Runs but no power and spits

[18Fiatsandcounting]

Good to hear! Sometimes it helps just getting these cars fully warmed up and putting a few miles on them.

-Bryan

[bdinardo]

Sorry for hijacking this thread but I've having very similar symptoms in my 1980 Fuel Injected, FI: Rough idle, spits when trying to apply the throttle, black soot smoke coming from tailpipe. All 4 spark plugs are black and sooty so it's definitely running rich. The car has been running great with NO problems for months (about 30 miles a week) and it just started acting up the day after a quick drive where it ran great.

I've tested the thermo time switch and cold start valve and both are working properly (turning on for about 5 seconds). I confirmed the distributor has not moved either (I marked the base of the distributor to the head when timed).

Question for the group, what could have changed seemingly overnight to go from running great to poorly and seemingly very rich?! Any help would be appreciated as I continue to try various other diagnostics. Thank you in advance.

[18Fiatsandcounting]

My first guess would be that a wire (or wires) came loose, and I'd start by checking the connector that goes to the AFM (that thing above the air filter. My second guess would be that the air vane in your AFM is sticking.

-Bryan

[spider2081]

Another possibility for over rich conditions with the FI cars is the connector on the coolant temperature sensor and/or the temperature sensor itself. The temperature sensor is located in the coolant "T". It is common for the pins to become corroded making a poor connection and that causes the car to run over rich.

[bdinardo]

Hello folks. Quick update. Still no luck on my Fuel Injected spider running correctly even after a nice drive the day before. I've checked a bunch of wires and ensured good connections. My AFM vane is not stuck and springs back nicely and turns the fuel pump on upon slight movement of the vane. I checked the thermotime switch and cold start valve and both are operating correctly (provides about 5 seconds of spray in 65 degree F ambient conditions. The holes in the cam gears are lined up well with the pointers at TDC so I'm confident it didn't jump a tooth. I went through a bunch of the Bosch electrical checks on the ECU and all of them are within range including the coolant temperature sensor at the Tee. My fuel pressure to the cold start valve during running is about 32psi...maybe just a hair low but still good I would think. I measured the vacuum at about 15 in hg. A little on the low side but again feel like it is good enough to not cause this awful rich condition and sputtering upon giving throttle. Any other ideas on what could be causing a very rich condition (black sooty spark plugs, black soot coming out of tailpipe and sputtering with no power upon trying to accelerate the car)? Thanks in advance.

[dinghyguy]

I do recall that one of our relatively regular posters had poor operation on his spider that was eventually traced to a clogged CAT. You might want to confirm the exhaust system is free flowing. Just a thought.

cheers
Dinghyguy

[18Fiatsandcounting]

It seems like you've checked everything that I would have suggested, and so my only suggestions are:

1. An issue with the ignition system, like a stuck advance mechanism, incorrect timing, etc.

2. An air leak in that large rubber hose that goes from the output of the AFM to the input of the throttle body. Or leaks in the intake manifold or plenum.

However, neither of these would cause the engine to work fine one day and then not the next day. That sounds more like an electrical issue, so I'm still thinking a connector came loose or has a poor connection. One other thought: The connector to the coolant temperature sensor (CTS, the one at the front of the coolant outlet from the head) has a bad electrical connection? This is fairly common.

-Bryan

[bdinardo]

Thanks for the insights... quick update. I removed the CAT and it was quite clean and unobstructed. I removed the fuel injectors to check if one was stuck open but those were operating correctly on the bench. After double checking various electrical connectors for proper impedence and everything being in spec I decided to dive into the distributor. Springs and rotor and cap all looked good so I decided to check the vacuum advance. Sure enough when I sucked on the hose from the intake to the dizzy, it was not holding air! I believe the diaphragm in the dizzy vacuum advance has deteriorated and will not advance properly which would explain my lower vacuum reading at the intake and poor running condition under load! I'll retort back once replaced to confirm if that fixed the issue but I'm hopeful.