Last ran in 2003, rough idle now

[Decommissioned]

First things first, this is a 1981 fuel injected Fiat spider engine swapped into a lancia scorpion.

The car hadn't ran since around 2003 but did run after the engine swap.

I've gotten it to be able to start and rough idle but it still has some issues to work through. At the bottom is a link to a video of it and it's current state.

I have a laundry list of known issues still to work through but I'm a little confused by the rough idle and looking for advice. When starting it needs some immediate throttle but then it's not very responsive to throttle once running. Almost no change in RPM.

So far I have:
- new fuel pump/filter (and all lines)
- replaced the injectors with used but working ones
- replaced timing belt
- checked compression
- replaced O2 sensor on exhaust
- replaced throttle position sensor
- tested and swapped the ECU with a spare
- tested and swapped the air flow sensor with a spare
- added inline fuel pressure (sits around 30psi when running)
- new spark plugs, oil/filter

Known issues:
- water pump leaking
- alternator not charging

Ive been mostly working through the Bosch L-jet FI trouble shooting guide, reading on forums (Ive got about 20 tabs open), and Bosch L-jetronic Fuel Injection Guide.

Things I plan to do:
- replace water pump. Can this wait until its running?
- check voltage at injectors, pump
- need to check thermotime switch

Some notes:
- Previous owner did the engine swap, looks professionally done, clean job with the engine wiring
- the dash is basically useless, the original wiring is rotted from sitting outside for so long
- there is definitely some more smaller things I've done engine related but cant remember it all
- excessive moisture is coming out the exhaust when idling, tested for gasket leak with a spill free funnel on the coolant reservoir, no signs
- exhaust smoke doesn't seem to be overly dark or light in color


Thats where it stands. Looking for any feedback on what I should focus on given the steps taken and current symptoms.




https://youtu.be/Dh53abKu2A4

[trooper26]

Having just needed to replace the pickup and rebuild a distributor on an '81 FI Spider, my thought goes immediately to spark/ignition. It doesn't look like you listed that as something you have checked. 20 years sitting could probably do a number on those various connections.

[18Fiatsandcounting]

I'm not much of an expert on FI systems, but one thing that comes to mind is a crack (leak) in the rubber ducting that goes from the output of the air flow sensor to the input of the throttle body. Since the engine runs, the injectors are firing, but if it doesn't speed up as you open the throttle, that tells me that the vacuum from the engine isn't opening the door of the air flow sensor as it should (which tells the ECU to deliver more fuel).

There could be leaks in the intake manifold other than the rubber ducting as well.

-Bryan

[Decommissioned]

Thanks guys.

I did forget to mention, I replaced the ignition control module and the magnetic pickup coil. I also just rechecked the gap on the pickup coil.

I have also sealed all the cracks in the air intake. This morning I checked and as the throttle opens, so does the intake door. I can also hear the fuel pump kicking in.

I haven't ran a timing light, maybe it's that simple. Early on I just hand twist the distributor to where the car sounded best but never came back to do it the right way.

The other thought is the alternator not working yet, would that cause the stumble and hesitation?

[Nut124]

To me that sounds like ignition timing is way off. Get the light and check the timing. To test, I'd try turning the distributor very slightly while idling. If timing is way off, idle will improve in one direction and stumble in the other. Need to be set with the light, not by ear.

I do not think a bad alternator could do it unless the voltage drops very, low, like way below 10V. Check battery voltage while it's idling.

[Decommissioned]

It runs!
Turns out the cam timing was off by a tooth on the exhaust side. I was so fixated on the Bosch system that I hadn't even thought to check it.

The "middle man" I bought the car from who is a lancia and Fiat genius changed the belt as a favor for me before I got it. I'm not blaming him by any means. The guy's been immensely helpful with the car but it gave me false security and I didn't think the check it. And after doing the job myself I can totally see how a gear could get misaligned. Trying to fit my fingers in between the engine and that's side of the car in the back of the scorpion is a pain.