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Thread: RRC 90 EFI testing

  1. #1
    mike 90 RR Guest

    RRC 90 EFI testing

    With most of my car having been rebuilt & restored, I am now starting to attend to the little things.

    I want to get the best out of the EFI and the fuel injectors, as it is "rich" with fuel ... There is a EFI specialist in Balcata (Perth WA) that I am going to see later on, and I would like a better understanding of what is going on prior to seeing them

    So ...

    The Model is RRC 1990, Hotwire 14CUX, non-catalyst, & I am running a 76degree thermostat

    I have tested the Ohm resistance with the following results

    Tune select resistor ... Measured 180 /// Suppose to be 446 to 494 ...... (This is not right)
    Coolant Temp .... Measured 450 /// Suppose to be 300 to 400 for 80 degrees (temp) ... (looks OK for 76 degrees)
    Fuel Temp (on the fuel rail) ... Measured 890 = 50 degrees (temp) // No temp is nominated in the manual ... (Looks OK for degrees)

    It is obvious to me that the fuel temperature would not be the same as the motor temp .... What is it meant to be??


    Now I know the 76 degree thermostat is not right for EFI ... But, I want to stick to this running temperature, as the car runs sweet under these conditions and gives me a buffer for the high temperatures and the problems of the associated motor failure's

    So what do the above figures mean in terms of ... "buy this part to correct the setup" .... I know that the coolant & fuel temp will need to be "Tricked" to achieved better readings ....


    Mike


  2. #2
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    you just self diagnosed it....

    Thermostat...

    The EFI in your car needs a 88 Deg C stat.. if not the engine runs cool and the ECU thinks its cold and then enrichens it.

    Run the right Stat and you will improve the economy

  3. #3
    mike 90 RR Guest
    Quote Originally Posted by sclarke View Post
    you just self diagnosed it....

    Thermostat...

    The EFI in your car needs a 88 Deg C stat.. if not the engine runs cool and the ECU thinks its cold and then enrichens it.

    Run the right Stat and you will improve the economy
    I hear what your saying ... But I don't want to go 88 Deg C stat.. Thats why I want to "Trick it" into thinking its at temperature

    Also the numbers on the tune resistor is not what it should be ... and this has nothing to do with engine temp (or does it?)

    Mike


  4. #4
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    I hear what your saying ... But I don't want to go 88 Deg C stat..Er if you want to cure the richness you do. That is why your coolant temp sensor reads too high.

    The ECU enrichens under 80C ( ie 400 Ohms), AFAIR about 5%. The only way you could trick it is to somehow get a lower Ohms engine temp sensor ( the one with the injector plug on the RH front of the manifold. )
    You can get an 82C thermostat , and I ran one for a while but this is pretty near 80c on a cold day.

    The tune resistor decides which country tuning program the ECU uses.This should not matter much as the cat program has a much higher resistance resistor.

    The fuel temp sensor allows the ECU to compensate for hot fuel and richen the mixture to compensate for the lesser density. Yours is OK .

    Really the only thing out of whack is that you have fitted a 76c thermostat.
    Regards Philip A

  5. #5
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    Quote Originally Posted by sclarke View Post
    you just self diagnosed it....

    Thermostat...

    The EFI in your car needs a 88 Deg C stat.. if not the engine runs cool and the ECU thinks its cold and then enrichens it.

    Run the right Stat and you will improve the economy

    ^^^^^^That

    And you "buffer" is a silly idea, if you have an overheating problem, you have an overheating problem, fix it, a cooler thermostat will merely save you being on the roadside by 20 seconds

  6. #6
    mike 90 RR Guest
    Quote Originally Posted by PhilipA View Post
    I hear what your saying ... But I don't want to go 88 Deg C stat..
    Er if you want to cure the richness you do. That is why your coolant temp sensor reads too high.

    The ECU enrichens under 80C ( ie 400 Ohms), AFAIR about 5%. The only way you could trick it is to somehow get a lower Ohms engine temp sensor ( the one with the injector plug on the RH front of the manifold. )
    You can get an 82C thermostat , and I ran one for a while but this is pretty near 80c on a cold day.

    The tune resistor decides which country tuning program the ECU uses.This should not matter much as the cat program has a much higher resistance resistor.

    The fuel temp sensor allows the ECU to compensate for hot fuel and richen the mixture to compensate for the lesser density. Yours is OK .

    Really the only thing out of whack is that you have fitted a 76c thermostat.
    Regards Philip A

    Thanks for that Phillip .... I had to start somewhere, and an understanding about the measured results of the Tuned resistor .... & also the relationship between the fuel sensor & the ECU

    I had thoughts of "Maybe" splice a line onto the temp sensor and install a switch in the cabin with a 300 Ohm resistor in it, to "Trick" the reading ..... but alas .... as Rovercare says ..... "Don't be Silly"


    I will install the correct Thermostat and hunt down some decent injectors



    Quote Originally Posted by rovercare View Post
    ^^^^^^That

    And your "buffer" is a silly idea, if you have an overheating problem, you have an overheating problem, fix it, a cooler thermostat will merely save you being on the roadside by 20 seconds
    We all have our silly ideas ... Some work ... some don't

    The 76 thermostat is a installed part from when I first got the car and was having issues A couple of years ago .....

