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Information About My Car

General Information on the ST185
Modifications To Date
Repairs To Date
Info On Joining The GT-Four Mailing List

I purchased my 1990 Toyota Celica GT-Four in January of 1997. This style model was classified as the ST185, and is a full time four wheel drive, powered by a turbocharged 2000cc Twin Cam 16 Valve engine, the engine is designated by Toyota as the 3S-GTE, and the turbo used for this model is the CT26. Mine is a Japanese market car which produces 222 hp, and 224 ft/lbs of torque in it's stock form. The other markets saw the GT-Four producing 200 hp, and about 202 ft/lbs of torque. The GT-Four was renamed for the U.S. market and called the All-Trac. Below is a picture of a stock engine (left) and my engine (right). As you can see from the picture, there isn't much space in these engine bays.

View Of Stock Engine Bay and View Of My Engine Bay
Click on the picture to view a larger picture of the engine.

Click on any of the logos below to go to that company's website

The following is a list of the modifications and other items added to date.  If you are interested in learning about the technical side of the GT-Four, click here.

Aquamist System2S Water Injection by ERL
K&N Air Filter
Autronic Programmable ECU
Twin Coil Direct Fire Ignition (Wasted Spark System)
Hybrid Toyota Turbo (CT20B/CT26)
 TRD Spark Plug Wires
Passion Automotive 2.5 Inch  Downpipe
Champion C57C Racing Spark Plugs
Custom 3 Inch Exhaust System
PCV Routed To Catch Can
HKS Super Sequential Blow Off Valve
TRD 1.3 Bar Radiator Cap
HKS Camshafts (264º Duration, 9.2mm Lift)
TRD Low Temperature Thermostat (71ºC)
HKS Adjustable Camshaft Gears
TRD Shock Absorbers
HKS 1.6mm Metal Head Gasket
TRD Lowering Springs
ARP Head Studs
Whiteline Adjustable Rear Sway Bar
T-VIS System Removed And Ported Out
Whiteline Camber Bolts
Upgraded Fuel Pump (Bosch Unit)
Brake Upgrade - Update To 11 Inch Rotors
Malpassi Adjustable Fuel Pressure Regulator
Porterfield R4-S Brake Pads
Intercooler Fan Added
Shifter Modification 
Blitz 540cc/min Injectors (pressure set to 52 psi for 630cc/min)
Luisi Leather steering Wheel
Twin Entry Fuel Rail (Using Earl's Hose & Fittings)
Custom Made Electroluminescent Gauge Faces
Custom Air Filter Enclosure
Interior Overhaul & Customize

Other additions to the car include the stereo system, which consist of mainly Pioneer equipment, a set of digital bar gauges (volts, water temperature and oil pressure) by Sunpro, an Autometer Boost Gauge, an Autometer A/F Ratio Meter, and an Autometer Electrical Fuel Pressure Gauge.
I recently changed to 16 inch wheels, and the tire of choice is the Yokohama A520 205/50/16.

Click On the Picture For A larger Image

The repairs that have been done to date are listed below. Click on a repair to to see more info. I have listed a maintenance schedule for the car, if you are interested click here.

Air Conditioner  Clutch and Gearbox Rebuild
Rear Diff Mount Overhaul Brake Caliper
Replace VSV for A/C Idle Up Replace Brake Pads
Replace Intake (Turbo Side) Hose Replace Radiator 
Replace Spark Plugs, Wires, Rotor and Cap Expansion Valve & Dryer For A/C

Symptoms:A/C would turn on and then cut out after 5 seconds, and A/C light would blink.
Parts:Revolution Sensor for A/C compressor was all that would have been needed, but as the compressor was making a little noise I decided to replace the whole compressor, which comes with a Revolution Sensor.

Symptoms:A clunking noise could be heard from the rear of the car when changing gears or suddenly accelerating. This seems to be a very common problem, so if you hear a thud or clinking noise from the rear of the car, you could check this first, click here for a diagram of it's location.
Parts:The Rear Mount for the Rear Diff was changed.

Symptoms:Idle speed would drop when A/C was turned on.
Parts:A/C Idle VSV.

