow acceleration does not produce the hesitation. Here's what I've done to date:

- new factory plugs, plug wires, distributor cap and rotor button
- changed oil & filter
- c/i flame trap
- c/i idle air control (has 2 pins, not 3 - no spec for resistance)
- checked ignition coil impedance (w/i spec per Chilton manual)
- checked grounds of ignition pwr stage (w/i spec)
- removed, c/i oxygen sensor (haven't tested in operating state yet)
- inspected all major vacuum lines
- siphoned old gas out of tank & replaced fuel filter
- added 3 gal of high octane gas plus can of injector cleaner
- ran entire tank out, installed new factory fuel filter & 5 gal high octane
- cleaned TB, new gasket, checked TPS (click at .15mm gap, none at .45mm gap)
- FI relay was replaced with factory part before storage
- air filter replaced with factory part before storage, c/i

Once on the open road, operation seems solid up to 60-65, no cutouts, no hesitation. Even after rapid de-acceleration, proper idle maintained and if smooth acceleration applied - no hesitation. Seems to be only when rapid acceleration is applied. FI relay was replaced with factory part before storage so don't assume a problem there. FP does energize at key ON, but I don't hear a "whirl", it's more like a "clunking." I'll check fuel pressure next - also haven't removed and cleaned injectors, although engine runs fine after warmed with no sputtering. Although, after the last road test, some idle hunt reappeared after warm start but disappeared within 2-3 minutes.

Any thoughts on order of testing would be greatly appreciated. Many thanks to the posts submitted, replies and the FAQs - what a wealth of *accurate* information. Better in most cases than my Chilton's book.

Tommy Bray
1990 740GL