TD4 irregular poor start when hot

Good morning, lads n lassies !! As the title suggests I have an irregular hot start problem on my 2001 (51 plate) TD4, as follows.

Sometimes when I make a series of stops ( such as going to several shops, etc., all within a couple of miles of each other), the car will refuse to start after a later stop, when engine is thoroughly warmed up. At other times it will start OK time after time. On the occasions when it does fail to start, once it is running again I can turn off and restart OK several times in succession.

Cold starts are always OK.

I have done some searching on the problem, and it would seem that it could be the cam sensor at fault, as they seem to be OK cold, but can break down when hot.

Current mileage is 150153

Am I on the right track regarding cam sensor, please ??

Thanks for any and all feedback

Jonty

Jonty1 said:

Good morning, lads n lassies !! As the title suggests I have an irregular hot start problem on my 2001 (51 plate) TD4, as follows.

Sometimes when I make a series of stops ( such as going to several shops, etc., all within a couple of miles of each other), the car will refuse to start after a later stop, when engine is thoroughly warmed up. At other times it will start OK time after time. On the occasions when it does fail to start, once it is running again I can turn off and restart OK several times in succession.

Cold starts are always OK.

I have done some searching on the problem, and it would seem that it could be the cam sensor at fault, as they seem to be OK cold, but can break down when hot.

Current mileage is 150153

Am I on the right track regarding cam sensor, please ??

Thanks for any and all feedback

Jonty

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Click to expand...

Hi Jonty.
I would say yes best way to find out is try and replicate the fault out side you home, and if the Fl will not start remove the camshaft sensor and stick it in the freezer for about 5-10 minutes, refit and see if the car starts on the button if so you have found your fault.

Arctic2 said:

Hi Jonty.
I would say yes best way to find out is try and replicate the fault out side you home, and if the Fl will not start remove the camshaft sensor and stick it in the freezer for about 5-10 minutes, refit and see if the car starts on the button if so you have found your fault.

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I cant remember which it is - the crank or the cam sensors - that is ONLY involved in starting.

Id be interested to hear whether when it DOES start it is smoky or essentially clean.
Also, bad hot starting can be a fuel pump in the way out.

If its also down on power (later model with but one fuel pump) that's a bit of a hint too.

Listen on switch on for the whine from the rear. (assuming wife is not in car)

When it starts, all clean, no smoke. In-tank pump changed about three weeks ago, fuel filter changed last week. No loss of power at all, goes like a train !!

Jonty1 said:

When it starts, all clean, no smoke. In-tank pump changed about three weeks ago, fuel filter changed last week. No loss of power at all, goes like a train !!

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OK, so the fuel is getting to the right place in the right quantities, except when it doesn't!

Now that may be one of the sensors - but not temp - think about it. A cold engine needs MORE fuel so if it thinks its cold when its hot, it will over fuel and smoke.

I suspect one of the crank or cam sensors.

Not doing its job when hot.

Lookie here

ROVER 75 MGZT ENGINE FAULT FINDING

In particular:

CAMSHAFT SENSOR varies - worse when hot. Indefinite. No affect on performance, only starting. Starting is much worse when hot.

CRANKSHAFT SENSOR. SEE CAM SENSOR


CAMSHAFT SENSOR. (quite common) This is used only during cranking to synchronise the timing by indicating when no1 cylinder is on its compression stroke. So if it is faulty, starting becomes difficult and may vary depending upon the temperature of the engine. Once running, as the sensor is no longer used, the car will run normally. This is one way to distinguish between camshaft sensor and crankshaft sensor failure. LOCATION: See photo right- its to the left of the red connector, (in front of the oil filler cap looking from the front of the car)
TIP
1) Try a squirt of East Start. If the engine stops once the easy Start has been consumed, this MAY suggest that the sensor is faulty.
2) Remove the sensor and place cool in a freezer or spray briefly with freezer spray, If the engine starts it could confirm the sensor is faulty.

