[Tylerhicks2000]

My wife has a 2002 4x4 3.3L none supercharged Xterra that is named Cronk. She was having some issues with it most concerning to me was antifreeze coming from somewhere under the intake. I took the plunge and peeled that sucker off. the leaks where coming from the coolant bypass hose and the very back passenger side pf the plenum. it took a good wile to clean and I fully understood why the old knock sensor went bad. The factory casting on all that is terribly rough so I smoothed and polished the plenum and intake. The old injectors are very brittle so I replaced them all and the O rings for the fuel rail. Wile I had everything off I replaced the valve cover gaskets and spark plugs and wires. FYI all parts are OEM. i replaced all of the vacuum and coolant hoses. Once it was back together I started Cronk up and was very pleased with the way he was running. That's win a gremlin came out and maid my life hell. after a few minutes it started to misfire. This hole time the code has been p0300 random multiple misfire. I tested the new intake gaskets buy spraying brake clean on them to make sure it had a good seal and it did. the plugs are all good except number one is usually still wet with fuel win I check it. I did a compression test and number 1 is 127 and they only went up from there. I replaced the fuel filter and presser tested that as well and its good. The cats where turning bright red so I ended up installing headers and all new O2 sensors thinking the cats where clogged and I did get a code for the O2 once. still misfiring, replaced the entire distributer and throttle position sensor because they were not completely to speck win tested. Still misfiring. win I remove one spark wire at a time the only one that doesn't effect how it runs is the number 1 cylinder. I swapped wires plugs and injectors and it still acts the same. I have even replaced the evap clinoid. now I'm thinking its ether the ECU or the number one having the lowest compression has a leaking valve or ring. I really don't want to do a rebuild if its not for sure the issue if anybody could help me in any way it would be such a blessing.

 

[Tylerhicks2000]

Buy the way I have set the timing at 10 the timing advance usually reads 15 or 20 with the TPS plugged in at idle at 890 RPM win test driving it has power win floored but if I take it easy it backfires a lot at 2000 RPM.

 

[MeToo]

Backfire sounds like a burnt valve, possibly the intake valve. That would also explain the lower compression. It could also just be some build-up that keeps it from closing completely.

 

[XT2015]

Backfire sounds like a burnt valve, possibly the intake valve. That would also explain the lower compression. It could also just be some build-up that keeps it from closing completely.

Agreed. Sounds like it's time to have a look at the valve assembly on the head that's home to the #1. A 2002 would have put in a lot of reps between now and then.

 

[Tylerhicks2000]

Backfire sounds like a burnt valve, possibly the intake valve. That would also explain the lower compression. It could also just be some build-up that keeps it from closing completely.

Any tips on how I could check it and clean it to get it to seat properly

 

[XT2015]

Any tips on how I could check it and clean it to get it to seat properly

Replace® 2342L - Driver Side Remanufactured Complete Cylinder Head with Camshaft (carid.com)
Link shows complete refurbished head assembly or individual valves etc. for sale.

 

[Tylerhicks2000]

So the timing belt and water pump was Recently done so I hadn’t checked it. Because of the issue and me really not wanting to do any kind of a rebuild I pulled off the top timing covers put a top dead center and it looks like it’s off buy one tooth. I’m gonna try replacing the belt and tensioner first.

 

[XT2015]

So the timing belt and water pump was Recently done so I hadn’t checked it. Because of the issue and me really not wanting to do any kind of a rebuild I pulled off the top timing covers put a top dead center and it looks like it’s off buy one tooth. I’m gonna try replacing the belt and tensioner first.

Worth a try.

