Will a bad EGR valve cause a misfire?
#61
You might want to read up on a leak down test.
First, how would you know it "failed"? The first level of usefulness of a leak down test is comparison to your engine at another time (using the same tool). There is no absolute pass/fail number, and the number you get with any engine will be different between testers. (While it's technically possible to calibrate the orifice in YOUR tester, I've never heard of anyone doing it.)
Even though you don't have a baseline reading, you certainly can use it to compare between cylinders. And for what it's worth, on my fine-running 3VZE, I get about 35% with my tester.
"If it fails the test I'm not going to know the why or where" No, actually, that is one of the GOOD things about a leakdown test. If you have a cylinder that seems to be leaking, you can HEAR it in the exhaust, or the intake, or in the dipstick tube, or sometimes by seeing bubbles in the radiator. You'll have leakage in those areas even with good cylinders, but with bad ones the noise will be pretty easy to pick up.
First, how would you know it "failed"? The first level of usefulness of a leak down test is comparison to your engine at another time (using the same tool). There is no absolute pass/fail number, and the number you get with any engine will be different between testers. (While it's technically possible to calibrate the orifice in YOUR tester, I've never heard of anyone doing it.)
Even though you don't have a baseline reading, you certainly can use it to compare between cylinders. And for what it's worth, on my fine-running 3VZE, I get about 35% with my tester.
"If it fails the test I'm not going to know the why or where" No, actually, that is one of the GOOD things about a leakdown test. If you have a cylinder that seems to be leaking, you can HEAR it in the exhaust, or the intake, or in the dipstick tube, or sometimes by seeing bubbles in the radiator. You'll have leakage in those areas even with good cylinders, but with bad ones the noise will be pretty easy to pick up.
When I say that I wont know there where or why,that is just me personally not knowing because of my limited mechanical knowledge,not to imply somebody else wouldnt know.
As far as no pass or fail,if you hear it leaking,especially a bad leak,wouldnt that be a fail?
I have done a leak down test on a 2 stroke before,and if it didnt hold air pressure for a certain amount of time,that was a fail,I assumed this test was the same way,but like you say I have a lot more to learn.
I am also concerned I wont be able to find top dead center for that cylinder to do the test.
Last edited by redskinman; 02-13-2017 at 08:46 AM.
#62
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Thank you for reply,I will def be doing some more reading up.
When I say that I wont know there where or why,that is just me personally not knowing because of my limited mechanical knowledge,not to imply somebody else wouldnt know.
As far as no pass or fail,if you hear it leaking,especially a bad leak,wouldnt that be a fail?
I have done a leak down test on a 2 stroke before,and if it didnt hold air pressure for a certain amount of time,that was a fail,I assumed this test was the same way,but like you say I have a lot more to learn.
I am also concerned I wont be able to find top dead center for that cylinder to do the test.
When I say that I wont know there where or why,that is just me personally not knowing because of my limited mechanical knowledge,not to imply somebody else wouldnt know.
As far as no pass or fail,if you hear it leaking,especially a bad leak,wouldnt that be a fail?
I have done a leak down test on a 2 stroke before,and if it didnt hold air pressure for a certain amount of time,that was a fail,I assumed this test was the same way,but like you say I have a lot more to learn.
I am also concerned I wont be able to find top dead center for that cylinder to do the test.
I think the primary concern is ring damage, secondary will be how well the valves seal against the head. This lets you decide wether to rebuild top and bottom, the head, or just replace the valve seals. It is going to need some or all.
I've been killing off mushroom and mold growth all day. I would have suggested maybe buying exhaust gaskets instead of the leakdown gauges, If the exhaust valves aren't wet with oil it would almost have to be the intake valve leaking the oil.. but now you have a new tool and can get a sense of the ring health.
another option would be a bore scope, but the low res digital one isn't that great, then you could gauge scoring and look for debris/chunks.. (a better version of the rag test)
That spark plug shows what is known as "oil coking", in short this is lubricant turning into abrasive and it's not good. Specifically it can and will destroy the cylinder walls.
