All,

I posted a few weeks ago with a host of issues I'm gradually working my way through on my '04 STR. So far I've solved most of the electrical gremlins, the cabin heat, and the engine running hot, mainly thanks to previous threads on the forum I have been able to read through and try previously suggested fixes.

So here's what I have left.

MIL, and repeated throwing of codes representing EGR flow error and both banks running lean. LTFTs sit around +18 at idle, down to around +4 at 2000-2500rpm. MAF is nice and clean. For some reason bank 1 always about 2-3% higher.

This screams vacuum leak to me, as many a thread before this one has discussed. I've been all over the engine bay with flammable gas (still got my eyebrows) to no avail. I've checked individual vacuum hoses - ones that are obviously vacuum hoses - and cant see any issues.

Here's where it gets complicated, as I have an LPG install. This means any hoses behind the back of the engine - in fact anything from the back 2 cylinders backwards - is essentially inaccessible as the limited space is filled with LPG hoses and wiring which I don't want to disturb too much by jamming my hand through. So here's my next questions:

1. Is there a vacuum link to the EGR valve or is it controlled entirely electronically?
2. If there is a vacuum link to the EGR, what does it look like, and where does it run?
3. Could a failing EGR cause a lean reading if there is no vacuum leak? Struggling to get my head around this one. (to be honest the whole idea of EGR confuses the hell out of me...) Gut feeling says yes, because if EGR flow was impeded as the engine would draw in more air than it thought it had, leaving surplus oxy for the metered fuel.

Next step is a smoke test at a garage £££, but I wanted a few more days looking for it myself before coughing up for that as it's already been an expensive month with coolant tanks, cracked alloys and the like(!).

Happy to post piccies of just how tight it is in there with the LPG gear if anyone's interested in seeing!

(Question 4. Have I missed something else really obvious and am barking up the complete wrong tree... )

There are gaskets that can fail, some of which are where you'll struggle to get. But you may have to, just as those whose valley pipe (aka hose under SC) fails have to.

All the hoses etc are in free downloads JTIS and/or JEPC, except those monkeyed with for your LPG.

Did you manage to find the source of the leak? My Recently LPG'd STR has exactly the same issue :S

Unfortunately I haven't fixed it yet.

I'm now quite confident it's not a vacuum leak, and I am therefore hazarding a guess at the egr valve being gunked or tube split. I originally thought this was a supercharger-off job, but it seems I can get to it without digging that far, probably inside a day for the round trip. So this is my next port of call - when I get a free day and decent weather(!), hopefully Sunday.

I'll take photo's and report back.

So today I finally had the free time, the weather, and able assistance from my old man to strip back to the EGR, remove it, and take a look. The EGR itself *seemed* ok, but it was a bit gunked. I decided to fit the new one I'd bought in anticipation, as I really don't fancy this job again!! I can confirm you CAN swap out an EGR without removing the S/C - even with all the extra gubbins from an LPG installation. The two bolts holding the EGR onto the intake elbow are a complete pain, however. I had a 1/4 drive ratchet with 3 extensions and 3 U/J's in a sort of snake arrangement to get at them. Not good design, and it is definitely a 2-man job - either side of the engine, one to guide the sockets on to the bolts and the other to do the turning.

Interestingly, the EGR tube I've read so much about rusting through or cracking was in remarkably good nick. So good, in fact, I suspect it has been changed recently. And when it was changed, someone has managed to get the exhaust manifold -> EGR tube gasket only around 1 stud of the 2, such that it was hanging out of the side, with some fantastic stains where the joint had been blowing. This may well explain my lean at idle issue, and my EGR flow code. Time will tell.

Unfortunately I got caught short on re-assembling above the throttle body by closing darkness, and now the pub is calling. Tomorrow AM I will reassamble and fire her up... watch this space, I will report back! I assume a hard reset afterwards (tocuh cables together..?) will clear the fuel trims andgive a 'clean slate' for the ECU to re-learn the engine, so I will perform this too. Wish me luck!

Just to close out my thread for future searchers - now fixed her back together, done a 140 mile mixed cycle sahkedown, and all seems well - no codes, no engine light, no Restricted Performance. Also boosted my fuel economy by about 8-9!!

