I have been asked about emissions on an 89 VDP and need some
advice. The car was tested on a chassis dynomometer and scored
well except for NOx, which was slightly high. Numbers were 0.2441
grams per mile Hydrocarbons, (allowed 1.4000), 4.676 grams per mile
CO (allowed 30) and 2.6949 grams per mile NOx (allowed 2.5).
The car was never fitted with an air pump. I’ve checked all the
hoses and intake manifold bolts, all are tight. The car has about
95,000 miles on it.
What is the most probably cause for the high NOx? Oxygen sensor?
I hate to just start thowing parts at it without a plan. If anyone
has had a similar situation, I’d appreciate knowing how it was
corrected. Thanks in advance.–
Pete 70 XKE (193K) 88 XJ6 (233K) 88 XJ6 (217K) 60 Mini
Severna park, Maryland, United States
–Posted using Jag-lovers JagFORUM [forums.jag-lovers.org]–
Visit the Jag Lovers homepage at http://www.jag-lovers.org for exciting services and resources including Photo Albums, Event Diary / Calendar, On Line Books and more !
NOx comes from the cumbustion temperatures going beyond 2500 degrees. The
function of the EGR (Exhaust Gas Recirculation) is to reduce NOx by reducing
the combustion temperature. It does this by recirculating some exhaust
gases. If the EGR valve is not opening it will result in high NOx.
The valve is normally closed during idle otherwise it will negatively
affect the idle. You can force the valve open at idle and the idle should
drop indicating that the valve did open and that the recirculation passages
are clear. Not sure about the Jaguar but EGR valves are usually vacuum
operated so you can open them with a vacuum source.
The Oxygen sensor should have nothing to do with NOx. The fact the
Hydrocarbons are low indicates that the car is okay in that area.
Assuming that the EGR circuit is working other considerations could be
anything which is causing an increase in combustion temperatures such as a
marginal cooling system or lean mixture. Even incorrect ignition timing can
cause the cylinder temperatures to rise and NOx to skyrocket.
Finally the catalytic convertor also pays a role in the reduction of NOx.
(at least with a 3-way catalysts)----- Original Message -----
From: “Jaguarpete” jaguarpete@aol.com
To: xj40@jag-lovers.org
Sent: Friday, September 01, 2006 3:16 PM
Subject: [xj40] Emissions
I have been asked about emissions on an 89 VDP and need some
advice. The car was tested on a chassis dynomometer and scored
well except for NOx, which was slightly high. Numbers were 0.2441
grams per mile Hydrocarbons, (allowed 1.4000), 4.676 grams per mile
CO (allowed 30) and 2.6949 grams per mile NOx (allowed 2.5).
The car was never fitted with an air pump. I’ve checked all the
hoses and intake manifold bolts, all are tight. The car has about
95,000 miles on it.
What is the most probably cause for the high NOx? Oxygen sensor?
I hate to just start thowing parts at it without a plan. If anyone
has had a similar situation, I’d appreciate knowing how it was
corrected. Thanks in advance.
Pete 70 XKE (193K) 88 XJ6 (233K) 88 XJ6 (217K) 60 Mini
Severna park, Maryland, United States
–Posted using Jag-lovers JagFORUM [forums.jag-lovers.org]–
Visit the Jag Lovers homepage at http://www.jag-lovers.org for exciting
services and resources including Photo Albums, Event Diary / Calendar, On
Line Books and more !
Visit the Jag Lovers homepage at http://www.jag-lovers.org for exciting services and resources including Photo Albums, Event Diary / Calendar, On Line Books and more !
Or the air pump might not be working if you did dot thoroughly allow the
engine to warm up. The air pump only runs during warm up to reduce
emissions which is one reason the engine has to be thoroughly warm
before testing to insure the need for the air pump has passed.
Most likely its the EGR valve though.
Jay 90 VDP Majestic
Dave wrote:> NOx comes from the cumbustion temperatures going beyond 2500 degrees.
The function of the EGR (Exhaust Gas Recirculation) is to reduce NOx by
reducing the combustion temperature. It does this by recirculating some
exhaust gases. If the EGR valve is not opening it will result in high NOx.
The valve is normally closed during idle otherwise it will negatively
affect the idle. You can force the valve open at idle and the idle
should drop indicating that the valve did open and that the
recirculation passages are clear. Not sure about the Jaguar but EGR
valves are usually vacuum operated so you can open them with a vacuum
source.
