Help, 1997 t-bird V8, has a service light on

[JMurray64]

Just for future refrence if you are going to go through all the trouble to pull the heads off that 4.6L do yourself a favor and go to a junk yard and ask them for 4.6L heads and intake from a 2001 up crown vic 2valve. slap some new valve springs to them and clean them up a bit and put it back together. if you still have your miss its obviously not mechanical and if the miss goes away you will of picked up an extra 35-40 horse's for your trouble.

[mach2race]

A friend of mine has suggested yet another mechanic. This guy claims he can find the problem, and even has the ability to re-flash the computer? Are these ECM's reflashable? The engine does not smoke at all, which makes me doubt there is a problem in the valve train. I have sprayed starting fluid around the intake on cylinder #5, with no noticeable change in idle. Mechanic #2 filled the intake with smoke, but found no leaks. For the most part, every mechanic has decided, the problem must be something inside the motor, due to the fact... they can't find anything wrong outside the motor. I have already spent too much $$$ troubleshooting this motor, so now I am hesisitant to send it to yet another mechanic. I am tempted to spend the $150 bucks on an ECM, as opposed to spending it on yet another mechanic, that can't find the problem. I am lost at this point.

[mach2race]

Thanks for the input guys. I've decided to take some time and think about my options. So, far I've been throwing money at a problem, that no mechanic can pinpoint. The car has 70,000 miles on it, but the car & engine look like new.

So I'm looking at my options.

1) take a chance that this new mechanic can find the problem. (its been to 3 reputable shops so far)
2) buy me an ECM module, change it myself... and hope the swap fixes it.
3) Pay mechanic to tear down the engine, to check the heads / valve springs... if this is the problem... repair or replace the heads.
4) Buy another motor, then either pay somebody to swap it out or try to change it myself (I'd have to buy me a motor lift, and a few tools.)
5) Run the car thru an auction, find my daughter another car.

What would you guyz do?
Thanks,
Mach

[TBIRD430]

A. I don't know how much you paid for this car, but it sounds nice & has low mileage.

B. Did option #1 give you an estimate ($) 1st before taking this car there & letting him know what all has already been done?

C. IMO, it would be too expensive for you to do option #3- some of us could do it ourselves and save major $.

D. I'm really leaning to option #5. Given all of the above info & having read this entire thread.

=o(

[BroncoJoe19]

Someone mentioned in another thread, that when they repleaced their wires, that they bought more expensive wires, and it ended up being that the new wires had more resistance than what the coil could overcome and it resulted in missfires.

[mach2race]

when the car starts, it starts up quick, but once the engine idles down, it begins to miss. It doesn't sound like its going to die, but it does run a little rough. as rpm increases, the engine gets rougher about 1500 RPm, s then tends to smooth out, as RPm increases. I kept the old plug wires, and have tried installing the old plug wires back... #5 still has a miss. The only reason i can't figure out why the mis-fire moved from cylinder #2 to #5. I have swaped the coil packs from right to left, and the problem doesn't move. It does appear that the previous owner swapped at least (1) of the coil packs out, probably troublshooting the same problem. the last mechanic thought both coil packs had been changed, both may be aftermarket coil packs. One is in a plastic case, the other is kinda transparent looking, so you can see the gel inside. But, all 3 mechanics believe the packs are working properly.

[BroncoJoe19]

Regarding the missfire moving from cyl 2 to 5.

Perhaps you initially had two bad cylinders, 2 AND 5. You said that it got better after you replaced plugs etc, but then you got a code for cyl 5. Just for the heck of it swap the coil wires for cylinders 3 and 5 as they insert into the coil pack, and see if the missfire moves to cyl 3. IF it does, that would definitely rule out a mechanical problem.

This is my understanding. The coil pack for cyls 3 and 5 should fire at the same time. One cyl is on compression stroke, the other is on exhaust. The one fired while on exhaust is "wasted"

[mach2race]

Update, last weekend one of the guys from another forum offered to help me diagnois the miss. We changed coil packs, the computer, but nothing helped. Our best guess is something in the exhaust valve.
However, Monday... another forum member wrote in with a similar problem. His intake was leaking around the thermostat housing, allowing steam to enter the #5 cylinder. This is the closest cylinder to the thermostat housing. I have noticed, that when the engine is cold and I have a new plug installed in cylinder #5.... the engine runs fine for about 20 minutes. Then eventually, you can feel it miss, then the check engine light will come on. The intake is not the original intake, probably the old one cracked and somebody changed it before i got the car. I've also been told that some of those aftermarket intakes are crappy and have rough edges, which can cause them not to seal properly. So, is there a way i can test this theory, without tearing off the intake? If i remove the plug on cylinder #5 and unplug the injector.... should I be able to see the steam escape thru the spark plug hole?

[mach2race]

Also, if this aftermarket intake is the problem, can I get a latemodel (2001 and up)4.6 intake off a crown vic or a mustang and simply transplant the entire intake, fuel rails, and components over to my 97 block? Or should i swap out the whole motor? Or buy a new intake? What years of intake are interchangeable with my 97 4.6 motor?

Thanks

[BroncoJoe19]

are you losing coolent?

Ford did have a problem with the 4.6L intakes on the Crown vics. I had to replace mine due to cracking.