Agree with Carl on possible dirty air filter condition which can cause rich running.
Carl / Terry,
Thanks for these tips. Carl, in particular, I was unaware of ports underneath the intake manifold. I’ll examine those for sure. Yes, a flooded canister would also cause this behavior. It happened to another vehicle of mine, a '79 International Scout that was nearly impossible to diagnose the run-rich issue – it turned out to be a flooded canister. Excellent suggestion to check. (Realistically, I’ll go in and simply plug the ports for the next test.)
The air filter is brand new. As are the plugs, wires, rotor and cap.
Previously in the thread, I DID come to the conclusion that the vacuum port for the cruise control bellows was disconnected and was causing a vacuum leak. I capped it directly at the throttle body as the cruise control is inoperative. I re-ran the emissions test, thinking that it was sufficient, but not at all – still ultra rich, even when the car was plenty hot.
My plan:
1.) Check the manifold vacuum ports / spigot from underneath the manifold.
2.) Check / disconnect the carbon canister (discreetly, so it passes visual)
3.) Pinch the cold start injector hose completely closed.
4.) Replace the CTS (which is out of range upon test)
5.) Replace the fuel rail pressure control unit. (Both of these already on order from Rock Auto.)
With all of that done, I’m going to bring it back for a pre-test at the smog center. I really hope that does it, there isn’t much left. I’ve checked for a misfire by pulling each injector connector in turn – each is operating properly as is ignition.
Again, thank you for the immensely valuable suggestions!
One last question: I gave a cursory look for where that carbon canister is located and it appears to be in the side firewall. Can anyone definitely confirm how to access it? All I see is the “tee” hoses branching off straight into the wheelwell.
Thanks much!
On early cars the canister was readily accessible with the bonnet open, Brian - on later cars it was in the left front wheel well…
The operating principles are the same for all, but more sophistication was added as time went on.
- One canister hose is connected, via a ‘T’ and
the C-pillars fuel separators, to the tanks -
above max fuel levels. - One hose is connected to a vacuum source,
nominally the crankcase ventilation - and a
restrictor to reduce vacuum to a minimum - Charcoal is fitted to divide the canister in two;
one part, with the vacuum hoses - the other
open to ambient air. - With engine stopped, vapor from the tanks are
vented through the charcoal to open air. The
charcoal adsorbs the fuel vapor from the tanks
so no fuel is vented out. - With engine running air is sucked from the
tanks and also through the charcoal from open
air. Adsorbed fuel in the charcoal is drawn into
the engine and is burnt. Hence there is no
actual vacuum in the canister just air flow…
If the charcoal solidifies, preventing air passing through; there will be vacuum in the canister - which may be passed on to the tanks. However, with normal fuel levels, only air is sucked from the tanks building up tank vacuum - which may prevent tank venting, and the tanks may ‘implode’. Remedial action is to replace canister/charcoal - which is a scheduled maintenance operation anyway…
If a tank overflows for some reason, usually failed return or changeover functions, liquid fuel may indeed be sucked into the engine - causing fat running.
In principle; the closed ventilation system/canister is an unlikely source of failed smog - but not impossible. The CSI is a more likely prospect, but other factors, like CTS, fuel pressure regulator and the AFM, cannot be excluded, of course…
Frank
xj6 85 Sov Europe (UK/NZ)
Frank,
Thanks for this. I’ve done some additional reading on the topic and believe my “vacuum valve to pressure canister” has failed, part number CAC3101 which is no longer available. In addition, one fuel tank has already been replaced on the vehicle. When I open the tanks immediately after a drive, there is a larger than normal “whoosh” sound, and when I don’t, I hear a tick, tick, tick, from the rear of the car which may very well be the tanks returning to shape, having been deformed from excess vacuum.
As the California Smog test also tests pressure of fuel tanks, luckily there isn’t an adapter for the Jaguar fuel fillers so that test is excluded. I’m not opposed to allowing the tanks to vent to the atmosphere for now. Since the carbon canister tank is hidden, it can’t easily be inspected.
