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Guide to thermostat and ECU sensor modification for the 97 TLS
This has been compiled from various threads in an attempt to produce an easy to follow guide to the best mod you can do to the TL from stock (in my opinion). Thanks go out to all those planeteers who have posted on this subject - you know who you are. Special mention goes to the thread from UncleMeaty, and I musn't forget Octofinger.
Reason for modification:
The stock 97 TLS has a poor cooling system design for several reasons.
The Solution:
Suzuki rolled out a revised cooling system from the 98 (SW) model onwards to alleviate these problems. The aim of this mod is to match the changes Suzuki made in either a cheaper fashion, or as a complete replacement of all affected parts. This obviously depends on the depths of your pockets.
Solution 1
Solution 2
Solution 3
Solution 4
This has been compiled from various threads in an attempt to produce an easy to follow guide to the best mod you can do to the TL from stock (in my opinion). Thanks go out to all those planeteers who have posted on this subject - you know who you are. Special mention goes to the thread from UncleMeaty, and I musn't forget Octofinger.
Reason for modification:
The stock 97 TLS has a poor cooling system design for several reasons.
- The ECU temperature sensor is mounted on the radiator. This causes the ECU to monitor temperature of coolant on the radiator circuit side of the thermostat. Therefore this means that the correct engine temperature is never delivered to the ECU, and as the ECU thinks the engine is running below 80 degrees Celcius, the cold map (choke) is continously applied. This aggravates the TL propensity for eating its own spark plugs, and will also cause poor running at small throttle openings, surging and poor fuel consumption.
- The stock thermostat is on the cold side, and also has a bleed hole to avoid hotspots. Unfortunately, when taken with number 1 this only compounds the problem with incorrect temperature monitoring.
- 1 & 2 above can also cause oil levels to rise indicitive of the oil becoming contaminated with gasoline.
The Solution:
Suzuki rolled out a revised cooling system from the 98 (SW) model onwards to alleviate these problems. The aim of this mod is to match the changes Suzuki made in either a cheaper fashion, or as a complete replacement of all affected parts. This obviously depends on the depths of your pockets.
Solution 1
- Replace the thermostat housing with the revised version, keep the existing thermostat and block off the bypass from the new thermostat housing. This is not the preferred solution as the system will still continue to suffer continuous bleeding into the cold part of the radiator circuit thus delaying warm up. The stock thermostat is too cold anyway.
Solution 2
- Replace the thermostat housing with the revised version, replace the existing thermostat with a hotter one, block off the bypass on the new thermostat housing and drill a 2mm hole for bypass in the new thermostat. This again is not the preferred solution for the reasons stated above. However, you should get a big enough improvement to stop using the cold map all the time.
Solution 3
- Replace the thermostat housing with the revised version, replace the
existing thermostat with a hotter one, cut into the radiator return hose (lower hose from water pump), insert a T-Piece to connect to the revised thermostat housing. This again is not the preferred solution as it does not match Suzuki's design. However, due to cost, this is the route that I followed.
Solution 4
- Replace the thermostat housing with the revised version, use the later model thermostat (or a hotter one), and replace the water pump housing with the later model version. This is the preferred solution as it matches Suzuki's intensions but is the most expensive route.