Does computer retard timing?
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Mountain Pass
Joined: Mar 2007
Posts: 153
Likes: 2
Does computer retard timing?
93 F150, 5.0, I was towing with this and it started losing power. I would go a few miles and all of a sudden it would have plenty of power. It was getting warmer but did not overheat. I was 300 miles from home. It did this all the way. I read somewhere that the newer trucks retarded the timing to keep them from overheating. Does my old truck have this feature also?
Lead Driver
Joined: Nov 2002
Posts: 9,555
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From: Concord, NC
There is an engine temperature compensation for the spark timing in the Ford computers used commonly with tuning software, so I would think that the truck would be no different. Hotter engine temperatures increase the likelihood of the fuel/air mixture to detonate, thus, timing is retarded slightly to account for this. We're only talking 2-3 degrees, though, likely not having an effect until at least 205°F, and it won't keep the engine from overheating. It's not like the fail-safe on the 97-up trucks where they deactivate cylinders to help cool the engine. You might notice a little less power, but I don't think it would be that dramatic. Definitely see if there are any codes stored in the computer and let us know what you find.
FTE Legend
Joined: Jun 2006
Posts: 31,930
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From: Ottawa, Ontario
The 5.0s have a knock sensor so they will retard timing if detonation is sensed. There are lots of other things that could cause loss of power as well, failing fuel pump, clogged fuel filter, intermittent vacuum leak, clogged exhaust, clogged intake filter, failing sensor... the list goes on. Did you get a check engine light?
Postmaster
Joined: Aug 2004
Posts: 2,908
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From: West Mansfield, Ohio
I've always wondered this, someone clear this up for me. I know that the computer helps control timing, but does it control spark timing, or fuel injection timing, or both? I've always wondered this, b/c the computer can't change the position of the distributor, thus wouldn't be able to change spark timing. Injection timing I can see working. But am I right here or no...?
FTE Legend
Joined: Jun 2006
Posts: 31,930
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From: Ottawa, Ontario
The distributor just sets the base timing, the computer will then adjust advance over a range of 25 or so degrees from there. The engine will operate with a certain amount of computer added advance most of the time, and it can decide to pull some of that out if conditions dictate. It wasn't until the motors went to a disributorless system that the computer got full control over advance and retard from the base setting.. or if you have a factory turbo/supercharged engine.
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Mountain Pass
Joined: Mar 2007
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The check engine light never came on. I know it blew a head gasket, just didn't know why. Also, per a previous post on here there is probably a broken or cracked piston. Oil in the air filter. GRRR
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Lead Driver
Joined: Nov 2002
Posts: 9,555
Likes: 40
From: Concord, NC
The computer has full control over ignition advance, in a relative sense from the base advance set by the distributor. The computer will always command a certain advance from trigger signal, whether the base timing is set to 10 or 30 degrees. This is why the base timing has to be correct--the computer depends on that trigger signal coming from the distributor to be in the same, correct place at all times. If you take a look at the rotor, you'll notice that the contact is pretty wide, which allows for the advance to be altered, but still allow the electricity to pass to the posts for each cylinder. The distributor itself does not alter timing at all. The base timing is where the PIP triggers the computer at all times, regardless of load, rpm, or anything else. The computer also controls timing of the fuel injectors, again from a pre-defined trigger signal position (base advance at the distributor).
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Postmaster
Joined: Aug 2004
Posts: 2,908
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From: West Mansfield, Ohio
Ahhh I see now. So the computer controls the firing of the coil, not the firing of each individual post in the distributor. For a second I thought that it was done inside the distributor, but it makes sense now. The wider prong on the rotor would allow for modifications!
Lead Driver
Joined: Nov 2002
Posts: 9,555
Likes: 40
From: Concord, NC
Right--moving the distributor changes the position of the signal that's sent to the computer in relation to crankshaft position, while the computer controls when the coil and injectors are fired in relation to that signal.
