What is considered a normal idle

jeffro312

Original poster
Member
Oct 4, 2012
442
East Haven,Ct
My Buick Rainier idles at what I think is a funny idle. Some days its smooth and nice next day rough and irradic

Here's a chart of rough idles
emydy5aq.jpg


abu7uga4.jpg
.

Add some revs
vujy9ugu.jpg
 

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jeffro312

Original poster
Member
Oct 4, 2012
442
East Haven,Ct
the roadie said:
That's in-line with what I get, although my variations are slower. How many miles since the last time you cleaned the throttle body, Seafoamed it, or changed the plugs?

No sure on exact mileage but plugs were done when I bought it in feb. So 10k throttle body prob in April or may sea foamed it about 2 months ago and she was parked for the last month.

Its a rough idle sometimes and if I just let it idle I can feel it surge a little sometimes
 

CaptainXL

Member
Dec 4, 2011
2,445
Rpm should be at 700 if I am not mistaken. At least that's what I have seen members report.

If not then I have been misled all along.
 

The_Roadie

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Nov 19, 2011
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700 is what folks report who are only looking at the tach with relatively low resolution, I think. With a scan tool or Scangauge you can get 3-digits of resolution. Of course, resolution is not accuracy, but it is 3-digits. The exact RPM commanded by the PCM after warm-up, and in the presence of no other parameters (like vacuum issues) that bump it up, is either 615 or 625, using HPTuners.
 

blazinlow89

Member
Jan 25, 2012
2,088
With torque 611 is what is usually starts at. It will bounce between 600 and 660 until warm.
 

jeffro312

Original poster
Member
Oct 4, 2012
442
East Haven,Ct
So I replaced serp belt. Cleaned my somewhat clean throttle body.

Here is new idle. Little better I guess right.


Still is randomly rough like I'll start it drive it'll be smooth. Then that night I'll I'll go and its rough. Then. Go shopping come back hour later and smooth again. Odddd
 

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CaptainXL

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Dec 4, 2011
2,445
the roadie said:
700 is what folks report who are only looking at the tach with relatively low resolution, I think. With a scan tool or Scangauge you can get 3-digits of resolution. Of course, resolution is not accuracy, but it is 3-digits. The exact RPM commanded by the PCM after warm-up, and in the presence of no other parameters (like vacuum issues) that bump it up, is either 615 or 625, using HPTuners.

No low resolution here. I use Torque and it tells me that both commanded and actual rpm is 700.

I guess the burden of proof is on those not using a scan tool to look at commanded rpm. Else there could be different programming for idle speed to correct certain conditions or to improve alternator output at idle.

Jeffro please post the pcm commanded rpm at idle. That should make things clear.
 

jeffro312

Original poster
Member
Oct 4, 2012
442
East Haven,Ct
CaptainXL said:
No low resolution here. I use Torque and it tells me that both commanded and actual rpm is 700.

I guess the burden of proof is on those not using a scan tool to look at commanded rpm. Else there could be different programming for idle speed to correct certain conditions or to improve alternator output at idle.

Jeffro please post the pcm commanded rpm at idle. That should make things clear.

Since you also use torque would it be possilble for you to record a graph of RPMs at idle at normal operating tempurature so i know why im comparing it to??

Not sure what the pcm commanded rpm at idle... but i have a clue so when i drive home ill record and post it in a couple hours... thanks guys for all opinions and help

Also would a vacuum leak raise idle rpms or lower them.... i am able to read all these signals from sensors just trying to familiarize myself with what they are supposed to be..

like i notice when i feel this odd surge that my 02 sensor voltage drops and the short term fuel trim has a large change to i think 10 or -10 i forget will confirm in a bit
 

jeffro312

Original poster
Member
Oct 4, 2012
442
East Haven,Ct
the roadie said:
The O2 sensor should fluctuate from high to low faster than once per second. Unless it's old (>100K miles) and getting sluggish from carbon buildup. How many miles do you have total?

