TS running rough

[GTVeloce]

So, I have been working on the the GTV TS the past few days but not on the engine. So, I was surprised to suddenly have it start to run rough, like it is down a cylinder. Any thoughts on what I should try? It was running fine and then suddenly it has changed. I checked the main things like plugs, leads and coils and everything appears to be in order. Leads, rotors, caps, plugs are all new. I pulled a few plugs and they all look about the same. Maybe cylinder two was a little wet.

I also checked the throttle switch and AFM. All good. Checked the resistance across the injectors and also fine.

It runs rough from idle and through the rev range.

Thanks
Julian

[Alfapride]

Few ideas
Are spark leads in correct order?
Any vaccum hoses disconnected or leaking? Is the rotar button the distributors on correctly? I know their basic checks but worth a try hope that helps!

[GTVeloce]

All good ideas! The car was running fine and I didn't touch the spark plug leads or rotar buttons. Still, no harm in confirming. I have triple checked all vacuum hoses. Having done a little research tonight pouring over manuals I am keen to check the RPM sensor and the O2 sensor tomorrow just to make sure I can rule them out.

[Cool Jesus]

Have you pulled the lead of each main plug to see if there is any change in idle? I also wouldn't assume that because it's new it's in good order, been caught with that myself. As you said, rough idle would indicate an issue with the AFM, but being checked I'd look for an air leak. Intake hose, various vacuum hoses, they an be virtually invisable so bend them around in particular in any molded corners of the rubber intake.
What TS did you transplant into the GTV?

[GTVeloce]

The TS is from an 88 75.

Ok, had some partial success. Did a number of checks this morning and discovered that pulling both plugs on cylinder two made no difference to it's running. Any other cylinder and the car wouldn't start. So, the problem lies somewhere around cylinder two but where? I checked the resistance across the injector and got the correct value (160). It could be a blocked injector but not sure how to test that without removing the rail.

What else? Sticking valves? I rebuilt the head about three years ago and the engine has probably travelled only 15,000km since then so unlikely.

The plug was a little wet when I checked it yesterday so perhaps I need to keep looking at ignition somehow. Back to basics again I guess.

[LukeC]

Try just swapping a single plug from a running cylinder into number two, start it and give it some stick. Once the pair of plugs foul, you need to get the pot firing properly to clear them.

My T-S engine (that I am currently in the process of swapping for a freshie), had sat for about 14 months before I put it in my GTV. It would foul a pair of plugs when idling while I was sorting out some other issues. It is quite a good engine (with only around 200,000 km on it), but they still fouled. Once it has been on the road a while, never an issue.

[Cool Jesus]

You say its wet. With what, oil or fuel?
Looks like no. 2 isn't firing for with no spark or no fuel.
Give the plug a good clean and crank it over momentarily then remove again to determine if fuel is in it, smell the plug. If so you have no spark  so either the lead, plug or dizzy cap is bad. You may have a carbon track in the dizzy. How hard is it to remove the fuel rail with injectors? It's fairly simple on my spider. If you can remove, disconnect the injector leads bar no. 2 place a bottle or jar over it and crank to see if fuel spraying.
Sorry about the disjointed advice. I'm on the road and typing on the phone. It's promising that you've narrowed it to no 2 cylinder though.
I know you've rebuilt the engine, but if you can, double check compression to just rule that issue out.

[GTVeloce]

Luke - you were bang on! I swapped one over and cleaned up both from cylinder two. It ran fine so I went for a good blast down the freeway. All fixed.

Thanks for your help.

[Cool Jesus]

Awesome, go the Alfa tune up