Testarossa - Ignition, Fuel Injection Problems - Sympathetic EFI Upgrade Pro

My partner and I have been working on Testarossa’s for some years now. Many of them come to us because they have running problems. Consequently we have had to trouble shoot a whole range of issues some of which are very complex, frustrating and time consuming to diagnose and put right. All the more so if the vehicle has been to several shops resulting in the root cause of the problem being masked by a series of well intentioned adjustments, generally to the Bosch K or KE Jetronic fuel injection system. The help of people like Steve Magnusson has been invaluable during these diagnostic exercises - we are fortunate indeed to have access to such helpful and knowledgeable individuals.

Many frustrated Testarossa owners will be familiar with problems such as: Running on One Bank; difficult Cold Start; Surging / Hesitation / Misfire; Hanging Throttle; Stalling; Irregular Idle; difficult Hot Start, Low Power Output etc etc. To make matters worse it is getting increasingly difficult to service and or source OEM parts for the fuel injection and ignition systems.

A well sorted Testarossa is an absolute joy to own. They are fabulous to drive when they run the way Enzo intended. They are very rapid, capable and surprisingly agile covering long distances at high speed in relative comfort. We love Testarossas and drive them regularly on long club rallies.
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Efforts to help a couple of owners in relatively remote locations prompted us to look at a way we could get a Testarossa to run well using an easy to fit upgrade kit. Our thinking was to see if we could produce a kit that essentially eliminated or bypassed most of the troublesome components on the vehicle but did not modify the vehicle in any way that would negatively impact the value. For those of you who are still interested this is what we came up with:

Photo 1 is where we started. We chose a 1988 Testarossa (LHD USA Specification) with KE Jetronic to use as a test mule. The drive train was unmodified apart from a Tubi exhaust fitted with cats.


Photo 2 is where we ended up – at least so far. The car is now fitted with a fully functioning prototype fuel & ignition system upgrade. The kit is designed to look unobtrusive like it is something that came from the factory. Those of you who know these cars will notice the EFI Fuel rails that use the ports for the original bosch mechanical injectors. You will also notice the RH Distributor cap has a spacer which houses the cam angle sensor needed to control the new EFI & Ignition system. The new ECU is located in exactly the same place as the original one (under the LHR Fender) and you would have to look carefully to see that it has been changed.


Photo 3 is a better view of the kit during fitting. It was considerably more difficult to achieve but we felt that it was important that absolutely no modifications were done to the car. Accordingly we managed to make the kit 100% reversible. We left components like the original fuel heads (blanked off) and the cold start injectors in place even though they are not used by the new system, to help keep an OEM look.
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Here are some of the main components that were fitted to the prototype. It basically consisted of a set of custom fuel rails, carefully selected electronic fuel injectors, collets that allow the injectors to fit in the original port without modification, fuel pressure regulators, cam angle sensor unit, throttle position sensor & adaptor plate, electronic idle speed control unit along with various brackets that allow fitting of the kit components without modification to the vehicle.

We replaced the OEM ECU with an Autronic SM3 unit (although any quality programmable ECU could be employed). The ECU is programed to manage all aspects of the new fuel & ignition system. The whole system is tied together with a very high quality custom wiring harness, which also links the new system to the OEM wiring harness.
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Photo 1 Close up of the EFI Injectors & Rail. The system is designed to use the original fuel pumps, the fuel pressure accumulators & fuel filters. The original fuel lines attach to a fittings on the new fuel rails. Correct fuel pressure is maintained by a fuel pressure regulator, fitted to the forward end of the rail. Excess fuel is returned to the fuel tanks via the original return lines.

Photo 2 A TPS (Throttle Position Sensor) was required which was fitted via an adaptor plate in the same position as the original Throttle Switch. Clearance was a challenge as was finding a switch that would work without modification to the vehicle.

Photo 3 The sophisticated CAM angle sensor is needed to give a accurate readings for TDC, engine rpm, firing order etc, in order to ensure that the new fuel & ignition mapping is highly accurate.

Photo 4 We didn’t want to use the original Auxiliary Air Valve arrangements as they can be the source of several running & starting problems. We came up with a fully programmable electronic idle speed control unit plumbed into the original ports in the intake & plenum chambers. Neat device that allows the system to eliminate several conditions that irritate Testa owners such as cold start, pulsing rpm during warm up cycle, idle compensation with AC & Thermo Fan switching.

Photo 5 Fully programmable ECU fitted in the same location as the OEM unit. The brushed aluminum base plate will be replaced with a black unit like the original.
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Photo 1 Initial base map upload. Startup & some initial trouble shooting. Followed by comprehensive Dyno & Road Tuning sessions.

Photo 2 Our friend Troy from TZ Tuning hard at work in his “office”.

Photo 3 We did back to back testing with a very similar unmodified car on the road and on the dyno.
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We drive these lovely old cars enthusiastically but with a high degree of mechanical sympathy. In general we don’t like dynos for precious road cars as they load the car in a way that we would rarely if ever do when driving. However a dyno is an invaluable tool for tuning this type of system. Our objective was always to improve drivability & usability under a broad range of conditions. However, our tuning also needed to establish peak torque / horsepower which included a couple of short trips to the redline to make sure all the parameters were as they should be. As an aside, the new system allows a rev limit to be set or indeed a “valet mode” switch if the owner wanted.

