Esprit Models
Esprit History
For Sale
Other Stuff
Buying & Running
Parts & Specialists
Other Esprit Stuff

FreeScan v.2.07
supports All 4 cylinder all Lotus Esprits models with GM Fuel-Injection.
Installer can be downloaded from here

FreeScan is a windows-based program that is able to communicate with the ECU which controls all all 4 cylinder Lotus Esprit models built between 1989-1999 (SE, S4, S4s, GT3). These cars were all fitted with the GM Fuel-Injection. This software can help with tracing problems with your Esprit including reading internal error codes and also making sure everything in running as it should. Many Esprits are currently running at less than 100%, don't let yours be one of them. This software is a must for all Esprit owners with GM Fuel Injection.

FreeScan runs under the Windows 95, 98 or NT4 operating systems and needs 800 x 600 minimum display resolution and one free serial port. It is recommended to have a 90 MHz or better Pentium and at least 32 MB of RAM. You will also need an interface cable that connects your PC to the GM ALDL port. All you need to run FreeScan is available at the LEW-Shop.

The data is in TTL (i.e. 5V), bi-directional (half-duplex) format and runs at 8192bps.

The Installer we are using was downloaded from the originator Andy Whittaker at:

The source code has now also been made available at :

Lotus Esprit World can supply you with everything you need to communicate with your Esprits ECU via your laptop. Click on picture below to take you to the E-Shop.

Contents of FreeScan Package
1. CD-R, containing the FreeScan installer utility for Windows and any drivers needed.
2. ALDL-PC 2 metre interface cable (either USB or serial)
3. Bound FreeScan Manual

FREESCAN can log the following ECU parameters.

Esprit Sample: Data Reference point.
Coolant Sensor V: Coolant sensor voltage.
Start Water Temp: Starting temp on engine switch on.
TPS V: Throttle position sensor voltage, typically 0.49 V at rest and 4.0V at 100%
Des Idle: RPM that ECM is trying to control idle speed.
RPM: Engine speed.
Road Speed: Road speed (MPH or KPH).
Crank Sensors: Reference pulse.
O2: O2 sensor voltage ranges form 0.01–0.9 V. Readings below 0.3V is lean, values above 0.5 V is rich.
Rich/Lean: Rich-lean voltage swing in the O2 sensor output.
Integrator: Normal reading around 128, The integrator is a short term corrective action which the BLM values are set.
BLM: Values vary between 80-130.
BLM Cell: There are 19 cells which the ECM learns, depending on RPM and MAP.
Injector Base PW: Duration in msec that the injectors are open.
IAC: Idle Air Control, system used to control engine idle speed.
Baro: Barometric pressure, typical about 0.84.
MAP: Manifold Air Pressure. Max value 2.24 which is approx 1.1 bar.
A:F: Air/Fuel ratio.
TPS: throttle position (%).
MAT V: mass Air Temperature senor voltage.
Knock Retard: ignition retard in deg as a result of knock detection Spark .
Knock Count: engine detonation counts.
BatV: Battery voltage detected by ECM.
Load: Engine load
Spark: Ignition advance in degrees.
Coolant Temp: Coolant temp in deg.
MAT: Mass Air Temperature (°C)
Wastegate DC: Wastegate solenoid % duty cycle .
Secondary Injectors DC: secondary injector % duty cycle .
Engine Running Time: Engine running time since switch on.
A/C Demand: Air con is on
A/C Clutch: Air con is on
Closed Loop In closed loop: ECM controls engine running using the O2 sensor feedback.


Paramater Units Typical Data Value (Range) If Data out of Range Refer to…
Engine Speed: RPM 0  
Desired Idle: RPM Depends on coolant temp  
Coolant Temp.: °C Close to ambient Code 14/15
Mass Air Temp: °C Ambient Code 23/25
MAP: kPa Close to baro Code 33/34
Baro,: kPa Dep. on attitude, ca. 0.85 Code 31
IAC,: counts 170  
Throttle Position: V 0.4-0.7 Code 21/22
Throttle Angle: % 0 Code 21/22
Oxygen Sensor: V Approx 0.455 Code 13
Injector Pulse Width: msec Depends on coolant temp  
Spark Advance: deg. 75  
Road Speed: MPH 0  
Fuel Integrator,: counts 128  
Block Learn (BLM): counts Not valid  
Block Learn Cell: Cell # 19  
A:F:   Not valid  
Open Closed Loop: 1 or 0 Open loop  
Knock Retard: deg. 0  
Knock Signal,: counts 0  
Battery Voltage: V 12.0 Check battery
A/C Demand: On/Off No  
A/C Clutch: On/Off No  
Time From Start,: sec number  