I thought about o2 sensors. I have 176051 miles no idea when anythings been changed since before 161k when I bought it my past cars threw codes when o2 was bad but I see how it could be lazy but not lazy enuff to throw code. I just hope o2 sensor for this isn't 250 dollars like of was for my previous vehicle. 00lexus rx300
 

jeffro312

Original poster
Member
Oct 4, 2012
442
East Haven,Ct
these are my o2 sensor voltages at idle

i am thinking that sensor 2 wich is after cat is pretty much dead as it stays at .7 constantly and it does as driving drop if the first o2 sensor goes two .1 the downstream will go .6 or .5 but then right back to .7

so is that a good assumption another idea i had is cat is clogged so sensor 2 isnt getting all the readings it should? but if that was true then it should be reading a constant lean voltage not rich? on the other hand the cat could just not be doing its job of burning gas fumes off? usually a constant rich means a dead sensor so im going to go ahead and replace this sensor (looks to be another PITA job) this weekend


sorry for typing my thought process but may help someone one day and you guys can chime in and clear up my thinking process haha thanks guys


On a side note the bad o2 sensor reading makes engine run rich in return makes engine vibrate alot unusually??? my first thought was motor mounts but this vibration is random.... sometimes its there when i start and for the trip others its completly gone when i start and for the trip......
 

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The_Roadie

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Nov 19, 2011
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Portland, OR
The post-cat O2 sensor is SUPPOSED to be stable. The cat is doing its job.

The pre-cat sensor is clogged with carbon, and is horribly sluggish. And note its variations are about the same frequency as your idle variations. The pre-cat O2 sensor is supposed to wiggle around 1 Hz.
 

jeffro312

Original poster
Member
Oct 4, 2012
442
East Haven,Ct
the roadie said:
The post-cat O2 sensor is SUPPOSED to be stable. The cat is doing its job.

The pre-cat sensor is clogged with carbon, and is horribly sluggish. And note its variations are about the same frequency as your idle variations. The pre-cat O2 sensor is supposed to wiggle around 1 Hz.

Your the best Roadie thanks man. I'll replace pre cat then. As I'm sure cleaning it won't be sufficient enough.
 

97blazer

Member
Nov 23, 2012
39
Interesting o2 sensor test sequence:

[video=youtube;KxhrCl3B22M]https://www.youtube.com/watch?v=KxhrCl3B22M&feature=related[/video]
 

Sparky

Member
Dec 4, 2011
12,927
Yeah that pre-cat O2 looks to be quite tired and worn out.

Have fun removing it from the manifold. I suggest soaking it with PB blaster for a couple days before attempting to wrench it out of there. Spray it when cold, then later go for a drive and get it warm. Repeat for a couple days.

I had to do an emergency O2 sensor yank and replacement a month or two after buying my truck and had to use a big pipe wrench to get it out of there. Spraying it would have helped I'm sure but I had no choice as it totally died suddenly. Thankfully the neighbor had said massive pipe wrench.
 

97blazer

Member
Nov 23, 2012
39
Sparky said:
Yeah that pre-cat O2 looks to be quite tired and worn out.

Have fun removing it from the manifold. I suggest soaking it with PB blaster for a couple days before attempting to wrench it out of there. Spray it when cold, then later go for a drive and get it warm. Repeat for a couple days.

I had to do an emergency O2 sensor yank and replacement a month or two after buying my truck and had to use a big pipe wrench to get it out of there. Spraying it would have helped I'm sure but I had no choice as it totally died suddenly. Thankfully the neighbor had said massive pipe wrench.

A fair amount of heat applied quickly -around- the sensor (not on it) can help. Just don't burn the car up... I've had trouble with 02 sockets, they will spread and slip. Reverted to an open-end wrench and got it. Lucky I guess. Apparently (I haven't verified this) the thread is 14mm spark plug so a plug thread cleaner will help clean the bung once the 02 is out.
 

CaptainXL

Member
Dec 4, 2011
2,445
jeffro312 said:
Your the best Roadie thanks man. I'll replace pre cat then. As I'm sure cleaning it won't be sufficient enough.

