UKC

Hello,

Hoping someone can help... my car of late has developed a bit of a problem (passed mot last week tho) where there is abit of a lump and power drop around the 2k rev mark, I predominantly notice it when its cold, but it does it when warm if i havent got my foot down and cruising around 2k revs. When foot is planted it doesnt happen.

Ive got no black smoke, no engine lights or other problems (except my radio still picks up only radio 2 if you remember my last thread on car problems). However, what ever is wrong with it is making it drink fuel (im getting 35mpg on long runs compared to 48+ a month ago)
Tyres all inflated to right pressure, brakes arent binding, and driving style hasnt changed.

Car is 07 plate, and done about 85k and serviced regularly.... was thinking it might be injectors, but its starting well...

Any ideas for me to investigate?

Edit: its a jag xtype 2.2d if that matters

In reply to balmybaldwin:

Caveat here - don't know much about cars, but I do know some diesels need to be run at motorway speeds regularly (weekly) to clear the DPF. Is it doing that?

In reply to balmybaldwin:

Again just kind of guessing here, but could it be mild clutch slip?

In reply to balmybaldwin:

Another person that can't help much but don't must turbos kick in around that rpm? Could be related?

Garages can perform a 'leak-off' test to test the injectors, I think you can even do it yourself reasonably inexpensively.

In reply to balmybaldwin:

Split hose between the turbo and the intercooler meaning it is sucking too much air in.

Get it seen to quickly as it makes the turbo run dry and if it goes pop it'll cost you a grand.

In reply to Nexonen:

No dpf on this model

In reply to Andrew Lodge:

That might make sense, any way to check if thats the problem visually or is it likely to be too small to spot?

P.s. thanks all for suggestions

In reply to balmybaldwin:

Mass Air Flow meter?

In reply to balmybaldwin:


It'll likely be hissing audibly. I'm not sure what the turbo would be running dry of but I can see that you potentially risk over-speeding it or running it into an inefficient operating region if there is a boost leak.

I'd try a Jag forum or a garage for more specific advice.
jk

In reply to balmybaldwin:

Its well seen theirs not may mechanics on here, will people please stop talking about turbo's! If its a common rail engine then in all likely hood its an injector problem on 1 or more injectors. A leak back test will confirm if it is or not. Other possibilities are ingress of air into the system from a connection or split pipe, or low pump pressure. Anyway its all symptomatic of a low common rail pressure at low revs so the fuel pressure/quantity is simply not instantly there when you demand it. Best place to look for answers is as already mentioned, a jag forum, not here

In reply to balmybaldwin:

Could it be the dual mass flyweel on it's way out?

In reply to pass and peak:

Low rail pressure due to leak/air ingress, is in 99% of cases a non-start fault. In most vehicles the ECU will not "switch" the fuel injectors on, until a minimum rail pressure is reached (around 200bar).

This being said, fuel problems would be down my list, behind:

An intercooler or Turbo pipe split big enough to make a difference, should be fairly obvious, change in sound, noticeable whistle/hiss with bonnet up when revved etc.

EGR fault; stuck or seized EGR valve, although this is usually smokey.

Intake manifold butterfly flaps; (Can't remember of the top of my head weather the jag has these fitted) Butterfly flaps located in the intake manifold, connected by linkages to a vaccum or electric actuator.
They either gum up closed, the linkage breaks, or the actuator fails resulting in restricted airflow. makes for poor acceleration until the turbo compensates. (also no smoke, so fits your symptoms).

Sensor fault; one of many.

Fueling; start with the fuel filter.

*all the above assumes a regularly serviced, looked after engine.*

Adam

In reply to balmybaldwin:
EGR valve problems often give similar symptoms since they open/close according to the pressures in the various pipes, as do split pipes around the turbo/intercooler arrangement.

I've seen the latter leak only under certain load/engine speed conditions and be basically undetectable without a rolling road! don't believe those that say you should hear it!

What are the filters like? Sensor faults might come in the software.

They are only suggestions though, happy hunting...

In reply to petellis:

In most cases you will hear it though Pete. A silent turbo pipe split is the occasional curve-ball in my experience.

In reply to craggyjim:
My DMF is on the way out and you don't notice it whilst driving, only at idle and the vibrations lessen massively when you press the clutch pedal.

Call me cynical but perhaps the mechanic intentionally/unintentionally caused a problem when performing the MOT.