[Crittenden]

My '81 GTV6 starts easily but idles very poorly with a bad misfire. I think cylinder 5 is not firing because the header still feels cool when 4 and 6 are hot. I'm suspicious of 3 also. The engine runs a little better, but not normally, when it warms up and at higher engine speed.

I've checked the spark plugs and their cables, and they are OK. #5 plug is not particularly wet, so I'm thinking its injector is clogged or not opening.

(Earlier this year the car sat for a few months, then it wouldn't start. I replaced the fuel pump and drained the tank, and it ran well for a while, but perhaps some old or dirty gas got to the injectors.)

So, two questions. What sort of diagnostic checks can I do on the injectors without specialized equipment? And is there anything else I should look at?

One other issue, I think it's unrelated but maybe it's a clue. The EXH TEMP light stays on when the engine starts, even though it's cold. We have rodents around and they've chewed through wires before. Would the light come on with a broken wire? I'm going to check my schematics.

 

[vintagemilano]

Greg’s Alfa Ljet guide is always a good place to start. Here, L-Jetronic Technical Info - Alfa Romeo GTV6 & Milano

Posts 29, 30 and 33 in this thread might be helpful if all else fails. My little project

 

[AlfaTasteless]

There's always the possibility of bent or stuck valves as well.

 

[alfaparticle]

Do a compression test, looking for cylinders that are lower than the others.

 

[Crittenden]

Thanks for the suggestions. I sent my injectors off to Rich at CruzinPerformance for cleaning and testing, replaced one, and that did the trick.

 

[Del]

Try using a FI cleaner in the gas once in a while. That stuff, such as Techron, does work based on my own experience with our FI Alfas.