Losing it now

[Peewee74]

Some advice/help folks, My W124 is giving me start problems right now.
I have searched for answers and have replaced various parts I don't want to keep throwing parts at it.
Anywhoo she was driving then I laid her up for winter but give a run once month to keep her right, then one evening a couple of months ago she would only fire and run with bonnet open.
So I've been trying to get her running ever since, replaced the rotor arm as it had built up too much resistance, OVP, dizzy cap, leads, plugs put in fresh fuel.
Plugs are wet but black carboned, she will crank for ever and occasionally will fire with high idle, blip the throttle to bring down revs eventually she will die out and won't start again.
She was running sweet up until winter, so ideas appreciated cos I'm like

 

[BlackC55]

What engine? Year? Mileage?

 

[190]

This will be Bosch ke injection system. One possibility is initial cold start enrichment. While cranking this is provided by an extra injector controlled by a thermo time switch or on later models by the ECU. I had problems with mine providing excessive enrichment because it wasn't shutting off when it should (thinking of your black plugs). You could try disconnecting it as temporary/diagnostic measure. Once started ongoing enrichment is managed by the ECU based on the coolant temperature. A faulty temperature sensor could impact on the amount of enrichment that is being provided. If you need to check the sensor with an ohm meter, approx. values when starting should be:

6000 ohms at 0 deg C
4000 ohms at 10 deg C
2500 ohms at 20 deg C

 

[Peewee74]

What engine? Year? Mileage?

My Bad Engine M102 2.3 petrol, year 1988, mileage 157,000

 

[Peewee74]

This will be Bosch ke injection system. One possibility is initial cold start enrichment. While cranking this is provided by an extra injector controlled by a thermo time switch or on later models by the ECU. I had problems with mine providing excessive enrichment because it wasn't shutting off when it should (thinking of your black plugs). You could try disconnecting it as temporary/diagnostic measure. Once started ongoing enrichment is managed by the ECU based on the coolant temperature. A faulty temperature sensor could impact on the amount of enrichment that is being provided. If you need to check the sensor with an ohm meter, approx. values when starting should be:

6000 ohms at 0 deg C
4000 ohms at 10 deg C
2500 ohms at 20 deg C[/QUOTE

Thanks 190, it is indeed KE Jetronic.
I had initially disconnected this as I read I needed it for the cold start, I read a resistance from the plug of it last night so I presume thats ok.
I also measured the 2pole coolant sensor for resistance and got nothing.
I noticed another sensor 2 pole but has vauum pipes on going to throttle body is burnt
I think I will replace both of these.
I did get her to fire last night but with high idle so I turned down the idle using the icv still a bit high though and when I put the air box on she died .
So I might unscrew some on the icv and see if I can play about till I get correct revs, then adjust K Jet with allen key whilst metering X11 diag plug.

 

[190]

On my 89 engine there were two temperature sensors.

1. A single pole connection on the side of the head which was the temperature gauge sensor.

2. A 2 pole sensor on the top of the head for the ECU inputs. This was in fact two sensors with the resistance being measured between each pole and earth. I'm working from memory now as I no longer have the car but if I measured the resistance between the two poles there was still a reading but it was twice the normal value as the sensors are effectively being measured in series. If you get open circuit for this measurement it seems unlikely both sensors have failed and you might get a reading between one of them and earth.

I recall seeing the thing with vacuum pipes but I'm not sure whether it's anything to do with the fuel injection.

You may be aware of this but go careful with the Allen key as the adjustment is very sensitive to even a small fraction of a turn.

 

[Peewee74]

On my 89 engine there were two temperature sensors.

1. A single pole connection on the side of the head which was the temperature gauge sensor.

2. A 2 pole sensor on the top of the head for the ECU inputs. This was in fact two sensors with the resistance being measured between each pole and earth. I'm working from memory now as I no longer have the car but if I measured the resistance between the two poles there was still a reading but it was twice the normal value as the sensors are effectively being measured in series. If you get open circuit for this measurement it seems unlikely both sensors have failed and you might get a reading between one of them and earth.

I recall seeing the thing with vacuum pipes but I'm not sure whether it's anything to do with the fuel injection.

You may be aware of this but go careful with the Allen key as the adjustment is very sensitive to even a small fraction of a turn.

The pole on the side of head is gauge.
Didn't know the 2 pole was going to Ecu, thanks for that one.
So when you say measure resistance between 2 poles are you putting positive across the 2 poles at the same time for a reading?
I'm aware it's very small increments of the key thanks

 

[AlexGTR]

You say the car only runs when the bonnet is open?

Do you have an immobilizer fitted? That could well cause problems if its not working correctly.

 

[Peewee74]

You say the car only runs when the bonnet is open?

Do you have an immobilizer fitted? That could well cause problems if its not working correctly.

There is a system on it but I have it switched off since I bought the car 5 years ago so it has never been an issue.

 

[190]

Didn't know the 2 pole was going to Ecu, thanks for that one.
So when you say measure resistance between 2 poles are you putting positive across the 2 poles at the same time for a reading?

I measured across the 2 poles with an ohm meter with negative probe on one pole and positive probe on the other pole. As the other end of each transducer is earthed that effectively measured them in series.

On mine the 2 pole temperature transducer went to the ECU and it was the ECU which controlled the cold start injector. I actually traced the wiring back to the ECU to confirm this. That confused me at the time because everything I'd read about Bosch KE talked about a thermo time switch directly controlling the cold start injector independently of the ECU.

I'm just wondering about you measuring a transducer to be open circuit. Could it be a thermo time switch rather than a resistance transducer ? A thermo time switch would be short circuit at low temperature (don't know how low though and it might need to be very cold) and open circuit when warm.

