MSefi.com read only forum (Jan.15,2018)

I have replaced my '85 Peugeot's L-Jet controller with MS II V3.0, keeping all the original sensors and injectors (except the AFM, which was starting to get patchy). The standard setup has a vacuum line to the fuel pressure regulator to reduce pressure under low load. Of course this is pretty common and seems to me to be a good idea (since it gives you more "resolution" to get a smooth idle).

One problem is that the Megatune VE table generator assumes constant pressure, so all the high vacuum stuff is far too lean. I've got it running and idling well enough, but I'd like to be starting with something more in the theoretical ballpark. So:

1. Has anyone written anything to generate a suitable table?
2. If not, I can write something (probably in Perl), but I'm not too sure on the theory (given you have vacuum helping the flow, but reduced pressure, hindering it). Would a simple scaling -- x1 at 100kPa MAP, x2 at 30kPa, linear in between, suffice? (I suggest 2x because my reasonable idle came at about 2x the original generated VE value).
3. Are there compelling arguments why I should ditch this idea and just block off the vacuum hose and run full pressure all the time? Like I said, variable pressure seems a good thing to me: less load on the pump, more time to get the work done, etc.

Thanks for any advice. And sorry if this is a frequent topic; I Googled around but came up blank.

Have fun,

Rob.

Thanks, Lance, for clearing that up. It gave me the confidence to press on with tuning the generated VE table and the car's running not too badly now.

But I have another injection question.

I have it running on one squirt per cycle, but the idle's slightly lumpy and I thought that changing to two or four squirts, (simultaneous or alternating) might smooth it up. The car's no fire breather and rarely sees the far side of 5000rpm, so extra squirts shouldn't be a problem at that end of things. Thing is, the car won't start and barely runs if I switch to two squirts and it becomes even worse switching to four. If I try alternating injection it runs even worse. Bumping up ReqFuel improves things pretty well for simultaneous, but it still runs like a badly adjusted concrete mixer if I try alternating.

I thought I might have miswired the injectors, but no, they're in two banks as per spec, common power, separate grounds.

I can hear each injector clicking OK. I guess there might be a lazy one being masked by one big simultaneous squirt, but it's not long since I had them cleaned and tested and I don't see how it wouldn't be just as masked with two smaller simultaneous squirts.

Since the injectors date back to '85, is there any chance that it's something else in the config (I was thinking opening time)?

No biggie, even at this early stage, the car's going about as well as it ran on the L-Jet with good prospects for improvement, but I'd appreciate any suggestions.

Have fun,

Rob.