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95 Spi Ptc And Lambda Heaters


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#31 FlyingScot

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Posted 14 July 2017 - 12:45 PM

Found time to check Lambda heater and found it was not working. No voltage on loom plug to sensor.
Checked cable through loom from heater relay earth to ECU pin 36, all good. Checked cable from relay output to Lambda plug, all good. ECU plug pin 28 checked to body earth, all good.
Also checked both 12 volt inputs to the relay, again all good.
Earthed heater relay coil by connecting a separate cable to the body and relay operated. With this connected i had the supply to the Lambda heater. It would appear that the relay is not getting the earth path through the ecu
I also checked the PTC relay earth to the ecu pin 6 and found 12 volt on that cable. Again if this relay was getting earthed through the ecu the heater would work.
Is there any way i can check the earth path through the ECU or does it need to be sent away to a specialist company?

If the "earth" through the ECU isn't working it suggests that something is amiss with the ECU.

What model is it to see if we can find a spare in Scottishmini

FS

#32 minidave54

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Posted 14 July 2017 - 05:41 PM

Hi, FlyingScott,i am away from home at the moment but will have a look on my return and post up the model number.

Dave

#33 minidave54

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Posted 15 July 2017 - 06:44 PM

My ecu model is MNE 101150 0205 4044

Can anybody help out with a known working spare.

cheers Dave

#34 FlyingScot

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Posted 26 July 2017 - 07:42 PM

That's a non Cooper coded one (linked to an immobiliser) unfortunately. Let me check and see what I have

FS

#35 minidave54

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Posted 26 July 2017 - 08:35 PM

Thanks F'S. The car is a Sprite and although it has an immobiliser/alarm box fitted it does not have a key fob with it.
Does this mean it has been modified in some way?

Dave

#36 Sprocket

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Posted 26 July 2017 - 09:14 PM

At this remote distance with the information available it does look like the lambda sensor is not responding efficiently, but without seeing the car for myself I just don't know.

#37 Sprocket

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Posted 26 July 2017 - 09:48 PM

Also, the stepper position is too low in my opinion. It should be nearer 35. This can be a result of a few things.

You need to try and get all the parameters reading correctly if only to eliminate them.

Do make sure you have indexed and adjusted the throttle cable correctly before proceeding.

Ignition advance should be 15 degrees + or - 5 degrees with stepper position around 35. Throttle position is roughly 0.3 to 0.4 volts. Manifold vacuum souls be at least 500mmhg. This should give you 850rpm all other things good.

As more air enters the engine, rpm will rise. The ECU responds first by reducing the ignition advance. If the advance is reduced below 10 degrees, the ECU then reduces the steps to bring the ignition advance back up to 15, while still maintaining 850 rpm. One likely scenario is that at some point in the last 20 years, someone has messed with the idle stops or base idle air screw ( this last one is easily eliminated as the seal cap should still be in place. There is absolutely no need to be messing wth this whatsoever! Leave it well alone). If you can be absolutely sure that the idle stops have never ever been adjusted, then the extra air is likely as a result of a manifold leak.

You can adjust the idle stop to bring the stepper position back up to around 35 only if you are confident there are no air leaks.

A poor manifold vacuum is a good indication the engine tune is off.

Going back to the lambda sensor, if you were asking me to look at this after seeing lambda sensor readings like those, I'd want to first see that the sensor reads in fresh air, but would likely change it out for a new one as a process of elimination ( and I'd use a genuine Bosch one at that) and then go from there. Again though, I've not seen the can so this is simply a guide.

#38 minidave54

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Posted 30 July 2017 - 08:33 PM

Thanks Sprocket, i appreciate how difficult it is to try and diagnose a fault from a distance. If i was a bit closer i would certainly pay you a visit. It would be good to have an expert eye give it the once over.

When i get a chance i will start by re-checking the throttle cable setting and is indexed correctly.
I will also check one or two hoses I might have forgotten ie to the purge valve and charcoal canister.
My vacuum reading is in the region of -590mmHg, so hopefully that says I do not any air leaks.

Most of the parameters i have are close to the figures you mention, it's just that they fluctuate and not steady.
I can not be sure that the idle stop has never been adjusted in the past. Is this in the area were the throttle cable lost motion is checked? 

Unfortunately to remove the Lambda sensor for testing on my car not easy as it has an lcb manifold, so makes it hard to reach without taking it off.

#39 FlyingScot

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Posted 31 July 2017 - 06:21 PM

Where is the lambda located on the lcb? Is the boss in one "leg" or is the cable extended and its measuring all 3?

FS

#40 minidave54

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Posted 02 August 2017 - 07:08 PM

The exhaust ports from numbers one and four join together to make one leg which goes down the back of the engine, and the sensor is fitted in this leg before it joins the single leg from numbers two and three in a "y" joint.

To remove the sensor the only way I can see it to remove the manifold. Unless somebody has a cunning plan for removing the Lambda with the manifold fitted.

#41 minidave54

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Posted 16 August 2017 - 08:29 PM

The car seems to be running ok at the moment, just the issues with the heaters and the Lambda sensor.

I have decided that for the rest of the summer i will just enjoy driving it.
During the winter i will drop the exhaust and replace the Lambda.
I will send the ECU to get checked over as i think this is causing the earth problems with the heater relays.

It will then be time to run the diagnostics again !!

#42 FlyingScot

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Posted 16 August 2017 - 09:28 PM

The standard manifold for this motor had the lambda screwed into the join between the "legs" of the exhaust manifold fold.
It samples the complete outlet gas stream

FS

#43 minidave54

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Posted 19 August 2017 - 10:45 PM

That is the main problem with an LCB exhaust manifold as the Lambda is only sensing the outlet gases from numbers 1 and 4 cylinders. Not sure how much of an effect this has on the ecu readings and the performance of the engine.




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