    Thanking you's

    Mike


  7. #7
    mike 90 RR Guest
    Thought I would elaborate a little further on the subject of the 76 thermostat and my main reason for "Wanting to keep this running temp"



    Over the time I have noticed the features & failures of the "Slipped liner" in these rover blocks

    Couple of things have stuck in my head as others have posted up thier problems and others have given answers

    One was .... To install the new liner, they heat up the block .... and when you boil or overheat the motor ... the liner can slip as the block can loose grip of the liner at this temperature

    Another was .... A comment was placed on a thread that mentioned that the rover block was never really designed to run 88 degrees ... Hence liners slipping .... It is only been setup this way for EFI

    The carby versions are running 76 odd degree thermostat ... and do not appear to complain about liners letting go (unless they have been boiled)

    So .... My methodology is that my motor is getting on (about 250k on the clock) .... and I am paying attention to keeping it in good condition for many more K's with trouble free motoring ....




    One solution that has been rolling through my mind is installing a wire & switch with a 300 Ohm resistor in it, and splicing it into the Coolant sensor connection ... Basically when the car is warmed up .... just flick the switch (located in the cabin) and force the Sensor to read the 300 Ohms which would = 85 degrees?

    /// Still thinking about it /// as in should it be less , say 200 Ohms //// is it worth all the hassle?


    Mike


  8. #8
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    The general concensus by the experts eg Tuning Rover V8s, is that 100C is the level to not exceed.
    Mine has now gone 165kk mostly with an 88C thermostat with no problems, but has NEVER been overheated.
    One overheat is too many.
    So my conclusion is that 88C is perfectly OK as long as you ensure that you have a clean rad,efficient 50-50 young coolant, good hoses, good viscous , good water pump, don't run with a blown head gasket etc etc.

    A 76 c thermostat will make absolutely no difference if you do not attend to the other things. Oh it may give you a nanosecond extra time to shut down.
    Of course the gauge doesn't move until about 100c also. LR sense of humour.
    Regard sPhilip A

  9. #9
    mike 90 RR Guest
    Quote Originally Posted by PhilipA View Post
    Of course the gauge doesn't move until about 100c also. LR sense of humour.
    Regard sPhilip A
    Thanks for that Phillip .... The car has a top notch cooling system ... All has been replaced .... When first purchased, 2yrs ago, It was bought as a weekend bush hack .... It's Overall condition and use has certainly changed since then

    Just trying to keep the ... "LR sense of humour" .... out of the equation

    Mike


  10. #10
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    Quote Originally Posted by mike 90 RR View Post
    With most of my car having been rebuilt & restored, I am now starting to attend to the little things.

    I want to get the best out of the EFI and the fuel injectors, as it is "rich" with fuel ... There is a EFI specialist in Balcata (Perth WA) that I am going to see later on, and I would like a better understanding of what is going on prior to seeing them

    Providing he has the diagnostics plug to hook into it!! But I wouldnt bother mate!
    So ...

    The Model is RRC 1990, Hotwire 14CUX, non-catalyst, & I am running a 76degree thermostat

    I have tested the Ohm resistance with the following results

    Tune select resistor ... Measured 180 /// Suppose to be 446 to 494 ...... (This is not right)
    Yes it is!!
    AUSTRALIA - 171-189 ohms Red resisitor pack (Non Cat)
    EUROPE - 446-494 ohms Green resistor pack (Non Cat)
    EUROPE / USA - 3700-4100 ohms White resistor pack (CAT MODELS)
    SAUDI - 864-956 ohms Yellow resistor pack.


    Coolant Temp .... Measured 450 /// Suppose to be 300 to 400 for 80 degrees (temp) ... (looks OK for 76 degrees)
    COOLANT SENSOR (LH side of manifold, NOT temp sender for gauge on RH side!)
    -10deg - 9100-9300 ohms
    0deg - 5700-5900 ohms
    20deg - 2400-2600 ohms
    40deg - 1100-1300 ohms
    60deg - 500-700 ohms
    80deg - 300-400 ohms
    100deg - 150-200 ohms

    Fuel Temp (on the fuel rail) ... Measured 890 = 50 degrees (temp) // No temp is nominated in the manual ... (Looks OK for degrees)
    PLEASE NOTE THAT FUEL TEMP THERMISTOR ON FUEL RAIL USES EXACTLY THE SAME FIGURES AS ABOVE


    It is obvious to me that the fuel temperature would not be the same as the motor temp .... What is it meant to be??
    Depends on engine bay temp or what the fuel rail can conduct heatwise. There is no "set" temp for fuel.

    Now I know the 76 degree thermostat is not right for EFI ... But, I want to stick to this running temperature, as the car runs sweet under these conditions and gives me a buffer for the high temperatures and the problems of the associated motor failure's
    76 is too cold for EFI!! ECU enrichment cutoff is 80 deg. Runs sweet coz its running rich!

    So what do the above figures mean in terms of ... "buy this part to correct the setup" .... I know that the coolant & fuel temp will need to be "Tricked" to achieved better readings ....
    Dont waste time and $$ doing this. You will find it will have adverse effects plus as its running colder than normal, will overfuel and possibly fault the ECU into limp mode if things go out of range on the settings.

    Your sensors are fine and providing correct readings.

    Mike

    Hope that answers your question! Have spent many a night on the injection system and as you have been for a run in mine, you know how "lively" it is even for a std ECU chip, just tweaked in certain areas!

    Biggest adjustments are in the TPS sensor, the MAF adjust screw on the back of the MAF unit and the correct setting of the base idle pin AND air bypass screw on the plenum, at least for a 3.9 anyway but if i remember right, 3.5 with 14CUX is the same.

    Other things like static timing of 6-9 BTDC with vac unit detached when setting make for some significant differences in the overall tune.

    Ring me if you want to make some adjustments!!

    Cheers

    Andrew

    Regards

    Andrew.

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