Allanr

Does anyone know which slots on the ignition monitoring relay plug to jump to get temporary use of the vehicle to prevent it from running on 4 cylinders. This relay appears on 89 and later 928's and receives signals from the two gas temperature sensors located in the exhaust.

borland

To avoid a cat fire, you should repair before running the engine. But this may be what your looking for.... Try this link...

https://rennlist.com/forums/928-foru...ol-module.html

Alan

Unless there is a problem with the monitoring relay itself then the reason it shut off is that there is no combustion in at least some of those cylinders. If you bypass this relay - you will almost certainly be shooting unburned fuel into the cats - DO YOU REALLY WANT TO DO THIS?

You need to fix the real problem then the monitoring relay will allow normal operation.

Likely causes - coil/distributor/ignition final stage/plug wires/plugs....

Start by swapping the ignition final stage connectors (does the bank failure swap to the other side?)

Alan

Rich9928p

Subject: Diagnosing Ignition Monitoring System
ATTENTION: Service Manager/Service Technician
Models Affected: 928 S4/GT/GTS From 1989 Models –

Concern: Checking of components after activation of the ignition monitoring system (injection circuit switched off fault codes 1131 of 1231). Activation may be caused by the following:
- Damaged or defective exhaust gas temperature sensors.
- Possible damage to the ignition coil wire left side (in driving direction) between the ignition coil and distributor cap.
- Poor grounding of the mounting plate for the ignition final stages.
- Poor physical connection of the electrical plugs on the ignition final stages.

Parts Information:
New version temperature sensor Part Number 928 606 155 02 New coil wire with
hose covering Part Number 928 602 040 01 (for left side)
Repair Information: 1. Check the left side ignition coil wire. Be certain the coil wire is routed freely and not under tension. If damaged, replace with new version.

2. Check all ignition components and connectors for corrosion, tightness, correct connection and damage. Repair or replace as necessary. If an ignition circuit has malfunctioned, an LED indication will be given by the ignition monitor relay located on the L-H control unit mounting plate.
Ignition circuit I (cyl. 1-7-6-4) Red diode
Ignition circuit II (cyl. 3-2-5-8) Green diode

3. Before replacing temperature sensors, check the voltage difference of both temperature sensors as per step 4 of this bulletin. Sensors are located in the exhaust ports:
Model '89-'90, cyl. 4 and 8
Model '91 cyl. 3 and 7
The function of the ignition circuits and light diodes located in the ignition monitor relay remains unchanged. It is not possible to determine from the LED display of the ignition monitor relay if one or both temperature sensors are defective or which temperature sensor has failed. When installing temperature sensors, coat the sensor adapter threads with molykote paste HTP (white) and torque sensors to 10 N-m.

4. The voltage difference of the temperature sensors must be checked in order to ensure proper operation of the ignition monitor system.

Checking sensor voltage difference:
- Start engine and bring to operating temperature.
- Loosen the mounting bolt for the ignition monitor relay and pivot the relay up to gain access to the plug terminals Do not disconnect the relay plug.

- Set volt meter to the millivolt range and connect leads between E1 and E2 of ignition monitor relay. A digital volt meter must be used. Polarity is not important.
- Measure voltage with the engine idling and again at approximately 2000 RPM. A maximum difference of +2.5 mV or -2.5 mV (depending on polarity) is permitted. If the voltage difference is above 2.5 mV, stop the engine, loosen and rotate one temperature sensor. Retighten sensor and check voltage difference. If the difference is above 2.5 mV, stop the engine and rotate the other sensor. If after rotating the sensors to different positions, the voltage difference is too high (above 2.5 mV) the temperature sensors are defective and must be replaced.

Rob Edwards

When I was doing the oiling mods stuff at Greg's, my car went into protection mode repeatedly. We swapped out the relay, didn't solve it. Did all the resistance measurements and all the testing as Rich outlined above from the factory TSB, and determined that the likely cause is a dead exhaust temp sensor. I have a spare pair but the headers make gettting to them a real PITA, so I elected for now to run a jumper. Like all the posts above suggest, it's not a good long term solution, but if you look at the 9 pin connector, there's a fat red wire feeding 12V power to the center slot. Then there are two 'output' wires to the sensors, E1 and E2. They have a red/yellow stripe and a red/green stripe. So to jumper things you just need a 'Y'/three way jumper that sends power from the center to both pins. Like so: