1999 Poor MPG after vavle job

I had a valve job done on my 1999 Grand Marquis, the garage had problems getting it running and had to redo a lot of work. Mine has sodium filled valves which surprised the mechanic at the garage. They replaced all the valve guides and three valves, I had gotten bad gas which caused some of the valves to stick with one bending and some of the rockers to fall off the cams. Believe it or not, this car did get around 30 MPG on the interstate and about 16 around town. Now I can only get around 20 MPG interstate driving. What could be wrong? I have new plugs, New K&N air filter that I did not have before. I also have noticed I have a lot of low end now and my car sounds more like a Mustang GT now. If I accelerate quickly from a stop and hold the pedal about 3/4, my engine seems to over rev and the trans does not shift to a higher gear unless I back off the throttle. Any ideas? Cam timing off or something.

My initial guess would be incorrect cam timing but it can be so many other things. One tooth off on either cam will not cause PTV but characteristics will be different and mileage will be worse.

Did the shop pull the cams and/or chains off? Maybe the heads were pulled and the job done on a workbench meaning atleast the chains had to come off. The valves and seals can be replaced with the cams in position but it would be easier to remove them.

I don't know of any way to check the cam timing other than to pull the front engine cover or to use a degree wheel and degree the cams to see if they are off.

IIRC, one tooth off would change the cam timing by about 10 degrees.

It may also be a computer or sensor problem. Since your shifting has changed, I'd look into sensors and the ECU. Connect a code reader to see if there are any stored codes. Note, most cheap code readers will only read OBD-II specific codes. Ford-specific codes require special scanners. My laptop program can pull them up. I've forgotten to plug the MAF back in on more than one occasion and the CEL never lit and shifting was unusual. After seeing my computer say it had no MAF data, problem solved. A normal code reader was not able to read that code.

It could also be an exhaust leak making it sound more like a Mustang GT and killing mileage at the same time. If the exhaust manifolds are leaking before the cats and HO2 sensors, then they will read lean and enrich the mixture wasting gas and the exhaust leak will makes things louder. It usually sounds like a tick when the components are cold.

Heads were completely removed and sent to a machine shop for service. Cams were put back on at that shop, not the garage. They had trouble getting it to run the first time around, the original mechanic who took it apart was fired mid way the job and someone else had to redo a bunch of things.They finally got it to run after four weeks in the garage, I don't know exactly what else they did to it. The car just sounds so different, I have looked for exhaust leaks when it was very cold (below 30°) usually as the cart warms up, you can see any leaks in the exhaust. I suspect the timing is off just enough to make it run the way it does. I do get a little pinging on hard acceleration at high RPM, which makes me think timing is off. I guess there could be a vacuum leak too. So many things it could be, I don't really trust this garage anymore. This is a very clean car, was great on the interstate with terrific MPG. It would be nice to have her around for another 100,000 miles if 30 MPG on the Interstate was obtainable again. Vehicle was built in Canada.

Remove the valve covers and front cover and re-time the engine. I'd say that may be a good start. Use a small ratchet to get the hard to reach bolts on the passenger side valve cover and remove the fuel injectors from that side to remove the valve cover.

It took me about 5 hours of actual work with help to get the valve covers and front cover off and back on, plus swapped cams. See the pictures link in my sig for some pictures of the front cover and valve covers removed.

They may have even damaged other engine components if it took them 4 weeks to get it to even start again. Might be worth it to just go to the junkyard and pick up "new" engine. For $500 give or take you can get a mid mileage newer engine. Go for a 2004 and up if you can. They offer a little more HP. You will have to use your wiring harness, fuel injectors, throttle body, etc.

This Auto has a interference type engine!
If cam to crank timing is off, noise, lost hp, and bent valves.
10% or one tooth not sure!

1) Check the compression on each cylinder.
2) Check ATF warm, and in the parked pos.

Is there any diagnostic trouble codes (DTC) being thrown?

If ''ok'', I would look at the MAF, and the upstream O2 sensors.

This Auto has a interference type engine!
If cam to crank timing is off, noise, lost hp, and bent valves.
10% or one tooth not sure!

1) Check the compression on each cylinder.
2) Check AFT warm, and in the parked pos.

Is there any diagnostic trouble codes (DTC) being thrown?

If ''ok'', I would look at the MAF, and the upstream O2 sensors.

Is it possible they messed up the timing the first time after assembly and that's why they couldn't get it running? Then as a result they bent a valve? Could the engine then be reassembled to correct the timing, but leave a bent valve in?

I would definitely check the compression.

Well, I called the garage that did all the work to my car two months ago and they are going to check it out. They said, it should get a lot more MPG than what I'm getting and it is very possible the cams are off a little. He said with the chain being so long they have made the mistake before. Anyway, they are not charging me anything to do the work or fix the oil leak that it had since the work was done. I hope they get it right this time, they have the cam gauges and everything to do the dob right. I guess time will tell. Thanks guys for all the replies, I told the mechanic what you thought my problem might be and he agreed.

Problem fixed, They had the timing off one tooth on both cams. The good thing is it didn't hurt the engine by bending any valves. It starts better, runs better and quieter, and has more power. Have not been able to check the milage on a trip until April 1st when I drive to Georgia and back in a day.