Today i checked the timing and base idle of my EF.

- warmed up engine and switched off
- connected tach and timing light
- earthed ECU pin and connected diode within the diagnostics plug
- started engine.

The engine fired up and idled (~700rpm) then moved to fast idle (~1200rpm) before settling to idle (~800rpm). Checked the timing but it was ~20 BTDC only to move to TDC about one minute later.

- stopped engine
- disconnected ISC plug
- started engine

The idle speed was within limits (600-800rpm) but i twiddled with the base idle screw and dropped the revs 100rpm and it idled well. Then the engine went a little spastic and started to hunt at idle - should have left things alone

I now get fault code 512 "base idle speed irregularity" and a hunting idle

Does anyone know what modes and timing intervals the I6 goes through at startup when the diagnostics connector is bridged ?

Any idea why moving and returning the base idle screw to its original settings would cause a hunting idle and how to correct it ?

Cheers.

After yesterdays adventure, started the car this morning and it ran well although the idle was slightly high Later checked for codes using key on engine off (KOEO) diagnostic mode and code 111 (system pass) was displayed.

This is really strange and i have no idea what would have caused yesterdays hunting idle and todays system pass Any ideas ?

Cheers

Did you use the .75mm feeler guage under the idle screw while assessing base idle figures?

This sounds like typical diagnostic mode behaviour. On the TFI equipped EEC, it will enter this mode and hold the timing static... to allow you to set timing via the dizzy.... it doesnt do you a whole lotta good on a coilpack EF... but i guess the programming was still in there...

Was the timing static at 20BTDC before moving to TDC? or was it tough to get a consistent reading?

I'd say the 512 was just a matter of the ECU seeing soemthing it didnt expect to see... if giving 111 now then i'd call it a day.

Yeh, i used a 0.75mm feeler gauge under the idle screw.



The confusing part is why is takes one minute to move the timing to TDC from it's solid 20 BTDC. I understood you do the adjusting of base idle when timing is set to TDC. The Gregories manual says you only have two minutes to set the base idle but i seem to loose one minute before i can even start ?

The other confusing part is why the system got itself into a tiz.. Really i didn't do anything wrong so this system is not confidance inspiring

Seems to be running OK now so i will leave it alone.

Cheers.