98 300tdi auto poor start

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shocker

shocker

Well-Known Member
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BODMIN MOOR,KERNOW
My dads 98 reg 300tdi auto has a history of taking hells own job to start.Its the fly by wire electronic pump type with the bosch Electronic Deisel Control ECU.Been through all the obvious stuff,seperator,clean lines,lift pump,filter,injectors checked,glow plugs,compression test.......and it still comes close to flattening a new battery (its had several) to start.

Not knowing much about this system the only two things I can think of now are a) sticking shut off solenoid,which I'll check today (dont hold much hope) and the fuel ECU.

I have access to another,working,ECU,but if I take the current one out and put another in whats likely to happen?I have the immobiliser reset,4 digit,code.......

I dont want to have to replace the injector pump,very pricey,and the other option seems to be bang a manual pump in and cable it up.But I can see this causing ECU problems too.

Anyone else been here?Any ideas other than main dealer or arson?
 
How/why so?Is this the correct impedence the system looks for in the sensor to allow start?

Any idea where I can rob one out of,other than MY 300tdi auto?:D:rolleyes:
 
Is this a common failing on the EDC system?Id like to know cos Im running one of my own now....no probs thus far,other than ABS which was solved with the info on here
 
shocker said:
How/why so?Is this the correct impedence the system looks for in the sensor to allow start?

Any idea where I can rob one out of, other than MY 300tdi auto?:D:rolleyes:
Click to expand...


This is the impedence that was identified by another member far more scholarly than myself. It has to do with the EU getting information for a cold start from the crankshaft sensor and this temp sensor. If the temp sensor is not sending the info that the ECU is expecting, it does not electronically advance the timing apparently.

Anyway I tried this on my vehicle and it worked. Go to an electrical component place like Maplins and get several resistors of differing values (2k 5k 10k). Then first thing in the morning (so whilst the engine is cold) take off the electrical connector to the temp sensor and bridge the connections with a 5k ohm resistor, then try starting the car.

Worked really well for me..........................................

Good luck

Dave
 
Any wattage should be fine-their should be no load there-do you not have and old telly or radio you can get one out of
 
Thats exactly what I was thinking,old TV....on the smaller resistors I have trouble Identifying them with the colour bands,the higher wattage ceramics have it printed on.

Dave,do you reckon its a good idea to make this a permanant by pass on the system rather than replace the sensor?

Thanks for all the help guys,much appreciated since I havent been making any input to the forum this last year.
 
shocker said:
Thats exactly what I was thinking,old TV....on the smaller resistors I have trouble Identifying them with the colour bands,the higher wattage ceramics have it printed on.

Dave,do you reckon its a good idea to make this a permanant by pass on the system rather than replace the sensor?

Thanks for all the help guys,much appreciated since I havent been making any input to the forum this last year.
Click to expand...


To be honest mate yes I do. When I did a series of experiments with this other gentleman who's name escapes me, the change in starting was like night and day.

He designed a simple circuit that led to a switch inside the vehicle so you could switch the "starting aid" on and off. One thing that was impressive was the way the tickover revs were raised with this resistor in place. It helped a lot in early morning starts and when driving away and warming up.

I'll have a delve on my pooter and see if I can find the thread.

Cheers
Dave
 
thebiglad said:
To be honest mate yes I do. When I did a series of experiments with this other gentleman who's name escapes me, the change in starting was like night and day.

He designed a simple circuit that led to a switch inside the vehicle so you could switch the "starting aid" on and off. One thing that was impressive was the way the tickover revs were raised with this resistor in place. It helped a lot in early morning starts and when driving away and warming up.

I'll have a delve on my pooter and see if I can find the thread.

Cheers
Dave
Click to expand...


Just found this, hope it's self explanitory. BTW just remebered you need to do initial tests with a 10k resister and then use a 5k resistor in this circuit.
 

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shocker said:
on the smaller resistors I have trouble Identifying them with the colour bands,the higher wattage ceramics have it printed on.
Click to expand...

Just remember; Black Bastards Rape Our Young Girls But Virgins Go Without...

Black - Black - 0
Bastards - Brown - 1
Rape - Red - 2
Our - Orange - 3
Young - Yellow - 4
Girls - Green - 5
But - Blue - 6
Virgins - Violet - 7
Go - Grey - 8
Without - White - 9

Don't worry about the last accuracy stripe, any will be close enough for this job...

ccode.gif



Although looking at paddocks a new sensor is only £10, so why not just buy a new one if bridging out works ok
 
Right,finally managed to get a look at this lump.......couldnt really try the short out or resistors as my father (alledgedly) didnt hear me when I said "dont start it until Ive had a chance to...." so it was already warmed up.

However,upon inspection the plastic electrical connector to the sensor was shattered from heat and all the insulation on the wire brittle,so obviously there is some kind of problem there.Doesnt look like the two cores of the wires were in contact but hard to tell until I cut it away.

Cant do anymore for a couple of days as dads got the car,but I'll post another update as the farce develops.
 
Lerk,not only very useful but funny too - thanks mate!

Dave,thats great,thanks for going to all that effort for me mate.I will try that on my auto first then build it into dads when he aint looking!
 
BTW, rather than thinking of multipliers just treat it as the number of 0's
eg. first two bands yellow (4) and violet (7) if the next was:

Black - 0 x 0's = 47ohms
Brown - 1 x 0's = 470ohms
Red - 2 x 0's = 4700ohms (or 4.7kohms - 4k7 in techy geek terms!)
Orange - 3 x 0's = 47000ohms (47kohms)...

You get the drift?
 
I was planning on putting an extra switch panel in anyway,so another switch wont go amiss,You can fit one where the coin try is,on the late RR classics theres a block of push-buttons there,the part No for the frame piece to hold them is AWR1159LNF and you can rob the actual buttons out of any rover of similar age,I got some from a 100/metro and a 400.

It would be nice to have the light switch on the dash by the steering wheel so I dont forget to turn the bypass off but Im unsure what switches that would fit there I could use.
 
UPDATE......

I obtained another plug from a scrapper as this type are only available on the loom and the current one was burned to a crumbling mess.As I chased the wires back I found that they were all melted and burned,couldnt define a short but who knows?Also the sensor plug to the back of the in manifold was hanging off.The cable bundle is tight behind the head,normally held by a bolt on clip,but it looks as though when the head was last off the wiring wasnt clipped correctly and has come too close to the exhaust manifold and hence melted.

With the lack of space its impossible to tell how far back the damage to the loom goes.I re-connected the air sensor on the in manifold and scarfed in fresh wires and put in a resistor.

But....its had no effect at all,no improvement.I suppose its possible with that much melting to the EDC loom that the EDC ECU is blown.

My first thoughts have been to try and obtain a new loom,and using the replacement ECU that I have,to diconnect the old loom and leave it in place and lay in the new one.I have a new coolant temp sensor and a selection of resistors.Being that its my elderly dads vehicle I dont think he will want the excellent switching add-on but I plan to fit it to mine when I get a minute.

Thanks to everyone for their input......if theres any more ideas or experience that anyone can add Id be very grateful,plus it will be another bit of info for future use.
 
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