Odd idle characteristic.
03-26-2002, 02:11 PM
#1
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Odd idle characteristic.
Okay, so I just changed my timing belt, drive belts, water pump, raised my idle to ~900RPM and advanced my timing to 18*BTDC. Car runs sooo much smoother now. I had to advance my cams 1/2 tooth past the timing marks on the rear upper timing cover to line up the timing marks on the cam sprockets with the white lines on the timing belt. Combine that with a K&N panel filter and the harshness/vibration at 4800+RPM is all but gone. My question is this, when idling, every 1-1.5 seconds, the engine will burp. Sounds like "buh" and the muffler will shake just barely. I think it's a small vacuum leak, because the exhaust will look/smell a bit rich when it happens and then be fine. Also, I'm going to replace the fuel filter and PCV valve this weekend. The car has basically never been touched except for oil changes, and I changed the plugs a few months ago. I'm looking at doing a full tune-up soon as well (TB cleaning time). It's been doing this for awhile. If anyone wants to do Cliff's Notes, feel free.
03-26-2002, 07:15 PM
#2
My max does this too. I'm thinking that just every once in a while one cylinder does not fire completely enough (or hot enough) to burn all the fuel injected into the chamber. Thus, you have a small miss and unburned fuel (which would explain the smell). Just a thought, probably wrong.
03-26-2002, 07:22 PM
#3
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Posts: n/a
I get that too, but mine goes away when I put into drive. I figure that under load (in gear) the injector pulse lengthens giving more time for these old injectors to open properly and allowing a burnable amount of fuel into the cylinder. Otherwise I find no other reason for this to happen.
03-26-2002, 07:26 PM
#4
Senior Member
Join Date: Aug 2000
Posts: 627
?
My car has done this for 72K miles now (since I got it at 65K). I never did figure it out. After replacing this and that over the years, but the car running exactly the same at idle, my only remaining guess is the fuel-injector O-rings.
03-26-2002, 08:48 PM
#5
Senior Member
Join Date: Oct 2001
Posts: 1,764
ok im getting that problem too
but mine is 10 thousand times the problems you guys are having,BLACK smoke comes from the tailpipe sometimes and its not oil the idel is soo bad its like 500 rpms and the almost stalls
----im gonig to have a FULL tune-up at the dealer in NJ ill tell you guys if it gets fixed..
----im gonig to have a FULL tune-up at the dealer in NJ ill tell you guys if it gets fixed..
04-07-2002, 12:09 AM
#6
Senior Member
Join Date: Feb 2001
Posts: 313
My money would be on the panel filter causing the problem. Put a standard filter in and the problem goes away. It appears with the panel filter it causes turbulance arounf the air flow sensor which causes the car to run lean and then the ECU compensates causing the rich mixture smell you talk of. Go to a CAI or pop charger type set-up and it should go away.
Brent.
Brent.
04-07-2002, 01:13 PM
#8
Member
Join Date: Feb 2001
Posts: 72
Re: Odd idle characteristic.
Originally posted by Badaxxima
Okay, so I just changed my timing belt, drive belts, water pump, raised my idle to ~900RPM and advanced my timing to 18*BTDC. Car runs sooo much smoother now. I had to advance my cams 1/2 tooth past the timing marks on the rear upper timing cover to line up the timing marks on the cam sprockets with the white lines on the timing belt. Combine that with a K&N panel filter and the harshness/vibration at 4800+RPM is all but gone. My question is this, when idling, every 1-1.5 seconds, the engine will burp. Sounds like "buh" and the muffler will shake just barely. I think it's a small vacuum leak, because the exhaust will look/smell a bit rich when it happens and then be fine. Also, I'm going to replace the fuel filter and PCV valve this weekend. The car has basically never been touched except for oil changes, and I changed the plugs a few months ago. I'm looking at doing a full tune-up soon as well (TB cleaning time). It's been doing this for awhile. If anyone wants to do Cliff's Notes, feel free.
Okay, so I just changed my timing belt, drive belts, water pump, raised my idle to ~900RPM and advanced my timing to 18*BTDC. Car runs sooo much smoother now. I had to advance my cams 1/2 tooth past the timing marks on the rear upper timing cover to line up the timing marks on the cam sprockets with the white lines on the timing belt. Combine that with a K&N panel filter and the harshness/vibration at 4800+RPM is all but gone. My question is this, when idling, every 1-1.5 seconds, the engine will burp. Sounds like "buh" and the muffler will shake just barely. I think it's a small vacuum leak, because the exhaust will look/smell a bit rich when it happens and then be fine. Also, I'm going to replace the fuel filter and PCV valve this weekend. The car has basically never been touched except for oil changes, and I changed the plugs a few months ago. I'm looking at doing a full tune-up soon as well (TB cleaning time). It's been doing this for awhile. If anyone wants to do Cliff's Notes, feel free.
04-07-2002, 05:22 PM
#9
the K&N air filter does not make the air more turbulent. It is oiled, so the oil is deposited on the tungsten element in the MAFS and this sends bad readings to the computer.
Just this past week I pulled all the injectors and replaced all the o-rings and seals and pintle caps and cleaned the filter screens. I must say it has made a difference, the engine missing problem has gone away, no more buh buh in the exhaust. When inspecting the injectors I could see which were leaking (although I would have like to have done a power balance test before hand, but did not have the $$). I have now 84,000 miles on it and The filter screens were pretty dirty. Last year I put in a K$N fuel filter that can be dissasembled and cleaned (SS filter element), I hope this will help insure cleaner filter screens for the future.
