just bought a 97 t-bird, but has service engine light? - Page 4 - Ford Forums

mach2race · 10-20-2009, 09:39

Mechanic #2 pulled the valve cover off, because we originally though the cam lobe might be bad. He said, the exhaust valve looked to be working fine. This guy specalizes on ford 4.6 motors, so I have to believe he would have checked this. I am totally lost on this one. I never seen a motor that missed, that couldn't be diagnoised. However, the last 2 mechanics are 99.9% sure, its something internal. Probably because everything else has been checked. The only other option to tearing the motor down, could be to changing the ECM... but all 3 mechanics believe the ECM is working as it should.

**rtg143** · 10-20-2009, 10:05

It's very hard to see a broken spring if it's very low. They still look good, unless you look VERY closely. If there was a problem lower, you'd hear a noise with it or use a lot of oil and maybe blowby.

mach2race · 10-20-2009, 11:33

I agree, the motor doesn't appear to have any mechanical issues, other than the miss. the engine starts instantly, and other than the slight shake from the miss, the car drives great. At higher speed, you don't seem to notice the miss. In gear, at idle... the RPm drops to about 600 rpms, which makes the miss more noticable.

mach2race · 10-22-2009, 14:11

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.

**rtg143** · 10-22-2009, 14:23

A broken valve spring won't make them smoke and if it's broken at one end. they'll still have good compression. The ECM is reflasheable but won't fix a miss. Not that I've seen anyway.

mach2race · 10-23-2009, 14:59

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

**rtg143** · 10-23-2009, 15:43

Taking the valve cover off is fairly easy to do. I would almost bet that it's a valve spring. I've replace several on the Crown Vics during those years. Look closely at the valve springs on that cyl. You can try pushing the valves down and see if they are easier to push than other ones. I really doubt that it's the ECM even though it's a possibility.

mach2race · 10-24-2009, 22:17

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 RPms 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.

**rtg143** · 10-24-2009, 22:42

I forgot that the problem moved from 2 to 5. That would definitely rule out engine problems. I'll check further, I have to refresh my mind on this system.

**rtg143** · 10-25-2009, 10:21

Here's the way the plug wires are supposed to be connected. Make sure they are the way it shows. When the coil fires, it fires 2 t a time. One gets the most spark and the other less. The next time they fire it switches and the other one gets the most spark. If the wires have been switched, it might cause that.