#63
Ok so I did the leak down test today but I believe I screwed the pooch and I didnt realize it till after I had put everything back together and I was too tired and disgusted with myself to start over,will tackle it again Sunday weather permitting.
So I tested cylinders 2,4,and 6 first.For the first 3 cylinders I had truck in gear with parking brake on.Then I took a lunch break and when I did the other 3 cyl I forgot to put truck in gear like I had the other test,this is where I think I pooched it.
So first cyl I tested was 4,where I thought I had the misfire.I did the test multiple times on each cylinder,it seemed like i would get a different reading depending on how fast I could get them coupled together.This Harbor Freight tester looks like it works a little differently then the other testers I have seen on youtube.At 40% leakage it still says that is moderate.
So cylinder 4 tested under 10 % 3 times.
Cylinder 2 I got readings of,10,20,and 18
Cylinder 6 I got readings of 25,30,and 30.
Then took lunch break
Came back,forgot to put truck back in gear.
Cylinder 5-40,38,35
Cylinder 3-34,40,45
Cylinder 1-40,40,didnt do a 3rd test
So after these other readings were so much higher then the first 3 I went back and checked cyl 2 and 6 again and got readings of 40%,a lot different then the first readings when I had truck in gear.
At no point did I ever hear any air leaking anywhere.I checked tailpipe,looked for bubbles in radiator,heard no air coming out of dipstick tube.
But I did forget to take oil cap off and listen there,and I listened for air at throttle body but forgot to open intake and listen.
So I tested cylinders 2,4,and 6 first.For the first 3 cylinders I had truck in gear with parking brake on.Then I took a lunch break and when I did the other 3 cyl I forgot to put truck in gear like I had the other test,this is where I think I pooched it.
So first cyl I tested was 4,where I thought I had the misfire.I did the test multiple times on each cylinder,it seemed like i would get a different reading depending on how fast I could get them coupled together.This Harbor Freight tester looks like it works a little differently then the other testers I have seen on youtube.At 40% leakage it still says that is moderate.
So cylinder 4 tested under 10 % 3 times.
Cylinder 2 I got readings of,10,20,and 18
Cylinder 6 I got readings of 25,30,and 30.
Then took lunch break
Came back,forgot to put truck back in gear.
Cylinder 5-40,38,35
Cylinder 3-34,40,45
Cylinder 1-40,40,didnt do a 3rd test
So after these other readings were so much higher then the first 3 I went back and checked cyl 2 and 6 again and got readings of 40%,a lot different then the first readings when I had truck in gear.
At no point did I ever hear any air leaking anywhere.I checked tailpipe,looked for bubbles in radiator,heard no air coming out of dipstick tube.
But I did forget to take oil cap off and listen there,and I listened for air at throttle body but forgot to open intake and listen.
Last edited by redskinman; 02-15-2017 at 11:38 AM.
#64
Crickets in here
My truck is an automatic so would that make any difference whether it was in park or drive? I'm wondering if this HF tester is just crap to get such different results.
My truck is an automatic so would that make any difference whether it was in park or drive? I'm wondering if this HF tester is just crap to get such different results.
#65
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A leak done test will only tell you so much. If you didn't have anything major then it might not be in the cylinders. You had spark plug(s) that looked like they had ash deposits on them. This could be the next place to check. Inconsistent spark could be an issue. So I don't have to go back a read 7 pages of thread. What codes is it tripping? If it's running that poorly it should be tripping something even if the CEL doesn't come on.
Edit: ok so if it's still tripping a code 71 it might be time to clean your EGR. It's not that hard, most people do the plenum and throttle body at the same time.
Edit: ok so if it's still tripping a code 71 it might be time to clean your EGR. It's not that hard, most people do the plenum and throttle body at the same time.
Last edited by thefishguy77; 02-17-2017 at 05:35 PM.
