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

["blackaddertoo" <blackaddertoo@xxxxxxxxxxx>]

Hi Nick and all

managed to slope off a site early, with tools in the boot and do 
some more testing.

checked diode with meter...reads 700 on diode test and tried with a 
test light and jump battery, lights one way and not the other so i 
think the didode is ok.

now with key on, in ignition positive power is ok at middle 
connection idle speed motor.

ground connection at idle mutliplug checks ok for continuity with 
body panel ie -ve ok.

checked continuity of other two connections at idle speed motor plug.
checks ok at ecu multiplug, ie no break in wire

checked pulse coil connection on left side of rear engine at fire 
wall...checks at 550 ohms...is this ok as specialT say this should 
be about 600+ ohms

the only lead lest to check is the feed from the coil...do i take 
off the coil cover and investigate there? i could not quite see 
where the leads go...assuming it connects at the ecu mutliplug.

tried again to start..runs 10 seconds then chugs and dies as if the 
engine is being starved of air/petrol...but it did idle fine with 
the brass screws adjusted.

one thing to note...a mouse has been living with the ecus in the 
corner behind the drivers seat.
the blue wire (i think it is the feed for the 02 sensor maybe?) or 
is the the coil connection has a small amount of chew marks, 
exposing the wire below...does not look like the wire itself has 
been damaged, however i think this looks like a shielded cable so 
can't be good.
maybe i might have to remove all the mutliplugs and the metal 
support and check all the wiring out.
if the lambda ecu/wiring was faulty would the car idle with brass 
screw adjustment? i thought not?

thanx for any help.

a mouse also chewed through my headlight wiring and the rear of the 
indicator plastic!!!! haven't found any dead ones though.

regards

Steve




--- In doc-uk@xxxxxxxxxxxxxxx, Nick Tomlinson 
<nickandkathryntomlinson@xxxx> wrote:
>
> The resistance test is a simple one on a diode and you remember 
correctly.
>   Diodes though can become 'leaky' when the PN junction breaks 
down which is why you check with the diode function. This will show 
the voltage drop across the junction and depending on type should 
show no voltage drop one way and between 500mV and 800mV the other.
>    
>   "
>   "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.""
> according to the workshop manual, does this input not just earth
> when the switch is closed (car at idle) so to test i earthed it 
with 
> diode removed then tried to start car.
>   "
>   Yes, the unit does earth this switched point when the throttle 
is closed.
>   The test  I give will show if there is any feedback voltage from 
the other circuit showing the diode has gone short, leaky or open 
circuit. I am presuming that you earthed this input at an earth 
point like the engine block or better yet the -VE battery post.
>    
>   Hope the circuit diagram I sent to you makes the connections 
clear.
>   Chances are you have an earth lead off somewhere so the unit 
isn't earthing at the earth pin.
>    
>   It's always harder to explain in words what you could do 
yourself in 20 minutes.
>    
>   This problem will be fixed soon.
>    
>   NickT.
> 
> blackaddertoo <blackaddertoo@xxxx> wrote:
>     Hi Nick
> 
> thanx for the reply. Don't worry you can talk technical as i used 
to 
> do a bit of hobby electronics, building transmitters etc, simple 
> logic circuits etc.
> 
> i thought the screw which has a lead to it earthed the ecu.
> i will recheck the multiplug earth.
> 
> i will check for continuity from ecu multiplug to idle motor. did 
> not have any wire long enough yesterday, as the car is parked away 
> from home.
> 
> "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.""
> according to the workshop manual, does this input not just earth
> when the switch is closed (car at idle) so to test i earthed it 
with 
> diode removed then tried to start car.
> 
> the diode, i must be wrong but i thought it would read continuity 
in 
> one direction ie no resistance one way and 100% the other, but i 
> couldn't remember back to my electronics days.
> 
> Regards
> 
> Steve
> 
> 
> 
> 
> --- In doc-uk@xxxxxxxxxxxxxxx, Nick Tomlinson 
> wrote:
> >
> > 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 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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