Misfire?
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Fleet Mechanic
Joined: Aug 2015
Posts: 1,835
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From: Candy Mountain
Misfire?
I have had popping or knocking noise on cold starts since the weather turned cooler. Sounded like an exhaust leak so I didn't worry over it. The sound would be louder and last longer the colder it was. Usually gone in less than 20 seconds. No other trouble to report.
Yesterday, it was a little below freezing. Truck started. Idle was erratic. Tachometer fluttered inconsistantly with apparent engine speed. Loud popping. Then it stalled and would not restart. Swapped ignition coil. No start. Swapped back to original coil. Swapped IAC. Started. Was rough, almost stalled but recovered. Noise faded as it warmed up. Tachometer was all over the place but improved as it warmed up. Drove the truck with no noticeable issues other than occasional tachometer fluttering.
The noise, rough start and erratic tachometer point me toward an ignition fault, yes? Bad wire/s or connection? Bad coil?
Yesterday, it was a little below freezing. Truck started. Idle was erratic. Tachometer fluttered inconsistantly with apparent engine speed. Loud popping. Then it stalled and would not restart. Swapped ignition coil. No start. Swapped back to original coil. Swapped IAC. Started. Was rough, almost stalled but recovered. Noise faded as it warmed up. Tachometer was all over the place but improved as it warmed up. Drove the truck with no noticeable issues other than occasional tachometer fluttering.
The noise, rough start and erratic tachometer point me toward an ignition fault, yes? Bad wire/s or connection? Bad coil?
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Fleet Mechanic
Joined: Aug 2015
Posts: 1,835
Likes: 363
From: Candy Mountain
Swapped the coil again this morning just to check the backup part and it fired right up. No stumble. Tachometer is still fluttering. Noise was still present but quieted very quickly.
Could be that yesterdays trouble was just the IAC and i have a exhaust leak and a tachometer module that doesn't like the cold.
Could be that yesterdays trouble was just the IAC and i have a exhaust leak and a tachometer module that doesn't like the cold.
Tuned
Joined: Dec 2005
Posts: 400
Likes: 57
From: Saskatchewan
The cold could just exacerbate any little issue in the system, like with connections. Your pulling apart connections and reconnecting them can break the corrosion and restore the connection to full capacity. It may not be a bad part, but just weak connections that get cleaned and restored by moving them. It doesn't hurt to pull and clean connections in the ignition system to reset and restore them. That is much cheaper than replacing parts, especially good parts, when the connection is just dirty, or weak.
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Fleet Mechanic
Joined: Aug 2015
Posts: 1,835
Likes: 363
From: Candy Mountain
Spent time this morning checking connections and found the spark plug terminals were loose. All of them. Pulled a plug and found that they are screw on "removable terminals."
Installed Motorcraft coppers with solid terminals. No more stumble or tachometer flutter. Still need to sort out my exhaust leak and test the IAC I pulled off to see whether it actually failed.
Installed Motorcraft coppers with solid terminals. No more stumble or tachometer flutter. Still need to sort out my exhaust leak and test the IAC I pulled off to see whether it actually failed.
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