Mike
1 posts
Joined: 14/03/2005 22:10:20
Location: Wokingham United Kingdom (Excluding channel Islands)
Incorrect coolant temperature reading
I have a 1997 Rover Mini Cooper twin point injection that has recently stopped indicating any engine temperature above the normal on the temperature gauge. Consequently the cooling fan is not cutting in when I am stuck in traffic queues. I have tried replacing the coolant temperature sensorin the thermostat housing but this has had no effect. I have also replaced the thermostat because this problem first occurred after an old thermostat became faulty and refused to open. Any ideas how I could sort this problem out would be appreciated. Thanks.
Posted: Mar 24, 2005 01:28 PM
Alexo
3 posts
Joined: 24/12/2004 12:47:13
Location: Bedford United Kingdom (Excluding channel Islands)
Twin point oil temperature gauge
Hi. I own a Mini 40 (twin point) which has an oil temperature gauge. The temperature reading has never been shown to rise above about 80 C, which I guess is a little on the low side!!! If anyone has any advice on what the possible problem could be, then itd be much appreciated. I dont fancy buying loads of bits and pieces in a trial-and-error effort to get it working properly. Thanks guys, Alex
Posted: May 05, 2005 02:09 PM
kjw911
36 posts
Joined: 10/04/2005 18:45:44
Location: BROADSTAIRS United Kingdom (Excluding channel Islands)
MPI Temperature Gauge
Anyone fitted a water temperature gauge to a MPI (like the old classic temperature gauge) If so how did you wire it. Thanks in anticipation.
Posted: Jun 17, 2005 06:20 PM
Stuart
12 posts
Joined: 14/09/2004 02:07:49
Location: Palmerston North New Zealand
Temperature sender C-ARA4445
I'm just trying to confirm if the sender unit C-ARA4445 that's included with the 2-core radiator is a switch or temperature sender?? I assumed a switch, but rather than a single temperature stamped on it, it has two: 88 and 92 from memory. I guess that means it switches (closes) somewhere between those readings? I tried heating it and measuring resistance but don't think I was getting it hot enough. ANyone know?
Posted: May 04, 2006 09:47 PM
LewisCr125
136 posts
Joined: 13/04/2006 17:03:39
Location: Old Knebworth United Kingdom (Excluding channel Islands)
That's a switch for when you have an electric fan. When that switch reaches a temperature it'll turn on the electric fan, If you have one.
Posted: May 05, 2006 05:19 PM
teabag
5 posts
Joined: 28/09/2006 10:21:57
Temperature gauge woes
Hi,
I have a 1275 MG Metro engine in my mini based kit car. It has a Mk1 Metro instrument cluster. The temp gauge reads very low, ie when the car is hot its barely reading a tenth of the way up the gauge.
I think it is suppled via a voltage stabaliser. This seems to work because the fuel gauge (also using stabalised volts) works fine.
I don't know if different temp sensor were fitted, with different resitance range. Alternatively, I guess the sende could be faluty. I can measure its resistance.
Does anyone know what the correct resistance over the range should be, or offer any ideas?
Paul
Posted: Oct 22, 2006 02:17 PM
john
14 posts
Joined: 10/10/2006 20:21:40
Location: ROBERTSBRIDGE United Kingdom (Excluding channel Islands)
PLEASE HELP.... temperature sensor fault !
PLEASE PLEASE CAN ANYONE HELP ?
I've just got the dreaded phone call from lucas to say that the poor running on my 98 cooper MPI, (according to the Diagnostic equiptment) is a reduced voltage from the temperature sensor to the ECU. They's said it could be a bad connection from the sensor to the ECU, or a fault with the ECU....... Is there any where i can start looking first, as there only advice, is for them to charge £45+, to have the ECU sent off and checked.
It does have quite a bit of rust at the bottom of the wind screen, where wares been getting in!
Thanks in advance.