 

[Paulsxterra4x4]

My wife has a 2002 4x4 3.3L none supercharged Xterra that is named Cronk. She was having some issues with it most concerning to me was antifreeze coming from somewhere under the intake. I took the plunge and peeled that sucker off. the leaks where coming from the coolant bypass hose and the very back passenger side pf the plenum. it took a good wile to clean and I fully understood why the old knock sensor went bad. The factory casting on all that is terribly rough so I smoothed and polished the plenum and intake. The old injectors are very brittle so I replaced them all and the O rings for the fuel rail. Wile I had everything off I replaced the valve cover gaskets and spark plugs and wires. FYI all parts are OEM. i replaced all of the vacuum and coolant hoses. Once it was back together I started Cronk up and was very pleased with the way he was running. That's win a gremlin came out and maid my life hell. after a few minutes it started to misfire. This hole time the code has been p0300 random multiple misfire. I tested the new intake gaskets buy spraying brake clean on them to make sure it had a good seal and it did. the plugs are all good except number one is usually still wet with fuel win I check it. I did a compression test and number 1 is 127 and they only went up from there. I replaced the fuel filter and presser tested that as well and its good. The cats where turning bright red so I ended up installing headers and all new O2 sensors thinking the cats where clogged and I did get a code for the O2 once. still misfiring, replaced the entire distributer and throttle position sensor because they were not completely to speck win tested. Still misfiring. win I remove one spark wire at a time the only one that doesn't effect how it runs is the number 1 cylinder. I swapped wires plugs and injectors and it still acts the same. I have even replaced the evap clinoid. now I'm thinking its ether the ECU or the number one having the lowest compression has a leaking valve or ring. I really don't want to do a rebuild if its not for sure the issue if anybody could help me in any way it would be such a blessing.

My wife has a 2002 4x4 3.3L none supercharged Xterra that is named Cronk. She was having some issues with it most concerning to me was antifreeze coming from somewhere under the intake. I took the plunge and peeled that sucker off. the leaks where coming from the coolant bypass hose and the very back passenger side pf the plenum. it took a good wile to clean and I fully understood why the old knock sensor went bad. The factory casting on all that is terribly rough so I smoothed and polished the plenum and intake. The old injectors are very brittle so I replaced them all and the O rings for the fuel rail. Wile I had everything off I replaced the valve cover gaskets and spark plugs and wires. FYI all parts are OEM. i replaced all of the vacuum and coolant hoses. Once it was back together I started Cronk up and was very pleased with the way he was running. That's win a gremlin came out and maid my life hell. after a few minutes it started to misfire. This hole time the code has been p0300 random multiple misfire. I tested the new intake gaskets buy spraying brake clean on them to make sure it had a good seal and it did. the plugs are all good except number one is usually still wet with fuel win I check it. I did a compression test and number 1 is 127 and they only went up from there. I replaced the fuel filter and presser tested that as well and its good. The cats where turning bright red so I ended up installing headers and all new O2 sensors thinking the cats where clogged and I did get a code for the O2 once. still misfiring, replaced the entire distributer and throttle position sensor because they were not completely to speck win tested. Still misfiring. win I remove one spark wire at a time the only one that doesn't effect how it runs is the number 1 cylinder. I swapped wires plugs and injectors and it still acts the same. I have even replaced the evap clinoid. now I'm thinking its ether the ECU or the number one having the lowest compression has a leaking valve or ring. I really don't want to do a rebuild if its not for sure the issue if anybody could help me in any way it would be such a blessing.

My experiences (in one years time I replaced three TPS and two MAF sensors, also on the 02 sensors I installed spark plug anti fowlers to space sensor back????

 

[Tylerhicks2000]

My experiences (in one years time I replaced three TPS and two MAF sensors, also on the 02 sensors I installed spark plug anti fowlers to space sensor back????

Im not sure I follow what your saying. Space what sensor back?

 

[Tylerhicks2000]

Well lesson learned, the timing was slightly off but that wasn’t the issue. Being that I didn’t completely refill the antifreeze after adjusting the timing as I was checking it with timing light (still misfiring) the low coolant allowed it to get hot enough to start evaporating the coolant and tipped me off to the real issue. Steam was coming out from under the plentem….. yep this hole time it was misfiring because the number one cylinder was getting antifreeze in it. There was coolant in my oil two I’m flushing it wile I wait for the machine shop to resurface the plenum. Please learn from my mistake the intake is aluminum and it’s extremely easy to cause it not to seal properly. All I did was try and reove corotion and I caused this issue I’m lucky I didn’t blow this sucker up. I defantly will only use a good flelt pro gaskets. But there it is the cause for this issue was imperfect intake seal again it’s hard to test the bottom half of the plenum seal. About a grand I could have saved in parts if I could have found the leak right away.

