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95 Spi Ptc And Lambda Heaters


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#1 minidave54

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Posted 06 April 2017 - 08:09 PM

The car had been sluggish when cold and not wanting to accelerate until after a mile or so when it had warmed up, so i ran a diagnostic with my Crypton ACT, the engine was up to normal working temperature. It said the PTC heater was not present.

 

I let it cool down and did some investigation checking the continuity of all the cables in the loom. I had 12v to the relay coil in the Relay Module but it was not energising. The earth cable for the relay to the ECU (pin 6)was checked and found to be good. I supplied my own earth connection to the relay and it energised, proving that the relay was good. Could it be a problem within the ECU?

 

While checking cables I tested the Lambda heater and found this was also not getting any voltage from its relay. Again it had 12V to the relay coil but was not energising. I checked the continuity of the relay earth to the ECU (pin 36) and all was good. Supplying a separate earth path for the relay and it energised. Again is this a problem within the ECU and should I be sending it away to be tested ?

The ECU earth was also checked for continuity, but if there was an issue there I guess the engine would not run at all.

 

To test the Lambda output is it possible to disconnect it from the main loom plug and check it with a voltmeter or must it be in circuit. The reason for asking is while carrying out the diagnostic test I had the following reading - Lambda 703mV, the idle was erratic between 840 - 860 rpm and the timing would not settle being between 15 - 18 deg. The fuel trap and all the service pipes have been replaced.

 

I'm hoping that somebody with more experience than me can help with a way forward.

Thanks in advance

 

Dave

 

 



#2 FlyingScot

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Posted 06 April 2017 - 09:00 PM

Hi Dave
The ECU provides an "earth" when switching the circuits. There are a few earth connections on the ECU plug but sounds like you have checked the relevant ones. What's the part number on the ECU?
The lambda sensor is an oxygen cell so will generate a voltage itself in situ which you can measure.

Sluggish when cold is usually the ptc as the SPi unit is a wet system and needs to heat to help vapouruse the fuel.

FS

Edited by FlyingScot, 06 April 2017 - 09:02 PM.


#3 minidave54

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Posted 07 April 2017 - 07:57 PM

Hi Scot

 

Thanks for getting back to me. The part number of my ECU is MNE 101150 0205 4044.

 

With the Lambda heater also not working it will probably also affect the running when the engine is cold.

To test the voltage output when hot, is it ok to disconnect it from the loom and use a meter, or as I have seen mention, leave it connected and cut back a bit of the cable insulation and test it that way.

Getting a Lambda reading of 703mV with no variation, does this suggest no output to the ECU?

 

With the PTC or Lambda relays not getting energised through the ECU does this mean it could have a fault needing to get sent away for testing?

 

Dave



#4 FlyingScot

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Posted 09 April 2017 - 07:26 AM

Dave
It's beginning to look that way, especially since the relays themselves work when grounded.
Your ECU is immobiliser coded so you won't be able to just swap it to prove it faulty.
Get a quote for testing - I'm not sure how much this costs, it might be easier to borrow an ECU with matched 5AS through your club?

FS

#5 minidave54

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Posted 09 April 2017 - 09:54 PM

Scot

Before in do anything with the ECU I will test the Lambda with a meter incase that is also a fault with the unit.

I think I will send mine away for testing. I have heard people recommend the company ATP.
Have you heard of any feedback by other tmf members of this company?

Dave

#6 Sprocket

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Posted 11 April 2017 - 10:58 AM

You say you have the Crypton ACT...... which memory card do you have for this? You should be able to use the ACT to read live values and test all the outputs. There is a pinned topic ALL about the lambda sensor.... have you read that?

One thing I have noticed is that the ACT sometimes does say that there is no PTC heater. It's something I think the ACT gets it wrong as it looks at the code embedded in the ECU which tells it what it's connected to. A software bug for want of a better word. It doesn't mean that it's not working.

