Mechanics

F 150

1984 Ford F-150 • 6 cylinder 4WD • 103,000 miles

Hello,

1984 Ford F 150 with 4.9 liter 6 pings under load going up hill. If you press the throttle all the way to the floor, the Pinging goes away. It is timed at 10 dg. BTC and appears to be advancing properly. This year has the TFI Distributor module on the Dist. It also has the flow or feedback 1 barrel Carb. New wires, correct new plugs etc.

Does this year have a knock sensor? Could it be running too lean or too rich at some point? Possible carbon buildup on some of the pistons?

Odd but really annoying problem. Any help appreciated.
Avatar
Ukeboy
August 10, 2011.



No it doesn't have one-Could be engine overheating/type of fuel -Try cleaning the EGR valve and see what happens

Rasmataz
Aug 10, 2011.
Will do. With the TFI Ignition, is it possible that the module or pickup coil could be failing at a specific RPM? Or. Do they either work correctly or simply fail?

Tiny
Ukeboy
Aug 10, 2011.
Do what I've suggested and then comback-

Rasmataz
Aug 10, 2011.
The EGR valve functions as it should. I removed it, and checked the diaphram. What DOES NOT appear to work is the vacuum connection where it attaches. It appears that there is a cellinoid that should provide vacuum to activate the EGR. Could be that there has to be high engine RPM for it to do that. I raised the idle to about 2000 rpm and still Zero suck.

Next step?

Thanks,

Karl

Tiny
Ukeboy
Aug 10, 2011.
It suppose to have vacuum thru the vacuum solenoid to open the EGR valve, its pinping due to high combustion chamber temperature

Rasmataz
Aug 11, 2011.
When checking the vacuum line from the EGR to the vacuum solenoid, I noticed that someone previous had placed a plug in the line, thereby rendering it non-op. I have removed the plug and and will now check to see if there is a difference in operation. In reading, the EGR apparently wouldn't open until the engine reaches high rpm. If there is no change, I will replace the vacuum solenoid and try it again.

Thank you

Tiny
Ukeboy
Aug 11, 2011.
Were you able to resolve your issue ukeboy?

Rivermikerat
Sep 17, 2011.
I never really solved the problem but.I changed the Carb and the ECM which I got at a junk yard from another 4.9 liter same year. The truck runs very well and now idles dead on at 650 rpm. I disconnected the EGR because when I hook up the vacuum hose to it, the engine fails (stalls) after driving about 5 to 10 miles. When capped off. No stalling. I know the vacuum cellinoid works because I tested it. Guess I am going to have to run it w/o the egr hooked up. I was under the impression that the EGR worked mostly on deceleration. Not under load where you get a much cleaner burn of the fuel. Still open to suggestions.

Thanks for getting back to me.

Tiny
Ukeboy
Sep 18, 2011.
It does work that way. Have you checked it and the vacuum line for leaks?

I'm here to help. I was looking through the open questions and found yours, so, here I am. : )

Rivermikerat
Sep 18, 2011.