# idle problems on my 1990 vg30



## mitsuspyder (Feb 27, 2009)

the idle on my pathy is not level or smooth, i tried turning up the idle speed and it remains the same. It is idling as if it is missing but when i check the ECU it doesnt suggest that. The only code i get is the knock sensor. Anybody have any ideas what could cause this


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## uhlstalker (Jun 2, 2009)

i have the same problem i am prolly going to replace the knock sensor and i get back to you


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## mitsuspyder (Feb 27, 2009)

thanks alot let me know what happens


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## pathfounder (Nov 16, 2009)

How many miles?

A rough idle can either be from something being wrong, but it also comes from age. An old engine where everything has worn a bit will cause a rough idle. This is because at idle, the engine is turning slowly and that gives more time for the rings and valve guides to leak. It also is the hardest for the spark plug to light the weakly filled cylinder, so if the mixture isn't perfect (such as contaminated with a bit of oil) it will stumble.

If you rev it up, does it ever smooth out? If not... you have an ignition problem, a plugged injector, or a flat cam lobe. Try pulling off a plug wire one at a time and seeing if anything changes. If it doesn't change, you have a dead cylinder.


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## mitsuspyder (Feb 27, 2009)

well i notice like in the morning when i leave it to warm up, like the normal white steam come off the exhaust, but when i move it, there is a lot of blue smoke coming from the exhaust until the engine is at normal temp, the idle isnt extremely rough but it will tend to want to stall


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## uhlstalker (Jun 2, 2009)

i advanced (twisted) my distributer and the stall problem went away.


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## mitsuspyder (Feb 27, 2009)

like by how much do u advance ur timing by????


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## uhlstalker (Jun 2, 2009)

not much, maybe a 6 degrees counter clock wise


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## julrichh (Jul 3, 2009)

*rough idle*

My pathy was idling rough with a P0305, misfire #5 cyclinder, replaced #5 fuel injector, now it runs great!


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## uhlstalker (Jun 2, 2009)

ok, a lot has went by so ill start with the knock sensor.
I figure hell ill get rid of the code so went to junk yard found a knock sensor for my car pocketed it went home took needle noose and pulled really hard on the wire in the back going to the knock sensor in till it tore off the sensor and bolted the other knock sensor to intake, plugged it in. hears the trick there is there is 2 pins on it but the right one is a blank so don't plug anything in to it just plug the one wire in on left side. bad new didn't really fix anything but made the code go away.

now i'm working with a random misfire can't figure out what is causing it to randomly misfire? need help 

my car has 263,000 miles on it


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## jtrich (Dec 8, 2009)

Have you run a compression check? I just got my 87 pathfinder with 107,000 miles on it and it has a rough idle. I ran a compression check and have 35 psi on cylinder #3. I put oil in the cylinder and ran the check again and the pressure came up to 50 psi which tells me it's not the ring but leaking valves. It runs very smooth just a slightly rough idle.
These engines must have problems with the valves, my wifes 01 quest broke the timing belt at 118,000 miles. (I know I should have changed it) I put a new belt on and ran a compression check to make sure it hadn't bent a valve. #1 cylinder had only 50 psi so I pulled the heads. The valve wasn't bent but just leaking. The seating face on the valve was black instead of shiny. I lapped the valves and put it back together and it ran fine. Before the belt broke it ran smooth but got crappy gas mileage. Now the mileage is back up. I will run the pathfinder like this for now and pull the heads in the summer.
James


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## uhlstalker (Jun 2, 2009)

thanks for the reply, I will run a comp test as soon as i get my hands on a gauge, and when the temp comes up cause it's COLD


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## jtrich (Dec 8, 2009)

I see your from Houston, I just bought my pathfinder from a guy in Houston. I picked it up a week ago. Its cold down here too, but I was out in the 35 degree weather Wednesday putting a timing belt back on the pathfinder so I could run it with some fresh antifreeze. I don't think the coolant had ever been changed in this one. When it warms up I will have to flush it some more. It has a lot of rust in there.
James


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