460 Timing Questions
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7th Gear
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460 Timing Questions
I have a 1994 F350 with the EFI 460. It has a set of headman headers on it with the EGR hookup, and the EGR is being used, not bypassed.
Currently the timing is set at 12 BTC, and it idles pretty high around 1500-1700 rpm, and I can feel a misfire at 40-60mph and at idle. The check engine light also comes on periodically.
I’ve seen people say anywhere from 6-14 degrees of timing works for them, so should I see what works best for me in that range, or is it a different issue other than timing?
Currently the timing is set at 12 BTC, and it idles pretty high around 1500-1700 rpm, and I can feel a misfire at 40-60mph and at idle. The check engine light also comes on periodically.
I’ve seen people say anywhere from 6-14 degrees of timing works for them, so should I see what works best for me in that range, or is it a different issue other than timing?
Hotshot
Joined: Jul 2020
Posts: 10,268
Likes: 2,563
From: Near Salt Lake City
Yes, test the codes and do both KOEO and KOER tests
A bad plug wire or boot will not set a code on a 1994
An intake leak will possibly set a lean code on a 1994 (not always)
That is what I would be checking
Intake air leak for the high idle (or thermostat not allowing the engine to get up to temp)
Secondary ignition components for the miss (cap, rotor, plugs and wires)
Codes (to possibly send you in the right direction)
Good luck
A bad plug wire or boot will not set a code on a 1994
An intake leak will possibly set a lean code on a 1994 (not always)
That is what I would be checking
Intake air leak for the high idle (or thermostat not allowing the engine to get up to temp)
Secondary ignition components for the miss (cap, rotor, plugs and wires)
Codes (to possibly send you in the right direction)
Good luck
Hotshot
Joined: Jul 2020
Posts: 10,268
Likes: 2,563
From: Near Salt Lake City
The processor is in control of the ignition timing and needs a reference
That is 10 degrees
Playing with 6 or 12 degrees just makes the processor dumb
Your miss may be attributed to just that
Reset to 10 degrees before getting too deep into this or any other problem
That is 10 degrees
Playing with 6 or 12 degrees just makes the processor dumb
Your miss may be attributed to just that
Reset to 10 degrees before getting too deep into this or any other problem
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7th Gear
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The processor is in control of the ignition timing and needs a reference
That is 10 degrees
Playing with 6 or 12 degrees just makes the processor dumb
Your miss may be attributed to just that
Reset to 10 degrees before getting too deep into this or any other problem
That is 10 degrees
Playing with 6 or 12 degrees just makes the processor dumb
Your miss may be attributed to just that
Reset to 10 degrees before getting too deep into this or any other problem
KOER:
311: Thermactor air system/fault during self run test
327: EVP/EVT circuit below minimum voltage
KOEO:
334: EGR closed valve voltage high
Truck still has the misfire with these codes being thrown and at 12 BTC
I will set the timing to 10 BTC and see if the codes and misfire go away before I dive more into this problem
Lead Driver
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7th Gear
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I am curious if I have the vacuum lines routed correctly though. What do you think?
On the 3rd and 4th picture, the red vacuum line runs into the vacuum tree on the intake manifold, and the black line runs into the bottom fitting on the EVR, and the top line on the EVR runs into the EGR.
I do not have the smog pump hooked up so the smaller piece of the EVR is plugged.
And except for the Fuel Pressure Regulator vacuum line, and the red vacuum line from the vacuum tank, all of the other fittings on the vacuum tree on the intake manifold are plugged
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Lead Driver
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Remove all the vac lines from the intake manifold and cap them. If idle falls to normal, plug one in at a time until you find the leak circuit. With idle that high, if it's a vac leak, it's likely the booster.
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7th Gear
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Hotshot
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You could answer your question. With the engine running, disconnect the hose at the intake manifold then put a plug or stick your finger over the nipple on the manifold to stop the vacuum leak.
Hotshot
Joined: Jul 2020
Posts: 10,268
Likes: 2,563
From: Near Salt Lake City
With my current timing (12 BTC) the check engine codes I got were
KOER:
311: Thermactor air system/fault during self run test
327: EVP/EVT circuit below minimum voltage
KOEO:
334: EGR closed valve voltage high
Truck still has the misfire with these codes being thrown and at 12 BTC
I will set the timing to 10 BTC and see if the codes and misfire go away before I dive more into this problem
KOER:
311: Thermactor air system/fault during self run test
327: EVP/EVT circuit below minimum voltage
KOEO:
334: EGR closed valve voltage high
Truck still has the misfire with these codes being thrown and at 12 BTC
I will set the timing to 10 BTC and see if the codes and misfire go away before I dive more into this problem
IMO 2 degrees of timing will not cause a misfire either
Check the ignition secondary parts, cap rotor plugs and wires
The caps in my processor were causing a misfire I chased for years in denial of processor failure
You might have the wrong color EVP on it
The processor sure wants to see that EVP move and know that it has a working EGR
If mine, I'd take the headers off and get the EGR back to factory and make it work
That should solveboth the check engine light and the drivability problem IMO
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