Tech FAQ

Emissions

For the DENSO 4-wire oxygen sensors, the two black wires are designated for the “Heater”, the blue wire is designated for the “Signal” and the white wire is designated for the “Ground”.
The side with the greatest amount of metal border should be placed towards the exhaust manifold or piping. If the border appears to be the same, the gasket can be placed either way.
The 4-digit number represents the last digits of an internal DENSO part number of the sensor element, and can not be used to identify a specific sensor, because in many cases, the internal element is used for multiple sensors with the difference being wire length and connector shape.
The most common thread size is M 18 x 1.5, however in rare occurrences the size is M 14 x 1.0.
By examining the original part number etched onto the sensor, you can determine the proper sensor type. The original part number prefix for a Toyota Oxygen sensor is ‘88465-xxxxx’ and the prefix for a Toyota Air Fuel Ratio sensor is ‘88467-xxxxx’.
No, those sensors are NOT interchangeable. The engine control units (ECUs) are programmed to receive a specific signal and signal type. An oxygen sensor is comparable to an on/off switch whereas an Air Fuel Ratio Sensor is more like a dimmer switch.

Fuel

The DENSO First Time Fit program is designed on the original equipment specifications. Although DENSO fuel pumps can be rated at low-flow, mid-flow and high-flow, we cannot recommend varying from the original design and specifications.
Any fuel that is accepted by the original vehicle manufacturer, is acceptable by DENSO.

Heat & Air Conditioning

Most all of the DENSO First Time Fit compressors are wet, and are provided with a full system charge of compressor lubricant, unless the compressor is specifically labeled as DRY.
Yes, the part number for a 6-pack of 250 cc cans is 999-0101.
No, ND-Oil 8 is a patented formula with proprietary additives to enhance the performance and longevity of DENSO compressors. However, of the lubricants available throughout the industry, PAG-46 is the closest to ND-OIL 8.
The ‘wet’ compressors provide the same amount of lubricant as when the original compressor was first installed and used; and after the system is initially activated, the lubricant is dispersed throughout the system, leaving only a partial amount in the compressor. Without removing some of the new oil to equalize the oil amount in the compressor, the system will have an excessive oil charge will lead to higher pressures and a poor system performance.
In case of a compressor failure, this safety system disengages the compressor clutch and the idle-up vacuum switching valve (VSV) to prevent breaking the compressor drive belt. Once activated, the system will also cause the a/c switch lamp to blink, notifying the driver of the condition.
No. A RPM Sensor is generally used only on applications where the compressor drive belt is shared with another belt-drive component which is more relevant to the safety/drivability of the vehicle (i.e. – alternator, power steering).
The a/c system monitors the engine speed from the igniter/engine control unit (ECU) and the compressor speed from the RPM sensor respectively. The a/c amplifier compares the ratio of the compressor speed to the engine speed. If the ratio falls outside of the preset parameters, it is judged as locked, and the safety system disengages the compressor clutch and the idle-up VSV.
Yes, as of January 1, 1993 all DENSO compressors are manufactured with shaft seals and o-rings designed for either HFC134a or R12 refrigerants.
Although original DENSO shaft seals are only available through the vehicle OEMs, they are replaceable. However it is only recommended to attempt seal replacement for a 10P type compressor, since the seal is assessable through the front housing and compressor disassembly is not required. SPECIAL SERVICE TOOLS are required for this repair, not just needle nose pliers.
The compressor displacement varies based upon the type of the compressor and our product line has several different sizes. The compressor type, included on the identification label contains the abbreviated displacement (i.e. – a SCS06 compressor has an approximate displacement of 60cc’s; a 10P08 compressor has an approximate displacement of 80cc’s; a TV10 compressor has an approximate displacement of 100cc’s; a 10PA17C compressor has an approximate displacement of 170cc’s and a 10S20F compressor has an approximate displacement of 200cc’s).
The washers, or shims are used to establish an air gap between the pressure plate and the rotor. Please refer to the enclosed air conditioning clutch installation instructions for additional information.

Ignition

The higher the number, the colder the plug.
No, only certain part numbers and applications.
That is dependant on the engine modifications that were performed. Always start at the stock heat range and refer to the specifications of the performance part suppliers. Generally, go one heat range colder for every 75-100 Horsepower increase. This is only good for internal engine modifications, add-on nitrous, supercharger, or turbocharger. The heat range does not have to be changed on bolt-on items such as: air intakes, exhaust (mufflers), or throttle bodies.
The U-Groove design on the ground electrode allows for a larger flame front and improved ignitability.
The life of the plug depends on the conditions and amount of modifications to the vehicle. The more power that is added the shorter the life of the plug. Generally, Standard/Resistor plugs – 30,000 miles; Platinum plugs – 60,000 miles; Iridium Long-life – 100,000 miles and Iridium Power – 30,000 miles.

Pump

951-xxxx is used to designate the individual fuel pump; 952-xxxx is used to designate the individual fuel pump strainer; 950-xxxx is used to designate a fuel pump kit (normally combines 951-xxxx and 952-xxxx); 953-xxxx is used to designate a fuel pump module assembly;and 954-xxxx is used to designate the individual fuel pump tank seal.