 

[Paulsxterra4x4]

Well lesson learned, the timing was slightly off but that wasn’t the issue. Being that I didn’t completely refill the antifreeze after adjusting the timing as I was checking it with timing light (still misfiring) the low coolant allowed it to get hot enough to start evaporating the coolant and tipped me off to the real issue. Steam was coming out from under the plentem….. yep this hole time it was misfiring because the number one cylinder was getting antifreeze in it. There was coolant in my oil two I’m flushing it wile I wait for the machine shop to resurface the plenum. Please learn from my mistake the intake is aluminum and it’s extremely easy to cause it not to seal properly. All I did was try and reove corotion and I caused this issue I’m lucky I didn’t blow this sucker up. I defantly will only use a good flelt pro gaskets. But there it is the cause for this issue was imperfect intake seal again it’s hard to test the bottom half of the plenum seal. About a grand I could have saved in parts if I could have found the leak right away.

Could be a few things( mass air flow sensor, TPS sensor, clean carbon off of throttle body,) A head gasket is quite a job, I preformed this a few years ago ( 3 day job) replaced timing belt in the process. I probably know more than many people, after owning three X's 2005,2003 ,2002 , good luck.

 

[Tylerhicks2000]

I had the head honed and still have a misfire buy fixing everything else turns out I have a bad exaustvalve on the number one cylinder.

 

[Paulsxterra4x4]

My wife has a 2002 4x4 3.3L none supercharged Xterra that is named Cronk. She was having some issues with it most concerning to me was antifreeze coming from somewhere under the intake. I took the plunge and peeled that sucker off. the leaks where coming from the coolant bypass hose and the very back passenger side pf the plenum. it took a good wile to clean and I fully understood why the old knock sensor went bad. The factory casting on all that is terribly rough so I smoothed and polished the plenum and intake. The old injectors are very brittle so I replaced them all and the O rings for the fuel rail. Wile I had everything off I replaced the valve cover gaskets and spark plugs and wires. FYI all parts are OEM. i replaced all of the vacuum and coolant hoses. Once it was back together I started Cronk up and was very pleased with the way he was running. That's win a gremlin came out and maid my life hell. after a few minutes it started to misfire. This hole time the code has been p0300 random multiple misfire. I tested the new intake gaskets buy spraying brake clean on them to make sure it had a good seal and it did. the plugs are all good except number one is usually still wet with fuel win I check it. I did a compression test and number 1 is 127 and they only went up from there. I replaced the fuel filter and presser tested that as well and its good. The cats where turning bright red so I ended up installing headers and all new O2 sensors thinking the cats where clogged and I did get a code for the O2 once. still misfiring, replaced the entire distributer and throttle position sensor because they were not completely to speck win tested. Still misfiring. win I remove one spark wire at a time the only one that doesn't effect how it runs is the number 1 cylinder. I swapped wires plugs and injectors and it still acts the same. I have even replaced the evap clinoid. now I'm thinking its ether the ECU or the number one having the lowest compression has a leaking valve or ring. I really don't want to do a rebuild if its not for sure the issue if anybody could help me in any way it would be such a blessing.

You would not get coolant into engine from under intake, only head gasket. the coolant lines and hoses under the intake would be noticed as steam or leaks on the ground. I'd try plugs plug wires vaccum hoses

 

[Tylerhicks2000]

You would not get coolant into engine from under intake, only head gasket. the coolant lines and hoses under the intake would be noticed as steam or leaks on the ground. I'd try plugs plug wires vaccum hoses

The lower intake has coolant ports that connect both sides of the engine between the coolant ports and the intake ports it's only like one third of a inch it's a very job to get wrong but it ended up being a bad valve

 

[XT2015]

I had the head honed and still have a misfire buy fixing everything else turns out I have a bad exaustvalve on the number one cylinder.

You can "hone" a cylinder bore but how do you have a head "honed"? Did you have the head "resurfaced"?

 

[RacerXXL]

You can "hone" a cylinder bore but how do you have a head "honed"? Did you have the head "resurfaced"?

My guess would be the head was milled to ensure that the surface was straight and true