If you want to see if the O2 sensor is the reason for your idle variations you can unplug the sensor and see if it smooths out. Duane at Realfixesreal fast explains this in one of his O2 sensor videos.

To remove the sensor your are gonna want to clip off the wire to remove it with a socket. So cleaning it isn't an option. Don't remove it with the 02 socket or it will strip. If it gets stripped you will need a pipe wrench to take it out. in order to use a pipe wrench the heat shield needs to come off. can be a real pain if not tackled right from the start.
 

jeffro312

Original poster
Member
Oct 4, 2012
442
East Haven,Ct
CaptainXL said:
If you want to see if the O2 sensor is the reason for your idle variations you can unplug the sensor and see if it smooths out. Duane at Realfixesreal fast explains this in one of his O2 sensor videos.

To remove the sensor your are gonna want to clip off the wire to remove it with a socket. So cleaning it isn't an option. Don't remove it with the 02 socket or it will strip. If it gets stripped you will need a pipe wrench to take it out. in order to use a pipe wrench the heat shield needs to come off. can be a real pain if not tackled right from the start.

Thanks guys for all the info. I'm going to assume when I bought car the dealer replace exhaust manifold as old on was cracked. So only 10k miles since sensor was installed. I'll tackle this Sunday (my only day off) and see results.

You have me curious about unplugging it I thought about that but just assumed unplugged is same as bsd;/ not working. Give it a shot
 

CaptainXL

Member
Dec 4, 2011
2,445
jeffro312 said:
Thanks guys for all the info. I'm going to assume when I bought car the dealer replace exhaust manifold as old on was cracked. So only 10k miles since sensor was installed. I'll tackle this Sunday (my only day off) and see results.

You have me curious about unplugging it I thought about that but just assumed unplugged is same as bsd;/ not working. Give it a shot

Yeah. Your scan a few posts back of sensor 1 looks ok. It's switching from 900 to 100 millivolts just fine. At idle it will switch about once every second as shown on a scan tool. At least that's what Duane's video confirms. So it's not necessarily slow unless it does this off idle as well.

If the sensor is old (> 100,000 miles) I would change it as part of good preventative maint. If it's relatively new (which I would definitely check out) then I wouldn't mess with it. Even the new sensor I installed about 10,000 miles ago still required some muscle to unscrew when I replaced my exhaust manifold. And yes it did have antiseize on it.
 

The_Roadie

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Nov 19, 2011
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Portland, OR
CaptainXL said:
...At idle it will switch about once every second as shown on a scan tool. ...
I'm seeing about 5 seconds from peak to peak on his screen shot. 5, 10, 15 seconds as on the bottom edge time scale. I think that's about five times too slow. I misplaced my Bluetooth adapter, or else I'd look at Torque to confirm, but am I missing something about the time scale?
 

CaptainXL

Member
Dec 4, 2011
2,445
the roadie said:
I'm seeing about 5 seconds from peak to peak on his screen shot. 5, 10, 15 seconds as on the bottom edge time scale. I think that's about five times too slow. I misplaced my Bluetooth adapter, or else I'd look at Torque to confirm, but am I missing something about the time scale?

Hmm. It could have something to do with the type of scan tool used. Of course Duane is using a fast Verus which might make a difference. A quick search on the web tells me that with multiport fuel injection engines the O2 sensor switches about 5-7 times per second at 2500 rpm. If I use my scan tool data to see what it should be at idle I don't get any figures. It only tells me to see if it is switching between 0 - 900 millivolts. If the O2 sensor wasn't switching like it should at 2500 rpm then the pcm should throw a P0133 (slow response) CEL. That's my take on it.