The Oxygen sensor should have nothing to do with NOx. The fact the
Hydrocarbons are low indicates that the car is okay in that area.
Assuming that the EGR circuit is working other considerations could be
anything which is causing an increase in combustion temperatures such as
a marginal cooling system or lean mixture. Even incorrect ignition
timing can cause the cylinder temperatures to rise and NOx to skyrocket.
Finally the catalytic convertor also pays a role in the reduction of
NOx. (at least with a 3-way catalysts)
----- Original Message ----- From: “Jaguarpete” jaguarpete@aol.com
To: xj40@jag-lovers.org
Sent: Friday, September 01, 2006 3:16 PM
Subject: [xj40] Emissions
I have been asked about emissions on an 89 VDP and need some
advice. The car was tested on a chassis dynomometer and scored
well except for NOx, which was slightly high. Numbers were 0.2441
grams per mile Hydrocarbons, (allowed 1.4000), 4.676 grams per mile
CO (allowed 30) and 2.6949 grams per mile NOx (allowed 2.5).
The car was never fitted with an air pump. I’ve checked all the
hoses and intake manifold bolts, all are tight. The car has about
95,000 miles on it.
What is the most probably cause for the high NOx? Oxygen sensor?
I hate to just start thowing parts at it without a plan. If anyone
has had a similar situation, I’d appreciate knowing how it was
corrected. Thanks in advance.
Pete 70 XKE (193K) 88 XJ6 (233K) 88 XJ6 (217K) 60 Mini
Severna park, Maryland, United States
–Posted using Jag-lovers JagFORUM [forums.jag-lovers.org]–
Visit the Jag Lovers homepage at http://www.jag-lovers.org for
exciting services and resources including Photo Albums, Event Diary /
Calendar, On Line Books and more !
Visit the Jag Lovers homepage at http://www.jag-lovers.org for exciting
services and resources including Photo Albums, Event Diary / Calendar,
On Line Books and more !
Visit the Jag Lovers homepage at http://www.jag-lovers.org for exciting services and resources including Photo Albums, Event Diary / Calendar, On Line Books and more !
In reply to a message from Jay sent Sun 3 Sep 2006:
It’s an 89. There’s NO air pump and NO EGR valve. What can I do
to lower NOx emissions without having to resort to a new catalyst?–
The original message included these comments:
Or the air pump might not be working if you did dot thoroughly allow the
engine to warm up. The air pump only runs during warm up to reduce
emissions which is one reason the engine has to be thoroughly warm
before testing to insure the need for the air pump has passed.
Most likely its the EGR valve though.
Visit the Jag Lovers homepage at http://www.jag-lovers.org for exciting services and resources including Photo Albums, Event Diary / Calendar, On Line Books and more !
In reply to a message from Jaguarpete sent Sun 3 Sep 2006:
Pete,
Knowing very little about the subject, but reading some
bumpf on automotive NOx reduction, it would appear that NOx
emissions are greater if the catalytic converters are not
good and hot for the test.
Did your '89 get a good run before putting it on test?
I always drive my car around (hard) for a few miles before I
get to the test station (which is only 1� miles from my
house) and leave the engine running whilst I wait for the
annual MoT to commence. It so happens that NOx emissions are
not part of the UK test on a '91 car - but all the other
readings on my car are way below the limits so I convince
myself that my little tour of the neighbourhood before the
test can’t do any harm! :-)–
The original message included these comments:
It’s an 89. There’s NO air pump and NO EGR valve. What can I do
to lower NOx emissions without having to resort to a new catalyst?
Visit the Jag Lovers homepage at http://www.jag-lovers.org for exciting services and resources including Photo Albums, Event Diary / Calendar, On Line Books and more !
When they do an MOT they have to have oil and water temps within set limits
so that, even if the car is not hot when it arrives, it must be run until it
reaches the correct temps anyway, especially now it is all computerised and
recorded back a DVLA.
NW
I always drive my car around (hard) for a few miles before I
get to the test station (which is only 1� miles from my
house) and leave the engine running whilst I wait for the
annual MoT to commence
Visit the Jag Lovers homepage at http://www.jag-lovers.org for exciting services and resources including Photo Albums, Event Diary / Calendar, On Line Books and more !
