First off, I'm excited to join the 460 Club and build my 460 knowledge with the help of the skilled people on the website. I just want to start out saying that I am by no means a mechanic. I have very little experience under the hood of a gas motor but owned a diesel truck for the last two years (2005 Harley Davidson F-250 with the amazing/dreaded 6.0 ) up until sold it and bought this truck. That being said, I am a mechanical engineer. So the lack of hands on experience I have, I can somewhat make up for with my understanding of concepts so bare with me.

I'm having issues with the timing of my "new-to-me" 1988 F-250 4x4. It has the 460 EFI with the ZF-S542, and I can not get the timing right. The truck is completely stock except headers and exhaust, and I cut the intake horns.

The truck seems to have decent power up until about 3000 rpm and then it just seems to fall on its face. Now I've read that the cam kind of hinders this top end power, but I really felt like it was falling TOO much just to be the cam. After I did some research and got to looking around and piddling with it, I noticed that there was no SPOUT connector plugged in to the plug.....so being as I did not have a connector, I decided to throw a 20 amp fuse in the plug and see what happens. When I plugged the fuse in, I noticed the timing advanced so I was assuming that it would run a little better....boy was I wrong. I hit the throttle from under the hood a few times and found that it would sputter and pop real bad, almost like spark knock. I attempted to drive it down the road and that just was not happening.

So I borrowed a buddy's timing light and decided to check what the base timing was actually set to. I bumped my starter until the markings on the balancer were facing the ground and marked the timing marks with a white paint pen, pulled out the fuse I placed in the spout plug, and proceeded to check the timing. Come to find, the base timing was set past 30 degrees, close to 40!! Now like I said, I am NO mechanic....but this just does not seem right. I tried setting it back to the 10 degree base timing and when I plugged the fuse back in, same thing-running like crap. Pulled the fuse, set the timing back to the original 30-40 degrees, runs just like it did when I bought it.

I search forum after forum, and could not find anything that helped much. What I did find led me to believe I have some sort of electrical problem. I decided to replace the MAP sensor first, as well as the IAC valve. I ordered a new TPS sensor, but was unable to removed the two screws holding it in (I have ordered an impact driver, gonna attempt that this week). I also ordered a new fuel pressure regulator, at this point I am just waiting until I get a chance to really dive into that (I have FPR with the 3 screws on the bottom of the regulator, should be fun). I have not rechecked the timing since installing the MAP and IAC, I was really wanting to at least replace the TPS and FPR before I did, but I may go ahead and check it this afternoon. My real concern is that this is going to be an EEC issue and I haven't even been able to find one for sale

I have also ordered a OBDI code reader to see if any codes are being thrown, but I have no check engine light on so I am concerned it wont have any codes if the light is not on. If anyone has any advice on my problem or the direction I need to head to fix this, I would greatly appreciate it!!

Thanks!!

 

Sounds to me like the outer weight of the harmonic balancer with the timing mark has spun, and is no longer in line with the actual TDC mark. I've had this happen before, and it caused me to put my distributor in 90 degrees off last time I did head gaskets. Set Cyl 1 to tdc, and check the timing mark. To do this, pull the cyl 1 spark plug, and put a metal rod or wire inside, so it rests on top of the cylinder, and the other end pokes out of the plug hole. This will indicate when the cylinder is moving up and down, and you can rotate the crank by hand to find its highest position, this is TDC, see where your timing mark is.

 

That was another possibility that I had thought of. Ill pull the #1 plug this week and check TDC. You say I can rotate the crank by hand? I figured the motor wouldn't spin that freely. I assumed I would have to leave it in gear and let the truck roll until it was positioned TDC but if you think I can turn it by hand, that seems a lot easier. Thanks for your reply!! I'll make sure to keep the thread up to date

 

Sorry for for the confusion, when I said by hand I meant turning the crank with a breaker bar and socket on the crank pulley. If a manual, have some
one hold the clutch or leave it out of gear with the parking brake set and or wheels chocked. When I said by hand I meant by not using the starter to turn the engine.

You shouldn't be able to turn it with your bare hands, otherwise you've hit snapped rods or no compression.

 

Oh okay, thank you for the clarification. I didn't think I was man enough to turn it by hand! I'll take a look at TDC this week when I get a chance and let you know. Thanks again jtmalott!

 

Also, I believe my code reader will be here tomorrow. Will there still be codes stored if I don't have a check engine light on? I planned on hooking it up either way and seeing what it will tell me

 

Just remember the crankshaft rotates two complete revolutions for every "power cycle". Once for compression, the second time for the exhaust.

Be sure you are at TDC for the compression stroke. Otherwise you will be 180 degrees out.

One other thought for your timing observation: You did put the trigger for the timing light on the passenger side front cylinder (nearest the radiator)?

 

There can be stored codes with no Check Engine Light on. You can also fail one or more of the Key On Engine Off (KOEO) tests with no active CEL either.

Be sure to warm up the truck to normal operating temperature before running the KOEO tests and stored code (aka CM) display.

 

Okay is there any way to determine whether it is at TDC for the compression vs exhaust stroke? I'm assuming if it is TDC for the exhaust stroke than the timing markings on the balancer will be facing more towards the ground rather than up towards the timing indicator

 

Yes I definitely had it on the #1 plug wire, front left when looking at the truck from the front

 

Pull the distributor cap, the rotor should point to cyl 1 plug wire, or you can remove the valve cover and check that both valves are closed on that cylinder

 

If we are just trying to find the relationship between the harmonic balancer(timing marks) and the top dead center position of the #1 piston, it won't matter which stroke the valves or camshaft are on. The harmonic balancer and pistons always move together. Unless I am missing something here.

 

My comments were made in the theory that once you determine the harmonic balancer is slipped or not the OP would/could re-stab the distributor.

 

Hi,
To find TDC compression stroke.

Take a damp paper towel and wad it up and push it against and BARELY in the #1 spark plug hole.

Rotate the engine BY HAND CW facing engine.

The damp paper towel will pop out of the hole when you are close to TDC.

Then keep turning till your timing mark is correct (it will not be far!)

This then puts you at TDC on the compression stroke!

 

Thanks guys for all the replys! Unfortunately, as soon as I got a chance to go mess with the truck yesterday it started raining....of course its looking like its gonna rain again this afternoon but the rest of the week looks clear...for now. Hopefully I can get a chance before the weekend. I will keep everyone posted