Econ Tell Tale Light not working - 88 Bosch Turbo

[Esprit2]

judgea said:

Sanj, off the subject, but while I thought about it, are you familiar with the "econ" (economy) light on the 87 G-type? While having all belts serviced, mechanic must have disconnected the sender unit. Since my service, econ light no longer comes on (car runs great, I'm sure the economy feature is still working also). Do you know where the econ. connection is? I need some info. so my mechanic does not spend all day on an open ended search. Thanks.

Mark,

This was a little off-topic on the other message thread, so I'm taking the liberty of moving it to a new thread.

The High Temperature Thermal Switch is located on the top side of the intake manifold between #1 & #2 intake runners. There are two male spade terminals sticking up out of the top that should have wires connected. It's possible that the mechanic displaced one of the wires while working on the timing belt. If both wires are off and you can't divine which one went where, don't sweat it. It's not polarity-sensitive, so just put them on.

The Fuel By-Pass Valve is located at the bottom rear corner of the air filter box. A plastic sorta-cylindrical body with a larger spigot on one end that plugs into the airbox through a rubber grommet. A smaller spigot on the side has a rubber hose that runs forward to the side of the Bosch Metering Unit. An electrical connector plugs into the end of the plastic valve body… make sure it's plugged in.

The Fuel By-Pass Speed Sensing Relay is located in the relay box in the rear boot bulkhead… just aft of the coolant header tank. Remove the relay box cover. Looking forward, the relay is the large one on the top row next to the ignition coil. The relay energizes the fuel by-pass valve and econ tell-tale light on deceleration from an engine RPM of greater than 1600 until 1400 RPM when the throttles are closed. Make sure all the connections are clean and secure. There would be no reason for the mechanic to be in there just to do a timing belt, so any problem there is probably coincidental.

The Fuel By-pass and econ tell tale are activated when the throttle is closed. The "Normally Open" Throttle Position Switch (TPS) closes (turns ON) "just" as the throttle closes. If anyone has adjusted the idle speed upward without re-adjusting the TPS, it will not close to enable the Fuel By-Pass and Econ tell tale light.

Always loosen the TPS before adjusting the idle speed screw. Not doing so may result in the throttle bodies no longer being synch'd… ie, you may twist the shaft. Loosen the TPS, adjust the idle speed, rotate the TPS body until continuity is "just" made between switch pins 18 and 1, tighten the TPS retaining screws.

Pin 18 is common. Pin 3 should "just" make contact as the throttle closes. Pin 1 makes contact when the throttle is about 30 degrees open for another purpose… nothing to do with your issue.

You asked this question on the [e-mail] mailing list earlier, so I may cross-post this there as well.

Regards & good luck,
Tim Engel
Lotus Owners Oftha North