#66
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A small difference in cam angle could have left the valves open slightly, or possibly it could have just been the oilrings drying out.
You got even results across all the cylinders right? If so you you have a choice to replace the valve seals with the head in place, or tear it down and have the heads worked over.
How do/did the new plugs look when you pulled them this time? Was #4 oil soaked?
#67
No, being in or out of gear on an automatic transmission isn't going to cause differences. If you're concerned the crankshaft could have rotated you can lock it in place with a ratchet on the crank bolt, or just put a wrench on it for reference.
A small difference in cam angle could have left the valves open slightly, or possibly it could have just been the oilrings drying out.
You got even results across all the cylinders right? If so you you have a choice to replace the valve seals with the head in place, or tear it down and have the heads worked over.
How do/did the new plugs look when you pulled them this time? Was #4 oil soaked?
A small difference in cam angle could have left the valves open slightly, or possibly it could have just been the oilrings drying out.
You got even results across all the cylinders right? If so you you have a choice to replace the valve seals with the head in place, or tear it down and have the heads worked over.
How do/did the new plugs look when you pulled them this time? Was #4 oil soaked?
#4 plug still looked almost brand-new no oil on it. It doesn't have any miles on it yet just been starting it up in the driveway. The other plugs looked good.
I took my tester back this morning and did it even exchange for another one and will do some more test tomorrow and see what results I get.
What I don't understand is why I am not getting a code for a misfire? I have had a misfire the whole time and never got a code for it, just a lean condition code and the EGR malfunction code.
I havent put any miles on it since putting on the block kit.When I get home from work today I'm going to take it for a spin and put at least 50 miles on it,see if I get check engine light to come on and then I'll see how spark plugs look tomorrow.
Last edited by redskinman; 02-18-2017 at 06:52 AM.
#68
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2,4,and 6 we're all different readings. 1,3 and five were about the same.
#4 plug still looked almost brand-new no oil on it. It doesn't have any miles on it yet just been starting it up in the driveway. The other plugs looked good.
I took my tester back this morning and did it even exchange for another one and will do some more test tomorrow and see what results I get.
What I don't understand is why I am not getting a code for a misfire? I have had a misfire the whole time and never got a code for it, just a lean condition code and the EGR malfunction code.
#4 plug still looked almost brand-new no oil on it. It doesn't have any miles on it yet just been starting it up in the driveway. The other plugs looked good.
I took my tester back this morning and did it even exchange for another one and will do some more test tomorrow and see what results I get.
What I don't understand is why I am not getting a code for a misfire? I have had a misfire the whole time and never got a code for it, just a lean condition code and the EGR malfunction code.
You won't get a misfire code, that's an obd2 feature and relies on sensors we don't have (crank position).
Was it showing any signs of combustion there(plug #4) or is it still not changing the run character when you do a balance test(pull the sparkplug wire).
Might need to drive it to get the crankcase pressure up high enough to make that seal leak..
Hate to say it at this point but, how is the PCV valve, a new OEM one might fix it? (I'm not a fan of the junk the partstore gives us, at all!!)
If number 4 is firing, and fouls under higher engine speed or load. Try elimination of the crank vent system. You'll need to plug off the PCV valve on the intake and the fresh air vent to the air box(so you're not getting unmetered air), then attach breather filters on to the valve covers. Collapsed or otherwise plugged lines or a bad PCV valve will increase the crankcase pressure maybe enough to blow passes the valve seals.
#69
Not sure on the discrepancy, maybe not enough lube on the threads and or o-ring, or just flakey HF tools.
You won't get a misfire code, that's an obd2 feature and relies on sensors we don't have (crank position).
Was it showing any signs of combustion there(plug #4) or is it still not changing the run character when you do a balance test(pull the sparkplug wire).
Might need to drive it to get the crankcase pressure up high enough to make that seal leak..
Hate to say it at this point but, how is the PCV valve, a new OEM one might fix it? (I'm not a fan of the junk the partstore gives us, at all!!)