Just this past week I pulled all the injectors and replaced all the o-rings and seals and pintle caps and cleaned the filter screens. I must say it has made a difference, the engine missing problem has gone away, no more buh buh in the exhaust. When inspecting the injectors I could see which were leaking (although I would have like to have done a power balance test before hand, but did not have the $$). I have now 84,000 miles on it and The filter screens were pretty dirty. Last year I put in a K$N fuel filter that can be dissasembled and cleaned (SS filter element), I hope this will help insure cleaner filter screens for the future.
04-07-2002, 09:15 PM
#10
Originally posted by eric93SE
the K&N air filter does not make the air more turbulent. It is oiled, so the oil is deposited on the tungsten element in the MAFS and this sends bad readings to the computer.
the K&N air filter does not make the air more turbulent. It is oiled, so the oil is deposited on the tungsten element in the MAFS and this sends bad readings to the computer.
04-08-2002, 02:01 AM
#11
Senior Member
Join Date: Feb 2001
Posts: 313
Yup, that's what happened with mine. The distributor for the K&N panel said it does happen with some cars. You could modify the airbox to reduce turbulance I suppose, but you might as well go to CAI if you are going to do that.
Brent.
Brent.
04-08-2002, 02:05 PM
#13
IT'S NOT TURBULANT AIR
That's not what causes the trouble, and its not the MAFS screen which must be cleaned. It's the element in the center of the MAFS which is affected by the tiny oil particles which are carried out of the filter element. The tungsten element runs normally very hot and as it is cooled by air traveling across it, it is translated into a current, which is then sent to the computer in the form of a voltage singal. But if a small amount of oil is deposited on the element then when comming to an idle the element will be much hotter than it is supposed to be so the computer will set the air/fuel mixture incorectly.
04-10-2002, 03:41 AM
#14
Re: IT'S NOT TURBULANT AIR
Originally posted by eric93SE
That's not what causes the trouble, and its not the MAFS screen which must be cleaned. It's the element in the center of the MAFS which is affected by the tiny oil particles which are carried out of the filter element. The tungsten element runs normally very hot and as it is cooled by air traveling across it, it is translated into a current, which is then sent to the computer in the form of a voltage singal. But if a small amount of oil is deposited on the element then when comming to an idle the element will be much hotter than it is supposed to be so the computer will set the air/fuel mixture incorectly.
That's not what causes the trouble, and its not the MAFS screen which must be cleaned. It's the element in the center of the MAFS which is affected by the tiny oil particles which are carried out of the filter element. The tungsten element runs normally very hot and as it is cooled by air traveling across it, it is translated into a current, which is then sent to the computer in the form of a voltage singal. But if a small amount of oil is deposited on the element then when comming to an idle the element will be much hotter than it is supposed to be so the computer will set the air/fuel mixture incorectly.
I never cleaned the MAF element once in 4 years of ownership, and later sold the car with an OEM panel fitted and a rock solid idle. The K&N panel was never over oiled, the car just plain didn't like using it.
04-10-2002, 02:13 PM
#16
Just try a cheapo $10 paper filter. My brother has a VG 5-sp. His car also did NOT like the K&N panel. Switched back to the paper the idle was fine. Then I bought an used cone filter and again, the idle was fine. I of course tried all 3 in my VE maxima. All 3 were fine. Very odd but very true and I've seen many of the same stories. It's NOT the K&N oil. Or the car would not run on the cone filters very well either.
04-23-2002, 03:47 PM
#17
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I was thinking about this the other day and I came up with a theory:
Since our filters sit at an angle, I wonder if the fibers in the K&N are straight or just close enough to each other to allow excess oil to flow down and pool some towards the bottom. This would allow a somewhat excessive buildup and possibly allow some of it to be sucked into the intake tract and onto the MAF. I doubt the condition would be similar with Popchargers since they are exposed to engine heat which would affect the oil, nor would their shape allow such easy flow toward the bottom. Thoughts?
Since our filters sit at an angle, I wonder if the fibers in the K&N are straight or just close enough to each other to allow excess oil to flow down and pool some towards the bottom. This would allow a somewhat excessive buildup and possibly allow some of it to be sucked into the intake tract and onto the MAF. I doubt the condition would be similar with Popchargers since they are exposed to engine heat which would affect the oil, nor would their shape allow such easy flow toward the bottom. Thoughts?
04-24-2002, 03:42 AM
#18
Senior Member
Join Date: Feb 2001
Posts: 313
Originally posted by Badaxxima
I was thinking about this the other day and I came up with a theory:
Since our filters sit at an angle, I wonder if the fibers in the K&N are straight or just close enough to each other to allow excess oil to flow down and pool some towards the bottom. This would allow a somewhat excessive buildup and possibly allow some of it to be sucked into the intake tract and onto the MAF. I doubt the condition would be similar with Popchargers since they are exposed to engine heat which would affect the oil, nor would their shape allow such easy flow toward the bottom. Thoughts?
I was thinking about this the other day and I came up with a theory:
Since our filters sit at an angle, I wonder if the fibers in the K&N are straight or just close enough to each other to allow excess oil to flow down and pool some towards the bottom. This would allow a somewhat excessive buildup and possibly allow some of it to be sucked into the intake tract and onto the MAF. I doubt the condition would be similar with Popchargers since they are exposed to engine heat which would affect the oil, nor would their shape allow such easy flow toward the bottom. Thoughts?
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