A question for anyone that knows the 300 I6. I have an '86 F150 4X4, 4 speed manual. My problem is that the truck runs great with the timing advanced way too far. The only problem with this is pinging under load with 89 octane...93 almost takes care of it.

If I pull the spout connector and set the timing to 10 Deg BTDC (which is where it should be), the truck idles rough and diesels bad when I shut it down, but no knock or pinging. EGR and O2 sensor are new. Only happens in closed loop (hot)

Any ideas why....and what controls advance on this engine?

 

have you rebuilt the motor at all?
or the timeing chain could be streched out and need replacing



michigan mud duck 1

 

Thanks. The engine is original and has 95,000 easy miles on it. No oil consumption.

Timing chain stretch makes sense, however, there is no knock or ping until it warms up.

Any other thoughts?...

 

On the 300 I-6.

I believe all of the 300's used timing gears instead of chains. I had a problem on mine (when I had the 300 in it) that turned out to be a messed up fuel pressure regulator. The regulator had a pinhole in it and was causing gas to enter the vacuum system which really messed everything up.

Have you replaced any ignition components? It could be something there. Although I have heard that the 300's need the higher octane gas to run right. I know mine and my dads F-150's with the 300 were both like this.

Is there anything else you've replaced?

 

Just replaced the usual so far, Rotor, cap, plugs, wires,EGR, O2 sensor, air & gas filters. The fuel pressure regulator sounds like something I'll go after....Thanks for your help.

 

Get a fuel pressure tester and that will tell you whether your fuel pump is bad too. It might also tell you whether or not your regulator is bad as well.

Has anyone replaced the gasket where the throttle body bolts to the upper intake that you know of? Ford has had problems with these in the past. I know mine didn't have the correct one on it and it ran like crap.

 

A couple of things to consider ...There are a couple of marks on the pulley , only one is used for the ignition timing , its just a small mark on the pulley , not one of big indentations . Use the smallest one when checking the ignition timing . Its also possible the pulley has slipped , turned on its rubber bushing causing you to set the timing incorrectly . The Ecu controls the timing advance if you have an Efi system .

 

You may have misread the timing marks OR you may have excessive carbon build up on the valves. The carbon will actually get hot enough to ignite the fuel/air mixture too soon and will also cause it to diesel... also check for manifold vac leaks. let me know how ya make out.

Mike