2001 Dakota No Start P0505 code
Thread Starter
|
Registered User
Joined: Aug 2020
Posts: 8
Likes: 0
2001 Dakota No Start P0505 code
Long post about an ongoing problem...
2001 4.7l engine 75K miles
Truck has always had a flutter in the revs at idle--it would go up and down about 2-300rpms. Ran fine otherwise
Then it started to die at idle. It would restart and drive, though sometimes it took a couple of tries to start.
Then would not crank and had a "no bus" code in the odometer.
I replaced the TPS--no change.
The Idle Air Control valve was replaced by a shop--initially the truck started and ran normally, then the problem of "no bus" returned.
The shop told me that they checked all the sensors, which they said were good, and then they replaced the PCM and "cleaned" the throttle body.
The truck started and drove normal for at least one trip, then began requiring several times to start, but once it started it would run well. The engine malfunction light came on and it was throwing a P0505 and P0506 code.
The shop recommended replacing the throttle body, or removing and cleaning it. Turns out they had only sprayed some carb cleaner into it.
I brought it home.
The starts became harder over a couple of days, until eventually it would crank and start, but immediately die. If I started with a full throttle and kept the rpms at 4000 for a minute, then 2000 for a minute, then 1000, then it would idle with fluctuating rpms, and after that it would run well. It would continue to run well and restart easily and idle smoothly for the remainder of the day. But each time it sat overnight, it would return to the state of requiring high rpms and a warm up before it would idle smoothly and run well.
I disconnected the battery, removed and cleaned the throttle body, installed new plugs, and replaced the air filter. BIG DIFFERENCE--ran the best it ever has-- smooth idle, easy starts. Cleared the codes. No engine malfunction light. For about 2 days.
Now it has returned to the problem of it will crank and start easily but immediately dies, unless I keep the rpms up at 4000 for a minute, then slowly decrease rpms over several minutes. The engine malfunction light came back on. Once it is warmed up and driven it will restart without problems and drive well with smooth idling.
Today I disconnected the battery for 20 minutes. Reconnected and let it sit 5 minutes. Truck started immediately, idled easily. Engine malfunction light was off and no codes.
I expect that when it sits overnight, it will start having the same problem of not idling till it is warm. And the engine malfunction light will return while driving. And that disconnecting the battery will temporarily solve the problem.
So, I am not a mechanic but I'm handy with a wrench, and I don't know how to check sensors, voltage, etc. At this point I would rather swap out parts than to go back to the shop, for them to take their guesses.
My plan is to swap out the MAP sensor. If this doesn't work, what would you recommend? I'd rather swap out a part than spend more money at a shop, I've called around and its not a problem anyone seems eager to tackle.
If you are still with me, thank you for reading this far and I'd love to hear your thoughts
2001 4.7l engine 75K miles
Truck has always had a flutter in the revs at idle--it would go up and down about 2-300rpms. Ran fine otherwise
Then it started to die at idle. It would restart and drive, though sometimes it took a couple of tries to start.
Then would not crank and had a "no bus" code in the odometer.
I replaced the TPS--no change.
The Idle Air Control valve was replaced by a shop--initially the truck started and ran normally, then the problem of "no bus" returned.
The shop told me that they checked all the sensors, which they said were good, and then they replaced the PCM and "cleaned" the throttle body.
The truck started and drove normal for at least one trip, then began requiring several times to start, but once it started it would run well. The engine malfunction light came on and it was throwing a P0505 and P0506 code.
The shop recommended replacing the throttle body, or removing and cleaning it. Turns out they had only sprayed some carb cleaner into it.
I brought it home.
The starts became harder over a couple of days, until eventually it would crank and start, but immediately die. If I started with a full throttle and kept the rpms at 4000 for a minute, then 2000 for a minute, then 1000, then it would idle with fluctuating rpms, and after that it would run well. It would continue to run well and restart easily and idle smoothly for the remainder of the day. But each time it sat overnight, it would return to the state of requiring high rpms and a warm up before it would idle smoothly and run well.
I disconnected the battery, removed and cleaned the throttle body, installed new plugs, and replaced the air filter. BIG DIFFERENCE--ran the best it ever has-- smooth idle, easy starts. Cleared the codes. No engine malfunction light. For about 2 days.
Now it has returned to the problem of it will crank and start easily but immediately dies, unless I keep the rpms up at 4000 for a minute, then slowly decrease rpms over several minutes. The engine malfunction light came back on. Once it is warmed up and driven it will restart without problems and drive well with smooth idling.
Today I disconnected the battery for 20 minutes. Reconnected and let it sit 5 minutes. Truck started immediately, idled easily. Engine malfunction light was off and no codes.
I expect that when it sits overnight, it will start having the same problem of not idling till it is warm. And the engine malfunction light will return while driving. And that disconnecting the battery will temporarily solve the problem.
So, I am not a mechanic but I'm handy with a wrench, and I don't know how to check sensors, voltage, etc. At this point I would rather swap out parts than to go back to the shop, for them to take their guesses.
My plan is to swap out the MAP sensor. If this doesn't work, what would you recommend? I'd rather swap out a part than spend more money at a shop, I've called around and its not a problem anyone seems eager to tackle.
If you are still with me, thank you for reading this far and I'd love to hear your thoughts
Administrator
Joined: Apr 2010
Posts: 87,395
Likes: 4,213
From: Clayton MI
What brand IAC is in there? I have found the aftermarket fellers just don't work that great. Mopar is the only ones they seem to like.
The P0505 IS an IAC code as well. Are you still getting that? If so, think I would get a genuine Mopar IAC, install that, reset the pcm again, and see if the problem goes away.
The P0505 IS an IAC code as well. Are you still getting that? If so, think I would get a genuine Mopar IAC, install that, reset the pcm again, and see if the problem goes away.