If number 4 is firing, and fouls under higher engine speed or load. Try elimination of the crank vent system. You'll need to plug off the PCV valve on the intake and the fresh air vent to the air box(so you're not getting unmetered air), then attach breather filters on to the valve covers. Collapsed or otherwise plugged lines or a bad PCV valve will increase the crankcase pressure maybe enough to blow passes the valve seals.
You won't get a misfire code, that's an obd2 feature and relies on sensors we don't have (crank position).
Was it showing any signs of combustion there(plug #4) or is it still not changing the run character when you do a balance test(pull the sparkplug wire).
Might need to drive it to get the crankcase pressure up high enough to make that seal leak..
Hate to say it at this point but, how is the PCV valve, a new OEM one might fix it? (I'm not a fan of the junk the partstore gives us, at all!!)
If number 4 is firing, and fouls under higher engine speed or load. Try elimination of the crank vent system. You'll need to plug off the PCV valve on the intake and the fresh air vent to the air box(so you're not getting unmetered air), then attach breather filters on to the valve covers. Collapsed or otherwise plugged lines or a bad PCV valve will increase the crankcase pressure maybe enough to blow passes the valve seals.
I do have o PCV valve that I ordered couple months ago before I realized how hard it is to get to and I read they get very brittle and are easy to break off trying to get them out so I havent tried doing that.It does look easier to get to now that I have removed the EGR stuff,I will try pulling on it tomorrow and see if I feel comfortable trying to pull it out.
Thanks
#70
Registered User
I know it's alot of work but I did the egr/pair valve del and hardliners del and put four hole injectors in my 3.0l. Made a world of a difference. I welded the holes shut on the intake plate and the exhaust plate for the egr. If you take the pair valve off the bolt on the front of the intake that bolts the bracket to the intake has to be reinstall. If not you will have a intake leak. Just something to consider.
#71
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I have not pulled the spark plug wires again since the intial test I did last week.I guess I can drive it some tomorrow before I pull the plugs just dont want to get it so hot I cant work on it.
I do have o PCV valve that I ordered couple months ago before I realized how hard it is to get to and I read they get very brittle and are easy to break off trying to get them out so I havent tried doing that.It does look easier to get to now that I have removed the EGR stuff,I will try pulling on it tomorrow and see if I feel comfortable trying to pull it out.
Thanks
I do have o PCV valve that I ordered couple months ago before I realized how hard it is to get to and I read they get very brittle and are easy to break off trying to get them out so I havent tried doing that.It does look easier to get to now that I have removed the EGR stuff,I will try pulling on it tomorrow and see if I feel comfortable trying to pull it out.
Thanks
Not guaranteed but I expect the OEM valve for a v6 from a dealer is going to have a metal case like the 22rte one I picked up a few weeks back.
The plastic ones are junk, the injection molding leaves a raised area that doesn't get cleaned up before they assembled them it can cause it to leak when it should seal and could cause it to freeze in a closed position.
Not to mention that same part is specified for several engines in the partstore database and that means it's not properly calibrated to the engine like it needs to be. (Generic spring rate, generic valve weight means it's not going to do it's job properly)
#72
I know it's alot of work but I did the egr/pair valve del and hardliners del and put four hole injectors in my 3.0l. Made a world of a difference. I welded the holes shut on the intake plate and the exhaust plate for the egr. If you take the pair valve off the bolt on the front of the intake that bolts the bracket to the intake has to be reinstall. If not you will have a intake leak. Just something to consider.
http://www.lceperformance.com/EGR-Bl...-p/1016036.htm
#73
ew ew and ewww,
Not guaranteed but I expect the OEM valve for a v6 from a dealer is going to have a metal case like the 22rte one I picked up a few weeks back.
The plastic ones are junk, the injection molding leaves a raised area that doesn't get cleaned up before they assembled them it can cause it to leak when it should seal and could cause it to freeze in a closed position.