At the end of day you have got to love a pair of Testarossas at full noise (Happy to upload video if someone can tell me how to get the file size small enough).

An extended dyno session is pretty hard on any vehicle and the fact that these cars performed flawlessly on the Dyno (didn’t miss a beat, no elevated temperatures etc) is a testament to what an amazingly capable performance car Ferrari delivered in the Testarossa.
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The results so far? To date we are have driven the “mule” Testa over a couple of thousand kilometres and tried to include a range of conditions (mountains to coast, city stop / start, highway cruise, high speed & twisty country back roads). To say that we are delighted would be an understatement.

It is hard to convey fully in writing what the car feels like but our observations include:
Increased Power Output - we have picked up some more torque / horsepower, which was not a primary objective but never fails to please.
Throttle Responsiveness - is the most obvious and rewarding improvement. The Bosch Jetronic systems generally feel a bit dopey under foot taking a bit of time to respond to throttle inputs. This is vastly improved with the new system with the car feeling far more nimble / responsive under changes in throttle input.
Fuel Efficiency - is also improved (although these old car generally don’t get driven enough for this to be of concern to most owners).
Cold Starting & Cold Running - is transformed. The car can be started reversed out of the garage right way without the tendency to stall, idle erratically and generally trying to be embarrassing.
General Temperament - The mule starts, runs & drives beautifully under all conditions that we have tested it under so far. As many of you will know, the flat 12 (which behaves like two 6 cylinders, joined at the crankshaft) is very sensitive to balance between the left & right banks. If the balance is not perfect the car will need to be set up with a higher idle, be more sensitive to surging, stalling & running intermittently (cold) on one bank. The upgraded system is not at all sensitive to balance as it sees the engine as a 12 cylinder.

We love Testarossas. We love them even more with this sympathetic upgrade.

Imagine a Testarossa ownership experience free from the gremlins that go with; thermo time switches, potentiometric relays, protection relays, auxiliary air valves, cold start injectors, warm up regulators, vacuum limiting devices, corroded 30 year old electrical connectors throwing intermittent faults, air flow sensor plates, mechanical injectors, 30 year old Magneti Marelli Microplex etc etc. Steve Magnusson might get his life back & these lovely old cars might get driven a bit more often.

We had a lot of help from some great people doing this interesting project. A special thanks needs to go to Steve from EFI Hardware, Troy from TZ Tuning and Tim from Black Stallion Motors who were invaluable. You would be hard pressed to find a more friendly, helpful, knowledgeable, resourceful and innovative bunch of professionals to work with.
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Hi Joe, Injectors were sourced from EFI Hardware and are Bosch Motorsport 550cc EV14 P/N 851-550. Hope this helps.

Did not count the hours - spoils the fun and you might start to question your sanity!

 

Black Testarossa with EFIUpgrade Kit fitted. B)

https://youtu.be/NG8TWb3muLg

 

Similar car to the "Mule" White Testarossa used for comparison testing with Upgraded EFI Car. These cars sound pretty awesome on the dyno. White car has very similar Tubi exhaust to the Black car but without Cats. IMHO sounds the best.

https://youtu.be/dGRD4pNySM4

 

Hi Joe, sorry if it sounds like a heavy sales pitch - I can see how it might. Just being enthusiastic really - we put a lot of work into this and thought other owners might like to know what was done and how it turned out.

We don't have a commercial business and have no plans to sell these kits on a commercial basis. We have another couple of kits on the way which are already spoken for - they will be fitted to cars that belong to friends. We will certainly do more kits for friends but had not really planned to sell them widely.

I see it as a bit like Birdman - he made a great fuse box upgrade (initially for himself) subsequently he has been good enough to make them available to other enthusiasts (I have fitted several and they are great). He has a real job, will never get rich selling fuse box upgrades but there are a few of us that are very grateful that he makes them to help us keep some of these old cars running well.

Out of interest the kits that we are doing for friends are likely to come in under about 10k. So not cheap but the ECU, wiring harness, cam angle sensor kit and injectors are relatively expensive and the components add up. Having said that you can pour a lot of money into trying to get the OEM system to run like it should.

Hope this helps answer your questions.

 

I have been asked by a couple of people for some more photos of the engine bay. These are some I have on hand. Wiring is a little tidier on the newer kits. Image Unavailable, Please Login
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Thanks Melvin. Really happy with how it turned out. Might try to do one for a 400i next as they tend to suffer from similar ignition and fuel system problems.

 

Thanks Motob. Most of the cars we deal with don't have oxygen sensors. We chose the black car as a test mule because it is fitted sensors and catalytic converters (exhaust and cats are Tubi after market). However we found we got better results (performance & emissions) with out using the O2 sensors and closed loop. Having said that it would be easy to add some O2 plugs to the harness for anyone who wants to use them.
Be interesting to understand how your emissions testing works in the USA on older cars in case hooking up the O2 sensors is important.