TD4 turns over but will not run after work done

fanatic · Mar 21, 2014

Scope crank and cam sensors as I have had weird waveforms

terytool · Mar 21, 2014

got one doing the same did the low presser pump in the tank 'got injectors checked did number one still the same going to swop the other three I will let you know what happins

jedi · Mar 22, 2014

O my god there droping like flys

Will have a look at the black box diags thanks....

Irishrover · Mar 22, 2014

:welcome2::deadhorse:
Datatek...Certainly getting the brain working Keith. Just hope senility doesn't set in before it's sorted !!!
Fanatic.....Will definately scan both sensors when I get it running and take some pic's of the waveforms for each off the scope screen. Funnily enough, although it was running as rough as hell, the tacho was reading steady at around 750 rpm or so at idle !
Jedi...Look on the BBS site>shop>faultmate fcr>software>single vehicle packages and you will see the F/L option for type 1 and type 2 versions. It is locked to the VIN but can be unlocked to another car for a charge. Much cheaper than buying multi vehicle modules which I have.

Thanks for the input guys, To be continued......................:tea:

Irishrover · Mar 22, 2014

fanatic said:
Scope crank and cam sensors as I have had weird waveforms

:behindsofa:
Had a look at the camshaft cam through the sensor hole today to try and get the air gap. The lobe on the camshaft which acts as the "Trigger" is not a standard "Pear shaped" cam but more of a lug which is about 20mm long with a radius that maintains the distance between it's face and the sensor face as it passes. The distance from the sensor mating face on the camshaft cover to the cam face is 29.70mm. The length of the sensor "Probe" is 24.75mm-therefore the Air Gap is 4.95 mm.
Looking at the shape of the cam, I feel sure that this should give a square wave pattern with possibly an angular fall off at the peak as it reaches and passes the sensor.
The crankshaft sensor is triggered by a gap of 5 teeth from the reluctor ring on the flywheel plate which equates to about 3 deg. I should imagine that this form would be similar to the camshaft but not as pronounced as the camshaft is travelling at 50% the speed of the crank.
I will however do the scans as soon as it's up and running and let you know.
The scope I have is an Agilent, Laboratory type and is quite good.

Datatek · Mar 22, 2014

As the sensor is a hall effect device, the output will quite likely be a square wave. A near 5mm air gap seems quite large to me, the stuff I've worked on it's usually been 1 or 2 mm max.

Irishrover · Mar 22, 2014

Datatek said:
As the sensor is a hall effect device, the output will quite likely be a square wave. A near 5mm air gap seems quite large to me, the stuff I've worked on it's usually been 1 or 2 mm max.

:tea:
Hi Keith.....The gap is non adjustable as it's determined by the height of the cam cover. The sensor is retained by a screw to the cover and it sits flat unlike the ABS sensor which sits in a spring sleeve and the P38 crank sensor for example which is held by a bolt and can be shimmed to adjust the air gap. A session with the scope will show whether it's kicking out a signal....WHEN

I get it running

Datatek · Mar 23, 2014

Irishrover said:
:tea:
Hi Keith.....The gap is non adjustable as it's determined by the height of the cam cover. The sensor is retained by a screw to the cover and it sits flat unlike the ABS sensor which sits in a spring sleeve and the P38 crank sensor for example which is held by a bolt and can be shimmed to adjust the air gap. A session with the scope will show whether it's kicking out a signal....WHEN I get it running

If you can wind the engine over manually, you should be able to see it switching fine on your scope John.

jedi · Mar 23, 2014

Set the sensor up on the bench and get a cordless drill to spin a bit of metal past the front of it....and compare the good one with the old one? While your waiting for the injectors

Datatek · Mar 23, 2014

jedi said:
Set the sensor up on the bench and get a cordless drill to spin a bit of metal past the front of it....and compare the good one with the old one? While your waiting for the injectors

Hall effect devices respond to a magnetic field, any old bit of metal will not do.

jedi · Mar 23, 2014

Spin a magent across it? I doubt there is a magnet on the cam shaft but i could be wrong.....Flicking a metal object across an abs sensor gets a reaction.....

