Cruise control 4.4 TDV8 surging

[Graeme]

Cruise control constantly surges even slightly on flat roads, but much worse heading up-hill. The instantaneous fuel consumption display confirms consumption cycling over 1L/100 km on flat ground at 110 kph. Dropping the set-speed 1 notch whilst ascending hills can often cause quite a glitch in power delivery when speed is allowed to drop off too much after which the throttle opened very excessively.

Even though the ecm software may not have been updated in the 3 years since this vehicle was built due to very low usage, the behaviour seems to be too bad to be blamed on an early ecm software version as vehicles with these engines had been on sale for nearly 2 years when this one was built. I'll have a look for any disconnected vacuum hoses on the engine but would expect a fault to be logged if that was the cause.

[rar110]

Bugger. I don't recall reading about a surging problem with the 4.4.

Surging on our Peugeot 407 hdi was EGR related. It occurred in a particular rev range whether using normal or sport mode or cruise control.

I'd check the inter cooler hoses.

Or a plug dislodged somewhere.

[Cambo_oldjaguar]

If the vehicle is only three years old it's still under warranty? Take it back to the dealer & tell them to fix it?

[BobD]

Graeme, are you at home or out on the road somewhere? I assume you want to fix it yourself as usual, rather than travelling to a dealer, especially with the car out of warranty. What are you doing about diagnostic gear for the L322?


Perhaps something is sticking through lack of use, similar to your second turbo isolation valve on the D4!


The disadvantage of the nice new car is that you now have to go through a different learning curve and then you can advise everyone else as you do on the D4 site.

[GregMilner]

Sounds in some ways similar to my recent problem Graeme - as you know, that turned out to be a leaking intercooler hose. Plus, the cruise control crapped out on the same trip because of a separate but related problem, from memory the throttle linkage.
Fixed under warranty though.

[Graeme]

I'm at home and yes I'd like to be able to fix it myself, which would only be possible if a hose has come adrift. The selling dealer is 6 hrs drive away in North Sydney so I'd like to avoid an unnecessary return visit.

The car has used vehicle warranty for 5K/3 mths and I've already asked the service people at the (LR) dealer to do some research. The vehicle is accelerating too much then backing off too much so see-sawing, cycling about every 3 seconds.

The isolation valve should be closed because the engine revs are only around 1400 rpm but something could be sticking such as the primary turbo vanes. I gave it a boot-full pulling away uphill from a slow corner on the way home yesterday looking for smoke from the secondary turbo but saw none, not that there should have been any considering that it now has the updated drain. Today I could feel the surging at 100 kph so that exercise didn't change anything. I thought that the engine didn't burst into life the way the 3.0 does on full throttle so perhaps there is a problem with the primary turbo. The secondary coming on stream should have made a significant difference if that primary wasn't performing properly, although the secondary is only a helper at higher revs, not the main turbo. Perhaps for a few days I should run the engine to higher revs to give the vanes more exercise.

I will have my Faultmate Extreme's licence swapped because the fee is only an admin fee rather than an upgrade, but I need to reset a few specs (eg tyres size/speedo calibration) on the D4 beforehand.

Yes, there's learning to be done. I found the park brake emergency release cable today whilst looking for a spot to mount my Llams switch, which currently is dangling over the centre console. The release cable is under the cup-holders where a removable plastic insert covers the handle.

[Graeme]

Sounds in some ways similar to my recent problem Graeme - as you know, that turned out to be a leaking intercooler hose.I had already forgotten the details but will start checking tomorrow.

[Graeme]

The housing attached to the top IC hose has been leaking where it attaches to the throttle body, as evidenced by the oily soot around the join and nearby components. The housing almost rattled when wriggled because it was so loose but after having manipulated the inside seal the housing is not quite so loose. This information has been conveyed to the vendor's service dept. Thanks Greg!

[GregMilner]

Yep, exactly the same issue I had. Glad you got it sorted Graeme:-)

[Graeme]

Thanks for the reminder Greg - very worthwhile. The join was the first item that I checked and its looseness triggered alarms.

The service dept thinks it is more likely to be a turbo problem but they're considering my request for a new seal because the leak needs to be fixed anyway - I'm trying to avoid having to take it back. Also "surging" is probably overstating the condition as no speed change is discernible, just a push in the back then slight deceleration every 2-3 seconds. I've just learnt from the parts catalogue that the seal is not replaceable, instead with the top IC hose supplied as an assembly which means that the seal can't be messed-up when fitting either.

Unfortunately its been confirmed that the vehicle wasn't serviced prior to me taking delivery even though the salesman said that it had been when I asked. No entry in the service book and a service sticker from another dealer suggested no recent service. This pretty much guarantees that software hasn't been updated to the latest levels but it did have an oil service at 14K a year ago.

[GregMilner]

Mine wasn't so much a surging problem, it was more a loss of power. The leak in my IC hose might have been more pronounced than yours though.
Co-incidentally (or it seemed to be co-incidental) my cruise control died, but I suspect it was all tied together through the ECU systems.

[Graeme]

Mine hasn't been leaking much judging by only a light smattering of oil on adjacent components.