Rough Idle on Restart
#1
05-07-2022, 02:11 PM
Join Date: May 2022
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Rough Idle on Restart
Alright gurus, here's an interesting one. I've searched the forums and couldn't find a thread that described a problem quite like this one so I decided to ask the experts. I apologize if it has been covered already. If so, please kindly point me in the right direction. Right now I'm at a loss.
The Truck:
2005 Crew Cab 4x4 ST, 4.7L, VIN code N, 250K+ miles, auto, new to me 3 months ago.
The Problem: Here's the scenario:
When cold, the truck starts, idles, runs and drives fine, great actually, although maybe a little sluggish on power for a v8 in my opinion. As long as I don't turn off the engine, everything is fine. The problem surfaces once the engine has warmed up at least a bit, I turn off the engine for several minutes such as to get gas or run into the store, and then restart the engine. Then engine will restart without a problem and idle great, for about 5-10 seconds. Then it will start sputtering and choking out. If I have already put it in gear and started moving, it all of the sudden won't get out of its own way. No power. If I do nothing and let it 'idle' in park, sometimes it will finally die throwing a random misfire code. (Which is to be expected when the RPM falls to 150+/-) HOWEVER, I have discovered that once it starts sputtering, if I simply turn it off, let the engine stop, then restart it, all is right and well once again and the truck drives just fine, until I turn it off again. If I happen to be moving at the time, I simply throw it in neutral, shut off the engine, restart, put it in drive and keep going. This works, but it is a PITA, and tells me there is something wrong that I'd like to fix if possible. If the engine has been off for several hours before restarting, it will start and run just fine.
What's been done so far:
New TPS, MAP sensor, IAC valve, camshaft position sensor, EGR valve. Battery disconnected for several minutes to a couple hours during each swap (the egr took a while to get out!) and the ECM put through a relearning process each time. (Idle 2 minutes, Idle in gear 2 minutes, Idle with AC on 2 minutes). Each time the problem seemed to get a little better for a brief time, then I was right back to where I started. I can say that after the TPS/IAC swap, the truck did seem a 'bit' more peppy and has remained that way. Other than the P0300 code when the engine is allowed to die on its own, there are no other codes.
The fix:
I'm hoping somebody on here can tell me. The parts that were replaced were all items that indicated as possibly causing this type of problem in other posts. They were relatively inexpensive and I didn't mind changing them, especially on a 250K mile engine. But I don't want to just keep throwing parts at it. I'd like to find the actual problem and fix it. And hopefully improve the power and fuel economy a bit in the process (11.5-12 mpg avg.) I am at the end of my knowledge and am hoping someone here has either seen this problem or has a good idea of what the problem could be.
Thanks in advance for any help and suggestions (except get a new truck or engine!) I'm hoping to restore this truck back to some of its former glory.
The Truck:
2005 Crew Cab 4x4 ST, 4.7L, VIN code N, 250K+ miles, auto, new to me 3 months ago.
The Problem: Here's the scenario:
When cold, the truck starts, idles, runs and drives fine, great actually, although maybe a little sluggish on power for a v8 in my opinion. As long as I don't turn off the engine, everything is fine. The problem surfaces once the engine has warmed up at least a bit, I turn off the engine for several minutes such as to get gas or run into the store, and then restart the engine. Then engine will restart without a problem and idle great, for about 5-10 seconds. Then it will start sputtering and choking out. If I have already put it in gear and started moving, it all of the sudden won't get out of its own way. No power. If I do nothing and let it 'idle' in park, sometimes it will finally die throwing a random misfire code. (Which is to be expected when the RPM falls to 150+/-) HOWEVER, I have discovered that once it starts sputtering, if I simply turn it off, let the engine stop, then restart it, all is right and well once again and the truck drives just fine, until I turn it off again. If I happen to be moving at the time, I simply throw it in neutral, shut off the engine, restart, put it in drive and keep going. This works, but it is a PITA, and tells me there is something wrong that I'd like to fix if possible. If the engine has been off for several hours before restarting, it will start and run just fine.
What's been done so far:
New TPS, MAP sensor, IAC valve, camshaft position sensor, EGR valve. Battery disconnected for several minutes to a couple hours during each swap (the egr took a while to get out!) and the ECM put through a relearning process each time. (Idle 2 minutes, Idle in gear 2 minutes, Idle with AC on 2 minutes). Each time the problem seemed to get a little better for a brief time, then I was right back to where I started. I can say that after the TPS/IAC swap, the truck did seem a 'bit' more peppy and has remained that way. Other than the P0300 code when the engine is allowed to die on its own, there are no other codes.
The fix:
I'm hoping somebody on here can tell me. The parts that were replaced were all items that indicated as possibly causing this type of problem in other posts. They were relatively inexpensive and I didn't mind changing them, especially on a 250K mile engine. But I don't want to just keep throwing parts at it. I'd like to find the actual problem and fix it. And hopefully improve the power and fuel economy a bit in the process (11.5-12 mpg avg.) I am at the end of my knowledge and am hoping someone here has either seen this problem or has a good idea of what the problem could be.
Thanks in advance for any help and suggestions (except get a new truck or engine!) I'm hoping to restore this truck back to some of its former glory.
#2
05-10-2022, 02:01 PM
Rookie
Our Dakota does about the same thing.
Stone cold it's decent. Get it warmed up on the highway and it's peppy and nimble!
Do a warm start after getting gas or restarting within 30-45 minutes and it will start okay- And then act like it's running out of gas or air. Like it's being choked off.
I gassed it up yesterday- Started it up and it idled fair- Give it a touch of gas pedal and it started to stumble and tried to stall out. I wound up feathering the gas while putting it in gear so I could pull out. Coughing and sputtering for about 30 seconds to a minute. And just as quick? Suddenly the truck will take off like a bat outta he** and be 100% normal once again.
We're going to fully test the injectors, as we've done a full tune up (OEM factory plugs back in...coil boots replaced, etc...)
Sounds like the same symptoms you are having. I'll keep an eye on this thread to see how you make out, and if we figure out ours? I'll update as it might be related in somehow to yours.
Good Luck with it!
S-
Stone cold it's decent. Get it warmed up on the highway and it's peppy and nimble!
Do a warm start after getting gas or restarting within 30-45 minutes and it will start okay- And then act like it's running out of gas or air. Like it's being choked off.
I gassed it up yesterday- Started it up and it idled fair- Give it a touch of gas pedal and it started to stumble and tried to stall out. I wound up feathering the gas while putting it in gear so I could pull out. Coughing and sputtering for about 30 seconds to a minute. And just as quick? Suddenly the truck will take off like a bat outta he** and be 100% normal once again.
We're going to fully test the injectors, as we've done a full tune up (OEM factory plugs back in...coil boots replaced, etc...)
Sounds like the same symptoms you are having. I'll keep an eye on this thread to see how you make out, and if we figure out ours? I'll update as it might be related in somehow to yours.
Good Luck with it!
S-
#3
05-19-2022, 09:10 PM
