When we last left our 1989 All Trac Celica, the engine was partially bolted together and our next task was to repair the wiring harness. A 20 year old harness combined with a spaghetti wiring upgrades equals one hell of a mess. The wiring harness was completely stripped of its original loom and was completely redone with a fresh set of loom, electrical tape and all connectors were inspected for rust and cleaned.
Wiring was an important part of the setup because the original engine had been swapped out in favor for a second generation 3S-GTE from Japan. There were a few differences with this setup. The JDM spec engine did not come with an EGR valve or water to air intercooler. Slight wiring modifications were needed to ensure the car ran properly and did not throw any codes. I replaced the shielded wiring from the knock sensor to the ECU as this wire is a common problem with the ST165. It was responsible for CODE 52 during the initial diagnosis. Modifications were also completed to compensate for CODE 54. This code represents the missing water to air intercooler system. Specifically it represents the water level sensor within the system warning the water level is too low. In favor for an already installed FMIC, we wired the system accordingly to fool the computer that there is water in the system.
With a complete wiring harness, and plenty of time to spare, my spare time was used to clean components. Everything under the hood was cleaned and checked. From the manifold, Fuel injector rail, right down to the bolts, it makes for an easier build without the frustration of mixing dirty components with a nice clean head. Brake clean, rags, and a bench mount wire brush were my best friends. I also took time to clean years of dirt and grime inside the engine compartment itself. Removing all components off the firewall and strut towers allowed me to clean in corners that are normally impossible places. All components bolted in the engine compartment were also cleaned, wire brushed or painted black. I was very satisfied how well the engine compartments turned out. With the engine complete and a clean engine bay, the improved 3S-GTE was bolted in its rightful place.
3 months have passed since the car first arrived. We were ready for the initial start-up. There’s always something special about the first start-up of a project car that has had major work done on the engine. It’s probably something only motors heads like us will understand. A smooth start up and purring engine is always a good sign. Fine tuning was needed to complete the initial start-up and run phase before the test drive including ignition timing and idle adjustments. With engine at normal operating temperature and no codes in sight we took it out for the test drive. Our test drive lasted 3 minutes. Seems that misfire under boost has come back to bug us once again, but this time we have a permanent misfire present. Quick diagnosis indicated we had a cracked sparkplug in cylinder number 2. We originally purchased G-power NGK plugs with a cold rating of 6. I removed these plugs in favor for some NGK Iridium IX plugs with a colder range of 7. The colder range would better handle the higher compression ratio and increased boost levels we had planned to increase after a successful test run. Our second test run was as flawless as they could come. No more misfires under boost, powerful torque, and good acceleration, it was time to increase boost levels. Boost levels would be controlled via an AEM Tru boost gauge/boost controller. We made adjustments to the boost tapping it out at 15 psi. Slight adjustment of our ignition timing advanced it 2 degrees above stock. We had hit the Celica’s fuel cut system after passing 11psi of boost. This was quickly solved by disabling the stock Turbo Pressure Sensor. We have set the AEM system to take the stock units place by utilizing its built-in Overboost protection.
Power and reliability is ultimately what the owner wanted. Although the engine itself could probably handle more boost, limited tuning capabilities forced us to stop at 15 psi to be safe. Needless to say, 15 psi of boost is still an 8 psi boost over stock. A quick spool time along with increased torque and power has this once misfiring spiders home transformed into an all wheel drive beast.
Our last article will be dealing with the terrible handling and very present thump at the back of the car. Till next time..