Rough idling? Unusually slow acceleration in some occasions?
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Joined: Dec 2017
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From: FL
Rough idling? Unusually slow acceleration in some occasions?
I would like to share the experience of replacing one of the sensors that I found to contribute to rough idling which would happen for no apparent reason. Rough idling would also be accompanied with higher than normal idling RPM. In some other cases, my car would not accelerate as quickly as it would 10 minutes ago.
The cause of Engine occasional rough idling was found - The Camshaft Position sensor. It is located right behind the driver’s timing cover which main function is to report camshaft activity to aid ECM. In my case, due to factors which I couldn’t predict, the isolation of the wire became damaged over time causing sensor glitches.
There were few times when my Techstream would detect errors sent by this sensor. The number of these detections was very insignificant compared to how often I would be experiencing rough idling (especially after a long drive).
The possible DTCs that can be detected are either P1340 or P0340.
Now the key finding is that these DTCs May incorrectly report the failure of the eight cylinder igniter (ignition coil) and even show the name of this error obviously causing the driver purchase incorrect part to fix DTC. It looks like Toyota/Lexus service manuals contain info suggesting that there were “old” and “new” DTC codes implemented at some time. Therefore, additional test is required to verify if it’s indeed an ignition coil or camshaft sensor.
The time needed to replace this sensor is between 1 and 2 hours. What took me the most time is unplug the upper radiator hose which was so stubborn that I had to use additional tools to remove it.
The picture will show the area which got damaged causing periodic DTC to appear and consequent rough idling. The heat may have contributed to the way how ECM would analyze engine activity.
Pit Crew
Joined: Oct 2018
Posts: 171
Likes: 21
From: Manitoba
this is a good post. Quick story:
Wife's Sequoia goes in for timing belt and w/p at the local Toyota dealership as they charge $350 for labour. I supplied the Gates parts kit from Rock Auto. Everything seems great until about 4000 miles later, coming home with 7 kids on my daughter's bday party and she phones me to say she is stuck on the side of the road 10 miles from home with all the kids in the SUV. It will start, but then idle rough and then die. Can't keep it going even with feathering the accelerator.
Tow truck comes and brings it to the dealer which just happened to be the dealer that did the TB/WP. I pull the codes and it comes up as coil pack on cylinder 3. Leave a note about code and keys in the dealer drop box in the parking lot as it was 10pm and a weekend of course...and call them on the Monday when they opened up again.
Tech calls me and tells me and says it's a coil on cylinder 3. I say fine that's what i said in my note and they do the job for me as i couldn't be bothered as it was a simple swap and it was there already. They test drive it and all seems to be well. I pick up the truck and pay the invoice. I questions his labour cost as it was over an hour to swap the coil which should be less than a 30 minute job all day long even with bringing the car into the garage. But whatever, i pay and am on my way.
I get 5 miles down the road and the car stumbles and dies. Call the dealership and tell them to get their *** over to me with a tow truck and get it back to the dealership. they do and they take the whole next day to diagnose. Tech calls me and says it's the clip to the camshaft positions sensor that broke. I called bull**** on him as clips just don't snap off and break. Tell him i rebuild snowmobiles in the offseason and winter and that i pull off a **** load of clips and harnesses that NEVER break even in -20F. He then says that the wiring is frayed. I say how is that possible.....then i think back to a thread that i once read on the Sequoia forum that indicated that if the wiring harness is not routed back exactly the same way it was after doing a TB procedure it could rub on the serpentine belt and cut the wires. I tell him this and he goes back to his own story. ANYWAYS, they do fix it and they do not charge me a dime! But now the wife is pissed at the bill to do the coil. I write a nice, but to the point letter to the GM of the dealership and they take care of me by crediting my whole bill AND installing a new power antenna for the SUV.
So, yes, before you go and spend $$ on a coil pack, it could be the CPS.
sorry for the long reply!
Wife's Sequoia goes in for timing belt and w/p at the local Toyota dealership as they charge $350 for labour. I supplied the Gates parts kit from Rock Auto. Everything seems great until about 4000 miles later, coming home with 7 kids on my daughter's bday party and she phones me to say she is stuck on the side of the road 10 miles from home with all the kids in the SUV. It will start, but then idle rough and then die. Can't keep it going even with feathering the accelerator.
Tow truck comes and brings it to the dealer which just happened to be the dealer that did the TB/WP. I pull the codes and it comes up as coil pack on cylinder 3. Leave a note about code and keys in the dealer drop box in the parking lot as it was 10pm and a weekend of course...and call them on the Monday when they opened up again.
Tech calls me and tells me and says it's a coil on cylinder 3. I say fine that's what i said in my note and they do the job for me as i couldn't be bothered as it was a simple swap and it was there already. They test drive it and all seems to be well. I pick up the truck and pay the invoice. I questions his labour cost as it was over an hour to swap the coil which should be less than a 30 minute job all day long even with bringing the car into the garage. But whatever, i pay and am on my way.
I get 5 miles down the road and the car stumbles and dies. Call the dealership and tell them to get their *** over to me with a tow truck and get it back to the dealership. they do and they take the whole next day to diagnose. Tech calls me and says it's the clip to the camshaft positions sensor that broke. I called bull**** on him as clips just don't snap off and break. Tell him i rebuild snowmobiles in the offseason and winter and that i pull off a **** load of clips and harnesses that NEVER break even in -20F. He then says that the wiring is frayed. I say how is that possible.....then i think back to a thread that i once read on the Sequoia forum that indicated that if the wiring harness is not routed back exactly the same way it was after doing a TB procedure it could rub on the serpentine belt and cut the wires. I tell him this and he goes back to his own story. ANYWAYS, they do fix it and they do not charge me a dime! But now the wife is pissed at the bill to do the coil. I write a nice, but to the point letter to the GM of the dealership and they take care of me by crediting my whole bill AND installing a new power antenna for the SUV.
So, yes, before you go and spend $$ on a coil pack, it could be the CPS.
sorry for the long reply!
Thread Starter
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Joined: Dec 2017
Posts: 716
Likes: 168
From: FL
Thank you for sharing your experience with a similar issue. Yeah, when camshaft position sensor start malfunctioning, it technically may cause engine stall. I also know that other sensors in uz-fe engines also may compensate the lack of information, however, for unknown period of time.
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