Question about Jaguar XJS

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My 1994 XJS 4.0L Auto failed the Mot with off the scale emissions Second fast idle test - co% 7.456, HC ppm 1304, Lamda 0.765 Any suggestions, ecu, oxy sensor etc.

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5 Suggested Answers

  • 154 Answers

SOURCE: Test no pass

Have you got all your hoses running to the emmission control box (usually a round or rectangular box on the passenger side near firewall). Is the box old and needs replaceing? If you don't want to change because is very dear to do you could change your spark plugs and fuel filters? Also change your oil with a lighter oil a 55w/10 and oil filter and your spark plug leads with new ones 8mm diamiter would be good as it is less resistance for the spark which will aid in fuel burn and air filter change is good idea to, maybe 200 dollars or so to do this but all will help reduce your emmissions if emmission box isn't working properly. Hope this helps

Posted on Jul 26, 2008

  • 72 Answers

SOURCE: what will bring readings into limit

A failing oxygen (O2) -sensor will give failing emission tests. Normally you also get other symptoms:

- too high fuel consumtion
- bad acceleration, stalling problems, sputtering
- the check engine light comes on indicating that the engine control unit has recorded error codes (which will be related to readings of incorrect fuel/air ratio when read by the OBD diagnostics tool at a repair shop).

It is always a good idea to see if you can get any readings from the check engine light if present or much better by an OBD reader to be as certain as possible.

Another component that could cause failing emissions tests is the catalytic converter, giving a similar range of symptoms. To determine if this is the cause is not so easy on older cars with only one O2 sensor, it requires diagnostic skills and equipment. On newer cars with OBDII-systems it will give a recognizable fault code for the cat converter.

Then there are also the issues of the actual cause of malfunction in either or both of these components, is it due to old age and normal wear and tear or is it due to contamination from burning oil (blue tail pipe smoke) or anti-freeze (white smoke), misfiring, etc? Then the cause must be treated as well for a successful repair.

Normally these components have a very long life span and should not have to be replaced more than once or maybe twice for the sensors during the car's lifetime in an otherwise health engine.

Good luck!

Posted on May 25, 2009

  • 35 Answers

SOURCE: volvo 850 wagon failed NOx emissions test - badly!

Hey Pitloops!
It seems likely that one or both of your o2 sensors are acting up, or that your engine is sucking in unaccounted air from a leaking vacuum tube. Spray the tubes with "start gas" while the engine is idleing. If you hear it revving up when you spray the gas on the tubes you'll know there's a leak.
I'll sacrifice a squirrel for you and hope that the problem isn't your o2 sensors since they can be expensive to replace. Fcpgroton.com is probably the cheapest part supplier online if you'll need new sensors.
You might also want to clean your throttle body, as it usually gunks up with carbon deposits and sludge over the years. It only costs you the price of the carb cleaner to do it and the car will probably run better afterwards even if it doesn't solve the problem.
Good luck!

Posted on Jun 27, 2009

morse008
  • 1111 Answers

SOURCE: FAILED EMISSIONS

possible but could be head gasket or valves , or worn rings and is by passing the pistons going straight out the end ...or maby settings are wrong ? try carb cleaner and inspect visually air-filter etc.

Posted on Aug 26, 2009

  • 1 Answer

SOURCE: ASM 2525 NO ppm TAILPIPE EMISSIONS failure

I have a 94 Tbird with a reading of 790 NO ppm at 1871 RPM, I put about a liter of water into the intake at about 2000 RPM and changed vacum lines to EGR valve,(may have been cracked), now the reading is only 214 NOppm at 1348 RPM. This much change I don't understand. Maybe this info may help someone.

Posted on Sep 17, 2009

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possible but could be head gasket or valves , or worn rings and is by passing the pistons going straight out the end ...or maby settings are wrong ? try carb cleaner and inspect visually air-filter etc.

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and if so what are your engine codes?
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we cure your trouble that caused your engine light to come on and you will pass your test.
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