MFI Tuning

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hot66
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Re: MFI Tuning

Post by hot66 »

sounds like the throttle bodies and linkages need balancing if the left & right bank afr's dont come close to each other

interestingly my gauges wont read any richer than 10.2 ish ... it might actually be richer , but that seems to be the limit of the range read

Its not a cable , its a rod from the throttle pedal to the engine / gearbox area, then a pivot and another rod from there to the engine linkage
James

1973 911 2.4S
1993 964 C2
2010 987 Spyder
1973 MGB Roadster

Its not how fast you go, but how you go fast ;)
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g3ngs2
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Re: MFI Tuning

Post by g3ngs2 »

Thanks James,

I'd never really contemplated that it would be a rod (VW Beetle brain) though did whiz it out to a local garage this morning to get it up on the ramp to have a quick look to see if the starter had been miswired and causing the lack of battery charging. No such luck l

Would seem that way, I suspect the Innovate one's limit is 7.4 from the way it hangs at that number

I'll take a look at each sides linkages with the cleaner off and see what I can see (without interfering with anything)

I'll see what the folks who did the tuning have to say for themselves



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911hillclimber
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Re: MFI Tuning

Post by 911hillclimber »

Still think you need to get to someone who has real experience of these old systems, phone around as you say
73T 911 Coupe, road/hillclimber 3.2L
Lola t 492 / 3.2 hillclimb racer
Boxster 987 Gen II 2.9
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Re: MFI Tuning

Post by g3ngs2 »

That's the plan, I wasn't looking for anything mind blowing from the tuner, just to get it to a usable state.

It's not really that at the moment so the explanation I'm looking for is the correlation of the invoice to the outcome

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hot66
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Re: MFI Tuning

Post by hot66 »

do you have a carb synchrometer ? .... just to take some flow readings off each stack at idle .. if they are way off then you'll be able to have a go at the garage.


( if not, get one off amazon next day delivery eg https://www.amazon.co.uk/SK1-30-Synchro ... V5HM&psc=1)
James

1973 911 2.4S
1993 964 C2
2010 987 Spyder
1973 MGB Roadster

Its not how fast you go, but how you go fast ;)
911hillclimber
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Re: MFI Tuning

Post by 911hillclimber »

You can't hope to get any multi-choke induction reasonably working without a flow meter as said above by James.
When the engine is running it is especially critical and you will be so much further forward to success.

Back when Bob Watson did mine he roughed out the settings before going to rollers and had a very long slender shaft flat blade screwdriver (could have been a socket head) that poked right through the stationary engine to alter the mixture rack, about 12 to 14" long. It passed through the fan and through a large hole in the engine shroud.
Was a long time ago though!
73T 911 Coupe, road/hillclimber 3.2L
Lola t 492 / 3.2 hillclimb racer
Boxster 987 Gen II 2.9
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Re: MFI Tuning

Post by g3ngs2 »

Thanks both. The synchrometer should be here tomorrow.

The tools I had delivered from Rosepassion a couple of weeks ago (I think they worked out at about 70 quid delivered)

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Re: MFI Tuning

Post by g3ngs2 »

Good old Amazon prime!

So here's what the synchrometer has to say for itself....

So a little off, though have no context as to if the values are what should be expectedImage

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Re: MFI Tuning

Post by hot66 »

They should all be the same which kind of shows the garage don’t do a proper job… the CMA mfi book explains where a good start point is .
James

1973 911 2.4S
1993 964 C2
2010 987 Spyder
1973 MGB Roadster

Its not how fast you go, but how you go fast ;)
911hillclimber
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Re: MFI Tuning

Post by 911hillclimber »

Yes, way off. You have to adjust to all are equal rather than all are a value.
I guess this is at tick over or slow engine speed?

My 3.2 at tick over will pull 10.
Agree with James, the garage are not doing things right. Remember to uncouple the two sides of the engine via the cross bar link, add the cross bar back on after tweaking, and check again.
73T 911 Coupe, road/hillclimber 3.2L
Lola t 492 / 3.2 hillclimb racer
Boxster 987 Gen II 2.9
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g3ngs2
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Re: MFI Tuning

Post by g3ngs2 »

Yup all a bit disappointing.

Though with recalibration of the lambdas it shows left 14.3 and right 13.4 at temp / idle.

Very much the one wrinkle in what has been an a not too bad six months

Based on the above and what I've seen

Not getting to full throttle
Left and right out of sync
Butterflies not fully opening / in any

Resolvable but annoying... especially as the people on the suggested list are booked for a few months.

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neilbardsley
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Re: MFI Tuning

Post by neilbardsley »

Naively asked from the flat 4 owner. As a first try wouldn't you just try to raise left last from 2 to 5?

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Re: MFI Tuning

Post by hot66 »

neilbardsley wrote: Tue Aug 09, 2022 12:50 pm Naively asked from the flat 4 owner. As a first try wouldn't you just try to raise left last from 2 to 5?

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First needs to check all the butterflies are fully closed at idle ( rods off .. have a look down the stacks ) . ( butterfly position is adjusted on the throttle stops screws )

IF they are fully closed , then yes using the air bypass screws on the throttle bodies you can balance them all

then reconnect the rods and measure again .
James

1973 911 2.4S
1993 964 C2
2010 987 Spyder
1973 MGB Roadster

Its not how fast you go, but how you go fast ;)
neilbardsley
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Re: MFI Tuning

Post by neilbardsley »

Fair enough. I have to use the air by pass to balance my carbs on the same bank at idle. I had never considered that the butterflies could be in slightly different rotation because they are on the same shaft.

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Re: MFI Tuning

Post by hot66 »

neilbardsley wrote: Tue Aug 09, 2022 2:39 pm Fair enough. I have to use the air by pass to balance my carbs on the same bank at idle. I had never considered that the butterflies could be in slightly different rotation because they are on the same shaft.

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individual butterflies on MFI
James

1973 911 2.4S
1993 964 C2
2010 987 Spyder
1973 MGB Roadster

Its not how fast you go, but how you go fast ;)
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