Posted: Mar 01, 2007 01:41 PM
pickme
672 posts
Joined: 08/09/2004 23:10:14
Location: Chippenham United Kingdom (Excluding channel Islands)
Did they say which temp sensor? The air temp sensor is a green bodied thing in the air filter. They often go bad. You can just un-plug it but it'll run a full choke. They shouldn't cost much to replace and may well be common across the Rover range so maybe have a look under teh bonnet of a similar age Rover in your local scrap yard and see if you get lucky.
Posted: Mar 01, 2007 08:12 PM
Neil
28 posts
Joined: 11/02/2005 07:20:41
Location: Chichester United Kingdom (Excluding channel Islands)
Ask Lucas which sensor. ATS or CTS.
Both are supplied with 5Volts from the ECU. Remove connectors and measure resistance of sensor(s) at 20deg C. Should be circa 2500 ohms. Check again with engine hot at say 80deg C. Should be circa 320 ohms.
If both OK check 5v is supplied to one side of the sensor and if present check continuity in loom between sensor and ECU connector.
ATS will have a small effect on running but CTS will have a much larger effect not only on fuelling but also timing.
Posted: Mar 01, 2007 09:43 PM
Thanks neil
It sounds if you really know your stuff. I can now ask the right questions when i pick up the car tommorro and i can check most of the stuff you recomend myself....
Again, thank you so much.
john.
Posted: Mar 02, 2007 11:03 AM
Thanks Pickme
Do you know if by disconnection the air temp sensor (green bodied) i should notice a signifficant change in the running of the engine?
Posted: Mar 02, 2007 11:06 AM
Hi John,
Glad information of interest/help. WRT the question to Pickme (if I may butt-in): If the Air Temperature is open circuit, ie failed, or there is a fault in the loom the ECU will report a fault to the diagnostics used by Lucas. I believe that under these circumstances the ECU will just assume a nominal Air Temperature and carry on. I don't believe the ATS has a major effect on the ECU and is just "trimming" input to provide "fine" adjustment. With either the ATS or CTS if the sensor measures open circuit before buying a replacement, if you feel competent, as a test you can put a resistor across the connector to simulate the sensor. Say, 330ohm to simulate operation at 80 deg C. With that in place at normal temperature the engine should run very well. Effectively you are telling the ECU that the engine has reached normal operating temperature.
Posted: Mar 02, 2007 06:20 PM
Right,,,, here goes..
Lucas have told me that there is a voltage drop, back from the MAP sensor (in the intake manifold). They said it could be a break in a wire or a problem with the ECU. I've stripped all the wires from the sensor back to the ECU. There are no continuity prob;ems with any of the wires, and there is 5 volts to the MAP sensor (via the yellow with a pink tracer wire). I have noticed that the pink with a black tracer wire joins up with about 3 or 4 other pink with black tracer wires in the loom before they go into the ECU, however there doesn't appear to be a continuity issue. I don't know if its revevant but the engine will NOT run if i disconect the MAP sensor, however it appears to make no differance to the running of the engine if the green bodied air sensor is diconected.
Many Many thanks in advance.
John
Posted: Mar 08, 2007 04:06 PM
Mayfair86
95 posts
Joined: 02/11/2006 22:43:12
Location: Sandy United Kingdom (Excluding channel Islands)
I have a similar problem except mine is a 86 mafair so it doesnt have an ECU and i am not sure if it is the sensor or the wiring or what, it runs fine except the dial doesnt show anything when the engine has been running for a while.
Sorry this isnt any help but i thought this would be an appropriate thread to post my little problem in.
Hope you can help :)
Cheers in advanced
Josh
Posted: Mar 08, 2007 04:41 PM
Slightly confused now as at first apparently one of the temperature sensors is not working correctly. Now there's a problem with the MAP sensor.
When do you get poor running? Cold start? tickover? underload i.e. foot to the floor going up hill? cruising? Or is it constantly running poorly?
MAP (manifold absolute pressure) measures pressure differences in the inlet manifold. Pressure will vairy in certian conditions. Closed throttle there is a massive depression, open throttle there's hardly any depression. This pressure is measured and will adapt the fuel delivery. I guess on this type of system by adjusting pulse width of the injectors.
