Hi all... I recently bought a one-owner X150 XKR with low miles (40k) NOT from a dealer but a broker who had presented the car with a Health-check by the local Jaguar dealer.

So I didn't buy it blind from one of those 'prestige' dealers that scoop up the over 5 year old trade in's from the main dealers. Valet them, stick a big (lots of room to negotiate) price on them backed up by a Guarantee that has all kinds of caveats attached (electrics, hoses / pipes, sat-nav etc not covered)...

I knew what I was buying and budgeted for new discs, pads, full service (with Jag supplied plugs, fluids, filters). Had the car waxoyled (hope they didn't block the A/C evaporation pipe 'cos if they did there's going to be a soaking wet passenger footwell and a disgruntled mechanic taking out the dash to replace a little piece of pipe)...

And looked forward to learning to ease my way into supercharged driving - entirely different to an 80's Porsche 930 Turbo I owned back then - as well as learning to reverse through my standard size up and over garage door with 1.5" to spare either side with the mirrors out.

All good - but suddenly tempered by the fact that every time I had to make SMALL blip and brake on the throttle as I tentatively edged my way into the garage the ENGINE WARNING light comes on....

Once on the road the car didn't hesitate, drove / surged smooth and took off like a sling-shot with no apparent problems BUT the engine warning light glaring at me diminished the pleasure and excitement somewhat.

When my able mechanic plugged in his Snap-On ECU reader, it gave the following readout:

PO171 - System Too Lean (Bank 1)

PO174 - System Too Lean (Bank 2)

Once re-set it wouldn't reappear until once again I had to make tiny adjustments to the steering, brakes and throttle - moving at six inch intervals - and blip: the engine light's back on the dial.

I can't keep getting it re-set by the garage - and I can't ignore it in case it masks a newer, bigger problem somewhere later down the line...

So HELP! How do I get my ECU to disregard the signals / change its response to the very small blipped in-puts of throttle / brake and steering?

I'm hoping someone out there will know the answer.

Thanks JD

 

With a System Too Lean on both sides, there is a common vacuum leak somewhere, probably around the throttle body or elsewhere near the intake manifold. Take some Starting Fluid, the aerosol kind, and with the engine cover removed, spray a shortish (1-2 seconds) blast at various areas of the engine while running. When the RPMs noticeably increase about one second after the blast, your vacuum leak is somewhere near that area.
OBDII and all the computers in the world can't diagnose when and where a vacuum leak happens.

 

Most everything I can think of would make it lean when you aren't blipping the throttle as well. I'm tempted to recreate what you are doing to see if I can fault the system.

Suggested solutions:
Wider garage door
Narrower car
Grit your teeth and slam that entry/exit

Hope you are able to get better advice!

 

If this method fails to find any leaks then you'll need to get it smoke tested. Good luck.

 

^^^^ What he said, if you can find someone, usually any decent shop, with a smoke generator.

 

Thanks a lot Cee Jay - sounds like good advice... I will ask my guy to give it a go.

Failing that we'll set a smoke test as Jagtoes suggests.

As for Mhminnich - I like his gung-ho approach but best I stay calm, my eyesight and reflexes aren't what they used to be. Your thought that there could be other explanations if not for the 'throttle blips'... what if I said when the engine is idling (perhaps the throttle blips are irrelevant).

To get 3 responses the next day from this Forum is a real good surprise.

Actually - I'm a Forum virgin, so you'll appreciate that, like all first times, it's natural to be impressed.

I'll be sure to up-date you all.

And thanks again.

JD