[rjacket]

Hopefully the PCV will fix this.

I've read through this thread several times and I was wondering what were the circumstances where this high idle developed? Was it after maintenance? If so what maintenance? Or has it developed over time? If so, how many miles are on your Vulcan?

 

[ice445]

So, I checked the throttle body today and didn't see any issues. It was cleaned in September, when the intake gaskets and other items were replaced. View attachment 222126

If it was cleaned improperly the coating on it can be damaged

 

[retho78]

Hopefully the PCV will fix this.

I've read through this thread several times and I was wondering what were the circumstances where this high idle developed? Was it after maintenance? If so what maintenance? Or has it developed over time? If so, how many miles are on your Vulcan?

The idle was rough before due to the oil leaks from the manifolds. I replaced the upper and lower intake manifold gaskets, spark plugs, IAC and throttle body sensor. No leaks now and idle is smooth but just a little high. No check engine light or codes, and it has 76k miles.

 

[retho78]

If it was cleaned improperly the coating on it can be damaged

I used carb/throttle cleaner and wiped it with shop towels.

 

[rjacket]

The idle was rough before due to the oil leaks from the manifolds. I replaced the upper and lower intake manifold gaskets, spark plugs, IAC and throttle body sensor. No leaks now and idle is smooth but just a little high. No check engine light or codes, and it has 76k miles.

So before the work you did, the idle was at the correct level but rough?

Or it was too high as well as rough?

 

[retho78]

So before the work you did, the idle was at the correct level but rough?

Or it was too high as well as rough?

It was rough and high.

Even with the rough idle there was no CEL, which was strange. So, since I had everything out, I replaced the spark plugs, IAC and throttle position sensor. I didn't replace the EGR or PCV. The PCV was only cleaned and EGR has new gasket and o-ring to the intake.

 

[rjacket]

It was rough and high.

Even with the rough idle there was no CEL, which was strange. So, since I had everything out, I replaced the spark plugs, IAC and throttle position sensor. I didn't replace the EGR or PCV. The PCV was only cleaned and EGR has new gasket and o-ring to the intake.

Got it.

Long time ago I had slightly rough and high idle where car would speed up too easily at idle. Root cause was very short trips and non top tier gas for a few years had left deposits on throttle body.

But bigger consequence of short trips / non top tier fuel over time was low power due to gummed up injectors and maybe even deposits in combustion chamber. Car felt pretty normal but would not go over 75mph. Also poorer fuel economy.

Cleaning the throttle body (on both sides) fixed rough idle. A fuel injector cleaner in the gas tank began to give power improvement and I followed that up with the Regane complete fuel system cleaner (fuel system cleaners have much more of the cleaning chemical - PEA - than fuel injector cleaners). The improvement was huge. I could then hear some sort of scraping noise on acceleration so I did the $20 fuel system cleaning at Walmart where they drip in a cleaner through a vacuum hose. That actually took care of that noise.

Since then, it's been a case of almost always using top tier fuel, making sure there were longer trips mixed in, and a complete fuel system cleaner every 5k to 10k (which now does not really seem to do much thanks to top tier fuel and longer trips). I haven't had to clean the throttle body since. I also only use full synthetic oil.

If the throttle body was dirty, then I think it is definitely worth running a complete fuel system cleaner and consider an intake system cleaner either diy or walmart. Those same deposits on the throttle body would have also deposited themselves elsewhere. And since you've only got 76k miles on a nearly 20 year old car, it's probably done a lot of short tripping. If you're in a cold climate, it's the worst possible scenario for deposits since it takes even longer to get fully warmed up, but short trips in California was enough for mine to have problems after a couple of years.

Lastly, (on the Duratec at least), the instructions say once you remove the PCV valve, you have to replace it. The act of removing it supposedly means it won't work properly.

 

[retho78]

Got it.

Long time ago I had slightly rough and high idle where car would speed up too easily at idle. Root cause was very short trips and non top tier gas for a few years had left deposits on throttle body.

But bigger consequence of short trips / non top tier fuel over time was low power due to gummed up injectors and maybe even deposits in combustion chamber. Car felt pretty normal but would not go over 75mph.

