ignition problem????
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Freshman User
Joined: Jul 2002
Posts: 48
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ignition problem????
Hi,
My 460 has a rough idle since I have it (6 months).
Today, I conducted an ignition test to see if there's fire on each cylinder.
Unpluged spark plugs wire one by one on the cap while engine running to see if there's one or more missing, that could be the cause of my rough idle.
# 1 and #6 didn't make difference when unplugged one by one.
Unplugged the wire at the spark plug and I can tell you that there was spark!!!!.
Change #6 spark plug with #7 to see if SPlug is the problem. #6 didn't make difference plugged or not. Spark plug is dry and light brown (normal). Compression check and read 140psi.
Is there difference with the idle speed on each wire unplugged or it's supposed to be the same drop on each cylinder?
Any tips please!
Wally
My 460 has a rough idle since I have it (6 months).
Today, I conducted an ignition test to see if there's fire on each cylinder.
Unpluged spark plugs wire one by one on the cap while engine running to see if there's one or more missing, that could be the cause of my rough idle.
# 1 and #6 didn't make difference when unplugged one by one.
Unplugged the wire at the spark plug and I can tell you that there was spark!!!!.
Change #6 spark plug with #7 to see if SPlug is the problem. #6 didn't make difference plugged or not. Spark plug is dry and light brown (normal). Compression check and read 140psi.
Is there difference with the idle speed on each wire unplugged or it's supposed to be the same drop on each cylinder?
Any tips please!
Wally
Moderator
Joined: Dec 2001
Posts: 22,436
Likes: 17
From: Louisville,Ky.
ignition problem????
It should drop about the same on each cylinder. What year is it? Is it fuel injected? Are the 2 wires in question in the right spot? or are they reversed?
If it is port injected, you could have a couple of bad fuel injectors.
If it is port injected, you could have a couple of bad fuel injectors.
Senior User
Joined: Jun 2002
Posts: 263
Likes: 1
From: British Columbia
ignition problem????
Look for a manifold leak, stuck EGR valve, bad wires, bad cap or rotor. Just a few things to consider 
Nick from the frozen north
1974 F-250 4X4
soon to be 429
dana 60 front and rear
Nick from the frozen north
1974 F-250 4X4
soon to be 429
dana 60 front and rear
Postmaster
Joined: Aug 2001
Posts: 2,882
Likes: 0
From: Nevada
ignition problem????
How old are the plug wires? If more than two years, I'd replace them. The 460 produces an enormous amount of underhood heat, especially in the summer.
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Elder User
Joined: Jul 2002
Posts: 526
Likes: 0
From: USA
ignition problem????
oddly enough i had a similar problem with the number 1 and number 6. pull off the wre and no change at all. guy at the shop i had my truck in at the time wanted to do a compression test, and an engine diagnostic, but i didnt let him do it cuz he was asking 200 bucks. but anyhow, i had the carb cleaned and reset the timing and idle adjustments and now she runs real nice, dont know if the miss is still there, if so its too small to notice. but i will be replacing the plug wires, plugs , cap and rotor around christmas and that should clear everything up i think.
1977 F250 460
C6 Hedman Headers
Dual 40 series
edelbrock performer
holley 4160
msd 6a and blaster coil
1977 F250 460
C6 Hedman Headers
Dual 40 series
edelbrock performer
holley 4160
msd 6a and blaster coil
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