Not to mention that same part is specified for several engines in the partstore database and that means it's not properly calibrated to the engine like it needs to be. (Generic spring rate, generic valve weight means it's not going to do it's job properly)
Not guaranteed but I expect the OEM valve for a v6 from a dealer is going to have a metal case like the 22rte one I picked up a few weeks back.
The plastic ones are junk, the injection molding leaves a raised area that doesn't get cleaned up before they assembled them it can cause it to leak when it should seal and could cause it to freeze in a closed position.
Not to mention that same part is specified for several engines in the partstore database and that means it's not properly calibrated to the engine like it needs to be. (Generic spring rate, generic valve weight means it's not going to do it's job properly)
#74
ok put 75 miles on truck last night.Check engine light came on,its flashing code 25,which I believe is lean condition.
Took truck for short spin this morning and pulled plugs to get ready for leak down and found something disturbing.
Spark plug1,2,5 and 6 looked fine,spark plug 4 was dark and had some oil on it like before,but sparkplug 3 is what is freaking me out.The gap in it was huge compared to others,it had a growth sprouting up from center electrode,and ground electrode had a round indention in it,wtf?
On to the leak down
EDIT!! THINK I FOUND PROBLEM ON WHY PLUG ON 3 WAS ALL JACKED UP,ADVANCED AUTO HAD WRONG PLUG STUCK IN RIGHT BOX AND I DIDNT NOTICE IT WASNT THE SAME PLUG.THE OTHER 7 I RECEIVED FROM THEM WERE THE RIGHT PLUG
Took truck for short spin this morning and pulled plugs to get ready for leak down and found something disturbing.
Spark plug1,2,5 and 6 looked fine,spark plug 4 was dark and had some oil on it like before,but sparkplug 3 is what is freaking me out.The gap in it was huge compared to others,it had a growth sprouting up from center electrode,and ground electrode had a round indention in it,wtf?
On to the leak down
EDIT!! THINK I FOUND PROBLEM ON WHY PLUG ON 3 WAS ALL JACKED UP,ADVANCED AUTO HAD WRONG PLUG STUCK IN RIGHT BOX AND I DIDNT NOTICE IT WASNT THE SAME PLUG.THE OTHER 7 I RECEIVED FROM THEM WERE THE RIGHT PLUG
Last edited by redskinman; 02-19-2017 at 09:12 AM.
#75
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I was ready to cry for ya man, lean code and description of a melted spark plug, then I saw the photos and could have fell out of my chair laughing.
Always always check the gap on spark plugs before you put them in. And double check the part numbers stamped on them..
#4 is either oil fouled or showing rich. (Sorry I'm color blind) would you guys say that's more orange, red, or brown/black.
Try cleaning up the sparkplug threads in the head, if they look like the sparkplug it's getting a bad ground and loosing power. This will rule out if it's fuel fouled. If it's not fuel fouled it's ready to come apart and replace the valve seals, maybe even the guides. At which point you have to decide what your budget is, a new drop in head, full machine re work, or doing an in place valve seal replacement.
Always always check the gap on spark plugs before you put them in. And double check the part numbers stamped on them..
#4 is either oil fouled or showing rich. (Sorry I'm color blind) would you guys say that's more orange, red, or brown/black.
Try cleaning up the sparkplug threads in the head, if they look like the sparkplug it's getting a bad ground and loosing power. This will rule out if it's fuel fouled. If it's not fuel fouled it's ready to come apart and replace the valve seals, maybe even the guides. At which point you have to decide what your budget is, a new drop in head, full machine re work, or doing an in place valve seal replacement.
#76
I was ready to cry for ya man, lean code and description of a melted spark plug, then I saw the photos and could have fell out of my chair laughing.
Always always check the gap on spark plugs before you put them in. And double check the part numbers stamped on them..
#4 is either oil fouled or showing rich. (Sorry I'm color blind) would you guys say that's more orange, red, or brown/black.