Thinking out loud, if I occlude the vacuum port for the charcoal canister system at the throttle body (and then re-hook up the hose for visual), and then disconnect the lines from the fuel tank that go to the charcoal canister, would this effectively ensure that fuel isn’t being drawn in via a filled charcoal canister?
The more I think about how the vehicle behaves with the massive vacuum in the fuel tanks, and the fact that this exact scenario happened to me once before on my International Scout, I’m keen to (safely) disconnect the system for the purposes of the smog check. I’m really leaning toward this as a problem, if not a contributor to the problem.
Thanks!
Brian
- fond memories of my 9 IHc Scout II> Sure liked that old Binder. Only the fact tht it laced AC caused me to part with it. Looked great . ran great. took lot to get it past SMPG. even had to go to a referee at one time.
Get it good and hot Screw down the idle jets til it barel kept runnign. Oh. I swppped in a Ford Ctalyctic coverter. Mush better than the GM pan cake tpe. then, shop made a cat a back dual syste Ran and sounded much better\\Visoit almst amny “junk yard” that has some old Gzm cars. rob one of the cnnister. Same as the jaguar un it!!!
Cut ylurs open. recharge the charcoal fish stores have it\The cannisters do not haave a bad effect on engine performance.
CA SMOG is a PITA!!!
hate each session. altough st f the folks are nice.
Crl
1 Like
**
To elaborate, Brian - the valve is not really vital for tank venting…
The ‘normal’ source of tank vacuum is the consumption of fuel - as levels drop, the vacuum increases. As vacuum increases, the valve opens towards(!) the tanks (at some 1,5? psi) to let air into the tanks.
(This is the vital point; without air let into the tanks the very powerful fuel pump will eventually remove all fuel - and vacuum may theoretically reach near 14+ psi. At which the atmospheric pressure on the tanks’ outside metal will be 14+ psi - and the tanks will collapse long time before that)
Likewise, if tank pressure increases, fuel expanding, like while standing in the sun; the valve opens from the tanks - venting vapor into the canister. Pressure in the tanks is of course not a problem - it will be very low and the tanks can easily take high inside pressure…
When engine stops the vacuum in the tanks (1.5 psi) will be retained by the closed valve. The Californian regime of testing basically checks that the tanks are not leaking fuel into the atmosphere - that indeed the fuel fuel is sealed in. Whether they test this by applying vacuum or pressure, or whatever, I don’t know…
However; working as it should the system is supposed to maintain tank vacuum build-up after driving/using fuel - and you get the ‘whoosh’ when opening a tank lid. It does not in itself imply any malfunction…
Assessing the ‘whoosh’ is somewhat tricky; the amount of ‘whoosh’ depends both on the vacuum level, the amount of fuel used and the amount of air space/tank levels. The less fuel in the tanks or the more fuel used, the more ‘whoosh’…
Also, the tanks’ ventilation commute - tanks are connected to each other via the fuel separators, and have the same vacuum. So if you open one lid you get the ‘whoosh’ when you then open the other lid - there is no ‘whoosh’…
Of course, if engine vacuum is applied to the tanks the vacuum build-up is more rapid. This usually caused by solidified charcoal in the canister blocking the canister’s air inlet - the charcoals special characteristics deteriorate over time, ‘poisoned’ by fuel. Otherwise the engine will rather draw air from the canister’s air inlet remedies by replacing the charcoal/renewing the canister. There is normally no actual vacuum in the canister; its more a matter of a slow air flow throughout…
There are other fault permutations, but these are the main ones…
As an aside; on later cars a ‘purge valve’ was added - a vacuum operated valve closed the connection between the canister and the vacuum source. To preventing the vapor escaping to open air via the engine…
A second aside; it’s very unusual for raw fuel to be drawn into the engine via the canister- it can, as said, only happen when the tank level reaches the vent hose at a tank. Which requires that the tank overflows - which is a fault in itself. To be remedied by appropriate actions…
A a third aside; check where the canister vacuum hose is connected to the engine. On later versions it was connected to the crankcase ventilation pipe - which has relatively low vacuum. And check also that a restrictor is fitted to the hose…
Frank
xj6 85 Sov Europe (UK/NZ)
1 Like
Gentlemen,
The quest continues: I retested yesterday and missed it by that much – on the 25 mph test.