Cleaning the throttle body (on both sides) fixed rough idle. A fuel injector cleaner in the gas tank began to give power improvement and I followed that up with the Regane complete fuel system cleaner (fuel system cleaners have much more of the cleaning chemical - PEA - than fuel injector cleaners). The improvement was huge. I could then hear some sort of scraping noise on acceleration so I did the $20 fuel system cleaning at Walmart where they drip in a cleaner through a vacuum hose. That actually took care of that noise.

Since then, it's been a case of almost always using top tier fuel, making sure there were longer trips mixed in, and a complete fuel system cleaner every 5k to 10k (which now does not really seem to do much thanks to top tier fuel and longer trips). I haven't had to clean the throttle body since. I also only use full synthetic oil.

If the throttle body was dirty, then I think it is definitely worth running a complete fuel system cleaner and consider an intake system cleaner either diy or walmart. Those same deposits on the throttle body would have also deposited themselves elsewhere. And since you've only got 76k miles on a nearly 20 year old car, it's probably done a lot of short tripping. If you're in a cold climate, it's the worst possible scenario for deposits since it takes even longer to get fully warmed up, but short trips in California was enough for mine to have problems after a couple of years.

Lastly, (on the Duratec at least), the instructions say once you remove the PCV valve, you have to replace it. The act of removing it supposedly means it won't work properly.

Thanks for the input. I take short trips with it and already added fuel system cleaner (3 bottles) with each gas fill up using 89 octane. I also tested the fuel injectors and they all seemed to function properly.
I will wait for the PCV and purge valve solenoid to come in and replace and go from there.

 

[rjacket]

Thanks for the input. I take short trips with it and already added fuel system cleaner (3 bottles) with each gas fill up using 89 octane. I also tested the fuel injectors and they all seemed to function properly.
I will wait for the PCV and purge valve solenoid to come in and replace and go from there.

Yes definitely change the PCV before trying much more.

Re fuel system cleaner, you won't get any extra benefit from using more than 1 bottle in a fill up. Just make sure you use one with PEA in it.

Also, for continuous dosing, either use top tier fuel or a fuel injector cleaner. Or you can use a small amount of the complete fuel system cleaner - Redline have a suggested amount in their instructions.

There's actually a lot of science behind the products including the dosage needed for it to work, and that is reflected in the instructions.

 

[retho78]

The PCV came in today and going to swap it out tonight and will see what happens. Also, did a scan with another tool and found some trouble codes (please see attached pdf file), and O2 sensors reading lean (line items 139 to 148). The line items 72 to 78 shows No Fault, so I'm confused with the two results.

Battery is new and could it be that the alternator is weak?

 

[rjacket]

The PCV came in today and going to swap it out tonight and will see what happens. Also, did a scan with another tool and found some trouble codes (please see attached pdf file), and O2 sensors reading lean (line items 139 to 148). The line items 72 to 78 shows No Fault, so I'm confused with the two results.

Battery is new and could it be that the alternator is weak?

P1000 is set when you clear trouble codes and requires drive cycles that meets certain criteria to remove. Apparently you cleared the codes 18 miles ago but only had 1 warm up so it's possible you haven't met the criteria to clear the code yet.

Battery voltage low - you can go get the battery tested at Walmart or an auto parts store. Or use a multimeter to read the voltage yourself once the surface charge has dissipated. You said it is a new battery so all that might have happened is that it needs a charge. Alternatively, the trouble code is in a particular module (the GEM) so maybe there is some sort of issue with the wiring to the GEM or the GEM. But it is simple to check this if you can access the pids for battery voltage in the PCM and GEM while the car is key on engine off and compare them.

Alternator does not seem to be weak since you have a voltage reading of 14.1v when the engine is running and even a max of 15.7v.

Ignition key in circuit fault - there is probably some wear and tear in the tumbler related to the tumbler knowing the exact position of the key. I have this code as well and it does not cause any issues.

 

[Automender12345]

Your long term fuel trims are high at least on bank 2 and a little high on bank 1. Both O2 sensors are showing lean on the report. It seems like you have a vacuum leak. Also was the engine fully warmed up when you did the test because the report indicates the engine is cold. When the sensor is bad it can lead to issues with the fuel trims.

