Ideas on a random no-start condition?

[LateFan]

We did the torch test on the o2 sensor. Hot, it reads about .93V, then drops right off below .1V with the heat off. Black & sooty (not anymore).

So we know that's working.

With clean plugs and spare DME, it started right up, smooth as can be. Dropped to 700, perfect idle.

So we took it right to the shop tonight and left a note, in case it doesn't start tomorrow!

[LateFan]

my idle creeps all over when cold...

The part below seems to have been cut off from the top of your post - only came thru on the email notification...

"I also have an 86 eta thats died immediately after start. I also had a problem that cause no start that was from a relay underneath the driver dash cover, something the bentley missed because they cant assume 30 year old relays sticking."

That's interesting - was it ignition-related or fuel, do you know? Did it just not start, or was it sputtering rich?

I'll look at those soon. Thanks.

[LateFan]

Independent shop says no air leaks, it holds pressure, and the brake booster seems tight.

He says it started and ran fine for him.

The spare DME??? Fingers crossed.

[Frankus12]

The part below seems to have been cut off from the top of your post - only came thru on the email notification...

"I also have an 86 eta thats died immediately after start. I also had a problem that cause no start that was from a relay underneath the driver dash cover, something the bentley missed because they cant assume 30 year old relays sticking."

That's interesting - was it ignition-related or fuel, do you know? Did it just not start, or was it sputtering rich?

I'll look at those soon. Thanks.

it doesnt sound like your problem, thats why i deleted it. but Whatever relay it was, it was causing the DME to not receive power, this was the day after i bought the car. It would just crank, absolutely no sputtering at all. I followed all the bentley procedures and ended up replacing the main and fuel pump relays (which didnt fix it) and eventually figured out how to test for power at the DME connector and found there was none. after a weeks worth of online reading, somewhere someone mentioned it could be the ignition switch, and that the circuit for dme does run under the dash, so i just pulled the lower dash cover and slapped all those relays around and it fired right up. Idk which critical relays are down there because i was so happy it was working i didnt care to replace them, if the problem ever reoccurs, which in almost two years time it has only twice, ive just kicked the cardboard bolster and slammed the door and it starts.

[LateFan]

Well, knock on imitation wood grain vinyl, he has started and run really well for three weeks with no problems, cold & hot.

It looks like the last resort on most peoples lists, the DME, was causing some intermittent screw-ups. But I would recommend you start at the top of Jim Levie's troubleshooting list and work down it in order. Massive vacuum leaks were our first issue, then senders, a worn AFM, a worn out ICV, valves too tight, etc.

So I think this thread is done - thanks, all, for the good advice.