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Now, with actuator plug connected, engine start and rpm is 650. And, I joined this pin 3 to negative of battery and suddenly, the rpm rose to over 1to1.5k. please take special note of this. I don't understand!!!
Attaching one of the control wires directly to ground is the same as the PCM applying a 100% duty PWM signal. What happens if you do that to the other PWM control wire? Does the RPM reduce/engine stall?
 

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Discussion Starter #562
Attaching one of the control wires directly to ground is the same as the PCM applying a 100% duty PWM signal. What happens if you do that to the other PWM control wire? Does the RPM reduce/engine stall?
Yes yes, when I apply ground to 1, the engine is about to stall!!!!! And I removed very quickly to continue engine running!!
 

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Right, so it sounds from that like the valve itself working then, which backs up the result of the AC test from earlier.

I think the next step would be to check the actual PCM control duty on both control wires. I'd expect both control signals to add up to 100%. In other words, if you measured 80% duty on one wire I would expect there to be 20% duty on the other. But like I said, you really need an oscilloscope to properly measure the PWM control signals. Some multimeters can measure the duty of the signal but they aren't able to measure the voltages. For that you need a scope.
 

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Discussion Starter #564
Until now, plug cable no.4 has been changed, IAC valve cleaned, TB unit cleaned, but not such expected results to restore rpm to 850 which would then definitely stop that little vibrations!!!

At this time, I'm really disappointed now!!!
 

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Discussion Starter #565
Right, so it sounds from that like the valve itself working then, which backs up the result of the AC test from earlier.
And, but why i got voltage readings about 1.5 on both pin 1 and 2 when grounded??

And about 10.6 v on 3 when connected with positive of battery??
 

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You said earlier that pin 2 was a 12V supply now your saying it has 1.5V?
The control signals are on the ground side of the circuit, so you measure them with reference to battery positive.
 

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Discussion Starter #567
You said earlier that pin 2 was a 12V supply now your saying it has 1.5V?
The control signals are on the ground side of the circuit, so you measure them with reference to battery positive.
Sorry, it's typing errors..

It should be pins 1 and 3. Both were individually tested with reference to positive terminal of battery which then gives similar reading 10.6 Vol. Why I'm not getting 12.60 v???

Also, when grounded individually on negative post of battery, they still show about 1.5 voltage each separately!! Shouldn't they show 0 volt reading??
 

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Discussion Starter #569
Because as per this video, it shows complete 12.6 and 0 v ground..
You may kindly refer to this Toyota.... especially from time 4.20 minutes...
https://youtu.be/JI_3eMf7i18

Meanwhile, all iscv and it's connector etc etc are fine, what would be our next step to restore to 850 rpm??
 

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Discussion Starter #571 (Edited)
Tested with actuator removed from TB unit.
When plug is disconnected, the valve opens a bit. This is ok.

When plug is connected and key is on, the valve opens halfway. Maybe just 10.5 Vol is applied between 2 and 3.

Now, plug disconnected, apply 12.6 v to 2 and 3 to ground to the idle actuator side, then the valve opens fully. Maybe because of 12.60 volt.

Tested with actuator attached to TB unit.
The confusion starts here...
1. At 10.6 v, valve opens halfway. However, i dauds that this is not functioning when plug is connected to actuator, since the moment plug is connected, the rpm drops significantly. If it were opened halfway, I guess the rpm would be normal.

2. Plug disconnected means valve fully opened!! What is letting to open fully when plug remain unconnected??
 

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I think you need to start looking else where for the cause of your low idle speed. Everything with the valve seems to be working properly. You should maybe take a look at the engine live data on your scan tool to see if that shows you what the target idle speed is. The target idle speed is the speed the PCM is commanding the valve to achieve. Maybe the valve is doing exactly what the PCM is asking it to do. Most modern engines also log a trouble code if the actual idle speed is to far from the target. Have you checked to see if there is an idle control code logged?
 

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Discussion Starter #573
Checked with odb2 and no such trouble codes etc are obtained. So, at this time, everything again seems ok. 😌😌😌
 

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Have you checked your coolant temperature on the scan tool data list? That is the main input that controls what the target idle speed should be. It would be worth taking a look at the throttle position data too.
 

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Discussion Starter #575
Coolant temperature is normal as shown in OBD2 as well as the temperature gauge in the instrument cluster is always normal. Coolant level also ok!!!
 

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Discussion Starter #576 (Edited)
I think you need to start looking else where for the cause of your low idle speed. Everything with the valve seems to be working properly.......
In pursuance of several posts relating to low rpm, I did several tests on ...

1. Coil pack which gives about 0.1 ohm on the primary circuit and about 17kohm on the secondary circuit. Each coil has 2 high terminal outputs. The other coil also gives the same results. Each coil plug connector has 2 wires each.

2. Injectors test which gives about 17 ohm each in 4 injectors and each injectors has 2 wire plug connector. Surprise is that when key at ON only, one wire gives 12 v when grounded and the other wire has about 3.5 v when grounded individually. Why?? Is not one wire is supposed to give 0 Vol or remained ground wire?? This is the confusion!!!!

Really looking forward for quick solutions now!!!

Thanks.
 

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the other wire has about 3.5 v when grounded individually. Why??
Because the injector is switched off. What your seeing is the open collector voltage of the injector driver transistor inside the PCM.

Thang Tons said:
Is not one wire is supposed to give 0 V
It is only 0V when the injector is being switched on by the PCM. The length of time the injector is switched on while the engine is running is so short your meter wouldn't be able to display it.
 

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Discussion Starter #578
Meanwhile, referring back to iscv..
Case..
1. Iscv unplug from TB unit and when check physically, it's valve open about 1/4. This is ok.

2. When key is at ON, it's valve open about 1/2. When one wire is grounded to negative post of battery as was mentioned in earlier post, the valve opens fully.

Now, engine started and rpm shoots over 1300.

Confusion is that just as the iscv plug is connected to TB unit, the rpm significantly and gradually drops to 650 again. Does it imply that the valve is less opened (way less than 1/4 as mentioned above)???

I think if the amount of valve opened was the same as when disconnected from TB unit (1/4) as in case 1, the rpm would come to about 850.

Or, if the valve was opened as in case 2 above, will not the rpm rose to 850??
 

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As I said before, the valve is opened and closed by the PCM to maintain a target idle speed. So you need to compare the actual engine speed to the target value in order to know whether the valve is doing what it's supposed to. Looking at the physical movement of the valve is pretty meaningless because you don't have anything to compare it to.
 
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