15 replies to this topic

[ROXTEE]

Hello Everyone,

I recently had an engine swap, below is the facts:
Standard MG metro Engine block 1275cc from standard mg metro.
Standard SPI's cylinder head (from standard 1275cc spi engine)
standard SPI's ECU (from standard 1275cc spi engine)
standard SPI's single injection unit (from standard 1275cc spi engine)
standard gearbox, 3.44 final ratio
K&N air filter
LCB RC40 EXH and twin DTM tail silencer

The fuel consumption is ~35 mpg and this is under very normal driving style: no high rev, very gentle gear change, top speed no more than 70 and average speed 90% of the time 50-60(4th gear). I think 35mpg is a bit too far for that,

I was been adviced that the fueling and timing all is controlled by ECU, so what could be wrong what can be done to improve the problem? could anyone give me some suggestions?

Thank u very much for your help

Regards

Roxtee

[Guess-Works.com]

did all the spi gear come from the same car ?

[ROXTEE]

Hi Guess-works:

No. the gearbox is from that original MG Metro, but been repaired, replaced the worn parts(bulking rings, layshaft...etc) and fitted central pick up pipe.

thx for any advice.

[Guess-Works.com]

No, I mean did the injection system and ECU all come from the same car ?

also the cam in the MG metro engine is different to the one used in the SPi this may be causing you the problem.

[Boycie]

I'd say that's a bit down.. but not much. If it helps, my 1098 carb with a 3.44 diff achieves 39mpg in similar driving conditions.. you have lots more power than me though.

[ROXTEE]

Yes Guess-works, the injection system and ECU all come from the same car---my previous spi 1275cc, actually, the air filter and LCB RC40 whole exh system all from the same car. only the enging block and gearbox is from MG METRO.
The cam can make so much difference? as my previous spi engine can run easily with 45 mpg in hard drive.

Edited by ROXTEE, 09 March 2010 - 12:30 PM.

[ROXTEE]

Thanks Boycie, yes, i do feel its more powerful than my previous spi with mg metro cam and 3.44 diff, becuase i can hear/feel that power from engine, but, i dont know why that i didnt feel accelation any faster? should be the higher final diff ration, the accelation faster rite? cant feel that, strange.
cause i didnt rev hard enough? because the box just rebuild, still running in, so i drive gently.

[Guess-Works.com]

The original Spi engine would have had a 3.1 final drive ( unless it was a cooper where it would have had a 3.2 ) this will have a small effect on your MPG as you'll be using a few hundred more RPM for the same speed with the 3.4, what it also means is with the quicker acceleration capabilities you will be a little more right foot happy...

[ROXTEE]

Thanks a lot Guess-works,
Is there any way can improve the fuel consumtion? or say, insure that fueling is alright through the whole rev range?
Can the spi's ecu be adjusted?(RE-MAP? or similar thing?) to make it spot on?as well as the power and torque?

Thanks a lot

Regard

Roxtee.

[datsun100a]

you need to use an injection friendly cam.

[The_Mistro]

You can't remap the ecus, they constantly take readings from all the sensors and make adjustments to the fueling and timing etc, try it with a standard air box, the more air the more fuel will be needed to stop the mixture becoming lean

[Pauly]

I would say its something to do with the cam, im suprised its running well with it. You need an injection cam, which are more mild.

[ROXTEE]

change cam will result in engine out and in, its not something i would like/ able to afford to do at the moment. I just want to see what can be done to the existing engine system, by some minor modification.

from what u guys suggested, the ECU can not be mapped/adjusted, how about change to a cooper's ecu? will that make it better?

what im really concern it: my mg metro + spi injection probabily is about 70+ bhp now, for this kind of power, not very much, so that makes 35mpg seems too much compared to the power, that's why i want to do make it have a better mpg to match the a bit low power.
am i wrong on this?

[MiniJosh92]

Changing the ecu is only straight forward if yours & the one you are replacing it with are un-coded. If not you'll have to change all the immobiliser etc as I understand it, but someone who knows more about spi's will be able to confirm this.

[Pauly]

Theres nothing much you can do at the moment, injections sort of run them selves, ECU's need to be replace like for like (same ecu code and there are coded and un-coded types).