CX 2.5 Starts but will not idle

[Hydraulique]

I have a 1985, Series one CX Prestige with injected 2.5 liter engine. It had been sitting for about 5 months and now starts up only if I tap the gas but runs rough, and will not idle even when run to temp. Most recently It backfired once. I have checked the intake path and all seems tight. Plugs all look ok and seem to be getting spark. Compression is great at 150. New gas in tank and I drained tank to be sure all was clear. I ran some techron in the gas to see if I could clear a bad injector- no luck. I did install a new battery before this round and I now see one yellow wire and spade connector that is not terminated on the left side near the battery. No obvious destination. Anyone encounter this situation before? Thanks!

[mickthemaverick]

Not sure what you mean by 'tap the gas' ?

[myglaren]

Not sure what you mean by 'tap the gas' ?

Blip the throttle!

[Hydraulique]

Yes, Just so. Pardon my americanism. I found it would start if I blipped the throttle- but ran rough. Normally, that would flood the engine. Thanks

[xantia_v6]

I am not sure exactly which injection system your car has, but typically the early Bosch systems fired the acceleration enrichment fairly directly from the TPS, regardless of the other sensors.

I would firstly be checking the coolant and air temperature sensors and the wiring to them.

[Hydraulique]

Thanks all. Problem is solved. The Backfire I mentioned was enough to split the plastic intake manifold. Hard to see, as it was the bottom section that split. I had seen a similar issue and solution at this years Rendezvous and finally checked. Solutions was 1/4" aluminum channel stock, glued and clapmped over top and bottom seams with 3M panel bond. Car now starts and runs "normally", though still needs a tune up. The split can be hard to find, but it totally screws things up. Hope this helps another CX owner.