Omega Owners Forum

Omega Help Area => Omega General Help => Topic started by: RossMk2 on 17 April 2010, 17:41:39

Title: Top Dead Centre Reading (TDC)
Post by: RossMk2 on 17 April 2010, 17:41:39
Been fault finding with "My Naff Code Reader" for other reasons and the TDC reading is worrying. Flutters around 8-12 then can suddenly drop to 0-2 sometimes even into the minus readings and when it does the idle goes up.

My question is what controls/monitors TDC?
Title: Re: Top Dead Centre Reading (TDC)
Post by: Marks DTM Calib on 17 April 2010, 20:02:07
crank shaft sensor
Title: Re: Top Dead Centre Reading (TDC)
Post by: Welung666 on 17 April 2010, 20:04:13
Did that bank 2 lambda code come back Ross?
Title: Re: Top Dead Centre Reading (TDC)
Post by: RossMk2 on 18 April 2010, 10:48:20
Quote
Did that bank 2 lambda code come back Ross?

need to get the other sensor put back in mate will do tomorrow as for now it's left unplugged and the readings are more balanced. Crank shaft sensor pops up every now and again then when reset goes and I cannot pin point what's making it come back. What's annoying is if the crank sensor is fubar again, that's like 3 in 2 years an this is a gm sensor!
Title: Re: Top Dead Centre Reading (TDC)
Post by: RossMk2 on 18 April 2010, 16:47:36
Changed Crank Sensor and its exactly the same:

Spark angle at TDC is around 9-12 then drops to 0-2 and the idle goes up.
Title: Re: Top Dead Centre Reading (TDC)
Post by: Kevin Wood on 18 April 2010, 17:46:08
This value is reporting the timing advance that the engine ECU is using. It's normal for the ECU to vary the timing to stabilise the idle speed. My guess is that the ECU is  doing just that. If the idle isn't unstable, there are no trouble codes and the car drives OK I don't believe you've got anything to worry about.

Kevin
Title: Re: Top Dead Centre Reading (TDC)
Post by: RossMk2 on 18 April 2010, 20:36:09
Quote
This value is reporting the timing advance that the engine ECU is using. It's normal for the ECU to vary the timing to stabilise the idle speed. My guess is that the ECU is  doing just that. If the idle isn't unstable, there are no trouble codes and the car drives OK I don't believe you've got anything to worry about.

Kevin

Interesting. The idle isn't perfect but the desired speed (according to readings) is 600rpm and mine can jump 575-615rpm. When the spark angle drops as I say the idle flies up to 750-800rpm but so does the desired idle speed?