Re: [doc] re still doesn't idle ok

[Nick Tomlinson <nickandkathryntomlinson@xxxxxxxxxxx>]

You said you checked the earth by:
  "earth check with continuity tester from screw into base to car body, 
to ecu multiplug"
   
  This mounting screw just holds the ecu to the metal frame which is earthed.
  The earth on the ecu is actually one of the pins on the 6 pin multiplug so check this first using the test:
   
  "Put your multimeter to volts. Connect the red cable of meter to 
jump start post. Use black lead to check for earth at ecu MULTI PLUG, meter 
should read battery voltage."
   
  Check continuity of all wires from the idle speed ecu plug.
  Especially those to the idle speed motor.

  "so how do i check the input from the coil/distibuter (which i assume 
gives the rpm signal (also runs the rev counter input?)"
   
  Said this in last message 
  "You can check for continuity using the resistance setting on the 
multimeter and check for wire continuity between the switched side 
of the coil to the ecu plug, (remove the ecu first). If there is a 
suppressor, temporarily disconnect it in case this has gone bad."
   
  Your test on continuity test through the diode would give a result dependant on the positive feed from your multimeter for the continuity test. This will be blocked or passed through (in laymans terms) due to the characteristic of the diode itself, hence the diode test.
   
  Put the diode back in the circuit and do the test as in my previous message
   
  "Put your multimeter to volts. Connect the red cable of meter to 
jump start post. Use black lead to check for throttle switch input (AT THE ECU MULTIPLUG) meter should read battery voltage with throttle closed (switch 
operated) and no voltage with throttle open."
   
  Do you have a circuit diagram of the idle speed ecu ?
   
  NickT.
  
blackaddertoo <blackaddertoo@xxxxxxxxxxx> wrote:
  hi Nick

thanx for the post...i know a long one but here hoes..

earth check with continuity tester from screw into base to car body, 
to ecu multiplug

connected test light to main power ecu multiplug...lights with 
ignition each time (tested fuse-ok)

check throttle switch input before/after diode, continuity before 
(with earth) non afterbut reads about 700 on doide test on meter
from your comment this looks about right but removed diode 
completely to test further. does not activate continuity buzzer on 
positive or neg current...thought it should.

have not checked coil to ecu or ecu plug to idle plug

thermister has been replaced a couple of weeks ago...reads about 
1800 ohms cold so that is ok i think.

tried earthing the throttle input and starting the car....car did 
the same...runs for 15 secs then chugs and dies.

car idles ok (1500rpm) with brass screws adjusted so i assume co 
adjustment is ok otherwise it would not run?


so how do i check the input from the coil/distibuter (which i assume 
gives the rpm signal (also runs the rev counter input?)

i'm running out of things to test but surely my problems are here 
somewhere.

Regards

Steve

--- In doc-uk@xxxxxxxxxxxxxxx, Nick Tomlinson 
wrote:
>
> How did you check the earth connection at the ecu multi plug?
> 
> Have you checked for a switched connected at the ecu multiplug 
from the throttle switch?
> 
> Put your multimeter to volts. Connect the red cable of meter to 
jump start post. Use black lead to check for earth at ecu, meter 
should read battery voltage.
> 
> Put your multimeter to volts. Connect the red cable of meter to 
jump start post. Use black lead to check for throttle switch input, 
meter should read battery voltage with throttle closed (switch 
operated) and no voltage with throttle open.
> 
> With the ECU plugged in, check the multiplug that goes to the 
idle speed motor, the centre pin should have 12v on it (with key in 
ignition and tuned to position 2) continuously. The ecu momentarily 
earths the outer pins to open and close the motor.
> 
> You can check for continuity using the resistance setting on the 
multimeter and check for wire continuity between the switched side 
of the coil to the ecu plug, (remove the ecu first). If there is a 
suppressor, temporarily disconnect it in case this has gone bad.
> 
> The white lead from the distributor to the ecu is from the 
negatively switched side of the coil. If this was short then the car 
would not run at all.
> 
> 
> The Diode should be tested using diode function on the 
multimeter ideally not resistance.
> Reading should be between 500 and 800 with test leads one way 
round on the diode, and no reading (ie infinite) the other way round.
> The diode is there to stop feedback voltage going to this 
circuit, as the throttle microswitch operates a couple of other 
circuits too.
> 
> I would say from your resistance tests that this diode would 
appear to be open circuit.
> Temporarily connect this wire to permanent earth for idle 
testing purposes only. Does the car idle now?? If it does then the 
diode will need replacing. Note which way round the diode is when 
you removed it and replace it with another the right way round.
> 
> I am presuming that you have check for wire continuity between 
the idle speed motor multiplug and the idle speed ecu multiplug.
> 
> Have you measured the thermister resistance?
> Do this by using your multimeter on resistance and connect to 
the 2 pins on the idle speed ecu multiplug. If you get no reading 
(open circuit) then the connector to the thermistor connector plug 
may have fallen off or the thermistor itself has gone bad.
> If you get no resistance, you can make some short fly leads to 
enable the multiplug to be connected to the ecu by 2 pins (on the 4 
pin block) and the thermistor ecu inputs to a 10 kilo ohm resistor 
to simulate the thermistor. If the car now idles then this is the 
problem.
> 
> NIckT.
> 
> 
> blackaddertoo wrote:
> Hi all
> 
> an update on my idle problems
> idle ecu and idle motor checked and working by martin at DMUK.
> now removed motor, blocked pipes and adjusted screws...car idle ok 
> at 1500 rpm.
> checked power to ecu ok at plug, checked switch ok at engine but 
> diode reads no resistance either polarity. (should it?) n moved 
for 
> further testing.
> checked ground connection at ecu - Ok.
> put Eecu and motor back in, shorted the diode/microswitch input to 
> earth...car idle 30 second then dies. exactly the same problem.
> removed diode short...idle 30 secs then dies.
> 
> so i am left to check the input from the distributor (should the 
car 
> idle if this is dead and hence the ecu does not know engine 
speed??)
> and if the leads from the ecu to motor are OK.
> 
> if i put a test light on the connector at engine end and switch 
> ignition, should there be a short positive signal on the one (to 
> either close the motor or open?)
> 
> then remove the microswith...do the same and the other lead should 
> go positive.
> 
> that is correct is it not, middle lead to motor is ground and the 
> other run motor positive one way and positive the other to close 
the 
> air valve??.
> 
> Thanx for reading this!! and sorry to bore you. i am determined to 
> resolve this (and enjoy it really!!)
> 
> 
> 
> 
> 
> 
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