Tuning MFI - patience or immediate redo ?
I have a 72T (MFI) recently rebuilt, new TBs too, which was running great, IMO (honestly it felt like it made 180hp and sounded like a banshee) but admittedly it was hard to start after a couple of days of rest despite the hand throttle (like a carburated car with dry bowls), it also clearly ran too rich and had high idle.
I took it to my long time specialist (whom I've had nothing but good experiences with, and worked at a dealer when these things were new). The plugs he pulled out were as sooty as I ever saw, no idea how they fired, so he readjusted all linkages on the TBs, played with the pump, broke out his special tools and notes, etc... He did warn me I'd have to come back after a couple spirited drives, for more fine tuning once things sort of settled down with the new settings. Hmm, not sure I understand how MFI settings can change after a few drives but OK...
Problem is, the car now feels like *crap*. I feel like I lost 40hp, 3200 rpm passes by in engine stutters that completely kill the acceleration (fuel delivery?), no banshee roar whatsoever, it's like a castrated engine... but hey, lower idle, and it probably does run leaner now. I trust the guy and he'll make it right, I'm just wondering if there is ANY benefits of me driving it "as is" for a couple days or if I should immediately take it back? It's my first MFI car (prior were CIS or carbs) so I profess ignorance here, but I really don't see a mechanical injection magically fixing itself to this extent (esp. as it was running great before, so it's not like something was stuck and is gonna loosen up more, seems like bad settings to me). Should I ask for slightly richer settings again? Just trying to not ruffle feathers here, in case I'm wrong and there's something to be gained from some driving prior to a redo... Wasn't cheap either, but the customer isn't always right, so I'm checking here first ;-)