New exhaust now with pics 19/01/2010

  • I had a new exhaust back box section fitted today!
    but now my idel has droped to about 500 rpm, any ideas why
    the back box on their was a standard thing with 2 round pipes out the ass of it, now i have a 4 inch jap cut,
    which they had to pipe up half way to the silencer due to a load of holes on the pipe work.

    but why has this effected my idel????

    and whats the best way to adjust it up on the cable or using the screws on the throttle body?

    thanks jon

  • it'll be because the zorst has low back pressure.
    im sure peeps who have adjusted will be along to help soon. :D

  • oh yeah post some pix

  • i shall be taking some pics to mo, as i got to fix the front splitter, that got damaged when i picked the car up, bloody A frame hit it,but nothing a bit of gd filler work wont fix

  • when i installed my ze i ran it on the complete k8 manifold and standard k8 exhaust inc cat. It did drop it down to 148hp! lol. When i had the 2.5 headers full stainless exhaust built i had no problems with idle.
    Wonder if the ecu needs to be reset to re-adjust? but then not sure if an obd1 ecu is that intelligent!. Think i might be something like disconnecting battery negative, put key in ign position hold brake pedal for x amount of secs ( possibly 10 ) then reconnect battery.

  • You will find the idle is run by the ecu if it has dropped you may have a fault as the ECU will sort out any difference in back pressure and adjust the engine running to compensate. A friend of mine always recommends when you change something like that is bung it on a machine to have any fault codes reset and everything put back to how it was meant to be then when you start it again the ecu gets everything sorted and settled.

    Heres some Mazda ECU fault codes and reset procedures all the info for doing it yourself is for models pre 1995, they changed some bits after 1995 so if its later its probably recommended to get someone out with a diagnostics machine or make one yourself like I have written at the bottom of the page.
    Try the disconnect battery and pump brake pedal to clear the codes thats pretty risk free unless you have a non factory immobiliser

    Carbureted Models

    System malfunctions detected and stored in the emission control unit can be displayed using the self-diagnosis checker tool No. 40-H018-9A1. Any current or memorized malfunctions are indicated by a displayed code number and a corresponding buzzer. A monitor lamp on the checker indicates oxygen sensor operation. A normal air/fuel ratio is indicated by a continuous flashing of the lamp. The lamp will not light continuously if the air/fuel is lean and will not light at all if the mixture is rich. Refer to the manufacturers instructions for operating procedures of the self-checker tool.

    Fuel Injected Models

    A system selector tool No. 49-B019-9AO or equivalent on OBD systems and tool No. 49-T088-OAO or equivalent on OBD II systems, can be used to diagnose the main input or output devices. Systems are displayed as code numbers appearing on the system checker. Refer to the manufacturers instructions for operating procedures.

    Clearing Trouble Codes

    Carbureted Models

    Disconnect battery ground cable for a minimum of 10 seconds to clear trouble code stored in the memory.

    Fuel Injected Models With OBD

    Disconnect battery ground cable for a minimum of 10 seconds, then depress brake pedal five times to clear trouble code's stored in the memory.

    Fuel Injected Models With OBD II

    Connect SST (NGS) tool to data link connector 2. Then select "Clear Diagnosis Codes" function and erase diagnostic trouble codes from the NGS memory.

    Diagnostic Codes - Mazda
    These codes cover ALL mazda's and some listed may not be associated with MX-3's

    Fuel Injected (Before 95)
    Except RX-7
    1 Ignition Pulse.
    2 Distributor - No 2 Signal.
    2 No 2 Signal (626 and MX-6).
    2 Crank Angle Sensor - No 2 Signal (1992-1995 929, MX-3 1.8L).
    3 Distributor - G or G1 Signal.
    3 Crank Angle Sensor - G Signal (MX-3 1.8L).
    4 Distributor - No #1 Signal or G2 Signal.
    4 Crank Angle Sensor - No 1 Signal (MX-3 1.8L).
    5 Knock Sensor.
    6 Vehicle Speed Sensor.
    6 Air Flow Meter (MX-3 1.8L).
    7 Knock Sensor - right hand side.
    8 Air Flow Meter.
    9 Water Thermo Sensor.
    10 Intake Air Thermo Sensor - Air Flow Meter.
    11 Intake Air Thermo Sensor - Dynamic Chamber.
    12 Throttle Sensor.
    14 Atmospheric Pressure Sensor.
    15 Oxygen Sensor or Heated Oxygen Sensor - left hand side.
    16 EGR Position/Function Sensor.
    17 Feedback System or Closed Loop System - left hand side.
    23 Oxygen Sensor or Heated Oxygen Sensor - right hand side.
    24 Feedback System or Closed Loop System - right hand side.
    25 Solenoid Valve - Pressure Regulator.
    26 Solenoid Valve.
    27 Solenoid Valve.
    28 Solenoid Valve - EGR Vacuum side.
    29 Solenoid Valve - EGR Vent side.
    30 Cold Start Injector Relay.
    34 IAC Valve.
    36 Heated Oxygen Sensor - right hand side.
    37 Heated Oxygen Sensor - left hand side.
    40 Solenoid Valve - Triple Induction Control System & 02S Replay.
    40 Solenoid Valve - Variable Resonance Induction System Solenoid Valve - VRIS 1.
    42 Wastegate Solenoid Valve.
    46 Solenoid Valve - VRIS 2.
    65 A/C Signal - PCMT.
    67 Coolant Fan Relay No. 1.
    69 ECT Sensor.


    To make an indicator so you can read these error codes yourself, without having to bother your friendly local Mazda technician with his expensive special service tools, you will need, a Light Emitting Diode (LED) and a resistor. These can be purchased at Maplins RS or any other similar electronic hobbyist supplier for spare change.
    You’ll also need a separate short length of wire. (An unpainted paper clip will do) If you buy a red coloured LED, you will need a 2000 Ohm resistor, or any other colour will need a 500 Ohm resistor. (If you happen to already have a selection of resistors, any value within about +/ - 25% of these will do).
    Simply solder one lead of the resistor to one lead of the LED. It doesn’t matter which side of the diode you put the resistor on, but it will pay to take note of which is the longer of the two leads on the diode, as this will determine how you plug it into the car.

    Now turn on the ignition, but don’t start the engine. The LED will light up for about five seconds (assuming you got it the right way round) before it starts flashing out the error codes (if there are any). This will give you a chance to get around to where you can see the indicator. Count the number of flashes to indicate the malfunction code. If the code is a two-digit number, the tens digit will be displayed first with a long flash, then after a 1.6-second dark pause, the ones digit will be displayed with shorter flashes. If there are multiple codes, they will each be separated by a four-second pause and may include two-digit codes, so pay attention. (For example, one long flash followed by three short flashes would be a code of 13) The codes will repeat after four seconds so don’t worry if you miss them the first time.
    Take as long as you need to record the codes and then refer to the Fault Codes chart shown.
    Keep in mind that the indicated device may not be faulty itself, but may have a bad electrical connection, or some other fault may be making it have an abnormal signal. The fault codes are stored by the ECU indefinitely, so after you’ve done something to cure the problem, you need to clear the codes by disconnecting the car battery for a minute or so. This will wipe the computer of its error codes. Now you can drive the car again for a while, and re-check to make sure the error code hasn’t come back. (If you didn’t clear the ECU’s memory, it will still have the old codes.) Hopefully, as several others and I have been able to, you’ll be able to use this information to find the cause of whatever’s wrong with your car.


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