More Dash prolems-Underfuelling

[lowlancer]

Having trouble with fuelling on Dash motor. Refuses to run properly on the small injector. Idles very rough and then cuts out, and will not rev easily at all. I think it’s underfuelling, as it won’t start unless I pump the gas hard. When it does start, it stutters and eventually cuts out when idling. When I try to rev it, it runs on 2 or 3 cylinders and essentially won’t rev at all. I don’t have the other injector set up to kick in as yet, but it should idle and rev to 2000rpm without it.
When I connect the big injector to be the main injector, ie: idle etc, it runs mint. No smoke, idles nice, and revs out well, turbo spools etc. Kicked into life after no running for a month instantly, and ran on all 4 after about 2-3 seconds of running on 3.
I’m confused. It’can’t be timing as it runs mint on the big injector, plus I’ve checked that.

Also, I’m checking my manifold pressure, and it’s showing around 25Hg at 1500rpm idle. I have my idle set high I know, but is that sort of manifold vacuum right? The Microtech uses manifold pressure as a trigger for kicking in a staged injector, and I thought there being a vacuum so high (or low haha) was odd. I suppose under proper load whilst driving would make this way different, but then how would I get the injector to kick in whilst not driving?

The other thing I want to know, is what sort of time should I have my injectors opening for? I’m guessing I’d need to balance it out between a decent mist, and enough fuel for all four cylinders.


Any answers would be appreciated, as I’ve gotten motivated on this again, and would love to take it for a thrash before it sells.

[AB]

How was it set up when you got your microtech tuned? If you change that then it wont run because the fueling will be way out. Does the microtech control spark too?

[lowlancer]

Hasn't been tuned as such

what size is a normal Starion injector?

[AB]

If it hasn't been tuned then you gotta expect it to not run at all, you just got lucky that it happens to work with the large injector. You should get it set up how you want it then take it in to be tuned, or get a wideband oxygen sensor and tune it yourself.

Normal injectors are around 800cc I think, 880 sounds familiar?

[lowlancer]

MIcrotechs come out of the factory with base settings, so that engine will run, and coarse tuning will cause it to be easily tuned on road.

I think the issue is that the fact it's a small injector, instead of a 800-880cc is causing troubles. What I'm doing instead is putting two big injectors in, and doing a blanket drop on all fuel maps, to allow for the extra size.

Let you know anyway

[ProZac]

I dont rekon Microtech would have the spec's on a dash motor to send you a computer with even a basic tune? They're not a very common motor... I say you stick 2 big injectors in it and take it to a workshop to get tuned... Tuning on the road will never get you acceptable results i rekon. Dont worry about running them staged, it'd be a silly idea if you had an aftermarket computer, just makes it more complicated than it has to be = easier for something to go wrong. Unless even with super low duty-cycles it overfuels at idle, then try running them staged... But i wouldnt think that'd be a problem.

Lub your car tho man :).

[lowlancer]

I dont rekon Microtech would have the spec's on a dash motor to send you a computer with even a basic tune? They're not a very common motor... I say you stick 2 big injectors in it and take it to a workshop to get tuned... Tuning on the road will never get you acceptable results i rekon. Dont worry about running them staged, it'd be a silly idea if you had an aftermarket computer, just makes it more complicated than it has to be = easier for something to go wrong. Unless even with super low duty-cycles it overfuels at idle, then try running them staged... But i wouldnt think that'd be a problem.

Lub your car tho man :).

you're right, they don't. The rep said it will still work as he had the ecu set up to run staged injection from factory, but that can be changed easily. Problem is, it was under the assumption I was using the standard Starion injector as the first one, which is way bigger, about 800cc. Therein has laid my problem till now.

I'm going for two big injectors then doing a coarse road tune. Unless I keep this car, which I doubt, it won't be getting a shop tune.

Cheers dude, dig your car too

[rallidave]

Unless I keep this car, which I doubt, it won't be getting a shop tune.

dude, if the microtech is not properly shop tuned or even has a base tune you are gunna have to expect the engine to idle all over the place and have a too lean/ rich mix all the time

[lowlancer]

Yeah haha

Thanksfully the microtech software is awesone to use, so it's idling beautifully now