Hard to start in the cold ???
Thread Starter
Senior Member
Joined: Dec 2008
Posts: 242
Likes: 6
From: Iowa
Hard to start in the cold ???
So I recently put new plugs, wires, oxygen sensor, egr valve, exhaust manifold, and coil packs on my 97 4.6L. It rund much better now but still has two troubling symptoms. I was told to try the throttle position sensor.
1) I live in IA and park outside so the truck gets quite cold at night. When I start it in the morning, the rpm's drop way down and the truck will not stay running unless I hold the gas to keep it at 1000-1500 rpm for about 30 seconds. After that it is fine every time.
2) While driving and lightly accelerating the truck shakes or shudders. If I let off the gas or floor it, the shudder goes away. It also still shakes a little bit when idling but it is better since I replaced the coil packs yesterday.
What do you think???
1) I live in IA and park outside so the truck gets quite cold at night. When I start it in the morning, the rpm's drop way down and the truck will not stay running unless I hold the gas to keep it at 1000-1500 rpm for about 30 seconds. After that it is fine every time.
2) While driving and lightly accelerating the truck shakes or shudders. If I let off the gas or floor it, the shudder goes away. It also still shakes a little bit when idling but it is better since I replaced the coil packs yesterday.
What do you think???
Junior Member
Joined: Dec 2008
Posts: 3
Likes: 0
I had the same problem last winter. When the temp dropped, I'd have to gas it to keep it from choking itself out. Once it got good and warmed up, the problem typically went away.
The shop might try to tell you it's a fuel pump. That was my $800 mistake last winter!
After a little digging, I went back and had them replace the Idle Air Control Valve(IAC)---I have a 99 f150 with a 5.4...it's on the top of the motor but back towards the firewall. It was waaay too cold from me to try and get the little nuts/bolts back together without dropping them into the motor! Turned out the part and labor isn't too bad--I think I had it done for around $200 or so.
The IAC has a solenoid in it. When your foot is off the gas and the throttle plate closes, the computer sends a signal to the IAC to adjust the solenoid, thereby allowing a way for air to bypass the throttle plate and maintain a smooth idle. Over the years, the IAC gets gummed up and starts sticking/jamming. If it jams(cold weather encourages the problem) then the vehicle essentially chokes itself out. Once it warms up(thereby freeing the jam) the problem usually self corrects, though only temporarily.
If you're looking for something to do, I suppose you could try to take it apart and clean it, but since you got it off, you might as well just replace it--they don't cost much. ONce mine was done, she purred like a cat.
As for the other studdering/shaking...probably an ignition coil or something. You'll get a "check engine" light on that. You'll need to provide more specifics about the problem/symptoms for us to dig into that problem.
Good luck! Let us know how it turns out.
The shop might try to tell you it's a fuel pump. That was my $800 mistake last winter!
After a little digging, I went back and had them replace the Idle Air Control Valve(IAC)---I have a 99 f150 with a 5.4...it's on the top of the motor but back towards the firewall. It was waaay too cold from me to try and get the little nuts/bolts back together without dropping them into the motor! Turned out the part and labor isn't too bad--I think I had it done for around $200 or so.
The IAC has a solenoid in it. When your foot is off the gas and the throttle plate closes, the computer sends a signal to the IAC to adjust the solenoid, thereby allowing a way for air to bypass the throttle plate and maintain a smooth idle. Over the years, the IAC gets gummed up and starts sticking/jamming. If it jams(cold weather encourages the problem) then the vehicle essentially chokes itself out. Once it warms up(thereby freeing the jam) the problem usually self corrects, though only temporarily.
If you're looking for something to do, I suppose you could try to take it apart and clean it, but since you got it off, you might as well just replace it--they don't cost much. ONce mine was done, she purred like a cat.
As for the other studdering/shaking...probably an ignition coil or something. You'll get a "check engine" light on that. You'll need to provide more specifics about the problem/symptoms for us to dig into that problem.
Good luck! Let us know how it turns out.
So I recently put new plugs, wires, oxygen sensor, egr valve, exhaust manifold, and coil packs on my 97 4.6L. It rund much better now but still has two troubling symptoms. I was told to try the throttle position sensor.
1) I live in IA and park outside so the truck gets quite cold at night. When I start it in the morning, the rpm's drop way down and the truck will not stay running unless I hold the gas to keep it at 1000-1500 rpm for about 30 seconds. After that it is fine every time.
2) While driving and lightly accelerating the truck shakes or shudders. If I let off the gas or floor it, the shudder goes away. It also still shakes a little bit when idling but it is better since I replaced the coil packs yesterday.
What do you think???
1) I live in IA and park outside so the truck gets quite cold at night. When I start it in the morning, the rpm's drop way down and the truck will not stay running unless I hold the gas to keep it at 1000-1500 rpm for about 30 seconds. After that it is fine every time.
2) While driving and lightly accelerating the truck shakes or shudders. If I let off the gas or floor it, the shudder goes away. It also still shakes a little bit when idling but it is better since I replaced the coil packs yesterday.
What do you think???
