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Final update, swapped in a new ECU unit today and it works exactly the same as the secondhand unit I tried to replace the one in there The repair place where I sent my old one were unable to find a fault no matter what they did . However substitution had already proved it to be faulty but that's the way my life goes
Anyway trials today have confirmed why the low vacuum in o/d, the aerodynamics are simply too much for the tall gearing ( 25mph/1000rpm ) to cope with. Drop it into straight top and I see 15" at a steady 3000 , exactly the same as POS and previous Pop. That was the reason I changed the axle out when I was using the 3 speed as the standard Cortina 2 litre axle ( 3.54 I think ? ) was also giving 25/1000 in top and swapping to the 4.1 estate axle brought it down to 20mph/1000.
Well you live and learn ( still!).
thanks for the offer kev
Kev, you really need to pop down here to see me I DO love it , it's got a great stance and is just so usable.
nnnnnnnnna you gotta keep that one arfter all that work n sell the other one this way
enjoyed reading the thread sounds like you have it sorted
a model a's more you
Thought I'd just clarify a few bits and bobs due to PMs and questions asked of me.
The engine wasn't put together to be the best on economy in the world nor to be the fastest ( wouldn't have chosen a Pinto if I'd have wanted that !) , just to be a torquey robust usable motor on an AUTO. What I've been trying to achieve is the best MPG from THIS engine combo in this vehicle and working within certain limitations. The engine is meant to make around 140 bhp against a stock figure of 115. 140 is only a little bit shy of a 3 litre v6 output that'll give you 25 on a good day.
Pinto is vastly lighter than than the V6 but the big killer is the amount of torque from the V6 . The back axle is a 4:1 to get the overall gearing required and is the weaker of the 2 Cortina axles. The A is producing enough torque to make the axle tramp and with the latest timing set up it's more torquey than ever.
The timing figures for the FR30 and the FR34 have been shown earlier and the difference in duration of 3' produces 4bhp more. This is down to the higher revs achievable on the FR34 injection specific( quoted at 20bhp gain )with a power band from 1000-6250 as opposed to the high torque/towing /automatic recommended FR30 producing 'just' 16bhp additional with a 1000-6000 power band.
0-60 is pretty much the same as my old POS which weighed around 15cwt with about 120bhp ( with 33mpg being cautious and 27 having fun) so I guess I'm pretty happy ... I still may play with the visor to improve aerodynamics ...and I do have an opening screen in the corner of the garage as well... LOL
...and todays results. Test route driven again using top 1:1 gear only , 28mpg. Well that's it , as good as it has ever been so I'm happy . As I drive it on LPG mainly that works out at the same cost as roughly 52ish to the gallon...just need to reset the lpg now.
So observations as to what is going on to reduce the mpg leads me to the a large loss due to trying to push a shed though the air! My best MPG using the Pinto EFi , with a modified cam , was in my Pop giving 35 on a run. However experience with a visor on a 100E with a 1300gt cost me 5mph and 5 mpg. Even with 220bhp on my old chopped A pickup and a shorter louvred visor still showed that at higher speeds there was detectable wind resistance .
Oh yes, MPG improves if I drive with the windows up! Once again , due to the body taper with the windows down the interior back of the cab adds to wind resistance. On my old chopped A it had an opening screen and this also helped to prevent air build up on the screen.
Also additional performance costs fuel , power doesn't come from nowhere and I'm pretty happy with the trade off for the extra torque this set up produces, it's certainly no slouch to 60mph.
Economy would probably improve with a swap back to a standard Injection cam or possibly stepped down to the FR30 cam, a favourite of mine with short overlap and high lift but slightly less duration than the FR34
As mentioned elsewhere larger tyres contribute to rolling resistance and this tyres ARE wider than those on the Pop.
Now, to sell or keep ...still makes me smile every time I use it
Things get stranger?
So, haven't checked the brake drag yet but have altered the cam timing.
Just a few cam specs first.
STD 24 64 70 18
FR30 20 60 60 20
FR34 22 61 61 22
Best mpg I've ever had from the A is 28 on a run , which works out the equivalent of 56 on LPG hence why I've never really chased this problem down.
Carbed engine with FR30 33 at 3000 3 speed auto
injected engine with FR30 35 at 3000 3 speed auto
Injected engine with STD cam 2500 (o/d) 40 4 speed auto
MPG dropped from 28 to 23 . I reset the cam from standard pulley to vernier and it required 6' advance to time it correctly , dropped to 15 mpg and bugger all vacuum.
Changed the ECU the other night and moved from 15 to 23 mpg
Adjusted the cam timing tonight BACK to it's ' incorrect' ( ?) set up and gained 3" of vacuum and back up to 28pg ( approx). ?
I retarded the cam so the inlet opened later but also stays open later so the timing inlet is opening at approx 16BTDC now and closing at 67 ABDC.
From above I've worked out when the ECU called it a day ( when it dropped from 28 to 23 )
Tomorrow ( hopefully ) I'll knock the cam forward to 2' ( so it'll be 4' retarded )and see what effect that has on vacuum.
On the 23 mile test run although the vac is improved in o/d it's still in the yellow rather than green section.
I'm going to try the same route just using top rather than o/d . All the other mpg figures I got where in top and I'm wondering if the (lack of ) aerodynamics and tall gearing 25mph/1000 are simply too much for it to cope with?
If the test drive in top gives better mpg but higher revs and better vacuum it looks like I'll have to be at least modifying the visor to try to lose some drag ( I have a cunning plan !) or simply run it in top all the time.
Again not forgetting that lack of vacuum in o/d will be upping fuel pressure and hence enrichening the mixture still.
Things get stranger?
Obviously with this problem it's self perpetuating . Lack of vacuum also brings in the fuel pressure regulator earlier and the rich mixture causes further loss of vacuum.
I'd rather not start another saga thanks
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