93LX5.0L5SpdConv

It was running fine for a 45 mile ride with a few stops then it was parked for an hour. When I started it it immediately was mis-firing and about to stall without me feathering the gas pedal. Checked cap/rotor-wires-plug connections, all OK, started it - same thing, then unhooked the battery for 30 minutes, hooked it back up, started it - same thing.
Limped it home feathering the gas pedal at stoplights and pulled codes - no KOEO codes, and crazy KOER codes. Put new batteries in code reader, same thing - 81, 82, 61, 51, 1(yes, just 1), 2, and others flashed up while the test was running... The only ones in the code reader memory now are (in this order) 51,2,61,1.
What's going on here?

93LX5.0L5SpdConv

Just checked timing, it's fine

93LX5.0L5SpdConv

As it idles there's a little "bonk",hollow backfire sound - like a liitle drum, not real loud.

mjr46

how are tune up parts?? new? recent?? could be an issue with the dizzy and or tfi

93LX5.0L5SpdConv

Plugs have a few hundred miles on them, cap/rotor due to be replaced in next week or so just on principle, but they're clean (that's another issue, since I've had the car, 90+k miles, every cap/rotor has needed to be cleaned every 2-3 fill ups/few hundred miles - short circuit?), wires are a couple years old, I checked their resistance a few weeks ago - fine, no surprises there. Dizzy's original but the timing bolt is tight. Any way it may have jumped/lost a tooth on the gear to the cam?

I'm thinking maybe a computer issue? I've never seen codes so erratic and no-repeating - I've pulled them 3 times each KOEO & KOER. Several sensor codes came up, but only the ones I mentioned stayed in the memory. This computer was installed in late spring 2009.

Last time I pulled KOER when I hit "test" on the reader it shot up to almost 3000rpm and stayed there - I shut off the engine after about 10 seconds of that, code reader said 000, nothing else.

93LX5.0L5SpdConv

This started immediately when I cranked it. No warning at all before then - actually running smoothly, I had just cleaned cap/rotor yesterday.

At this point I'm thinking loosen and to turn the dizzy, see if it gets back in time. It's scary bucking and popping with SPOUT out to check timing.

93LX5.0L5SpdConv

TFI's been on there at least since I bought it at 91K (194k now) miles 10 years ago, certainly can't rule it out...

93LX5.0L5SpdConv

Could EGR cause symptoms this severe, starting so quickly? Been awhile since I cleaned it, I've never replaced it.

mjr46

only way it jumps ign timing is sheared roll pin on dizzy gear, inspect distributor and make sure bushing is not worn out often times when such occurs you can see the reluctor wheel hitting the stator and or marks on such inside the dizzy

93LX5.0L5SpdConv

OK, will do that today. I've replaced dizzy's before but not on this car, can you point me at a how-to write-up?