Help. I'm sure someone will re-direct me if I'm in the wrong area.

Almost two years ago my 1995 xj6 failed to pass California's smog test. The last test after making "repairs" showed a reading at 15 mph exceeding the maximum by 19 and at 25 mph exceeding maximum by 21. The repairs ran over $1600. I received a waiver to operate the car for 2 more years which will end shortly.

Before going for one more smog test, I'm wondering: will an oil change make a difference? will the kind of oil matter? will the octane of the gas matter? will the source of gasoline matter in terms of brands (Shell vs Arco, for example). Do these factors affect HC emissions?

Two years ago I was told the two suspected problems were: cracked coils and deteriorated catalytic converters. I'm unwilling to invest in replacing these on such an expensive gamble that it will correct the problem.

I've had very little problems with this 1995 Jaguar in the 14 plus years I've owned it. Any advice would be appreciated before I consider turning it in.

Thank you.

 

....you dont mean to imply that you have not done an oil change in the last 2 years right?
anyways coils are not that expensive and at 15 or so years old its time to replace them even if just as maintenance. check for visible signs of failure(cracked on top, cracked boot, plug hole full of oil), and clean all of your connections.
Chances are unless youve been driving the car in a very rich condition for a very long time the cats are fine, do not mess with them until youve run out of other options

 

I would sure like to know about the "new coil" advice. Is there some symptom like misfiring (car shuddering on acceleration )? Is the CEL on? Any codes?

 

I appreciated the two replies to my original thread.

I have been changing the oil...I wonder about the coils though I haven't had any problems in smoothly operating the car, from start up to turning off the engine. Report two years ago said: coils are cracked but no misfires; no trouble codes. Mileage has been fairly consistent ever since I've owned it and hasn't declined in the last years.

Read through googling the factors that affect hydrocarbon emissions such as air pump filter, catalytic converters, ignition system, etc. Feel a bit more informed but not directed toward any particular action.

This 1995 xj6 sedan has only 122,000 miles on it. It rides beautifully and has been great all these years. Hate to let it go...I'm sure you know how I feel. Recent hwy mileage was about 25 mpg.

Smiles, Anne

 

If there are no misfires noticed and no OBD codes, then I very much doubt the coils are an issue.

Have you read about how to clean the mass air flow sensor (MAF) on an X-300?.

IIf you can get someone to scan the LTFT and STFT fuel trims and post that. it would go a long wayt towards a better guess of what's going on.

 

To put it another way ... OBD was specifically introduced to help maintain the emissions related health of engines. Therefore, on a OBD equipped vehicle it is the first place to look before randomly changing parts.

 

You are right, Plums. That is what i was trying to say!