John Speake

The other plug on the water bridge is for the dashboard water temp sensor.

Be careful not to confuse your early fuse panel with the later version used on 85/86 Euros.

A standard 53 relay is ok in the XV11 position.

I would suggest checking that there isn't any fuel getting into the vacuum lines from either of the pressure regulators or the fuel damper. (due to fractured diaphragm)

Also, peel back the boot on the temp2 plug to check there are no bare wires.

shane_b

Sorry to sound dense, but where is the cold start injector located? I can't seem to find it.

John Speake

Your car doesn't have one, call off the search !

shane_b

:-) That would explain that then! I can go put the air box back in now then.

This is so frustrating as I am desperate to take the car for a blast!

shane_b

Thanks for the help John.

I just peeled back the boot on the temp2 plug and the wires are fine.

I am fairly new when it comes to the 928 technology. A VW Beetle / Camper this certainly is not :-) haha!

Could you elaborate on the info re: vacuum lines with my last paragraph in mind!

Cheers!

John Speake

There's a fuel pressure regulator at the back of each fuel rail, and a damper at the front centre of the engine. Each has a vacuum line, run the engine until it misbehaves, then switch off and them pull off each vac line in turn, checking for fuel or a heavy fuel smell. If either present then probably the diaphragm in the device has failed.

Are all the plugs equally black ?

JET951

Apart from what John Speake has mentioned about the possible fuel in the vacuum lines/ hoses that go to the fuel pressure regulator/ dampners ( 3 in total )

Also check ( with an ohm meter) the resistance / ohms of the TPS , meaning the Throttle Position Switch
, because these in old age get high in resistance for the very important idle contact , this is the on / off signal it sends to the ignition & fuel ECU's

We had plenty of these in old age give intermittent poor/ no idle because of this TPS

You check it by disconnection both the multi plugs from both ECU's & then identifying the terminal pins to check the ohms reading with a multi meter , we find they are often worse ( meaning high ohms) when the engine is hot , so we check them in both temp states

From Memory for a 1984 & 1985 M28/21/22 , the TPS was superseded some years ago to a 944 one , the reason I mentioned that is because the instructions in the W shop manual will be different in setting it up for idle contact , not much different , but different nun the less

John Speake

Unlike the US 85/86 32v that use similar LH and EZ-F controllers, the Euro 84-86 don't have an idle control system. The parts for it aren't even fitted to the LH ECU.

The idle switch isn't critical for the problem you have. There is a separate EZ-F idle map selected by the closed throttle switch but this only helps at idle, to prevent stalling.

JET951

Actually the TPS it is more critical than you would think , because if the idle contact ( ohms is too high ) the engine management ECU does not get the important idle signal & the engine at idle will be too rich because the incorrect / non existent idle contact makes the engine management ECU's think the throttle is open to some degree , but in fact its closed

When this happens ( engine hot ) they generally surge / stall in traffic

I remember Greg Grey ( some years ago ) had it on his 928S ( M28/21/22 ) and he had a terrible time diagnosing it , he was convinced it was the air mass , but all the while it was the TPS

shane_b

Typical..... I lent someone my multi-meter and can I remember who it was? no!

I hate it when that happens!