Its even more important on an older car. The converters can lose a bit of
efficiency as they age and either get coated or burnt off a bit. Converters
in general need to be hot to work. You want them as hot as possible for the
test. Also try to arrange such that you can get the car in quickly rather
than being parked for a period of time and cool down.----- Original Message -----
From: “Bryan N” sophistic@btopenworld.com
To: xj40@jag-lovers.org
Sent: Sunday, September 03, 2006 12:12 PM
Subject: Re: [xj40] Emissions
In reply to a message from Jaguarpete sent Sun 3 Sep 2006:
Pete,
Knowing very little about the subject, but reading some
bumpf on automotive NOx reduction, it would appear that NOx
emissions are greater if the catalytic converters are not
good and hot for the test.
Did your '89 get a good run before putting it on test?
I always drive my car around (hard) for a few miles before I
get to the test station (which is only 1� miles from my
house) and leave the engine running whilst I wait for the
annual MoT to commence. It so happens that NOx emissions are
not part of the UK test on a '91 car - but all the other
readings on my car are way below the limits so I convince
myself that my little tour of the neighbourhood before the
test can’t do any harm!
The original message included these comments:
It’s an 89. There’s NO air pump and NO EGR valve. What can I do
to lower NOx emissions without having to resort to a new catalyst?
Visit the Jag Lovers homepage at http://www.jag-lovers.org for exciting
services and resources including Photo Albums, Event Diary / Calendar, On
Line Books and more !
Visit the Jag Lovers homepage at http://www.jag-lovers.org for exciting services and resources including Photo Albums, Event Diary / Calendar, On Line Books and more !
Its very easy to get the water and oil temperatures up to spec. However it
can take considereably longer to get the catalytic convertors to their
maximum temperatures especially if you are warming the car by just idling.
Its even more of an issue when the cats are farther back from the engine.
Its not much of a big deal when everything is brand new. However when
everything is a little bit older and a little less efficient little things
can make the difference between pass and fail.----- Original Message -----
From: “Norman” norman_watkins.watkins@btinternet.com
To: xj40@jag-lovers.org
Sent: Sunday, September 03, 2006 3:10 PM
Subject: Re: [xj40] Emissions
Bryan
When they do an MOT they have to have oil and water temps within set
limits so that, even if the car is not hot when it arrives, it must be run
until it reaches the correct temps anyway, especially now it is all
computerised and recorded back a DVLA.
NW
I always drive my car around (hard) for a few miles before I
get to the test station (which is only 1� miles from my
house) and leave the engine running whilst I wait for the
annual MoT to commence
Visit the Jag Lovers homepage at http://www.jag-lovers.org for exciting
services and resources including Photo Albums, Event Diary / Calendar, On
Line Books and more !
Visit the Jag Lovers homepage at http://www.jag-lovers.org for exciting services and resources including Photo Albums, Event Diary / Calendar, On Line Books and more !
In reply to a message from Dave sent Sun 3 Sep 2006:
The car was run fairly hard on the 20 mile trip to the testing
station, and sat idling in the queue until it’s turn. The owner
was told to shut the engine off and leave the car. Less than a
minute later the monkey in the official coveralls restarted the car
and drove it onto the chassis dynomometer and ‘drove’ it through a
simulated road course. It seems to me that everything swould have
been at optimum operating temperature.
My only advice was for the guy to take it one of those Precision
Tune outlets with the emissions paperwork (including the printout
of the HC, CO, and NOx curves) and ask many questions. I suspect
the oxygen sensor may be reporting low levels to the computer,
which makes everything run leaner than it should. But I don’t have
the test instruments and I’m not about to start swapping parts
hoping that I’ll fix the problem.–
The original message included these comments:
Its even more important on an older car. The converters can lose a bit of
efficiency as they age and either get coated or burnt off a bit. Converters
in general need to be hot to work. You want them as hot as possible for the
test. Also try to arrange such that you can get the car in quickly rather
than being parked for a period of time and cool down.
Visit the Jag Lovers homepage at http://www.jag-lovers.org for exciting services and resources including Photo Albums, Event Diary / Calendar, On Line Books and more !
In reply to a message from Jaguarpete sent Wed 6 Sep 2006:
Mine failed on the HC test.
Gave it the best gas, changed the oil, put in K&N filter and ran it
until hot. When I went through again I got the same ‘‘technician’’
and got only a slight improvement.