1.) The CTS was DEFINITELY bad. Upon removing it, I noticed the internals were essentially powder and the two prongs could touch each other.
2.) I replaced the fuel pressure regulator on the rail as the original was still in place.
3.) I thoroughly examined the evap canister, valves, and lines. To cure the “fuel tanks whoosh” I took a 1/8" drill bit and cleanly drilled through the valve going to the fuel tanks. Worked like a charm. No more “whoosh.” (Records show the previous owner had to recently change one of the fuel tanks due to a leak, and I hear the telltale clacking as the tank resumed it’s shape after a long drive.)
4.) I took an air hose nozzle and checked for flow through the canister (and back and forth to the fuel tanks) with the improved (drilled) valve. Plenty of airflow in both directions and the canister is not prohibiting airflow. I also tested the canister in reverse and blew into the outlet to atmosphere. Plenty of flow.
Thus, the smog guy says when variations like this happen mid-test, it’s usually the O2 sensor. The only thing I did NOT change as it looked like it’s been changed already. His rationale was that as the car had been running richly for so long it’s likely fouled the sensor regardless of how long it’s been there. A new one from Rock Auto is only $27, so it’s on the way.
I’ll pop that in and go for a long drive and then the retest. That said, the improvement made by replacing the bad CTS made an enormous difference in the test numbers thus far.
I thought I’d post the update for those following the thread and also as an opportunity to say THANK YOU again for all who have contributed.
– Brian in San Diego.
1 Like
**
That is much appreciated, Brian - too few do that, leaving us in the dark as to the solutions, thank you!
The importance of the CTS is of course as expected. The numbers indicates that the engine is running too rich, and the inspectors remark is likely well considered. However, the O2 sensor shouldn’t really have to work very hard if the mixture control on the AFM is correctly set - probably set too fat. To be considered if a replaced sensor is unsatisfactory…?
Drilling through the relief valve is one way to eliminate all ‘whoosh’, of course, and certainly eliminate tank collapse. But it will also fail the Californian fuel tank pressure if applied. There should indeed be a bit of ‘whoosh’ with the system working correctly…
Was the CSI clamped for testing, or is it working properly - or at lest not leaking?
Thanks for reporting back - and a final report?
Frank
xj6 85 Sov Europe (UK/NZ)
Thanks Frank.
Good note on the CSI. I was so convinced in the CTS fault, given it’s patent obviousness after testing, that I neglected to tie off the CSI. Mostly because the smog shop won’t pass the “visual” inspection with a hose clamp on my fuel system, but also my own hubris in my diagnostics. I’m going to properly disconnect it before the next test after I replace the O2 sensor.
Great point on the fuel tank pressure test at Smog. The Jaguar is exempt from that test due to the fact that they do not have an adapter to fit the fuel fillers. I knew this prior to drilling out the valve.
I realized that I can’t remove the O2 sensor without the special socket wrench so that’s on the way. I’ll circle back in a week or so once I’ve got the next iteration of fixes.
If it fails again for any reason, the shop agreed to play with the AFM adjustments while on the exhaust gas meter for me. That’s our last resort.
As always, thank you, and I’ll be back!