I am not saying don't change it. It could very well be within spec but it is known that O2 sensors degrade over time. Replacing them can restore some performance and fuel economy. I am just not convinced that a slow O2 sensor would present problems like the OP has at idle.
 

jeffro312

Original poster
Member
Oct 4, 2012
442
East Haven,Ct
not sure if this will be readable but a short blip of a few sensors while driving down the highway


yea not sure how to delete a post this is useless ill try again

is that visable
 

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gboos

Member
Jul 22, 2012
34
jeffro312 said:
not sure if this will be readable but a short blip of a few sensors while driving down the highway


yea not sure how to delete a post this is useless ill try again

is that visable

Not visible at all .....
 

jeffro312

Original poster
Member
Oct 4, 2012
442
East Haven,Ct
how about this did i link this correctly???

[PDF]https://www.dropbox.com/s/0x7j3108wdpldbu/trackLog-2012-Nov-27_08-53-11.pdf[/PDF]
 

CaptainXL

Member
Dec 4, 2011
2,445
Nothing on that chart looks out of the ordinary. Try lgging all 6 cylinders for misfires but over a longer period of time ,not just a few minutes.
 

jeffro312

Original poster
Member
Oct 4, 2012
442
East Haven,Ct
ok soo now theres this loud ticking noise... anyidea. one thing after another

[video=youtube_share;ctLp9I_tB-k]http://youtu.be/ctLp9I_tB-k[/video]
 

CaptainXL

Member
Dec 4, 2011
2,445
jeffro312 said:
ok soo now theres this loud ticking noise... anyidea. one thing after another

You should remove the belt, start the engine and run it for a few seconds to see if the noise is still there.

It would be a good idea to put a vacuum gauge on it to see if you have valve issues.
 

jeffro312

Original poster
Member
Oct 4, 2012
442
East Haven,Ct
can u recoomend where to get this guage and where to connect it to test? is this something a autoparts will have on its list of loaner tools???

also where would i find what the vacuum should be
 

CaptainXL

Member
Dec 4, 2011
2,445
jeffro312 said:
can u recoomend where to get this guage and where to connect it to test? is this something a autoparts will have on its list of loaner tools???

also where would i find what the vacuum should be

Most auto parts stores have them for around $35. Most don't rent them.

In all honesty I think you should just take it to a shop or friend that knows what they are doing and work on it. It could turn out to be serious. Better to get an accurate diagnosis now rather than see you needing an engine from something as simple as a lack of oil or something.

If you get the vacuum gauge we can show you where to hook it up. Come back when your ready.
 

CaptainXL

Member
Dec 4, 2011
2,445
Using Torque I can confirm that my engine idles between 600 - 630 rpm when fully warmed up at idle. For some reason my mind was stuck on 700 but it's been a while since I looked at it.
 

jeffro312

Original poster
Member
Oct 4, 2012
442
East Haven,Ct
so i took previous advice and recorded the misfire count during a drive... not as long of a drive as requested

but just a sample ill drive longer tomarrow

https://www.dropbox.com/s/v3mujjpxo6xk40d/trackLog-2012-Nov-30_09-23-24.pdf

it still shows multiple misfires on different cylinders wich to me is random

wich makes life alot harder.. this sunday i will inspect plugs and coils etc test all i can test with tools i have. hope for something minor...

any ideas would be greatly apreciated thanks
 

CaptainXL

Member
Dec 4, 2011
2,445
jeffro312 said:
so i took previous advice and recorded the misfire count during a drive... not as long of a drive as requested

but just a sample ill drive longer tomarrow

https://www.dropbox.com/s/v3mujjpxo6xk40d/trackLog-2012-Nov-30_09-23-24.pdf

Well I see a bunch of misfires. Thats quite a lot for only a minute of time. When were the spark plugs last changed?

You are going to want to get a vacuum gauge on it as well to see if these misfires are due to a vacuum leak.

Change fuel filter and check pressure as well. Run some water remover (iso heat) and fuel injector cleaner as well. Fill up with top tier gas. 87 octane.
 

jeffro312

Original poster
Member
Oct 4, 2012
442
East Haven,Ct
CaptainXL said:
Well I see a bunch of misfires. Thats quite a lot for only a minute of time. When were the spark plugs last changed?