Going back to the lambda sensor, if you have a spare, you can connect it to the Loom with the sensor body sat on something metal with a good ground connection to the body. Start the engine and feel the tip of the sensor warming up. Be very careful here because that sensor will get ver very hot and you could easily severely burn yourself or melt plastic stuff or wiring! If you don't get any heat the sensor is faulty. The rest of the test functions are explained in the pinned topic. Read my last post in there from earlier this year.

#7 minidave54

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Posted 13 April 2017 - 08:10 PM

Found some time to have another look at the car again today.

 

Connected a spare lambda sensor to the loom, started the engine and the tip warmed up. Proving that the heater relay is working. I also had a voltmeter connected to the relay output to monitor the voltage which ran at 13.9V

In air sat on the oil filler cap I had a fixed reading of 403mV. When placing the sensor as suggested onto bare metal the reading remained the same 403mV. Guessing the sensor is passed it's best.

 

Next I connected my test box and re-connected the fitted sensor and started the engine. Run the engine up to normal temperature and monitored the readings. It has never done this before but the Lambda readings started to vary between 703mV and 630mV. It was not a clear up and down but it was varying. Possibly I have an intermittent wiring fault and with moving cables around has made a better connection, certainly something that needs looking into.

 

Something I did notice scrolling through the settings on the test box was that the engine RPM varied between 830 - 870 and the ignition advance fluctuated between 15 - 19 degrees. Could this be caused by a worn bearing in the distributor or another sensor with a dodgy connection.

 

Dave



#8 Sprocket

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Posted 13 April 2017 - 09:18 PM

A high volt (relative) reading suggests a rich condition. The fact that you are not seeing a huge change in values suggests there is deffo an issue somewhere, could still be the sensor its self. There are ways to test if the sensor does actually read a rich or lean condition thus truly eliminating the sensor as fault. One way to test this is explained in the pinned topic.

 

Idle advance is 15 degrees + or - 5 degrees. The ECU alters the ignition timing to maintain a steady idle RPM around 850rpm. If the ECU has to use more or less than the + or - 5 degrees to maintain 850rpm, the ECU will then activate the stepper motor to add or subtract air and again return the ignition advance idle control to within the + or - 5 degrees of 15 degrees.

 

There is a lot more to this than you are looking at. What about the stepper motor position? What about the inlet air temperature? Coolant temperature? all read from the ACT

 

Point here to consider. All the normal basic mechanical things should be checked first before diagnosing the engine management system. Compression test, plug condition and gap, distributor cap and rotor arm, plug leads, tappet clearance, Has the throttle cable been adjusted in the correct manor, and so on.

 

What modifications have been done on the engine if any?

 

Position of the thermostat in the housing is also very important. Persistent cool (relative) coolant temperatures can be attributed to this.  It seems to be a mistake made by those unfamiliar with the injection system when they've had it apart and put it back together wrong and can give similar symptoms to a faulty PTC heater (sluggish or hesitant). More common nowadays is the furring up of the sandwich plate take off and the inlet manifold its self restricting or even completely blocking off coolant flow through the inlet manifold where the coolnat temp sensor is located.



#9 FlyingScot

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Posted 13 April 2017 - 11:05 PM

Good points Sprocket especially about the mechanical conditions. - I have several people convinced it was a "fuel injection" issue when it turned out to be basic servicing requirements. I have also seen people fit the thermostat into the head instead of the sandwich plate or even fit the wrong temp stat - in these cases causing mayhem until the mistake was realised.

FS

#10 minidave54

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Posted 14 April 2017 - 07:15 PM

Hi Sprocket and FS, thanks for all the valuable advice above.

 

To answer a previous question about the Crypton ACT...the memory card I have for this is an ASC3 V2.0

 

A few days ago I carried out as well a checking the lambda sensor I also ran a diagnostics with the following results:

 

Engine speed............830 - 870 fluctuating

Stepper position........20 steps

Vacuum level............-596mmHg

Coolant temp.............86 deg

Inlet temp..................15 deg

Battery voltage.........14V

Throttle pot.............. 0.4V

Purge duty................58%

Lambda sensor........703 - 630mV

Ignition advance......15 - 19 deg  fluctuating

 

Today I had a look at the other suggested mechanical checks. The distributor cap, rotor arm and plug leads are all good, no signs of cracks or corrosion. The throttle cable adjustment looks spot on in the middle and the tappets are set as they should be. The plugs are a dark brown and certainly not black and sooty as you would expect from a rich running engine.

