Can somebody ID this new idle quirk?, starts & runs well -- until warm Options

[Prospectfarms]

(IMG:style_emoticons/default/beer3.gif) (IMG:style_emoticons/default/beer3.gif) (IMG:style_emoticons/default/beer3.gif)

O.K., I'm better now... D-jet is driving me to drink.

The 1.7 starts and runs well until it warms up. After 10 min. idling smoothly @ 900 it hesitates two or three times and stops idling at all, which means I can't keep it running long enough to set the timing. I can keep it going by feathering the throttle, but my nice smooth idle is gone. I reproduced the symptom three times in a row today.

By clamping off the Vac hoses one-by-one it appears the FI components seem to be doing what they're supposed to. No other vacuum or capacitance probs. found so far. Haven't checked the injectors.

This started after I repaired the ground strap on my distributor -- must have bumped something else. CHT?

I have the FI diagnostic checklists and am working on them. If this was a carburetor I'd say it was running with a clogged idle jet (IMG:style_emoticons/default/wacko.gif) . These symptoms seem specific and uncommon. At least I've not seen others posts that describe the same thing. Did I miss one?

[Tom]

You should measure the value of the CHT when it is warm.
Tom

[Prospectfarms]

You should measure the value of the CHT when it is warm.
Tom

Thanks, Tom

my last "idea" (IMG:style_emoticons/default/screwy.gif) -- to ground the CHT when the engine was about to stall-- was a round-a-bout way of checking it warm. Your note brought me back to reality .

Unconsciously, I think I was trying to avoid the trouble of removing the ECU when it was hot. (IMG:style_emoticons/default/rolleyes.gif) (I've so far done my resistance checks at the ECU 24 pin harness)

I'll check the warm CHT at the ECU pin and also check the warm MAP values at the same time. (IMG:style_emoticons/default/idea.gif)

I'm going to do this now and report back later.

Appreciate the help!

[Prospectfarms]

You should measure the value of the CHT when it is warm.
Tom

Thanks, Tom

my last "idea" (IMG:style_emoticons/default/screwy.gif) -- to ground the CHT when the engine was about to stall-- was a round-a-bout way of checking it warm. Your note brought me back to reality .

Unconsciously, I think I was trying to avoid the trouble of removing the ECU when it was hot. (IMG:style_emoticons/default/rolleyes.gif) (I've so far done my resistance checks at the ECU 24 pin harness)

I'll check the warm CHT at the ECU pin and also check the warm MAP values at the same time. (IMG:style_emoticons/default/idea.gif)

I'm going to do this now and report back later.

Appreciate the help!

Started engine, ran well for 15 minutes, hesitated and stalled as usual.

MAP and CHT resistances are within spec at "warm" (=/- 200 F). These values are from the ECU connection pins. I couldn't detach the CHT sensor wire from the harness. There is a terminal block but the spade would not pull out with moderate force and I was afraid of breaking the plastic cover.

Don't have a vacuum tool, so I can't test MAP "leak down."

Next check is the throttle/air distribution manifold assembly looking for something out of order (like a big a-s hole) underneath. Also the cold cold start valve for leakage.