You are going to want to get a vacuum gauge on it as well to see if these misfires are due to a vacuum leak.

Change fuel filter and check pressure as well. Run some water remover (iso heat) and fuel injector cleaner as well. Fill up with top tier gas. 87 octane.

hey captain i do have to thank you very much for your quick replys as they are informative.

plugs were changed like a month after i bought the car and ive put 10k on since i bought the car i put the plugs recommended on the old site forgot what they were by now..

fuel filter was also changed a month or two after the plugs.

and i usually put 93 octane in just because its a habit from previous cars i had required it so i figured im used to paying extra higher octane cant hurt right?

going to try and get a vacuum gauge tomarrow and fiddle around on sunday.. my day off
i will check plug conditions and what not and go from there.

question is will i cause further damage by driving like this ?

thanks for quick replies and inputs... this forum is an encylopedia of information and i love learning about my car.

im the kind of guy that seems to beable to fix anything as long as i know how it came apart and how it is supposed to work before i attempt anything. once i understand what it does and how it works i figure out the rest
 

CaptainXL

Member
Dec 4, 2011
2,445
jeffro312 said:
and i usually put 93 octane in just because its a habit from previous cars i had required it so i figured im used to paying extra higher octane cant hurt right?

Unless you got a tune that requires 93 octane I wouldn't use it. 87 is all that is required. It's just a waste of money. It won't give you more power.

Higher octane will create carbon deposits and over time will cause engine wear, overheating, and poorer fuel economy.

My advice is to use 87 octane and save your money for a tune or any repairs you will need down the road.
 

jeffro312

Original poster
Member
Oct 4, 2012
442
East Haven,Ct
CaptainXL said:
Unless you got a tune that requires 93 octane I wouldn't use it. 87 is all that is required. It's just a waste of money. It won't give you more power.

Higher octane will create carbon deposits and over time will cause engine wear, overheating, and poorer fuel economy.

My advice is to use 87 octane and save your money for a tune or any repairs you will need down the road.

thanks again captain
 

jeffro312

Original poster
Member
Oct 4, 2012
442
East Haven,Ct
So I pulled my plugs today for inspection. This is what I saw.

huha2uvy.jpg


At first I was like wtf what's this silver pasty stuff and just as I posted this picture my brain decided to function and actually access memory and remember oh duh when I put the plugs in I put that stuff on threads. Not sure if was supposed to.

Anyways I'm assuming cylinder one is near firewall and 6 is front of car so cylinder 2,3,4 seemed to have or had oil in the well none on the spark area other then that they seemed to look OK and good cleaned them up a little.

5ypu7ubu.jpg


How do I go about cleaning in there without damaging anything.



Anyways the idles still kind of rough other day I got in argument and took off flooring it down the street then onto the on ramp till I hit 90mph then drove normal. Since that my idle has smoothed out as in in neutral for the most part I cannot tell vehicle is running
 

CaptainXL

Member
Dec 4, 2011
2,445
Ok, you might have excessive blowby. What can happen is the crankcase becomes overly pressurized gases leak past the worn piston rings. When this happens the oil is forced past seals. In this case the valve cover seals. There are six, one for each spark plug well. Clean each spark plug well with carb cleaner to get rid of that gunk. Just shoot it down around the side of the well and into the hole. Then clean each of the spark plugs threads off with carb cleaner as well. You don't need that silvery antiseize on them because you only torque each plug to 13 ft/lbs. Rent or buy a compression tester and see what each cylinder is at both dry and wet. See a Chiltons manual on how to do a compression test. Return to us with results,
 

Sparky

Member
Dec 4, 2011
12,927
A little oil down the wells isn't uncommon. Blowby would cause pressurization of the crankcase, not the valve covers. As long as the plugs and coils aren't swimming in oil I wouldn't be too concerned. I've seen this on all makes of cars.

Wouldn't be a bad idea to make sure the valve cover bolts are tightened to spec though. Sometimes they work a little loose and that can cause oil seepage.
 

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