just bought a 97 t-bird, but has service engine light? - Page 3 - Ford Forums

mach2race · 10-12-2009, 09:51

UPDATE!!
Hey guys paid $60.00 for a professional diagnois. Electrical system is working properly, 60,000 volt at spark, fuel injector is passing fuel properly. Guy that owns the diagnois center believes the exhaust valve is not opening on cylinder #5, resulting in mis-fire of cylinder #5. he says, the lobes on the camshafts are pressed on, and believes the cam shaft lobe has either slipped, or move completely off to the side, so vlave is not moving... sounds bad. Has anybody ever heard of this? I am taking the motor to a mechanic tomorrow, to have him pull the valve cover and check to see if the exhaust valve is the problem. At this point, not sure if the motor is worth repairing, or should i be looking for a replacement 4.6 motor? IS a bad cam shaft a terminal condition? May be cheaper to change out the motor? What do you guys think??

**rtg143** · 10-12-2009, 10:19

We've had plenty of 4.6 motors in our police cars and never had that happen. After the valve cove is pulled, you can see if the past owners serviced it properly. If it's clean inside, I would just repair that problem. Those engines are good for over 300,000 miles if serviced properly.

mach2race · 10-12-2009, 19:22

This last guy, did another Compression check of cylinder #5. It was 117lbs. This was comparable to the other cylinders he checked.This last guy I took my car too is pretty sharp. he used a scope to listen for exhaust sounds in the intake, and also filled the intake with smoke to check for leaks. He used his snap on computer to manual fire the injector. Soon as it fired, fuel pressure dropped from 80 to 60lbs, so he believes the injector and rail is fine. He also verified the timing and spark of the coil pack, recording a 60,000 volt spark. He said, you have fuel, compression and spark. the only reason I can see for a mis-fire would be no exhaust path. He did mention the rocker may be loose, laying under the valve cover. I guess it could be a spring issue, but he seemed to think a lobe may be slipping on the camshaft. I dunno know? Tomorrow, i will be taking it to a mechanic who specializes in rebuilding ford Mod motors. Hopefully, tomorrow we will know.

**rtg143** · 10-12-2009, 19:35

We had some valve springs break but most made some noise.

mach2race · 10-14-2009, 10:56

Latest update!!
T-bird is still at the mechanic's shop. He removed the valve cover to check the valve train. Everything looks to be fine. HE did another compression check. He got 160lbs, with only a 5% leakdown. He believes the valves are Ok. This is the second mechanic that has looked at the t-bird. He is also scratching his head. He is trying yet another injector, but is not leaning towards an ECM issue, basically, he can't find any reason for the engine to miss. The last mechanic hooked up a vaccum guage and said the vaccum was rock solid. He also filled the intake with smoke, to look for a crack or leak in the intake. I'll get him to do a compression check on the cylinder number 6. Again, everything checked OK. I do feel a little better, at least the valve train seems to be OK, and its nice to know that the same problem that has kicked my butt for the last 3 weeks, is now kicking (2) mechanincs butts, each of these guys have reputations for being good. Unfortuantely, I'm paying the bill for all this labor
Thanks guys, so far you guys have been right on the money.
Any other idea's or suggestions?

JCribb · 10-16-2009, 03:12

wow I have never heard so much trouble over one cylinder. On the up side 4.6's are plentiful If you decided to go the replacement route.

mach2race · 10-19-2009, 08:53

UPDATE.... Strike two!
The 2nd mechanic just threw in the towel. He was to the point of buying and swapping parts, in hopes that he might find the problem. Since that could be expensive... I've decided to take the car to the Ford stealership. Hopefully, they can check the ECM, and determine if its bad. Both of the mechanics I have taken the car too, have reputations for being pretty sharp. But, they have both ran out of idea's. I'm begining to wonder if this t-bird will ever get fixed?

**rtg143** · 10-19-2009, 08:56

Hope you keep us updated. Hope they can find what's up.

mach2race · 10-19-2009, 16:47

UPDATE....STRIKE THREE,
Took the car to the stealership, this afternoon. first, they told me they could test the ECM. They lied. They could only confirm that the computer was controlling the fire and fuel.
The FORD tech, worked on the car for a couple of hours. At the end, he said... I am 99.9% sure, you have a mechanical issue in the motor. He guessed, perhaps a weak valve spring, but that was only his best guess. The mechanic from last week, suggested I run the car thru an auction and get rid of it. He said I would be looking at $1000. just to pull the heads. the car is really nice, but I have already invested $2200 in the car, plus $300 more in labor. My daughter really likes the car, but I am getting very discouraged. At this point, i believe it is safe to rule out a simple spark, fuel injector issue. I could try a new computer ECM for $150 bucks, but all three mechanics, believe the computer is probably OK. This motor has 70,000 miles, so i could look at replacing the motor, but I was told a 2000 model 4.6 will not work, it needs to be an early 4.6. I don't know what to do?
Any suggestions?

**rtg143** · 10-19-2009, 20:44

I would say to pull the valve cover on the side with the miss and see if the valve springs are okay. We've had springs break. sometimes low and the didn't make noise but wouldn't close tight when running.