My car has had a cold start issue for a long time. First start of the day, it'll stumble like it wants to die for about 5 seconds, then clear up and run normally. If I shut it off and restart it, it fires right up, and will any other startup for the rest of the day. There's just something about that cold start that it doesn't like. I've already replaced injectors, fuel pump, fuel pump regulator, O2 sensor, etc... just ran some BG 44K thru it.

Im just thinking maybe that 9th injector isn't really doing anything, but nobody here ever says theirs has failed. I remember my sister having a Beretta with the 2.8 back in the day that did the same thing. She'd always have to give it some gas in the mornings to get it going.

Its usually the thermal switch that controls the injector that takes a dump. Symptoms are just as you are describing if not worse. They are not available anymore but sometimes pop up on ebay.

When you replaced your fuel injectors which fuel injectors did you buy?

It was awhile ago, but they are yellow Bosch injectors (have Ford logo on them). I bought them from Southbay.

I actually did try unplugging the connector, and noticed zero change in how the engine started when cold. This is why I'm thinking it's not really doing anything.

I did buy a delete kit, but I know I'll need to get a ECM tune before I install it. How much better does the '89+ setup start compared to the 85-88 with the CSI? I had an '89 IROC but that was almost 25 years ago so I can't remember.

Yes you will need to add cold start enrichment.

I wouldn’t say one starts better or worse than the other. In my experience the 9th injector works just fine when functioning correctly as does main injector enrichment. You will just eliminate that system and it’s parts and never have to worry about it again. That’s what really makes that later setup better.

I've had the exact same cold start issue for a long time as well. I eliminated the 9th injector and had it tuned but the issue never changed. I even swapped the original injectors with new Delphis. Same as you, car will restart and run great the rest of the time.

I don't think my valve was failing but the line was corroded and dripping a bit at the fuel rail so it had to go.

Darn. It's a mystery for sure.

My 88’ had this same issue. Blocked it off and had it retuned. Never had an issue again.