Spark plug question (97 4.6 T-Bird)

I've been told many times that if there was a sparkplug that gave you lower emissions and better mileage don't you think the manufacturer would use it? As for the oil burning: on a car with 190,000 miles, I doubt using a quart of oil every thousand miles is out of line. I certainly wouldn't go to a heavier grade or use any additives to stop it. You might want to do a compression check and/or a leakdown test to see what kind of shape the cylinders, valves and rings are in, but personally, I wouldn't worry about it.

On emissions, it either passes or it doesn't, and a good mechanic can tell you what the best time is to bring the car in for emissions..Often when the car is warmed up and driven a little hard before bringing it in. Often it's a faulty component that causes a car to flunk. I seriously doubt spark plugs or a different oil will make a difference. Now, that said, if the car is smoking you might be able to hide that, but I can't see a car that only burns a quart every thousand miles smoking.

Forget changing the plugs - if it's not misfiring it won't gain you anything. Put fresh oil in for the test - 10W40 or 15W50 will cut the oil consumption to less than half - which will keep the hydrocarbons down and keep the cat functioning (clean). And really, a yankee quart every 1100 miles is NOT a serious oil consumption rate.

I would add to the rest that if the car only gets short runs around town to get it out on the highway to get the cats up to temp. so they burn off any build up in them before testing.

Thanks to all, much appreciated.

A few years back you helped me with changing the gasket on the oil filter housing. I'm an old (as in no longer) boat racer and as soon as it was time for an oil change (bought it new) I switched to a 20-50 racing oil. Seems to have worked out Ok but I always wondered if that impacted the aforementioned gasket. Switching to the lighter oil upped my mileage noticeably (to my surprise) but since I am 'paranoid' and it is winter, I may go ahead and change to something heavier for a while.

Thanks again.

When I had to go through that here in Florida I would purchase one of the many gas additives that the autoparts stores sold that advertised to reduce emissions. It would always help my 79 Corvette pass the tests, if I didnt' use them I was doomed to failing the test. I don't know if they still sell them as they stopped emission testing here years ago.

I would not worry about the plugs at that mileage unless there is a misfire.

The only thing you may want to do is clean the MAF with a good residue free aerosol electrical cleaner. Make sure the air filter is not choked with a ton of visible crap.

The oil consumption on the 4.6L V8 is as often as not is valve seal leakage with nothing to do with pistons, rings or cylinders. 1qt/1100 miles is not excessive. IIRC, Ford still specifies 1qt/750 miles or more as excessive on most of their rngines. Keep in mind that a qt of oil every 1k miles is something like 1 drop every 800 feet - really miniscule. Most engines that appear to have zero consumption are simply replacing consumed oil with combustion byproducts (blowby).

Your best bet is to continue using the lighter 10w30 oil. The 4.6L seems to not circulate the higher viscosity oil well resulting in noisy timing chains and valves until fully warm. Ford now recommends a 5w20 for pretty much all of it's vehicles. I have stayed with 5w or 10w30 in all of mine since they predate Ford's 5w20 recommendations. I have a couple north of 1/4 mil miles with no oiling problems other than valve seal replacement. The worst one on oil consumption at 1qt/600 miles is very close to the low end of the emissions requirements - about as clean as it was new. The cats are not affected as much by oil consumption as they were in the early years since oils have been reformulated to remove components that are adverse to the cats longevity.

The best thing for the test is a fresh oil change followed by a nice drive a normal temperatures just before plugin' her in for the sniffer test. If it then fails, you can examine the test results for clues to the guilty system or components. There may also be stored fault codes. You may want to visit one of the parts stores to besure there are no stored codes. Here in GA, a stored fault code is an automatic failure even if there is no light. They don't take the time to determine the code is or is not related to the emissions portion of the system.

Lugnut

Thanks much. Is it possible to replace the valve seals without removing the heads?

Doing a manifold R&R to repair leak in heater pipe bracket mentioned in earlier post and there was a noticeable oil residue around the intake seal areas and inside the intake manifold. Can that be valve seals also?

Guide seals on MOST engines CAN be replaced without removing the heads, but there is a trick involved - requires use of a length of rope and a few special tools.

Mechanics have ways of doing lots of things, but you absolutely have to do a leak down test or something similar to determine where and what the problem is before you do any work. IMHO I still don't think you have a serious problem. Before you start freaking out do the simple things first, air filter, warm up the car and blow out the crap, and see how it does on the emissions test. Some mechanics can test emissions before you actually do the test.

Thanks. I've cleaned the MAF (do that regularly) and the air filter is new. Should make it to smog tomorrow or Wednesday. I'll post the results.

Why would you put heavier oil in it in the winter???

People think that heavier oil will stop oil from burning off and getting past the rings and guides. This may be true, but the tradeoff is poor lubrication and premature wear.

Passed easily: (thanks again for the tips) HC actual = 6/3 allowed = 49/33 CO actual = 28/25 allowed = 47/44 NO actual = 214/229 allowed = 409/696

OK - I have no idea where the OP is located, so if the weather is terribly cold or not - and a 10W30 or 10W40 is the same thickness when cold - but 10W40 will, all other things being equal, be consumed at a slower rate. As for the wear, it can actually balance out, depending on what driving the car gets. Yes, thin oil (low number before the W) lubricates quicker when cold - but in some cases thicker (higher number after the W) oil lubricates better when warm, and the engine spends a lot more time running at temperature than it does starting with thickened oil. And as a mechanic I don't buy the explanation the manufacturers are giving for using 5W20 oils (better lubrication when cold). It is a CAFE issue much more than an engine wear issue. The clearances in engine bearings have not changed appreciably in over 35 years. The improvements in quality control and finish quality means the mean clearance may well have INCREASED as there are fewer high spots to cause restricted clearance. When a clearance was specified as 10 thousanths of an inch it was very common to have a few percent of the bearing surface less than 5 thousanths of an inch - which caused (required) accellerated wear to get "broken in". That does not happen on today's engines to any extent.

If the OP is in a very cold part of the continent he might want to consider a wide range synthetic oil (like a 5W50) to get both advantages.

I'm in Southern California. I did switch to 20/50 Valvoline Racing Oil and when I compared my emissions printout to the last one two years and

15k ago it was /significantly/ better.

Significantly better /this/ time.

Your NO is a bit higher than I would have expected. It can usually be corrected easily by cleaning the EGR ports on the

4.6L V8. You may want to do that before your next test if you get a little slack time.

Lugnut