1987 Ford F-150 EFI I-6 problems

[mcne]

I just had a diagnostic done on my engine that has 170,000 miles. When it is cold it had consistant hesitation and was a pain to drive. Once it warmed up it ran o.k. and the hesitation would go away. The diagnostic showed that everything was within specs except: Ignition timing was high as well as emissions. The mechanic recommended new spark plugs. He believed that the ignition timing and high emissions were a result of the engine computer trying to compensate by adding more fuel and timing for poor combustion due to old plugs. I changed my plugs with Autolite platinums. My plug wires and cap and rotor were recently replaced so I left them alone. I also disconnected my battery to reset any codes or calibrations the computer might have had. Now my truck runs much, much worse. It is barely driveable even when warm. There is a huge power loss and surging. The truck will barely make it to 35 mph now. I hear a loud ticking most of the time when I try to acellerate. I have disconnected the computer two more times just in case the memory was not cleared the first time. When I have the engine in park or neutral the engine runs well and will rev to the moon. The ticking sound is either barely there or non-existent. When I put it in drive and try to motor down the road it runs horrible. Why does it run well in park or neutral but not when it has a load on it? I am also wondering about the plug wires arching. I do have the plastic spacers to keep them apart the best I can. Do you think that could be the problem? I ran my code scanner and it shows the same code I had before I changed the plugs. It says my EGO has a constant lean condition. Anyone have any suggestions? Thanks, Brian.

[matt_helton]

did it have platinum plugs before??? if not then go back to a standard autolite plug and then go from there.

[mcne]

They are the same plugs.

[Tyson]

Are you sure they are gapped correctly? if so Id also change out your wires to be on the safe side and look at the dist cap make sure it has no cracks.

T

[tedmales]

the ticking you hear is probably a plug wire arcing. at night start it in a kind of dark area and it will be much easier to see. u can pull each plug wire while the truck is running and see which one does not affect the idle. then when you figure out which one it is check the plugs, its very easy to crack the insulator on the plug.

[tkr]

Sounds like maybe the ticking sounds is a spark plug wire shorting to ground. Give a quick inspection and make sure all the wires are on the plugs and cap tight. If so, have someone sit in the truck with their foot on the brake and rev the enging a little in drive. While they're doing that grab a water spary bottle, spary the wires and watch for sparks.

[1992f150]

if you pull the spark plug wires off while its running, be sure you are wearing rubber gloves and dont lean on the fender/firewall/any grounded part.

[curt]

Try the start it in the dark thing first, some computers may give you problems with the old unplug the wire while running trick. Also they make cheap wire pulling pliers with about a 1/2" circular cutout that fits over the boot and has rubber in it to keep from damaging the wires. When you pull the right wire, the motor soqnd won't change...Curt

[Jack]

You will need help with the dark test, you need to put a load on the motor, as you said it runs fine in nutral. Have someone put it in gear with foot on the brake then a little gas to simulate driving condition. Then look for "the dancing angles" it must be very dark no street lights or keep the hood down some to block the light. My guess is that pulling the plug wires they got pulled apart at the boot. Also there may be a problem inside a plug, The only way I know to check this is to use an engine scan (not sure what it is called, but it has a screen and will look like a hart rate monitor) to see the resistance at each plug fireing and will tell you wich one is the problem.

[mcne]

Replying to all- Thanks guys. I am going to try everything tonight. Someone asked if my plugs are gapped correctly. YES. I also have spark plug wire plyers so those should help keep me from getting toasted. I have never heard of the water bottle trick. Does that make the archs more visible? I appreciate everyone's help. Hopefully I will find and fix the problem. I will let you know how it turns out tonight or tomorrow. Brian.

[tkr]

the mist from a water sprayer decreases the resistance(easier path to ground) so the arc will be more prevalent.

[yotatech]

Could it be that your intake boot is cracked and when the engine loads up and twists it pulls apart and opens a vacuum leak. Ive had that happen to a couple customer cars before.

[mcne]

Why would a leak in the intake cause a vacuum leak? If I completely unbolt the intake tubes that connect my air cleaner to the intake manifold, my engine should still run the same. The only difference is now my air will be unfiltered. Maybe you are talking about a different part? Brian.

[1992f150]

If your engine is EFI, then it wouldn't measure the airflow correctly.

[mcne]

My truck is speed density not mass airflow. I understand it would cause a problem if it was mass airflow. I checked my wires with the water treatment last night. I saw several problem areas on two of my wires. I cut up some old vacuum hose and put it around the areas where the wires were touching my accellerator cables. When I checked again the arching moved to another area where the wires were not touching, but very close to an object. Then I zipp tied them out of the way and rechecked. The arching on the wires is gone, but I can see some electrical glowing on the small wires that come from my wiring harness going to the plug that connects to the distributor. Is some glowing normal when they are wet? I also can see the electricity through the end cap of my coil plug wire at the 90 degree turn. Is that normal? I disconnected one of the arching plug wires and ran the engine. The ticking went away and the truck runs with its normal hesitation and lack of power. Which is great news because hopefully my wires were causing the problem this whole time! Anyways I reconnected everything and took it for a test drive and it is still running poorly with ticking (although the ticking is slightly less). It does seem to run better, compared to before I insulated the two problem areas on the plug wires. I have not checked the resistance on the wires yet. If I had been driving around for a long time and those two wires were arching would that ruin the wires or change their resistance? Then after I fixed the problem the engine will still run bad because the wires are junk? I do not think the wires I put on were top quality ones. Anyone have any recommendations for plug wires for Fords? I have heard the Ford Motorcraft wires are the ones to get. What is the difference between cheap plug wires and good ones? Just how much rubber insulation they have? Thanks for all the help guys. Brian

[tkr]

Definitely replace the complete wire set with Motorcraft wires. They may be $40 or so more than the cheap wires, but you won't have this problem again. Once a wire arcs a few times it leaves a "carbon track" which makes it easier to arc there again.

[mcne]

Thanks I will take your advice. Brian