Td5 hesitating at junctions........

[Jimbo]

The 110 is playing up, normal driving is fine, but when I go to pull away from a junction or roundabout it falters slightly - just as I start to come off the clutch and give it some gas. Doesn't do it every time, but when it does I need to 'tickle' the throttle to get it to go - and then it goes fine. It's almost like when a petrol engined car starts to stall as the tickover is a bit low - but the 110 idles fine.

The throttle is a fly-by-wire thing - there doesn't seem to be any flat-spots on the throttle pedal, and no fault codes have been logged in the ECU

I know there's some sort of electronic damper thing on the clutch pedal - to stop the engine from surging when you dip the clutch, could that be playing up ?, any other ideas ?

[burgerman]

 Oil in the loom ??  Just a thought  :-k  ;)

[Jimbo]

That thought had crossed my mind too - just need to find 10mins to whip the plug off the head and have a look !

[burgerman]

 Just take the drivers seat and cover off and remove the connecter from the ecu, you will see straight away, takes 2 mins , you will only need to remove the rocker cover to replace the engine/injector loom, they cost about £40, did ours a couple of weeks ago, but by chance it was spotted before it caused any problems  :) 

[Porny]

Jim,

Plug your Nanocom in...

Look in the live data section, and you should be able to see the brake and clutch switches  ;)

Also, have a look at what reading your MAF is giving at idle, it should be between 50 and 65 ish kg/hr.

At the same time, have a look at the MAP readings.  Give the Defender a rev, and it should move from 102 ish at idle, to about 114.  You can also check this on the go.... when you are making proper boost pressure.


Ian

[Jimbo]

Ian,

Nanocom had a few faults logged - the usual 10-1, 10-4,10-5,14-1,14-4 and 14-5 due to the 110 not having aircon or ABS.

It also logged a 2-8, Ambient pressure circuit, and a 4-3, Coolant temp cct - but I'm guessing the 4-3 was due to the engine being stone cold.............the 2-8 was a logged fault, anything to worry about ?

Live data looks normal, MAF reading around 56-57 once the truck had been running a few mins, MAP 101-102, ambient pressure 102.

Switches - Nanocom shows the clutch switch to be OFF when you press the clutch pedal to the floor, and ON when the pedal is released.

It also reckons that the T-box is in LOW, when it's actually in HIGH, and vice-versa - but I seem to recall you saying that LR fiddled the ECU software to make it easier for townies to drive ?

I'm going to check for the dreaded oil in the injector loom and give everything a once-over now.

Jim

[Jimbo]

Hmm, no oil in the injector loom - so some good news  :roll:

I took the MAP (manifold air pressure) sensor out, it was soaked in oily gunk, so cleaned it up with some carb cleaner and left it to dry in the sun. Took the intercooler hose off the inlet manifold expecting to find loads of oil (cos the MAP sensor was caked in it) - but it was all quite clean.

Checked the MAF sensor, looks clean, no crud blocking the mesh cover, air filter and inlet pipes all ok too.

Re-assembled everything, and checked the figures with Nanocom - all the same as before.

Took the truck out for a warm-up run, then a blat once it was up to temp............and the hesitation problem has gone  :-.

It's either some electrical/sensor gremlin that's decided to play hide and seek with me, or cleaning the MAP sensor did the job.......weird !

[Landy Andy]

Well done Jimbo, just keep those fingers crossed.

Andy

[BS3143]

Jimbo,

           You will have fixed it by cleaning the MAP/IAT sensor. The MAP/IAT is a combined sensor, the Inlet Air Temperature part is the black rod section, which causes no problem but the Manifold Absolute Pressure is a small hole to the base of the sensor, right at the base of the black rod, this contains a peizo crystal and this is were the problem starts. On higher mileage engines old deposits block this small opening causing the fault you had. Service does not call for this ever to be removed and cleaned unless diagnostics pull it up. The answer is ever 12 000 miles, remove and clean, also checking the green "o" ring is not split. Clean with rag and cotton bud, harsh cleaners will damage the sensor. Do not push the cotton bud right into the hole, just remove debris from surface. 

           Hope this helps,
                                         Ian.

[age]

Sorry to butt in guys - my CSW Td5 at 145k seems to be startng to do this....  Could you just describe for an imbecile where the MAP sensor is to remove and clean?!  Thanks, A

[BS3143]

Hi,

    The Manifolld Absolute Presssure sensor is to the left of the engine looking in from the front bunper. Remove plastic engine cover, 3 bolts, and lift clear. To the left of the head is the intake manifold, running front to back. MAP/IAT sensor is half way along on the side facing the head. Sandwiched between the manifold and the head. Unlpug the Amp connector and remove the two set screws either side. Sensor make need slight twist to break "o" ring seal. Clean, carefully and replace. Ensue seal does not drop out of the plug when reconnecting.

                                                   Ian.

[Jimbo]

But it may not fix your problem...............my hesitation is back, no worse, but it's back 

I'm wondering if it could be a fuel starvation problem, as it's far more noticeable when I'm sitting at an 'uphill' junction.

I've checked the cylinder balance figures at idle, and they seem stable-ish, although cylinder no2 seems to jump around from -5 to +5..........dodgy injector maybe ?

[Jimbo]

Well, my 'fix' was certainly short-lived  :roll:

Judging by the wet area on the floor under my clutch pedal, and the fact that my left boot has some nice fresh stains on the toe, I reckon the clutch master cylinder is about to let go.

I reckon that the master cylinder has been leaking for a while, so the fluid level has dropped a bit, which in turn is causing the 'anti-surge' switch on the master cylinder to play silly-whatsits, and is causing the hesitation at junctions - and as it's more noticable when the front of the truck is pointing up hill, a drop in fluid level somewhere would seem to be the cause.

And now that my brain has registered this possible cause, I've also realised that the gear change has been getting a bit clunky lately..........not so bad when you're driving along, but quite noticable when trying to engage first when stationary  :doh:

Time to surf Paddocks splendid website I think.

[age]

Thanks chaps - will do the MAP anyway.  Had the new master cylinder last year....... don't you just love em!!! A

[NRS91]

mine does this two... causes much hilarity for my passengers
apparently it can also be due to the anti-stall switching off when you press the loud pedal

[richo]

fuel filter?

[Jimbo]

fuel filter?

Nop, clutch master cylinder............ :?

The master cylinder has some sort of switch that detects when the clutch pedal is depressed, the switch signals the ECU to drop the revs (think it's called an anti-surge switch). As the seals had gone on my master, and the fluid level had dropped, the switch wasn't doing what it was supposed to at the right time - so as I was pulling away from junctions (lifting off the clutch), it (the switch) was telling the ECU to drop the revs, hence I was getting the hesitation.

An added bonus is that the gear change is now a lot slicker  :roll:

[richo]

Thats an interesting fault you had there mate.Who would of thought of that one.
Glad your sorted