Datatek · Mar 23, 2014

jedi said:
Spin a magent across it? I doubt there is a magnet on the cam shaft but i could be wrong.....Flicking a metal object across an abs sensor gets a reaction.....

Most ABS sensors are inductive and respond to metal moving, HALL effect devices do not, they respond to a magnetic field. If you don't believe me look it up on Wikipedia.

jedi · Mar 23, 2014

I belive I belive....so is there a magnet on the camshaft? Is it magnetic.... maybe its fallen of or the camshaft has become de magnetised.....interesting stuff.

Datatek · Mar 23, 2014

jedi said:
I belive I belive....so is there a magnet on the camshaft? Is it magnetic.... maybe its fallen of or the camshaft has become de magnetised.....interesting stuff.

That's certainly a good call, I was suprised about the airgap Irish quoted.
Of course another possibility is that it's not a true Hall effect device but some sort of hybrid device, with LR anything is possible.

Irishrover · Mar 23, 2014

:welcome2:
Dusted the scope off and connected the sensors up on the bench. 12V+ to pin 1, Neg. to pin 3 and the neg. clip on the probe and pin 2 (Trigger) to hook on probe. Wave form changes to square wave in proximity of ferrous metal irrespective of being magnetic or not. The sensor was switching up to approx. 8mm away (Air gap).
Both the original and new sensors performed the same, including the waveforms and a trigger voltage of 4.8V+.
Will put the original on the car tomorrow, the lobe is currently below it and I should get it to be activated when I connect the scope up given the bench "Air gap" test.

terytool · Mar 23, 2014

did you check both l/p pumps or just the one in the tank I have only done the one in the tank?????feel a fool

Irishrover · Mar 24, 2014

terytool said:
did you check both l/p pumps or just the one in the tank I have only done the one in the tank?????feel a fool

:welcome2:
Only the one behind the rear wheel arch. After the new one was fitted, the diagnostics showed no fuel pressure problems. It also put the engine fault lamp out, in addition fuel was gushing out of the feed with a fair amount of pressure to injector no.1 when he cranked the engine after slackening the nut on the feed pipe.

fanatic · Mar 24, 2014

High pressure pump hasn't put swarf in injectors?

john t · Mar 25, 2014

http://www.landyzone.co.uk/lz/f9/td4-injector-testing-251479.html

if your injectors are firing, there is not much else that will prevent it from running , providing you can get an injector/injectors out , doing this test takes very little time to carry out, you dont need to remove the cam cover , or cam sensor, and doing the test like this eliminates possible causes such as fuel pumps, cam sensor etc,

really you have been ****ing about for quite a while now, and going round in circles,

good luck

Irishrover · Mar 25, 2014

john t said:
http://www.landyzone.co.uk/lz/f9/td4-injector-testing-251479.html

if your injectors are firing, there is not much else that will prevent it from running , providing you can get an injector/injectors out , doing this test takes very little time to carry out, you dont need to remove the cam cover , or cam sensor, and doing the test like this eliminates possible causes such as fuel pumps, cam sensor etc,

really you have been ****ing about for quite a while now, and going round in circles,

good luck

Whilst I appreciate your contributions to this topic and will do the test you have posted before I refit the injectors, I take exception to your comment "****ing about". I have worked on engines, albeit except diesels, for donkeys years and have never "****ed about". As an engineer all of my working life I have always adopted a methodical approach,trying to isolate possible trouble causing areas. The injectors came within that remit and rather than dismantle them myself they were sent to a specialist company for servicing. Most of the delays are caused by turnaround times and weekend delays to shipping. Another contributor which was put forward was the camshaft sensor, luckily I have the means to check it's operation which I have done and this is o.k.
When the car was towed to the garage after breaking down diagnostics were run which highlighted a fuel pressure problem, this was rectified by fitting a new LP pump and filter. The car then started with a tow and was running rough. As the injectors had been reconditioned at no cheap cost, they were returned for checking on specialised Bosch equipment under warranty.
After spending in excess of £800 to date...I hardly call this "****ing about". If you are so confident that it's a simple fix I suggest you come up here, at my expense and get it running in five minutes.

TD4 turns over but will not run after work done

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