 

[Peewee74]

I measured across the 2 poles with an ohm meter with negative probe on one pole and positive probe on the other pole. As the other end of each transducer is earthed that effectively measured them in series.

On mine the 2 pole temperature transducer went to the ECU and it was the ECU which controlled the cold start injector. I actually traced the wiring back to the ECU to confirm this. That confused me at the time because everything I'd read about Bosch KE talked about a thermo time switch directly controlling the cold start injector independently of the ECU.

I'm just wondering about you measuring a transducer to be open circuit. Could it be a thermo time switch rather than a resistance transducer ? A thermo time switch would be short circuit at low temperature (don't know how low though and it might need to be very cold) and open circuit when warm.

I went into the stealers yesterday to get the diagram of the head section in order to get a name on all the sensors on the top of the block.i got the diagram and the list of part numbers and names of the 3 sensors I want to figure out what they are and what they do as I need to figure out this start issue.
So the 2 pole switch above is listed as a temperature gauge sender or continuous injection system, I dont think its the gauge sender as that's working with it disconnected so what is the continuos inj system sender units purpose.
The next one is single pole which is listed as switch automatic fan coupling or water temperature gauge &fan coupling.
The last one is listed as a Thermovalve opening at 50 degrees etc or valve at cylinder head;ignition control.
The young lad at the counter wasn't much help in knowing what these items are or what they do, so that's my question here folks does anyone know the purpose of these switches as above particularly the thermo valve as my one is scorched /burnt. I would like to test them rather than throw parts at it.
I hope this makes sense lads as I want to sort this start issue and like to know what the items do.cheers fellas

 

[BlackC55]

Start from the basics. Fuel, spark and timing. Does it have it all?

 

[Peewee74]

It did start last week when I replaced all sparks,leads and rotor arm.she died when I put the air box back on.Any ideas?

 

[190]

.....so what is the continuous inj system sender units purpose.
......The next one is single pole which is listed as switch automatic fan coupling or water temperature gauge &fan coupling.


The last one is listed as a Thermovalve opening at 50 degrees etc or valve at cylinder head;ignition control.

Continuous Injection System is another name for Bosch K otherwise known as CIS because it injects fuel continuously but varies the amount unlike solenoid type injection systems which are not continuous. So what they are saying is this is the sensor input to the ECU which controls cold running enrichment To check it measure the resistance across the sensor.

The last one is what I was referring to as the thermo time switch. Thermo valve must mean the cold start injector which is an electrically operated solenoid type injector. Sounds like this sensor should read open circuit above 50 Deg and short circuit below 50.

 

[Peewee74]

Continuous Injection System is another name for Bosch K otherwise known as CIS because it injects fuel continuously but varies the amount unlike solenoid type injection systems which are not continuous. So what they are saying is this is the sensor input to the ECU which controls cold running enrichment To check it measure the resistance across the sensor.

The last one is what I was referring to as the thermo time switch. Thermo valve must mean the cold start injector which is an electrically operated solenoid type injector. Sounds like this sensor should read open circuit above 50 Deg and short circuit below 50.

Thanks for the info 190, will test or replace these as they would relate to the issues I'm having.

 

[Peewee74]

ok folks, so she eventually fires after lots of cranking from cold with foot to the floor.
I leave to idle until she gets to operating temperature as I want to tweek idle enrichment screw, but just as she gets to temp she cuts out and wont fire until its cold again.
What should I test for now.
Any ideas folks before I snap.

 

[brucemillar]

Peewee

Do not give up. I do not your know your engine! but I would suspect a temp sender is is giving an incorrect reading to the brain telling it not to allow start or deliver incorrect fuel. At the cost of temp senders (and apologies if you already have) I would change them all.

Does anybody know on here what senders are talking to the brain that would cause non-starting?

 

[Peewee74]

Peewee

Do not give up. I do not your know your engine! but I would suspect a temp sender is is giving an incorrect reading to the brain telling it not to allow start or deliver incorrect fuel. At the cost of temp senders (and apologies if you already have) I would change them all.

Does anybody know on here what senders are talking to the brain that would cause non-starting?

Thanks, I had replaced the 2 pole sender last year or it could be longer, the only one that looks dodgey to me as it has burn marks on it is the thermo vac one but it is also a year or so old.
I have read that the thermo vac one does bugger all any way
I ideally would like to know a foolproof way of testing these sensors now as Im sick throwing money at parts and also I think you should able to bench test most items, again open to correction.

 

[Bellow]

I'm assuming the ignition is triggered from the distributor and not a crank position sensor (CPS symptom when failing is OK cold start but no running when hot).

I leave to idle until she gets to operating temperature as I want to tweek idle enrichment screw, but just as she gets to temp she cuts out and wont fire until its cold again.
What should I test for now..

If there is any doubt that the ignition is failing, then install a strobe thingy on one of the HT leads. If it stops flashing as the motor dies....

I have a 42 page technical manual on Bosch KE system. Too large a file to post here but if you want it, pm me an e-mail address and I'll send it to you.

 

[Peewee74]

I'm assuming the ignition is triggered from the distributor and not a crank position sensor (CPS symptom when failing is OK cold start but no running when hot).



If there is any doubt that the ignition is failing, then install a strobe thingy on one of the HT leads. If it stops flashing as the motor dies....

I have a 42 page technical manual on Bosch KE system. Too large a file to post here but if you want it, pm me an e-mail address and I'll send it to you.

Thanks, yes KE system , so no CPS.
Brand new leads, so strobe is out I think.
I have several tech manuals from Bosch KE, so thanks, I probably have it.
Unless you can confirm as to weather or not it has a troubleshooting section it's probably the one I have and will need to look thru it.