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Coolant temp


Andy 3i

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Just a quick one guys, trying to narrow down my poor running and emissions issues. I've changed IAT, PCV valve, MAF, ICV (second hand), TPS (second hand) and literally just changed the coolant temp sensor for the ecu (not the one for the gauge). Basically the emissions are still sky high and I'm wondering 2 things...

 

Firstly, a dodgy earth somewhere. I don't know where the earth for that would be even though my multimeter says it has an earth doesn't mean it can't be dodgy.

 

Secondly, there doesn't appear to be a live feed a the plug for the coolant temp sensor. I get no volts whatsoever.

 

Now I know it's impossible to rule out any dodgy wiring and I haven't checked continuity between the plug and the ecu but this is my next port of call. Which pin would it be on the DESK ecu? Obviously if there is no power at the ecu end then I'm guessing possibly a dicky ecu.

 

The emissions are as follows; CO: 3.76-4.54 fluctuating (I would expect around 0.06 for a car with no cat). HC: 540-670 fluctuating (I would expect around about a max of 200ish).

 

Basically, is there anything I could of missed? I know it's a bit of a ramble but I've got ideas that need putting down :P

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Well yes and no...it was running pretty shite before but since I've done the clutch it's started dying after being left to idle. It could be cos of the lumpy cam I suppose. The bit that I'm tripping on is the fact I haven't got a live feed at the coolant temp...is it meant to have one?

 

Reference the mapping...surely it wouldn't run quite so rich on standard map?

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I wouldn't be surprised if the cam is affecting emissions, it shouldn't that bad as it's not a particularly hot cam, but it is possible. It shouldn't make it run poorly though, that does sound like another issue.

 

Yeah the IAT and coolant sensor are NTC type sensors. You should have a +5v feed at one side and ground at the other. You should test this without it plugged into the ECU though, as the way it works is by pulling down the ECU's 5v to a lower voltage. The ECU has what's called a "pull-up" in it, which is not particularly strong (think, high value resistor), so a lower resistance to ground (the NTC) will cause the voltage to drop. The ECU then monitors this drop.

 

Bottom line, yes one pin in the plug should be +5v without anything attached.

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The emissions are as follows; CO: 3.76-4.54 fluctuating (I would expect around 0.06 for a car with no cat). HC: 540-670 fluctuating (I would expect around about a max of 200ish).

 

We're running a 2L on a standard ECU and no CAT. It runs sweet and tests at 1.3% CO, 125ppm HC, with both readings stable. I shouldn't think you'll get anywhere near .06

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Thanks for all the comments guys. Found a broken wire for the coolant temp sensor which has been repaired now. I'm guessing its made some improvement because its not dying now.

 

As for engine, it's a 2.0 zetec, 130 inlet.

 

Oh Steve, I meant 0.6...typo

 

After I've repaired the wire and have power at the sensor the emissions have for worse ?(

Edited by Andy 3i
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slightly pff topic and im sorry for the hijack but just out of interest what should the emmisions be below on an escort in order to pass an MOT

 

Depends on year of engine:

 

http://www.motuk.co.uk/manual_730.htm

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