My 97 F150 4.6L with 100K will barely run, no engine vacuume, the exhaust on driver's side glows red. Have been told it was the Cat. Converter plugged. Not the problem. Then a shop mechanic suggested the coil pack on that side was bad. His analysis was based on unburned fuel on that side making the pipe glow red. I am not really the type to throw parts at it. Any suggestions? This thing runs really bad. The engine will still barely run with the brake booster vacuume hose pulled off, no change. Help!!!

 

How did you check the exhaust? I would doubt the coil would be the problem.

 

I broke the exhaust loose from the manifold on that side. How about low fuel pressure causing a lean running condition?

 

If anything, the extra unburned fuel will cool it down. Have you checked your injectors?

 

No, I have not checked the injectors. What would I be looking for?

 

Are you saying that with this poor operation you have no CEL light?
No code set?

That is the first thing you look at.
Check fuel pressure.
Ignition is working.
Check ignition timing, it can be done if you know how. Late timing will heat the pipes.

 

No Check Engine Light. No codes either. Yes, it is crazy I know.

 

I'll check the timing. I kinda suspect the fuel filter. I am ashamed to say it has not been changed since '98 probably 70K miles ago. My first instinct was that it had jumped valve timing. I understand that with the lower mileage the chains and gears are not a problem, usually. I have religiously kept the oil changed every 3 - 4K since new. I have already cleaned out the TB intake "nostrils", replaced the sensor. It had a lot of carbon in the "nostrils" but no fix the problem.

 

Actually, I'd go with the mechanic. He actually sounds like he knows what he's doing.

Unburned fuel due to a misfire usually burns in the exhaust manifold, turning it cherry red.

You most likely have a severe misfire.

Leave the brake booster connected. It's important that it not be open to atmoshpere.

Steve

 

I would go with the fuel filter. They should be done more like every 30K. And yes a lean mixture will cause you to run very hot. The lean problem may also be due to the vacuum problem, if the map sensor(manifold absolute pressure) is not sensing any engine load.... it will not give you any fuel. higher vacuum=more load=more fuel.

you can also check the coil by using an HEI spark tester, it looks like a spark plug, and you insert it in the spark plug wire and then clamp it to ground. then start the car, if you see a big blue spark, everything is good.
Or if you want to be cheap and dont want to buy stuff, take 1 or 2 plugs out at a time and place them on the engine block while still in the plug wire... look for spark.
if you want to check spark without the engine running pull the fuel pump fuse or relay. start truck, let it run out of gas, then test.

Im not sure if ford uses a waste spark system or not, but if they did and you were lacking spark you would have a mis fire on 1 odd cylinder and 1 even. You would have 2 misfires. But if its coil per plug you may only have 1 bad coil and 1 misfire....

DONT TOUCH SPARK PLUGS AND WIRES WHEN CRANKING OR RUNNING--- UP TO 100,000 VOLTS! ZOW! it wont kill you but it hurts.

 

The red exhaust is due to fuel burning in it. A fuel filter won't cause this. A misfire or an overly rich mixture will.

COP systems are not waste spark systems. Each cylinder has its own coil.

Steve

 

Thanks Steve. This is the early version 4.6 with the coil pack on each side. I'll check the coil pack with a tester. Hopefully I'll know soon!

 

Andy, When you checked the cats, did you disconnect both down pipes from the exhaust manifolds ? you might try it just to see if it clears up.

 

If it turns out to be defective coil packs, hope you will consider our Screamin' Demon Coil Packs for the 4.6 at:

http://www.performancedistributors.c...50ignition.htm