**
That really is an essential adjustment with a marginal ‘fail’, Brian…
If you got those test readings with CSI connected; it’s working as it should - no need to clamp or disconnect it. You could of course clamp it while the shop checks exhaust gas - just to verify that it plays no part…
As an aside: the blow-through at the canister will work either with the charcoal intact or if the charcoal has shrunk/is missing to allow air to bypass it. In the latter case; the system is inoperative - but you don’t need to tell the inspector that…
Frank
xj6 85 Sov Europe (UK/NZ)
SUCCESS! Now that’s a clean emissions report. I replaced the O2 sensor and it crossed the line very cleanly. HOWEVER, I almost failed the “visual” portion because of a mystery hose. Turns out the smog guys have to fail any car that has a hanging, unplugged hose that may be part of the emissions system. I just noticed it myself and the two prior smog checks, the inspector missed it as well.
I dug in with a mirror and a flashlight (as it’s all under the intake manifold) and can see that it heads up to a clamp and then further to the end of the engine where it plugs into a small canister containing three ports. One of them follows back to the main “t” where the opposite end is directed to the charcoal canister.
Since the most logical thing under there is the distributor vacuum advance, I grabbed that hose and pulled on it – it’s not connected to anything.
Question: Should I simply buy a connector and connect these hoses together? Does the hose coming off of the canister sound like it should go directly to the distributor, or is there some other sort of “tee” or intermediary where they might plug into?
The inspector believes he also hears a vacuum leak and the Idle RPM is running too high at around 1200.
Any opinions welcome, and thanks for helping me to get this car to pass emissions!
Brian
**
It’s a bit bewildering, Brian. Anything directly or indirectly connected to the charcoal canister is related to the tank ventilation - it is not related to the distributor…
Later version of the tank ventilation system had the addition of a purge valve which involved three hoses. The valve (possibly your 'small canister) is closed with the engine not running (no vacuum). One hose on the ‘small canister’ connects to a vacuum source, controlling the valve. One hose goes to the charcoal canister - and one to the charcoal canister’s purge connection - sometimes the crankcase ventilation tube.
Ie, there are two hoses with vacuum; one controlling the purge valve - the other doing the actual purging of the canister when the engine is running. Which hose is which is not immaterial; it is important that the airflow from the charcoal canister is very low - so a grommet (a 'strangler), is fitted to the actual purge hose. The other hose just operates the purge valve - and can have manifold vacuum…
The third hose connects to the charcoal canister, of course…
The logic behind the set-up is that with the engine stopped; the purge valve is closed - preventing tanks from venting into open air through the engine/manifold. Ie venting must only go through the charcoal canister - which adsorbs the petrol vapor. If you think this is excessive - blame California…
Additional remarks; your engine is still set up too rich, and requires the help of the Lambda/O2 to pass emissions.
1200 rpms in hot idle is definitely too high - it should be some 800. While a vacuum leak is possible - have you tried adjusting the idle? A disconnected hose is a vacuum leak and clearly audible, but will only increase idle by less than some 50 rpms…
In any case; congratulation with passing - and with the work well done…
Frank
xj6 85 Sov Europe (UK/NZ)
I suspect it’s the vacuum advance regulator, EAC4399, as seen here
The function of this device has been discussed many times and an archive search will reveal lots of info. Here’s a bit from the FAQs
https://www.jag-lovers.org/xjlovers/xjfaq/delayvalve.htm
It’s been a long time but I don’t think it should be plumbed to the charcoal canister at all. There’s a decal under the hood showing the plumbing of the hoses but the info should be in the archives as well
Cheers
DD
**
It certainly should not if this is indeed the vacuum advance regulator, Doug…
But he should at least verify if the dist has vacuum - and whether it is manifold or ported…
Frank
xj6 85 Sov Europe (UK/NZ)
Gentlemen,
Allow me to close out this thread with a result: The two hoses ARE in fact supposed to be one hose that connects to the vacuum advance. There was a plastic connector which broke. I nipped off the ends with the broken connector in them each, and fitted a new one. Voila! I now have vacuum advance again and I no longer have a suspicious smog guy who is obliged to fail any vehicle with open ended hoses visible.
Thanks again for all of the advice!
Brian in San Diego
1 Like