 

[rjacket]

Your long term fuel trims are high at least on bank 2 and a little high on bank 1. Both O2 sensors are showing lean on the report. It seems like you have a vacuum leak. Also was the engine fully warmed up when you did the test because the report indicates the engine is cold. When the sensor is bad it can lead to issues with the fuel trims.

LT fuel trims are not valid after 4 mins with engine coolant temp reading "cold".

 

[retho78]

Thank you for the replies. So, I replaced the PCV and didn't see any changes to the idle, drove it for about 5 to 7 minutes and let it idle for couple minutes while the live data scan was running. Here's the latest live data report.

Also, the alternator voltage has dropped to 13.2

I do have a battery tester and charger so will test it tomorrow.

Still waiting on the purge valve to come in and if no changes after replacing it, then will have to do a smoke test to find the vacuum leak.

 

[rjacket]

Thank you for the replies. So, I replaced the PCV and didn't see any changes to the idle, drove it for about 5 to 7 minutes and let it idle for couple minutes while the live data scan was running. Here's the latest live data report.

Also, the alternator voltage has dropped to 13.2

I do have a battery tester and charger so will test it tomorrow.

Still waiting on the purge valve to come in and if no changes after replacing it, then will have to do a smoke test to find the vacuum leak.

You're misinterpreting the alternator data.

Also, bear in mind that the vehicle is relearning every time you reset the codes.

Did you check your PCV elbow as well as all the other vac hoses that chart advised do not show up in the LT fuel trims?

Some data needs to be analyzed over time rather than as a snapshot. For example for the battery, you want to connect it to the multimeter at rest, leave it connected, and then record the low and high during and after start. The alternator voltage can be 13.2v at a point in time, but that is meaningless if you have a high of 14.6v which for some reason you are ignoring.

Your oxygen sensors should oscillate between approx 0.1v to 0.9v, and that refers to the oxygen sensor #1 (not #2) on bank #1 and bank #2. Again, a snapshot would not be helpful.

Misinterpreting data is as bad as not diagnosing which simply leads to changing parts.

 

[retho78]

You're misinterpreting the alternator data.

Also, bear in mind that the vehicle is relearning every time you reset the codes.

Did you check your PCV elbow as well as all the other vac hoses that chart advised do not show up in the LT fuel trims?

Some data needs to be analyzed over time rather than as a snapshot. For example for the battery, you want to connect it to the multimeter at rest, leave it connected, and then record the low and high during and after start. The alternator voltage can be 13.2v at a point in time, but that is meaningless if you have a high of 14.6v which for some reason you are ignoring.

Your oxygen sensors should oscillate between approx 0.1v to 0.9v, and that refers to the oxygen sensor #1 (not #2) on bank #1 and bank #2. Again, a snapshot would not be helpful.

Misinterpreting data is as bad as not diagnosing which simply leads to changing parts.

Okay. I did check PCV elbow and didn't see any cracks. Also, checked all visible vac hoses/lines and didn't notice any cracks. I did notice the 14.6v but curious why it was only reading 13.2 on the scan tool and multimeter. I will check it again tomorrow while at rest, during and after start.

 

[retho78]

Also, noticed this issue on line items 167 and 168.

 

[rjacket]

Also, noticed this issue on line items 167 and 168.

View attachment 222159

Yes I saw that which is confirmation that your high idle isn't what your pcm wants to see.

Re your alternator output, if you have a scan tool that can record it over time, get it to do that and then look at the graph at the end of a journey.

In a post Steve83 said a mechanic's stethoscope with the metal part removed is good for listening for vac leaks. But if you have access to a smoke machine, then that would probably be even easier.

Here's an example of some diagnosis of a Taurus with a vac leak using a smoke machine and data:

 

[retho78]

Tested the battery and alternator, and appears to be working good.

 

[ice445]

Well I looked through all your data, and bank 2 LTFT is a little bit high, but anything under 10% shouldn't cause any issues like this. I'm curious, when the car is running can you visually inspect your accessory drive? I'm wondering if you've got a dragging accessory or pulley that the car is trying to compensate for. That idle value is about right for when the A/C compressor is engaged, although looking at the data the car isn't asking it to be. I'm not sure what the engine load should be (I don't have the ability to compare on my car), but 15% seems high for just idling.