20SEH Running problem...

[Nova_Tek]

Evening all,

Needing some help with this as it seems to be getting worse.

The Cav SRi 8v 20SEH is running really bad. It idles rough and erratic, mpg is down, power seems to be holding back and EM Light is coming on.

It's quite odd as the EM Light will come on when you press on the throttle and when you let go, it goes off. The ignition system is new i.e. dizzy, rotor arm, leads, plugs. The engine is running on all 4 and plugs are showing that it is running ok (light brown deposit on plug). Idle control valve is now brand new, CTS is only a couple years old, battery is new.

When we do an EML flash it gives us that battery voltage is below 10v. Volt gauge shows 13.5v, got a reading across the battery terminals with the engine running and it is above 13v as well.

When I disconnect the Air flow meter engine cuts out, so I'm assuming that is running ok.

All I can think of is replacing all sensors one by one until the problem has been resolved but I need ideas to work out a process of elimiation. Earth strap next to alternator looks fine and gear box one is still ok by the looks of it too.

I am stumped!

:(

[staggy_gsi]

Remove all the earths and make sure they are gleaming before refitting. Im struggling to think what this could be. Is the ECU getting hot when the cars running? I have known the ECUs to overheat before

[Nova_Tek]

Did some checks today. Took apart the airbox and cleaned the AFM and wiring to it, cleaned the throttle body, and connecting rubber elbow. Replaced a split/frayed fuel rail hose. Changed the octane plug for another one I had. Checked the earths too. The ECU and wiring is dry as a bone, couldn't visually see any problems.

Ran the engine after and it started and idled from cold fine. My brother drove it round the block to see how it ran and he said it was great.

Then the engine got to full operating temp and that's when the EML started going on an off. Foot on throttle EML on. Foot off no light. This also brought back the erratic idle. This made me think the CTS could be an issue as it would be the oly thing I can think of that relates to temperature. The Cav has no Lambda sensor.