Symptoms:I am not sure, the hose was obviously weak, it was brittle from age, and during removal, part of the hose split. A temporary fix until I could get a new one was to use red silicone to seal the split.
Parts:The Intake Hose for the Turbo Side.

Symptoms:The car would misfire at high RPM's
Parts:The Spark Plug and the Wires needed changing, I also decided it would be a good idea to change the distributor cap and rotor the same time.

Symptoms:When changing from fifth to fourth gear there was a crunching (this had been happening for a few months), then the clutch started slipping.
Parts:All syncros, No.2 Hub Sleeve, No.2 Hub, Bolt (for reverse idler gear shaft), Nut (for manual transmission output shaft), Bearing (for output shaft front), Pressure Plate, Clutch, and Bearing.

Symptoms:When changing brake pads, I noticed there was some minor leakage from the piston seals, the dust boot were in bad condition and the sliders were very stiff.
Parts:Caliper Kits for front and rear, and new brake fluid.

Symptoms:Brake noise as a result of the pad wear indicators rubbing on disc. Note: I check my brakes regular, and as such never let them get this far, so I would never hear this noise, but if the stock pads get far enough down they will make noise.
Parts:Brake Pads (inspect the condition of the clips and backing plates, and change if necessary)

Symptoms:Noticed coolant stains on the radiator top tank.
Parts:Replaced Radiator, just the top tank could have been changed, but I opted to get a new radiator.

Symptoms:A/C was not cooling as it should and I noticed oil coming from the drain hose for the A/C, this could indicate a faulty (leaking) expansion valve or a leaking evaporator. When the A/C was checked it was noticed that the high pressure was a bit to high, a sign of the dryer being suspect.
Parts:Expansion Valve and Dryer.

Info About The Mailing List

To join the GT-Four e-mail mailing list, click here and fill out the online form. The mailing list is a valuable asset to any GT-Four owner, with the sharing of knowledge that helps us all to learn more about the car, possible problems and solutions.


08 Sep 98: Added oil lubrictaion diagram, click here.
08 Sep 98: Added diagram of fuel injector to "Basics of Fuel Injection" page.
08 Sep 98: Added diagram of turbocharger system to "Technical Information" page.
10 Oct 98: Added "ST185 Engine & Trans Diagrams" page.
10 Oct 98: Added "Explanation Of Fuel Injection Maps" page.
18 Oct 98: Added "Oxygen Sensor Diagnostic Test" page.
18 Oct 98: Added "Brake Caliper Overhaul" page.
01 Nov 98: Added "Calculate Your Fuel Requirements" page.
15 Feb 99: Added  "updated pictures of new engine color scheme".
15 Feb 99: Added  "picture of instrument cluster painted with metalizer aluminum paint".
02 Apr 99: Added  "The stock Fuel and Ignition Maps in the ECU".
02 Apr 99: Added "Picture comparing internals of stock ECU to G-Force ECU".
28 Mar 00: Added "Info & Install Procedure for an Autronic Programmable ECU".
23 Jul 00: Added "Info & Install Procedure for 2.5 Inch Downpipe".
23 Jul 00: Added "Info & Install Procedure for Upgraded Fuel Pump (Bosch unit)".
29 Aug 00: Added "Latest Dyno Results Using Street Dyno".
18 Jan 01: Added "Info & Install Procedure For New Air Filter Box".
04 Mar 01: Added "Water Injection - The True Story (Facts and opinions on water injection)".
29 Dec 01: Added "Performance Information (0 - 60 MPH time)"
29 Mar 03: Added "Custom Electroluminescent Gauge Faces"
04 Feb 05: Added "Interior Overhaul & Customize"
04 Feb 05: Added "Twin Entry Fuel Rail (Using Earl's Hoses & fittings)"

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This page was created by Dennis Heath.
If you should wish to ask a question about the GT-Four/All-Trac, you can join the GT-Four Mailing List, where I, and many others with GT-Four's, might have your answer. For information on joining go to

Please note that I am not a mechanic by trade, and that any information offered on this web page is free and without guarantee. Should you choose to perform any of the procedures listed on this site, you will be doing so of your own free will, and I will not be held responsible or liable for any damages that might occur from using information obtained here.