460 Misses Only When Warming
Thread Starter
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Junior User
Joined: Nov 2002
Posts: 78
Likes: 0
From: British Columbia
460 Misses Only When Warming
92 460 in a F250, 200K.
This problem has been persistant since I purchased the truck last August.
When the truck is warming up it misses intermittently. The tack jumps down for a split second, and jumps back up. No stall. It is not consistant, but it will do it 4 or 5 times before completely warm. The odd thing is that it seems to do it part way through the warming process and not generally (but has) when dead cold. It does it under power or at idle in drive or park.
Shortly after I purchased the truck, I had the plugs, plug wires, rotor, cap replaced + throttle body cleaned. The 02 sensor was done about 3 years ago.
In the winter when it was colder and more of a problem, I had the throttle position sensor changed. Didn't solve it.
No engine light.
She burns a bit of Oil (litre every 800k).
I was thinking that maybe the o2 sensor is getting clogged due to the dirtier exaust caused by the oil consumption. It apparently doesn't kick in until 600 degrees.
Could a bad plug wire cause this symptom. (shows OK on scope when warm)
Thanks for any help....
Doug
This problem has been persistant since I purchased the truck last August.
When the truck is warming up it misses intermittently. The tack jumps down for a split second, and jumps back up. No stall. It is not consistant, but it will do it 4 or 5 times before completely warm. The odd thing is that it seems to do it part way through the warming process and not generally (but has) when dead cold. It does it under power or at idle in drive or park.
Shortly after I purchased the truck, I had the plugs, plug wires, rotor, cap replaced + throttle body cleaned. The 02 sensor was done about 3 years ago.
In the winter when it was colder and more of a problem, I had the throttle position sensor changed. Didn't solve it.
No engine light.
She burns a bit of Oil (litre every 800k).
I was thinking that maybe the o2 sensor is getting clogged due to the dirtier exaust caused by the oil consumption. It apparently doesn't kick in until 600 degrees.
Could a bad plug wire cause this symptom. (shows OK on scope when warm)
Thanks for any help....
Doug
Elder User
Joined: Jul 1999
Posts: 877
Likes: 2
From: Missouri
460 Misses Only When Warming
You might want to have the coolant temp sensor checked. That is how they act when bad.
Dennis
1999 F-350 Powerstroke
1977 Highboy 429 4-speed 35"s
1972 Ranger on a 1978 F-250 4x4
frame 466 Pulling Truck
Dennis
1999 F-350 Powerstroke
1977 Highboy 429 4-speed 35"s
1972 Ranger on a 1978 F-250 4x4
frame 466 Pulling Truck
Thread Starter
|
Junior User
Joined: Nov 2002
Posts: 78
Likes: 0
From: British Columbia
460 Misses Only When Warming
I ran a site search on the TFI module and learned quite a bit. One thing that stuck out was that the engine almost always cuts out completely. The engine will then need to sit for a while before it will restart.
My 460 will miss, but will not quit. I had a more mechanically minded friend suggest that this may have something to do with the engine trying to come out of the "cold open loop mode". He suggested that it can be caused by a sensor that relates to heat. Apparently the open loop mode switches to some other mode "unopen mode maybe" once the engine gets to a certain temperature. This would explain why it pretty much always does this when it hits a certain point in the warming cycle.
I am trying to isolate the most probably cause and then start buying parts from there. Process of most probable cause elimination.
Thanks for the help.
Coolant temperature is at the top of the list so far.
I changed the thermostat a few months back(after market part I assume), but the dumby temp gauge still only shows about a quarter of the way up.
Go Vancouver Canucks Go
Doug (North Of the 49th parallel)
My 460 will miss, but will not quit. I had a more mechanically minded friend suggest that this may have something to do with the engine trying to come out of the "cold open loop mode". He suggested that it can be caused by a sensor that relates to heat. Apparently the open loop mode switches to some other mode "unopen mode maybe" once the engine gets to a certain temperature. This would explain why it pretty much always does this when it hits a certain point in the warming cycle.
I am trying to isolate the most probably cause and then start buying parts from there. Process of most probable cause elimination.
Thanks for the help.
Coolant temperature is at the top of the list so far.
I changed the thermostat a few months back(after market part I assume), but the dumby temp gauge still only shows about a quarter of the way up.
Go Vancouver Canucks Go
Doug (North Of the 49th parallel)
Elder User
Joined: Jul 1999
Posts: 877
Likes: 2
From: Missouri
460 Misses Only When Warming
A Haynes repair manual should tell you how to test all the sensors with an inexpensive volt meter.
Dennis
1999 F-350 Powerstroke
1977 Highboy 429 4-speed 35"s
1972 Ranger on a 1978 F-250 4x4
frame 466 Pulling Truck
Dennis
1999 F-350 Powerstroke
1977 Highboy 429 4-speed 35"s
1972 Ranger on a 1978 F-250 4x4
frame 466 Pulling Truck