Legend
Joined: Feb 2005
Posts: 8,058
Likes: 183
From: Fort Worth, TX
The P0505 is generic. Even moreso, the IAC itself is a "dumb" circuit. There is no feedback. The PCM sends a command and can only assume that the IAC is responding.
It sounds to me like the IAC "sensor" (which is merely a bipolar stepper motor) is not moving the amount that the PCM is commanding - or not moving at all. To HeyYou's credit, if it's not a Mopar sensor (most shops LOVE using bottom-grade parts from parts stores to maximize profit), it should be - *IF* they are even still available.
To properly troubleshoot this would require a DRB-3 tool (which has a dedicated IAC troubleshooting section) and a compressed air source, with the TB removed from vehicle but still plugged in (or otherwise, the throttle blade propped open if left on vehicle).
Particularly the whole "it works fine hot, but fails cold" thing again points me to a motor issue - something about the pintle getting locked up in place until things get warm and loosen up. Wiring is rarely a thermal/time related issue, and the PCM usually wont do that (replacing the PCM was likely a profit-inducing money grab).
It sounds to me like the IAC "sensor" (which is merely a bipolar stepper motor) is not moving the amount that the PCM is commanding - or not moving at all. To HeyYou's credit, if it's not a Mopar sensor (most shops LOVE using bottom-grade parts from parts stores to maximize profit), it should be - *IF* they are even still available.
To properly troubleshoot this would require a DRB-3 tool (which has a dedicated IAC troubleshooting section) and a compressed air source, with the TB removed from vehicle but still plugged in (or otherwise, the throttle blade propped open if left on vehicle).
Particularly the whole "it works fine hot, but fails cold" thing again points me to a motor issue - something about the pintle getting locked up in place until things get warm and loosen up. Wiring is rarely a thermal/time related issue, and the PCM usually wont do that (replacing the PCM was likely a profit-inducing money grab).
Thread Starter
|
Registered User
Joined: Aug 2020
Posts: 8
Likes: 0
What brand IAC is in there? I have found the aftermarket fellers just don't work that great. Mopar is the only ones they seem to like.
The P0505 IS an IAC code as well. Are you still getting that? If so, think I would get a genuine Mopar IAC, install that, reset the pcm again, and see if the problem goes away.
The P0505 IS an IAC code as well. Are you still getting that? If so, think I would get a genuine Mopar IAC, install that, reset the pcm again, and see if the problem goes away.
UPDATE: the mopar part for the part number that they sold me costs about $80
Last edited by barngal; Nov 7, 2021 at 10:56 PM.
Thread Starter
|
Registered User
Joined: Aug 2020
Posts: 8
Likes: 0
The P0505 is generic. ...
Particularly the whole "it works fine hot, but fails cold" thing again points me to a motor issue - something about the pintle getting locked up in place until things get warm and loosen up. Wiring is rarely a thermal/time related issue, and the PCM usually wont do that (replacing the PCM was likely a profit-inducing money grab).
Particularly the whole "it works fine hot, but fails cold" thing again points me to a motor issue - something about the pintle getting locked up in place until things get warm and loosen up. Wiring is rarely a thermal/time related issue, and the PCM usually wont do that (replacing the PCM was likely a profit-inducing money grab).
I will repost how it does over the next couple of days, I am suspecting that tomorrow it will have the hard start and engine code again.
If this is an air leak problem, and I have checked all the hoses the best that I can, I'm thinking to replace both the throttle body gaskets, maybe the manifold gaskets, torquing all to the correct specs, and see from there.
I may replace the gaskets without replacing the map sensor and IAC sensors, though it is tempting to just do the map while I'm in there...
Alternative is to switch throttle bodies, I have a used one but it needs cleaning...
If I'm not getting anywhere with these steps, I know a good shop, they probably have the equipment to diagnose the problem, they just take so long to get into...they aren't cheap, but they are worth it...
Administrator
Joined: Apr 2010
Posts: 87,395
Likes: 4,213
From: Clayton MI
The P0505 is generic. Even moreso, the IAC itself is a "dumb" circuit. There is no feedback. The PCM sends a command and can only assume that the IAC is responding.
It sounds to me like the IAC "sensor" (which is merely a bipolar stepper motor) is not moving the amount that the PCM is commanding - or not moving at all. To HeyYou's credit, if it's not a Mopar sensor (most shops LOVE using bottom-grade parts from parts stores to maximize profit), it should be - *IF* they are even still available.
To properly troubleshoot this would require a DRB-3 tool (which has a dedicated IAC troubleshooting section) and a compressed air source, with the TB removed from vehicle but still plugged in (or otherwise, the throttle blade propped open if left on vehicle).
Particularly the whole "it works fine hot, but fails cold" thing again points me to a motor issue - something about the pintle getting locked up in place until things get warm and loosen up. Wiring is rarely a thermal/time related issue, and the PCM usually wont do that (replacing the PCM was likely a profit-inducing money grab).
It sounds to me like the IAC "sensor" (which is merely a bipolar stepper motor) is not moving the amount that the PCM is commanding - or not moving at all. To HeyYou's credit, if it's not a Mopar sensor (most shops LOVE using bottom-grade parts from parts stores to maximize profit), it should be - *IF* they are even still available.
To properly troubleshoot this would require a DRB-3 tool (which has a dedicated IAC troubleshooting section) and a compressed air source, with the TB removed from vehicle but still plugged in (or otherwise, the throttle blade propped open if left on vehicle).
Particularly the whole "it works fine hot, but fails cold" thing again points me to a motor issue - something about the pintle getting locked up in place until things get warm and loosen up. Wiring is rarely a thermal/time related issue, and the PCM usually wont do that (replacing the PCM was likely a profit-inducing money grab).