Try cleaning up the sparkplug threads in the head, if they look like the sparkplug it's getting a bad ground and loosing power. This will rule out if it's fuel fouled. If it's not fuel fouled it's ready to come apart and replace the valve seals, maybe even the guides. At which point you have to decide what your budget is, a new drop in head, full machine re work, or doing an in place valve seal replacement.
Always always check the gap on spark plugs before you put them in. And double check the part numbers stamped on them..
#4 is either oil fouled or showing rich. (Sorry I'm color blind) would you guys say that's more orange, red, or brown/black.
Try cleaning up the sparkplug threads in the head, if they look like the sparkplug it's getting a bad ground and loosing power. This will rule out if it's fuel fouled. If it's not fuel fouled it's ready to come apart and replace the valve seals, maybe even the guides. At which point you have to decide what your budget is, a new drop in head, full machine re work, or doing an in place valve seal replacement.
#78
Whatever that was wet on the plug is gone now,dont know if it was gas or oil.All plugs and wires had already been installed before advice in cleaning threads,will have to wait another day.
On to the leak down test.Had pretty much the same leakage shown on gauge for all cylinders,30-40%,I got different readings depending on how quickly I could get hoses coupled together without air escaping.
So the main thing to come out of this test that I didnt get the last time is this time I heard where the air was escaping from.Cylinders 2,3,5 and 6 I could hear air escaping when I took off oil cap to the engine.Could not hear anything from 4 or 6.I thought I might have heard a little from 4 but now I think it was my imagination.So what does that mean? I dont know if that means head gasket or something else or maybe thats normal,I'm reading where a small amount is normal.Even with me being able to hear air coming out its not like the gauge was moving past the initial mark,maybe if I kept it hooked up for a long time it might have eventually moved past 30-40%.And you have to remember,on this Harbor Freight tester 30-40% is still in the acceptable range,with a different tester like a snap on 30-40% would be really bad.
I filmed my test and hope to have it edited and be on youtube by tonight,unfortunately I'm not much better as a video editor then mechanic
#79
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You will want to get those threads cleaned up before moving on in the decision process. You could provide an alternate ground source but I don't think there is any room to get something on the plug like a jumper cable or big alligator clip.
The wet did it evaporate or did you wipe it off? If it evaporates it's not oil. That would be a good thing if it was just fuel, it indicates either the bad ground or a leaking injector as the cause both much more simple than valve problems.
Do not worry to much about the leak down results. But I'll try to explain the difference between valve leaks and ring leaks.. since you don't have clear access to the heads, valve covers in place. It will be a subtle sound change between the two. Air passing the rings has to travel through the crankcase and up the oil drainage path, it will be a "distant" hollow sound. Air escaping the valves would travel through the intake or exhaust manifold primarily, a slight bit up the guides and around the valve seals which would have a higher pitch and magnitude than air passing out the rings. One major failure you would be concerned about is unrestricted air flow, loud wooshing sort, that indicates air escaping out the sides (head gasket failure to atmosphere). Second would be the gurgling bubble sound of air passing thru the water column.
The wet did it evaporate or did you wipe it off? If it evaporates it's not oil. That would be a good thing if it was just fuel, it indicates either the bad ground or a leaking injector as the cause both much more simple than valve problems.
Do not worry to much about the leak down results. But I'll try to explain the difference between valve leaks and ring leaks.. since you don't have clear access to the heads, valve covers in place. It will be a subtle sound change between the two. Air passing the rings has to travel through the crankcase and up the oil drainage path, it will be a "distant" hollow sound. Air escaping the valves would travel through the intake or exhaust manifold primarily, a slight bit up the guides and around the valve seals which would have a higher pitch and magnitude than air passing out the rings. One major failure you would be concerned about is unrestricted air flow, loud wooshing sort, that indicates air escaping out the sides (head gasket failure to atmosphere). Second would be the gurgling bubble sound of air passing thru the water column.