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MG MGB GT V8 Factory Originals Technical - EFI Cheap Upgrade

I was messing around on Ebay and found this little gimmick. The company is advertising a 15% increase in HP if you use there little module. It is installed between the Coolant sensor and the ECU and looks to be just a few resistors, but changes the fuel/air ratio. I haven’t bought one, but wanted to get feedback from you all.

http://members.shaw.ca/advancetiming/id25_sl500_e_.htm

http://cgi.ebay.com/ebaymotors/ws/eBayISAPI.dll?ViewItem&item=2467769522&category=33597
Evan Amaya

Here is another "brand" of the same EFI Upgrade.
http://cgi.ebay.com/ebaymotors/ws/eBayISAPI.dll?ViewItem&item=2467669731&category=33597
Evan Amaya

Evan,

They are advertised all over the place, if you wanted to try it, buy a variable resistor from Radio Shack or similar, and wire it in series with the sensor and see what effect it has. Some TVR's had a similar device wired next to the ECU. I don't know how good they are though...I personally go for the 'squashing the regulator' mod as a quick & cheap upgrade.

Mike
Michael barnfather

Evan, what do you think the chance is of getting a 15% power gain from putting in a cooler thermostat? Essentially that's what's happening with this mod, in a round-about way. You trick the engine into running lean as if the engine temp was lower. Not a great idea, especially if you consider the added resistance to the circuit of more wire connections. At least that's the way I see it.
Jeff.

Jeff Schlemmer

It is just anouther gimmick to foo lthe ECU inot thinking things are not as they really are. The same thing is done with all the "HP MODS" you see for late model vehicles, they splice a resistor in the O2 circuit to fool the ECU. Like was said it is a <$1.00US resistor from radio shack.
Larry Embrey

If the adds are true by fooling various ECU sensors you can trade off (safely)performance for fuel ecconomy. So would I be correct in thinking that by fitting various resistances to a few different sensors and wiring them up to a multiple on/off switch you could have an ecconomy/"sport" mode setting? This might give you the best of both worlds for a few pounds.
R Weston

This thought had crossed my mind.........possibly using a rolling road to establish optimum settings......but it's probably easier (if not cheaper) to have the ECU re-chipped.

Is anybody using a rising rate fuel regulator ?

I took one off the old flap-valve system and am using it on the hotwire system (I'm not using Lambda sensors), but I am considering replacing it with a fixed rate regulator, to see if it makes a difference.

Mike
Michael barnfather

This is a common trick used on older computers before obdII. It tells the computer that the engine is not fully hot and therefore forces it to inject more gas. The tradeoff is that the computer will also limit full timing and no more real power will be developed. You will not notice any increase in power, only a better "throttle response". In general, OEMs limit power and lower emissions mostly during closed loop operation. At wide open throttle, all manufactures run a rich as possible to avoid running the engine hot. Lower emissions are not the goal here. Sure, you can add a little power at cruising speeds, but who wants that? If you have stock timing and fuel maps in the computer then the optimum settings will be at the highest rpm at which the engine draws the most air per stroke. This means engine at full operating temp, longest injector pulse width, max timing. Fooling the computer by altering its inputs cannot put you in a better fuel "cell" than optimum. You have to alter the computer outputs or the internal fuel and timing maps, but only if the engine really "needs" extra fuel because of changed engine breathing capabilities. Todays PCMs are pretty sophisticated and any change in one particular sensor can usually be detected by another sensor, making it harder to fool. Having said that, I'm not that familiar with Rover's ECUs, but I suspect that they are no different than early Ford, GM, Chryslers.
Joaquin

This is a common practice at the track, yu can do it with a resistor from Radio shack for about $.030
Bill Guzman

Something I've tried recently.
I've a non-cat tune resistor on the loom and I've set the air flow meter to a cat' voltage ie 1.7V (ignition on)across the two outermost wires (of the four). I did this because I don't have a CO tester but I do have a volt meter. Keeping in mind I don't know much about this, non the less a noticable increase in power on accelleration. I don't have a dyno or anything but previously when I accellerated hard from first gear I would get a short squeek from the tires, now a long drawn out squeel and a strong need to stabilize the back axle. Serious increase in take off power.
Peter

Pete, that's another thing for me to try then !

I assume that you're not using Lambda sensors ?

Joaquin,

The Lucas/Bosch ECU only controls fuel, not ignition, and it reverts to 'limp home' mode if Lambda sensors are not connected, which means these tricks will work as it has no exhaust information to refer to.
Pretty unsophistcated by modern standards.

Mike
Michael barnfather

Mike,
The down side is a slightly erratic idle, until the engine warms up.
It would be nice to have a table of CO output vs Voltage, or power vs voltage. Just a few points and plot a graph. It would be quite a resource for us amatures.
Any experts out there feeling generous?
Peter

This thread was discussed between 19/03/2004 and 26/03/2004

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