Dermot O'Hare will be looking after Freescan page information

CODE 26 FAULT by Paul Chandler

I had an intermittent engine check light. If I stopped the engine and restarted it then it could go away for days, I lived with this for a bit, but got fustrated when it came on while I was on the motorway robbing my boost until I could stop and reset it. The list of items on the code 26 list are:

- RPM relay
- Radiator relay
- A/C control relay
- engine overheat relay
- solenoid relay (throttle jack)
- ebpv solenoid
- wastegate solenoid
- canister purge solenoid
- check engine light bulb
- secondary injector circuit

As the cause for 26 is so wide, any search will find a fair bit of conjecture and you could find ten different people with ten different causes. I fiddled about blindly until freescan split the list in half, and then i focused on the items on that list.

Everyone with a chargecooled Esprit should use freescan Before posting about fault codes. The LEW lead and manual is one of the best things I have bought and without it you have only the guesswork of others to go by, which will cost you time better spent driving! Freescan split the code culprits into two groups and identified the places i should be looking: Secondary injector relay, fan relay, cannister solenoid and wastegate solenoid. It also said in the 'tip' line that something was probably open circuit.

I decided to blitz the fault rather than do individual components and wires. This is because as the fault is intermittant, if i did one single item at a time and then ran til the fault came - it could take ages as sods law dictates i would change the faulty item last. I phoned SJ and bought the Secondary injector relay, fan relay,and wastegate solenoid. This only came to about £40, i did not get the cannister solenoid (this comes as a complete assembly for about £60) the cost did not prevent me buying it, but as it requires (fairly easy) removal of the boot floor i thought i'd try the others first.

At the same time as changing these, i pulled every plug on the fault code (whether on my split or not) and cleaned the pins, and made tight any plug contacts that looked like they could be tighter. This action cured the fault and I have not seen it since. So i can't nail any individual culprit, but £40 and an hours time is worth a shot to get your boost back.

Code 26 Fault finding!
I have had a code 26 problem for nearly 18 months now. The fault was intermittent and would only appear during urban / low load condition driving. It would never appear whilst travelling down the motorway etc.

The solution was to replace the charcoal cannister solenoid. I had previously checked this and it was working (although with hindsight it was a little weak) so I started looking at other things.

My advice from all of this for anybody with a code 26 fault is, with the ignition on, short across the two pins on the ALDL connector that you use to read the fault codes. This should activate all the solenoids and relays associated with the fault code. Any that are not activated or are fairly weak are likely to be to blame. If the wiring is suspect this technique can also be useful because you can leave the pins shorted and wiggle all wiring whilst holding each relay and solenoid in turn. If any switch on and off then there it is likely that there is a problem with the wiring.

I realise that code 26 can be any one of 9 different things but this technique, which is stated in the engine management manual, applies. The symptoms of the fault can help narrow down which component is likely to be at fault. For example my fault was only apparent at low load and overrun conditions and it makes sense that the ECU tells the charcoal cannister to purge the fuel vapours under these conditions. Another example would be that if the fault occurred at high throttle settings when the engine is above 82 degrees C then the wastegate solenoid would be worthwhile looking at.

I hope that this is of some use to people as I know how frustrating it is to have this particular problem. It is well worth checking the individual compoinents before changing the ECU itself.

Danny Tattersall '93 SE Highwing negative code 26 problem.

ECU Problems

For what its worth..
I have a 4 pot but it was diagnosed with a fried ECU - easily done apparantly. I was speaking to Christopher Neils chaps at Donny last year and they put me in touch with Bluestreak who can triage and repair ECUs.

They're in Hucknall, Notts, and on 01623 753300.

Triage fee was £25 and they send you a document with your diagnosis. I found them quick and fairly cheap. Moreover they weren't given any indication of my symptoms beforehand to give them an unbiased start point and they hit on the culprits quick and problem solved. Mention Club LEW and Christopher Neil to them as well - seemed to work well!

94 S4

return to top
home email news esprit models road tests buying an esprit running an esprit esprit owners maintenance pictures for sale history Lotus models links