Sweeeet :-)

Good job well done!

Thanks for reporting back and I think you are right. The EGR tube was replaced and they fouled up the gasket install which was really the cause of all your problems. I bet the EGR valve was old but still working.

I would have changed the valve too as it is NOT easy to get at and you had already done all that work.

Any chance you could post a part number and price for the EGR valve? Does it come with bolts and gasket?

Did you reuse the two EGR bolts or replace with new? Everyone who has worked on the EGR has struggled with them and I figure you messed up the bolt heads a bit getting them off?
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Sure... Part No's and Prices (Jaguar Strugess Leicester)

JAJ88582 - N/STK VALVE-EGR £174.58
JAJ87734 - N/STK PIPE-EGR £87.53
JAJ88559 - N/STK GASKET £3.46
JAJ88560 - AC09 GASKET £3.46

NOTE there's a gasket missing here (2 parts = 3 joints) - from the Tube to the manifold. We copied the one we took out, from some raw material. I asked Jag for 'everything I'd need', sadly they missed one out.


I reused all bolts/studs/nuts, after giving them a good clean. The pair connecting the EGR to elbow weren't rounded at all, so they went back in. They were also quite shiny, so I suspect were replaced the last time this was played with. (Edit to add: ) The struggling for us was just locating a socket on them, and being in a position to get some torque on it to remove them. Once the socket was located and I'd worked out the right combination of U/J's and extension bars to dodge around the harness/lpg, they were actually pretty easy to remove. I suspect a car without LPG would require a different combo, though in this instance the hoses were almost perfectly placed to stop the snake of 1/4" drives twisting up, if you get what I mean.

aaaaaaaaaaaaand... it's back.

p0171 appeared yesterday, briefly followed by restricted performance for about 3 miles, followed by the transmission hunting about and jumping (lurching? seemed worse than the lurch descriptions I've read) between 2nd and 3rd. Looks like it must be multiple issues and I've only solved one :-(

You're probably looking for an air leak. Check fuel trims, engine hot, parked, at idle & 2500rpm.

OK, it has developed into a rough idle when cold too.

Still showing P0171, P0174, and P1000, with intermittent RP as per original symptoms before I replaced the EGR!

Been all over it for an air leak but no joy. Few hours free this arvo so will search again.

Fuel Trims:

Idle:

ST1 2.3
LT1 19.5
ST2 0
LT2 19.5

2500RPM:

ST1 -3.9
LT1 11.7
ST2 -5
LT2 13.3

Right then...

Starter for 10 is a cross-threaded oil filler cap. Wonderful. I'll be having words with the garage about that one.

Not that I'm claiming it's an absolute fix, but it definitely wasn't helping!

O M G - they should be able to cope with something so technologically advanced!!

Good find! The oil cap must be air tight or you will get a code.

Hope that will fix it. Any permanet damage to the cam cover or did they just cross thread the cap?
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Inspected and it looks OK, I think the torque-clicky feature of the cap prevented them just tearing the threads apart. Cleaned it and reseated and the fuel trims are both showing about 19LT and -15ST at idle.

How long does it take for the long terms to change? Or is that a 'how long is a piece of string' type question?

If that was your problem it should have fixed it when you got the oil filler cap tight again.

Maybe unhook the battery to give it a reset just to be sure?
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I figured it had fixed it, as the STFTs jumped to -15 and -16, essentially cancelling out the long term +19's, right?

My understanding was that over a few minutes idling the LTFT's would reduce because of the large descrepancy with the STFT's, until the STFT's were at or near 0. I was just interested what the typical time period for this to occur was, were I not to do a reset. It must have learned about the vacuum leak to set the LTFT's to +19 in the first place, right? But it didn't seem to do so on the 140 mile shakedown test just after I fixed the EGR valve, only when I pottered around town for 10 miles or so since that. I assume because it was spending a lot of time idling at the lights.

I'll reset it anyway so that it can fully re-learn.

The codes PDF is in the stickies & JTIS. At the front it describes the drive cycle in detail. You can disconnect battery (to clear KAM) and then follow that or just drive and though longer it'll relearn eventually - provided no faults block things.