INSIGHT INTO JAG ENGINE
Reading the article that was published from Stuart Anderson on the restrictive mode on his 2010 Jaguar XF (CM, Feb 2020), he noted that several error codes were evident on scanning and you replied accordingly. With the XF and the XJ series running both the 2.7 and 3.0-litre diesel engines, these error codes can also be thrown up from a severely cracked inlet manifold and also a split throttle body housing. Sadly, both seem to go hand-in-hand as I have had a 3.0 XF and current XJ with the same issues. Both vehicles flagged up the exact codes that Stuart has mentioned.
The design of the initial manifold was shocking, resulting in a thinner weakened edge close to the injectors on the driver’s side, which can be initially diagnosed by removing the engine cam cover and carefully peeling back the insulation around the injectors. Signs of oil leaks around the rear injector on the driver’s side are indicative of a cracked cover. Signs of excessive oil in between the two banks are indications of a cracked throttle body, just below its Y-junction piece. The passenger-side cover does suffer the same issue but more often directly on top of the cover by the aluminium identifying plate fitted during production.
Jaguar can carry out the work, for sums ranging from £1500 to £3000 – I wish that was a typo! – but a DIY job is achievable if the support bar for the injector rail is ‘modified’ to get at the last remaining bolt that holds on the inlet manifold. In the interests of the article, I won’t go any further because it’s quite involved from JLR’S point of view, but a decent patient DIY mechanic can complete the work in five hours with no real major issues.
The replacement inlet manifold from Jaguar is now on its 8th part revision and is best sourced from a dealer (this will provide the correct part with corrected design). Internet auction sites and the internet in general do offer the same item, but with its older part number, which would then cause issues further down the line – in as little as five years in the case of the inlet manifold.
As for the throttle body, a unit from an S-TYPE 2.7 will fit the 3.0 models with a good clean-up and swapping out the throttle motor. Seems a little weird fitting a much older inlet, but the part supplier was changed when the XF came into production and it seems that cost was an issue! Any secondhand part needs to be scrutinised before purchase, but as I have just completed the throttle body and the inlet manifold, I knew which parts to source straight away.
I have included the picture I took from the XJ when removed. The XF was exactly the same...
Alex Ward