Ing Output Stage

[sgouert]

I have an 88 951 I'm trying to get running so I can sell it. I don't have spark and all the sensors check out so I think it's the computers (again). Before I replace them I want to check the "ing output stage" that shows up on the wiring diagram (mitchell) but I can' find it. Anyone know where it is?

[ae1969]

Check voltage at the coil........ with ignition on. What do you get?

Do you have spark at the coil?...

[sgouert]

I have 12 volts at the coil

No spark

[ae1969]

1. If the car cranks normally then
- check for voltage at the injectors
- voltage at the coil

The voltage you got at the coil means the ingition switch is good.
Voltage at the injectors means the first set of contacts in the DME relay work. Do you have voltage at the injectors ?

2. No spark : Reference sensor is questionable. Did you check the ohms across the pins?

[sgouert]

I didn't check voltage at the injectors. I'll do that
tomorrow
Reference and speed sensors check out OK

[ae1969]

Originally posted by sgouert
I didn't check voltage at the injectors. I'll do that
tomorrow
Reference and speed sensors check out OK

When you check your sensors........ check them from the dme wiring harness. That way you can check if the harness has a short in it. The connectors are so brittle.... they normally corrode at the connectors! So you always want to rule out a short as well.

Even though the reference sensor checks out ok (ohms are to spec) the harness could have a short, sensor could be damaged, or wrong clearance and the sensor can still show in spec.....

The reference sensor reads of the pin on the flywheel. If the dme does not get this signal. No spark or injector pulse.

Take a look at your rpms on your dash, is the needle jumping while you crank ? (this is not a definitive test but lets check)