Technical Temperature-sensitive dying at idle

[MikeSalt]

Lambda sensors are all fine as far as I can tell, and I cannot swap them anyway because the wiring is all different lengths on the HGT. What I was saying is that I thought the engine was running fine at operating temperature because it had switched to closed loop operation. However, having observed their status with MES during a warm-up, I could see that they had successfully switched to closed loop operation, but the engine was still running rough until it got to operating temperature. I think I may have to admit defeat and go and see a specialist, but after everything that's gone on recently, I'm half tempted to let the scrap man have it and start again with a different car.

 

[MikeSalt]

A bit of a breakthrough! Out of curiosity, I disconnected the coolant temperature sensor. Of course, the EML wasn't happy about this, and it put the fans on full blast as a precaution. however, the engine run perfectly happily in this mode. Of course, it's not practical to use this in the real world, I'll burn my catalytic converter out in no time. However, it does say to me it's a lack of fuelling during the warm-up. I wonder if either the CTS or MAF are working, but not within their prescribed bandwidths, or perhaps a loss of linearity?

 

[Ziggy122]

You can test the ECT

If you have the type which can be unscrewed

A pan of water from cold to boiling with a multi-meter attached
A guage to stick in the water

And readings from Haynes manual - you can test quiet easily

Ziggy

 

[MikeSalt]

Ziggy,

After a night to sleep on it, I have come to the conclusion that something must have drifted out of calibration, not enough to light up the MIL, but enough to confuse the ECU. Unfortunately, Haynes doesn't have data for the HGT, so my plan instead is to remove the temperature sensor, but reconnect it to the loom and dunk it in a cups of water of varying temperatures. I can then use MES to compare what the ECU thinks the temperature is to something I can verify with my digital thermometer. I have a sneaking suspicion that the CTS is over-reading at lower temperatures.

Cheers,

Mick

 

[MikeSalt]

Well, found a potential culprit, the CTS is over-reading by at least 10% over its operating range, and as much as 20% in the mid range, which is where I am having most trouble. I must have looked a bit odd with a digital thermometer, laptop and bits of the car dangling in a cup of water under the bonnet. Will let you all know how it turns out, thanks for your help so far