please help - revs going up and down.

[BUSHWHACKER]

Code 12 Relates To Problems With The Crank Shaft Speed Sensor ON CERTAIN SITES.?????????????

here are some i found.

OBD1 Codes
1 Normal Condition.
2 Air Flow Meter signal.
3 Ignition signal.
4 Engine Coolant Temperature Sensor signal.
5 Oxygen Sensor.
6 RPM signal (Crank Angle Pulse).
7 Throttle Position Sensor signal.
8 Intake Air Temperature Sensor signal.
9 Vehicle Speed Sensor signal.
10 Starter signal.
11 Switch signal.
11 ECU/ECM.
12 Knock Control Sensor signal.
12 RPM signal.
13 Knock Control CPU (ECM).
13 RPM signal.
14 Turbocharger Pressure.
14 Ignition signal.
21 Oxygen Sensor.
22 Engine Coolant Temperature Sensor signal.
23 Intake Air Temperature Sensor signal.
24 Intake Air Temperature Sensor signal.
25 Air-Fuel Ratio Lean.
26 Air-Fuel Ratio Rich.
27 Sub Oxygen Sensor signal.
28 No. 2 Oxygen Sensor signal.
31 Air Flow Meter signal (Vacuum Sensor signal).
32 Air Flow Meter signal.
34 Turbocharger Pressure signal.
35 Turbocharger Pressure Sensor signal.
35 HAC Sensor signal.
41 Throttle Position Sensor signal.
42 Vehicle Speed Sensor signal.
43 Starter signal.
51 Switch signal.
52 Knock Sensor signal.
53 Knock Sensor signal.
54 Inter-cooler ECM signal.
71 EGR System.
72 Fuel Cut Solenoid signal.
78 Fuel Pump Control signal.
81 TCM Communication.
83
TCM Communication.
84 TCM Communication.
85 TCM Communication.

I'm sure they're the codes for the petrol Surfs.

Here's the diesel codes.....

http://www.toyotasurf.asn.au/techsite/efifaultcodes.htm

[ganghooks]

Fuel Solenoid

When it surges a puff of black smoke surges out the revs drop then come up again, I had this turned out to be the connector on the fuel solenoid mounted
on the fuel pump was loose and not on properly, you can simulate the symptoms
while engine is running by quickly disconnecting and reconnecting this connector
and you will observe the engine race up while disconnected and return to idle as you connect and blow out black smoke. The solenoid coil resistance on mine is 130 OHMS so if its not the connector it could be an intermittent solenoid coil.
or the relay switching the solenoid could have dirty contacts.