Jonty1 said:

Good morning, lads n lassies !! As the title suggests I have an irregular hot start problem on my 2001 (51 plate) TD4, as follows.

Sometimes when I make a series of stops ( such as going to several shops, etc., all within a couple of miles of each other), the car will refuse to start after a later stop, when engine is thoroughly warmed up. At other times it will start OK time after time. On the occasions when it does fail to start, once it is running again I can turn off and restart OK several times in succession.

Cold starts are always OK.

I have done some searching on the problem, and it would seem that it could be the cam sensor at fault, as they seem to be OK cold, but can break down when hot.

Current mileage is 150153

Am I on the right track regarding cam sensor, please ??

Thanks for any and all feedback

Jonty

Click to expand...

Hey there,

I've had this problem for over a year with only 30k on clock, a TD4 BMW variant (from 2004-2006).

The freezer test showed my cam sensor was at fault but when replaced with new 150 quid sensor still no joy. Changed the crank sensor (which actually keeps engine running once started, the cam aligns for starting only) and still no joy.

I changed the temp sensors (Coolant temp is a pain as need to drain coolant first) and air temp is easy it's the sensor staring at you on looking on engine air intake manifold (just before egr valve).

Finally bought a icarsoft diag - they are good reads codes for all land rovers, freelanders 1996-2004 incl. and it showed engine AC power fault (P03515) I also heard relays barking at me last few weeks so that would suggest maybe when hot there is insufficient power to starter motor...I've ordered new relays today so hopefully that'll sort it. If not then I'll take out the multi meter and test resistance across the cam sensor harness cable, this can go with cable age. Easy soln there would be a harness replacement (PART NUMBER YMQ001530).

So I'm very interested how you get on too

Cheers mate.

Anthony

ajfarrell said:

Hey there,

I've had this problem for over a year with only 30k on clock, a TD4 BMW variant (from 2004-2006).

The freezer test showed my cam sensor was at fault but when replaced with new 150 quid sensor still no joy. Changed the crank sensor (which actually keeps engine running once started, the cam aligns for starting only) and still no joy.

I changed the temp sensors (Coolant temp is a pain as need to drain coolant first) and air temp is easy it's the sensor staring at you on looking on engine air intake manifold (just before egr valve).

Finally bought a icarsoft diag - they are good reads codes for all land rovers, freelanders 1996-2004 incl. and it showed engine AC power fault (P03515) I also heard relays barking at me last few weeks so that would suggest maybe when hot there is insufficient power to starter motor...I've ordered new relays today so hopefully that'll sort it. If not then I'll take out the multi meter and test resistance across the cam sensor harness cable, this can go with cable age. Easy soln there would be a harness replacement (PART NUMBER YMQ001530).

So I'm very interested how you get on too

Cheers mate.

Anthony

Click to expand...

low voltage can cause all manner of problems and may be no more than a corroded battery terminal.

That will only really show up when starting as that's when current demand on the battery is at its highest.


If you have a voltmeter, check battery voltage when cranking and the check voltage on the wires just downstream from the terminals. (on the terminals first, then on the clamps, then elsewhere - you can stick pins through cable insulation to probe).

It is common practice on every car I have driven to power MOST of the electrics from a cable fed independently from the battery clamp, whereas the thick cable goes to the solenoid and thence to the starter.

That makes the battery clamps (or indeed the battery - and 30k miles and or ten years is about right for a dying battery) themselves the most likley source of low voltage when cranking as far as the main car electrics go.

A suitable meter is a couple of quid from anywhere that sells anything electrical.

Battery should be around 12v, dropping to 9-10v at worst when cranking.

I have tried to find any reference to that fault code, but if it is what you say - A/C fault - that might indicate a dying or dead alternator, or a slipping drive belt. That is consistent with a battery that's not getting charged...

Hi Lenny,

Yea the fault is power related to the air conditioning system, only showed up recently. I'll try the volt tests today thanks.

Also I'll check resistance across cam circuit to ecu once I locate wiring diagram on Rave.

Thanks for all your input, guys - just need to make it give the problem at home now !!