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V8 Tuning to the next level

97-Esprit V8

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During my upgrading and engine rebuilding I am also installing a very sophisticated piggy back engine management system. The AEM FIC-8 (Fuel Ignition Controller 8 cylinder) installs and uses a combination of intercepting signals and tapping signals to modify the fuel injection pulse width and the ignition timing retard (no advance is possible). The reason for not going complete stand alone is this car is still going to be a street car and programming the engine management for day to day use is extremely painful. The startup, warmup, light throttle cruising and acceleration are incredibly hard to get right via a stand alone.

So the piggy back system retains all of the good of the factory tuning and allows the boost fuel control and timing retard to be tuned for individual requirements. Some of the features of this system are as follows:

- ability to install larger fuel injectors (+100%)

- ability to clamp analog signals, for example the MAP signal to the factory ECU can be limited to what ever you want.

- ability to run dual tunes, for example a race fuel tune (fuel ignition and boost control) as well as a street fuel tune at the flick of a switch on the fly. Or in my case a water/meth tune which automatically switches when the water/meth isn't functioning. (read safe)

- ability to remove the secondary fuel injectors - they are shite

- Datalogging and wideband interface

- easy USB tuning on the fly

- boost control via the factory solenoid

- Onboard MAP sensor (40psia)

- maintains the factory IAT ignition timing retard and knock sensor capibilities

So I have decided to document the wiring installation, after scouring through the wiring diagrams and matching the the AEM manual, sorting out the wires needed and not needed and how the factory sensors work. I determined I need to splice/tap 28 wires in the factory harness. I will be mounting the AEM unit on top of the factory ECU (PS Mark I need my ECU I lent you know who your are :D




Wiring sorted (Left stays, right goes)


Factory wiring harness ECU plug opened up


Factory fuel injector (Left) stock GM LS1 fuel injector (Right)

More to come once I start cutting and splicing


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Paul, i think in your country there is no need for OBD-confirmaty checks then !? As you speak about stand alone engine managements ...wouldn't that mean those are not possible on street use, as long as the arrangement is not road certified by some sort of national transportation/road savety board (like the US/EU homologation standarts..) :D

This would allways be my greatest fear , as the rules in my country are so strictly on that. I have used an 'caught in the loop' injection timing device some time ago, but use now for ma experimental project just higher-capacity rated Bosch-injectors [same styling as your Chevrolet OEM]

What do you have ? (my are 380ccm, wich is on E85 still highly oversized and makes the step from normal to WOT-run rough..)


to name the things if I see them, that's what I call integrity..


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^ about 8 hours later the piggyback system is integrated into the factory harness. A few wires(orange and white) for additional features, wideband O2, and another analog signal, possibly water to intercooler coolant temperature. A good number of the wires (yellow and green off to the right) will be trimmed out completely once the car is running.


Edited by 97-Esprit V8
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Hi Paul,

Prep work is coming along nicely there.

Bet you can

1996 Esprit V8, 1998 Esprit V8 GT, 1999 Esprit S350 #002 (Esprit GT1 replica project), 1996 Esprit V8 GT1 (chassis 114-001), 1992 Lotus Omega (927E), 1999 Esprit V8SE, 1999 Esprit S350 #032, 1995 Esprit S4s, 1999 Esprit V8 GT (ex-5th Gear project), 1999 Esprit V8SE ('02 rear)

1999 S350 #002 Esprit GT1 replica

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  • 2 weeks later...

Lookin good Paul! I'm gonna have to head to Calgary soon to give you back you're computer... :thumbsup: It's kind of a lame excuse to go visit though.. should really just be to say hi! I may have to ship the computer to you by bus as we just baught a house (as you know) and I'm afraid that any trips are gonna be a problem for a little while.

Modifying esprit's.. now that's fun..

PS... I AM NOT A CERTIFIED MECHANIC.. I Have chosen to help those in need, in the past and must not be construed as being a certified technician.

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  • 10 months later...

What ever happened to this project?

Been on the back burner, bought a '01 996TT which is more then eaten into my time as it seems to run without much effort, unlike the esprit ;)

Seriously though, not much time so the car is just sitting. I hope to get working on it again for the xmas break. Need to get it back together and running for the summer, may look at selling once its all completed and buying a gallardo.

Look for some updates soon enough. Got a nice deal on a set of kinesis F110 wheels for the 996TT, looking to fit them on the LEV8. Found a place that will make up hubcentric spacers that change the bolt pattern from 5x108 to 5x130 for these wheels. Needs to be ~40mm wide, really the biggest thing i don't like about these cars is the lack of modern tire choices.


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