Got an issue with my Daytona....1987 Shelby Daytona Turbo 2 Intercooled. It'll stumble at idle, mostly when it's cold or still warming up.
It runs smooth for the first 20-30 seconds, when it's in closed loop. As soon as it switches to open loop is when the trouble begins.
The idle will sit around 1000-1100 and then drop as then engine stumbles. Sometimes it will die. Most times, the idle will bounce between 1000 rpm and near death. Other times it won't do this at all. Usually, once the car is warmed up, the idle is pretty steady. The engine also will intermittently fuss and fart at a steady cruise, like it's leaning out. All these issues made me think O2 sensor, but changing that has not fixed anything.

I've replaced and reset the Automatic Idle Control, the Throttle Position sensor and just recently the O2 sensor. The intake/exhaust gasket and throttle body gasket have also been replaced.
All the plastic vacuum lines were removed and a vacuum block fed by one big vacuum line is now in place.

Some thoughts are now on either the MAP sensor, others have said to check the speed/distance sensor. Another source says check to make sure the carbon canister purge solenoid is not stuck open and creating a vacuum leak there.

Any other ideas to look for? Anybody else had a similar issue?

Does it ever studder on deceleration like if you let 3rd run out and let off?

First off, it starts in open loop and then transitions to closed loop. Have you checked the trouble codes?

Two simple things to check. Cam timing and make sure you are setting the base timing correctly. One cog off on cam timing can cause odd issues and base timing especially is over advanced will also do weird things.

Sorry. I always get those backwards. Closed Loop runs off pre-programed fuel tables, open loop is when it checks the O2 for fuel trim.

It starts in Closed, then transitions to open.

No Codes.

Not that I've noticed. What it will do is randomly shut off the fuel. So, you could be accelerating, the fuel will cut off, it'll nose over, fuel will turn back on and backfire out the exhaust. But it rarely does that.
More often than not, if you're at a light throttle cruise in 4th or 5th, it will shudder and feel exactly like if it had a carburetor and was going too lean at cruise or over-advancing. It'll do this for 20-30 seconds and then, like someone flips a switch -- it will go back to normal.

Someone over at the Turbo Dodge board told me to check my canister purge solenoid. If it's stuck open or opening during open loop operation, it could be creating a vacuum leak.

Nope that is backwards/opposite.

LOL. See? I get them backwards even when I'm trying not to. EITHER WAY..... car runs solid for the first 20 to 30 seconds and then starts to sputter and die. But once it warms up, the idle issues all but go away.

The only time we had the cam a cog off (two different TII engines) it would rev past 5,000 rpm. Otherwise the engine ran flawlessly.

I would suspect the MAP, but...now we're just throwing parts at it.

I do not know about the reving part but I do know cam timing off 1 cog will result in several issues such as erratic running, o-2 codes, slight lack of power. Second item I strongly suggest is the correct base timing. If the base distributor timing is not set by the correct PROCEDURE it also can cause a host of glitches. Some people with the mind set they know everything will try to advance the distributor base timing which does nothing except to cause the computer to do many undesirable things. Commonly erratic idle, stall, and a lean ramping condition at cruise speeds. The distributor is just set in one position for a base reference signal. No different than running a crank trigger. Also the distributor if worn or the hall sync reluctor comes loose in the plastic it to can cause problems. The original poster needs to verify these 3 things. Or just keep guessing.

I'm not going to be foolish enough to claim that "I had a car that did just that!", but as the former owner of an '85 Turbo I Daytona, I would guess that your Hall effect sensor in the distributor is dying. The symptoms you describe are more typical for an ignition problem than a fuel problem.

one other oddball thing i discovered years ago. it wasn't on a turbo car, but had the same symptoms, first few seconds ran as it should cold, then spit & sputtered until warm, then idled as it should. no codes were set.
it turned out to be the coolant temperature sensor. it had that greenish coating that gets on all temperature probes, and was the original item. i replaced it and that cured the problem.
the only thing i can figure is, the sensor "thought" the car was warm, so it made the PCM use the lean fuel table for a warmed up engine instead of the richer one needed at cold start up.
i'm just throwing this out there. this was on my 86 chrysler lazer. [daytona wannabe]
one other thing about that car you might want to check is the plug that connects to the PCM for cracked wire insulation. [i'm guessing your PCM is under the battery as mine was] i developed other odd drive-ability issues that led me to believe the PCM needed replaced. when i went to remove the PCM, i discovered the insulation issue had turned the wires that "wonderful" greenish stuff which required me to get creative in fixing that molded plug end. after that issue was fixed, the car ran perfectly, and the PCM did not need to be replaced.
again, just my experience.