Decide to take it to another center (I did crank up the idle a bit)
got what I considered a less agressive tech who seemed to take the
drive easy. Passed with dramaticaly lower readings (40% lower).
Did notice that there were alot of mechanics plates going through
with me. So not sure if it was the different driver or the cneter
is known to be ‘‘softer’’.
Anyway I am now good for two years!
Tom–
The original message included these comments:
In reply to a message from Dave sent Sun 3 Sep 2006:
The car was run fairly hard on the 20 mile trip to the testing
station, and sat idling in the queue until it’s turn. The owner
was told to shut the engine off and leave the car. Less than a
minute later the monkey in the official coveralls restarted the car
and drove it onto the chassis dynomometer and ‘drove’ it through a
simulated road course. It seems to me that everything swould have
been at optimum operating temperature.
Visit the Jag Lovers homepage at http://www.jag-lovers.org for exciting services and resources including Photo Albums, Event Diary / Calendar, On Line Books and more !
Hi All.
I just thought I would share this with the members.
At the place that I am working from at present is where NZ 'ers have their
cars checked for the bi annual Warrant of Fitness (MoT) to the brits.
While we do not measure emissions at present the site does have a test unit.
As it appeared the workers were quite devoid of any cars to test I arranged
with the site manager to conduct a test on my '92 4 ltr.
I must admit that I was not expecting a great result, so imagine my surprise
when the results came back with the following figures;
Co 0.47% VoL
HC 177ppm
Co2 14.6% VoL
02 1.01% Vol
Lambda 1.026
The limits for NZ are;
Co 1.00% VoL
HC 300 ppm
They tested both tailpipes and the opposite side was;
Co 0.46 % VoL
HC 178 ppm
Co2 14.7% VoL
02 1.04 % VoL
So as far as NZ would be concerned that is a pass.
The reason I am surprised?
I replaced both the small cats in the down pipes with straight pipes and
the cats downstream with small bullet type mufflers a number of years ago
now, also the car is coming up for an oil change and the plugs top be
checked. And it is closing in on 200,000klms.
Regards Robin O’Connor
'92 XJ40 4.0 Ltr
Auckland NZ
Visit the Jag Lovers homepage at http://www.jag-lovers.org for exciting services and resources including Photo Albums, Event Diary / Calendar, On Line Books and more !
In reply to a message from Robin and Maureen O’Connor sent Thu 18 Jul 2013:
Hi,
To give you something to compare those figures to, here
are the results from the last MOT test for my own 4.0 xjr,
together with the permitted levels as it currently stands.
The entire exhaust system is original and the car now has
approx 126.000 miles on the clock.
CO. Max Limit. 0.200 Actual value. 0.121
HC. Max limit. 200ppm. Actual value. 7
Lambda. Min limit. 0.970 Max limit. 1.030. Actual value1.005.
The co2 levels are not listed on the pass sheet. I’m not
certain but I don’t think they test for co2 as part of the
British MOT ?
I’m told one return flight from the UK to the USA puts more
greenhouse gas into the atmosphere than the entire traffic
volume on the M1 motorway does over a 24 hour period.
cheers.–
The original message included these comments:
I just thought I would share this with the members.
The reason I am surprised?
I replaced both the small cats in the down pipes with straight pipes and
the cats downstream with small bullet type mufflers a number of years ago
now, also the car is coming up for an oil change and the plugs top be
Visit the Jag Lovers homepage at http://www.jag-lovers.org for exciting services and resources including Photo Albums, Event Diary / Calendar, On Line Books and more !
Hi Dave hope you got my E.mail ? Yes I would never be without an XJ40, in fact I still have the same one from that post back in 2013 although now the mileage is closer to 150,000.
I’m pleased to say its passed the MOT every year without any advisories for the past 8 years, the most recent was in November.
Pete. If the car has been out of use for a while change the oil and gas , take it for a good run. I store my car every Winter and every 2 years we had a test, it never failed and I have never changed had to touch the exaust system or cats 380,000km. Regards John
If O2 sensor was bad, you’d see it on both CO and HC. Just NOx out of specs on '89 (i.e. car without Exhaust Gas Recirculation), means that catalytic converters got old (his car has two). If they are original, they are relatively easy to replace. If not original, watch out, Cat shops tend to cut out old ones and weld new ones in, so you may not be able to do it yourself w/o cutting. I am having my rear one restored to the original condition, after last shop removed all flanges and welded everything to everything.