I'd check that the MAP sensor is properly connected. No leaks in the vaccum pipe from the inlet manifold to the MAP sensor.
Posted: Mar 08, 2007 05:14 PM
Not sure what you're refering to as there isn't any pipes to the MAP sensor...
Posted: Mar 08, 2007 06:44 PM
The SPI Map sensor is in the ECU and therefore there is a vacumn pipe from the manifold to the ECU. Yours is an MPI and the MAP sensor is in the Manifold and electrically connected to the ECU. I would not expect the ATS sensor to (relatively) make much difference to the running. (see previous reply).
The MAP sensor is the device that determines the engines fuelling requirements by feeding into the ECU manifold depression which is then turned into injector duration. Difficult to test other than by substitution, but if you have the equipment you can remove the sensor from the manifold, and connect via a tube to a vacumn pump and guage, and as you vary the vacumn you should see engine rpm rise and fall. This is crude but will at least prove that the ECU is responding to sensor input. (I believe that the MAP sensor is fed back into row B, ie centre row, pin 6 of the ECU connector).
ps How did Lucas change their view from Temperature sensor to MAP sensor. I really think you need to find a specialist who understands the MEMS unit. It's not rocket science but you need to know your way around.
Posted: Mar 08, 2007 08:36 PM
Neil,
Thanks so much. I was crossing my fingers, hoping you might offer some advice.
I've taken the MAP sensor out (but left connected) and put an air tight seal over the hole in the manifold. Firstly the car would'nt start without a bit of accelerator and it normally starts on the button, dispite the running problems. The car would just about run, but not without a fight and it certainly would not tick over.
I've checked the voltage to the MAP sensor and its exactly 5 volts and i've checked the voltage back into the ECU (via the Red with the green tracer, bottom left in the picture). When the ignitions on (not running) there is 4.66 volts back to the ECU, then when you start it, its about 1.9 and when you rev it it fluctuates and goes to about 2.9 volts.
Lucas are still advising that the best thing is to have the ECU sent off to be checked. I just begrudge spending £45+vat for them to say "oh sorry, it wasn't that, lets try something else"
I live near Battle in EAST SUSSEX and i can't find any one else to help.
Any advice is really appeciated, as the only next step is to hav ethe ECU sent off.
Thanks a million.
John.
Posted: Mar 09, 2007 11:32 AM
Chris
131 posts
Joined: 18/02/2005 08:56:10
Location: Leamington Spa United Kingdom (Excluding channel Islands)
Good afternnon,
Hope you are well today and I had a similar problem with my Mini running very rough. It transpired that an adequate spark was not being fed to the DIS syetem, which caused it to basically run on 2 cylinders.
1 & 4 were fine but 2 & 3 were not.
If this is similar to your concern, the fault is indeed with the ECU which cost me alot more that £45 + VAT.
Don't know if this helps.
Posted: Mar 09, 2007 12:32 PM
Taking out the MAP sensor and sealing the manifold is a good approach. If you just leave the MAP sensor in mid air I wouldn't expect the engine to run as the ECU wouldn't have a clue how much fuel to put into the engine, (although it may go into some sort of Limp Home mode). Easier said than done I know but you need to somehow pull a vacumn onto the sensor simulating it being in the manifold. One way is to rig up a syringe, t piece and vacum gauge and then try to start the engine. By varying the vacumn you should see the engine revs rise and fall. However you say that you see the return volts from the MAP fluctuate as you rev the engine and this indicates that the sensor at least reponding to manifold pressure. The question is is the calibration right or is the ECU interpreting things correctly. Substitution of sensor and/or ECU is the best way ahead but not easy to achieve. I am happy to discuss this with you on the telephone but not too happy to put my details on a forum like this! If you are reply with a contact number and I will give you a ring if you think it may help. (I believe, but am not certain, that the "proper" Rover test equipment can effectively simulate the ECU and or the sensors where as it looks like Lucas's generic equipment can not go that far). Is the car driveable?
I will watch out for a reply.
Good luck,
Posted: Mar 09, 2007 06:23 PM