 

The only problem I can see is when I carried out a compression check. I had readings of 190  160  160  190. Looks like an issue between numbers 2 and 3 cylinders, possibly a gasket.

Might have to take off the head for further investigation.

 

Dave



#11 Sprocket

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Posted 15 April 2017 - 09:08 PM

Resolver your mechanical issues and see where that takes you. If you're going to do the engine top end, make sure the thermostat is an 88c one that goes back in when you put it back together.

 

Check everything again with the ACT once back together and monitor the stepper position. I'd expect to see around 40 steps with the coolant and air temps you are seeing (more air, stronger idle, requires less advance). Everything else seems to be fairly representative (other than the obvious lambda readings), coolant temp maybe a little low, but the engine might not yet be fully up to temp. Difficult to tell when the engine is idling if the thermostat is a cooler stat than the required 88c, it's only really when you are cruising that the engine never reachs the required temp.


Edited by Sprocket, 15 April 2017 - 09:09 PM.


#12 minidave54

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Posted 23 April 2017 - 05:32 PM

Hi Sprocket, i should finally find time to take the head off this week to investigate the low compression in cylinders 2 and 3.

Question i have is, due to the readings i get with the Lambda would it be worth changing the sensor while I have things apart.
I have an LCB system fitted, so is easier to do at this point.

Also would it be recommended to go with a Bosch item. I belive the one fitted at the moment came from mini spares.

#13 minidave54

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Posted 21 June 2017 - 04:48 PM

Hi again guys. Well it all got busy after my last post. Replaced the head gasket and it leaked water out of the front, so removed the head and got it skimmed (that took the engineering firm a few weeks, back of the queue for commercial work ). New gasket and all ok.

It then became a rush to get my sons car rebuilt for IMM after some new panels and a re-spray. Some late nights and it made it with 2 days to spare.

 

My car mad the trip to IMM and back with no problems apart from the issue with the cold start PTC heater. Occasionally it would also be reluctant to accelerate for about 10 - 20 seconds after running through a village at 30mph. I felt like somebody had flicked a switch and all was normal.

On return from IMM it had an mot and again had problems with the emissions:

​CO.... 0.64         (limit 0.30)

HC.....286ppm   (limit 200)

 

It's not that far out but a fail for an spi with a cat.

 

I've now had time to run the diagnostics again, pretty much the same results as last time:

 

Engine speed............840 - 870  fluctuating

Stepper position........16

Vac level...................-588 to 604 fluctuating

Coolant temp............89 deg

Inlet temp.................23 deg

Battery voltage.........13.9 v

Throttle pot...............0.4 v

Purge duty................58

Lambda....................703 - 625 mV fluctuating slowly

Ignition advance.......14.4 - 17.5 deg

 

I also decided to run the engine at 3000 rpm which is what it would be run at for an mot test:

 

Stepper position.......45

Throttle pot...............0.7 v

Lambda....................703 mV

Ignition advance.......43 - 45 deg

 

The Lambda and ignition advance just seem wrong to me.

 

Sorry about the long ramble, but this has been an ongoing problem for a while and I really would like to get it sorted before I shout enough and rip it out and convert to a carb.

So I am hoping with all of the above information some of the SPi experts can show me a way ahead.

 

Dave



#14 minidave54

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Posted 27 June 2017 - 06:30 PM

Can anybody help with the above. Would like to get it sorted for the summer.

#15 genpop

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Posted 28 June 2017 - 06:34 AM

Hi,

what do you mean by vac level, is it map?

Check the hose from carb to fuel trap and fuel trap to ecu.Take ecu out,figure a thread of wool into the map inlet and have the ecu in the sun for a few hours. Check fuel trap as well. Rebuild all and tell us map, ignition advance and lambda on different revs.






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