I know this is an old thread, but came across it the other day while trying to diagnose a similar... nay, identical problem with my MSed Rover SD1. It’s funny how particular engines have idiosyncrasies that seem to be fairly common across the make?!?
So the first thing I was working on was cold acceleration (and I mean Australian cold, so 20-40 degree coolant temp). The thing would hesitate badly under a jab of the throttle until warm. Looking at the logs, the MAP would increase before the TPS registered a delta so this thing sucks a lot of air at part throttle. Changed the accel enrichment balance to 50/50 MAF/TPSdot and after some tweaks to the percentages, managed to eliminate the issue. Also noticed enrichment was lasting 2 secs instead of 0.2s leading to an unnecessary dump of petrol so I sorted that too.
Next issue was the one discussed here, and it was harder to diagnose as it didn’t really show in the logs (AFR was fairly steady). Car would catch and fire fine, run for a second or so and then revs would drop, occasionally cutting out. If it didn’t cut out, after 2-3 secs it would sputter to recovery and idle fine. If I turned it off and back on then... not a problem - only the first cold start would exhibit these problems.
Now, I’m not running spark yet as I always wanted to get the fuel dialled in and working first, and idle speed is still “managed” by the extra air valve, so settings around advance and stepper motor control weren’t relevant. This thing started and ran fine on the stock setup with the extra air valve, so I knew it was possible... just wasn’t sure what was causing the problem. Tried messing with the cranking PW which just caused it to crank longer, then last night I bumped the ASE buckets up from 30% to 60% and lo and behold, it started perfectly!
Repeated the test this morning, and again, not even a waver to the idle after catching. Looks like as others have said, these things need a lot of extra fuel just after start. Anyhoo, hope this helps someone trying to diagnose the same.
Cheers,
Tom