I think ALLPAR mentioned the same thing - Coolant Temp Sensor and it is something I have not checked. If it's coated in goop, it might be making the engine think it's too cold?
Hall Effect was the first place I'd looked. Modern replacements are junk. I have a known good Hall Effect in the car.
It's at my mechanic buddies place now. He used to be a Chrysler tech in the 80's and 90's so he's more versed than I am. He asked me specifically about timing and whatnot and I'm nearly positive I got it all where it should be but I gave him the go ahead to spend an hour and double check my work.

Been a while since Ive worked on one.
But best I remember ck the hall effect dist , the turbo has a dual pickup that where the plastic rivets come loose and cause running issues . one side is ignition and the other side is fuel

Also, the timing belt off 1 tooth will cause similar issues

I was a Chrysler Tech in 86 & 87, and drivability was one of the areas I had the cert for. 1987 was a long time ago. There is no way I would trust my memory (or most others memory) on how to trouble shoot the cars of that era, especially if the others would have stayed as a tech and learned all the later versions. Things were changing pretty quickly around that time frame, with lots of refinements and changes.

I do remember replacing a lot of hall effect pickup switches back then. I did not see any reference regarding the fuel pump pressure or fuel volume, or even anything about a fuel relay or asd relay.
I see lots of guessing going on, and a lot of parts swapping. Keep going in that direction and you only have another grand to spend to buy parts to try. Good Luck! Gene

So, you say not to trust your memory.... then point at areas to look. I don't trust your memory!!

Fuel pressure is good, fuel pump is recent. No idea how to check for fuel volume.
At idle with a fuel pressure gauge hooked up, the pressure will fall and that's when the engine will stumble, but then fuel pressure will rise and all will be well. I have replaced the pressure regulator recently but that didn't seem to help either. I have not bothered to check the Auto Shut Down relay as I was under the impression if it trips, it would cause a no start condition after a stall. My car will always restart right away even if it does stall at idle. I've never seen a code 42.

This is why I figured I'd ask the community.... this is a strange issue that only seems to effect my car. I'm basically to the point of tracking down another engine module and possibly another power module just to see if that changes anything. But that's not easy nor cheap when concerning a Turbo II car.

Fuel pump and ASD relays are out of the equation. It runs,,, they're fine

Its not uncommon for the fuel pressure to drop slightly as idle rpm drops. Issue is determining which one causes the other.
Welcome to the world of electronic diagnostics. Are'nt you glad your not flat rate.
I was and RARELY was any diag cut and dry.

Like I said ck belt timing, one tooth off will still run but can cause weird drive-ability issues .
Same goes for a loose reluctor wheel in the dist

Not trying to be a wise guy here but I always grinned when the FSM, as part of troubleshooting, recommended replacement of an electrical component with a "known good unit". If you were stupid enough to check one out of Parts and found that wasn't the problem, you then found they would not take it back because it was used. So Service was billed for it and you got to have a "coaching session" with the boss. I can't count how many cars left billed for new parts that really weren't the problem, you learned quickly.

Bottom line, I would still replace the Hall effect module for the ignition.

one nice thing about my lazer i owned back a bunch of years ago, i had a daytona parts car, and my one buddy had a few daytona parts cars in his barn.
it was easy to swap in a "known good part" when the need arose.
however, when my wiring issue with the PCM plug reared it's head, neither of us had an engine compartment harness. that brought on my creativity to duplicate the molded connection.

So far, I've had three.

My OE one.
A "new" replacement
Another OE one from a friends' parts car.

All three Hall Effects had the same effect: the car still stumbled at idle. I thought it was the wiring to the Hall Effect, so, I cleaned that up, made sure all the connections were tight and had good, clean signal back to the main harness connector. The reluctor inside the distributor is fine and is tight and doesn't wobble around.