Fluctuating idle on 1990 UK Testa

Si,

first port of call is to check all your plug lead - plug connections are sound. I had something similar on my 328 & found I had a slightly loose connection on two plugs. A bit of fettling in the spring clip thing in the plug extender sorted it.

I.

 

Was it working before you took the plugs out or was this why you took the plugs out?

From what you describe its almost certainly an ignition issue rather than fuel I think.

I'd be looking at the ignition system & checking from the spark plug backwards. Might involve removing the Dizzy caps & checking the individual plug leads for breaks etc (resistance test etc) . Not sure how much of a chore that is on the Testa....

Does the Testa use extenders between the plug & the lead like the 308/328? If so these can get burned through & cause arcing.

I'd also check the caps carefully for cracks and the rotor arms.

 

Hi mate, had the same problem on mine. I believe it is down to 2 regulators (look like small discs) on either bank of cylinders. They open and close to regulate air flow. I believe they can become stuck.

They are mega bucks to buy new but problem can be solved removing and cleaning/lubricating.

 

+1 -- first (and fairly easy) thing to rule in or out on your late euro F113B TR are items 16 in this jpeg. At high RPM and closed throttle plate (i.e., no load and very high intake manifold vacuum) they are supposed to open which allows some air to flow around the closed throttle plate. For a test (when having the problem), just manually pinch or block the larger air hoses closed (simulating a closed by-pass valve item 16) and see if it has any affect on gentle warm running/idling.

Wouldn't hurt to check that the throttle microswitch, item 8, is working correctly too. Can cause a wandering idle, but wouldn't really affect "pulling away" -- still always possible that you've got 2 things not working well and easy enough to check/adjust without getting greasy .

Does this mean:

1. The problem has consistently gotten worse and now the engine has quit running altogether, or

2. The problem had been consistently getting worse, but now has disappeared and the engine is running OK?
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Understood -- here's a jpeg describing which air lines to block/pinch:
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Sounds like a typical "lean surge" condition due to a vacum leak somewhere. Would not be as noticable on a cold engine due to the mixture being richer for a cold start.