cham

That's interesting. Do you think maybe the washers were crushed so much they were kind of stuck in the rim of the converter and/or manifold? Like as if they looked apart of the converter or manifold? This is straight out of the 2002 FSM; you can see it specifies the exact alignment of the washer and mesh washer: Edit: Just found what you were talking about. On RA looks like Fel-Pro 61339 is the "Mesh Washer" and 60835 is the "Washer". I can tell based on the photos. Also looks like the Fel-Pro "Mesh Washer" does reference the correct OEM P/n. They look identical to the OEM parts found on NissanPartsDeal. Can you attest to the quality of Fel-Pro for something like this? Or should I probably leave the factory washer/gaskets alone and reuse them if they are there? And I agree, no way I'm paying $90 just for these gaskets.

@hawairish did you reuse the "washer" and "mesh washer" in the exploded diagram screenshot in my original post? Maybe replacing just that washer gasket would suffice and not the mesh?

Yeah I saw some posts of people using an electric impact in its lowest setting and being careful with great success. I might try it on inconsequential stuff first. You're right, worse case scenario I can just use hose clamps in the mean time while I order the valve cover parts. Going to try to get them from oversees since they are a fraction of the cost for OEM, just might take a while.

Noted, I want to take off that resonator/rear-cat section off anyways to see if the pre-cats have broken apart and maybe lodged pieces within the resonator. But removing the entire exhaust would be nice so I can test for leaks off the vehicle. I'll try working at the bolts when the exhaust is warm and giving the bolts heads a nice whack before unscrewing to maybe free them up. Would you advise for or against an electric impact with extensions? Also I've got some pretty bad valve cover seepage onto my exhaust manifold/cat heat shields. The VCs are the next job after this but I wanted to address the cat issue first. If lets say I shear the heat shield bolts and can't get the shields back on during re-installation, will that increase my chances of a fire hazard since the oil will be dripping right onto the exhaust manifold? So far I haven't had any smoke just burnt smell after driving.

Hey hawairish nice to talk with you again! I was planning on removing that resonator/rear cat section with the downstream O2 sensor to give room for the pre cat egress. You’re saying that’s still not enough room? Yeah I certainly am worried about shearing off those upper 6 pre-cat fasteners. If it happens on the passenger side I don’t see how there’s anyway to remove the exhaust manifold on that side haha. Ive also wondered if maybe I should give that exhaust manifold a fresh new gasket. Are our exhaust manifolds and gasket (3.5L) ever known to crack or leak? I might do a smoke test once I remove that lower resonator section just to see if I have any manifold leaks and see if it’s worth it. Curious what an exhaust shop would charge and if they’d do it right. Did you replace the studs that connect the pre-cat to the manifold or just the nuts? Sent from my iPhone using Tapatalk

Anybody have experience with removing those pre-cats? My cats are starting to choke the engine out and I can tell the engine is struggling at highway speeds. I've had P0430/420 codes intermittent for a while now. What techniques are there to make life easier? I've been soaking as many bolts as I can get to with penetrant for a good while. I'm curious if the 6 bolt heads on the upper face/side of the cat are accessed from underneath or engine bay side. I saw a video of someone removing the entire exhaust manifold and cat as a unit for the driver side; but that looks next to impossible for the passenger side. I'm willing to remove the down pipe off the bottom of the pre-cat as well so I can lower the cat down and out. The FSM diagram makes it look like the bolt heads would be accessed from underneath shown in the figure below. Also it looks like for that upper six, some of the fasteners its a stud and separate nut where as some were just bolts. I'll probably have to remove those cat heat shields first before anything can be done. My question is, can all of this be done from underneath or will I have to remove the exhaust manifold and come from the top engine bay side?

Anybody running with gutted cats without adverse effects? I'm starting to think my catalytic converters are actually failing or clogging. Besides my P0430/P0420 codes I'm still getting, according to my scanner I'm only getting about 7 misfires averages total in the past 10 drive cycles. I can't imagine that would be the source of my issues like vibration in gear at idle and lack of power. My engine consumes so much oil I do not believe replacing with new converters would solve the issue for long. Not to mention so many things cause converters to fail and apparently it can be quick. I do not have emissions testing where I live. I'm sure it will make getting rid of the vehicle much more difficult when it comes time. Anybody been in my situation before, getting at those pre-cats is difficult and to have new ones fail soon after installing would suck. I guess if I were to replace I'd go with the Magnaflow "OEM" line. Anyone gone with cheaper brands with luck?

I’d stay away from aftermarket valve covers, never heard any good things about them and I believe NissanPartsDeal has a discount right now on most parts. I’d be interested in the aluminum valve covers as long as everything works and bolts back up like factory. Can’t say I’d be super stoked about a gap like Hawairish says between the ignition coil seal and spark plug tube if using the 2002 coils with the 2001 valve cover. Obviously replacing that #1 coil with the 2001 coil seems easy enough.

Ah I see thanks Chris! The vibration basically goes away for me if I put my transmission in neutral or park at a stoplight. If you stayed in gear in 1st while at a stoplight would it vibrate and try to stall as well? Also did you have to reprogram or perform any relearn procedures when replacing the MAF sensor? Sent from my iPhone using Tapatalk

I gotcha. I think I might replace the IACV for the hell of it next time I go in to replace my valve covers. See if I get any results. Just to be clear, you were having a full vehicle vibration at stoplights in gear once the engine is warm? It would go away in park and neutral? What is this ABS issue you were talking about? Were you saying that might have something to do with the RPM sag and vibration in gear? Sent from my iPhone using Tapatalk

Thanks for the update CamperDan, let us know if the problem comes back or not. I’ve been monitoring my g/s and it’s at about 3.6-3.7 at idle warmed up. Sounds like it’s good and I have been cleaning it over the years. Correct me if I’m wrong though, you replaced your idle air control valve at one point correct? Do you remember it fixing any vibration or stumbling back then? Also did you use oem factory MAF sensor? Sent from my iPhone using Tapatalk

I'll be patiently waiting for the results, thanks for keeping us updated! Just got a new smoke machine so in a couple days I'm going to be very thorough finding any intake or exhaust leaks. Thought about testing EVAP leaks as well but I've got to get a handle on purge solenoids and lines first as I'm sure some areas are supposed to purge smoke. Also because my tailpipe has fallen apart (can't get a great seal when smoking) it's almost better to find leaks by looking for liquid condensation forming after you start up a cold engine.

Gotcha, fleurys in another thread titled "Random Misfire Help!" mentioned being able to read misfire count with an OBD2 scanner but did not mention the one he uses. I'll ask the guys at Nisscan if its possible, regardless I'd imagine NDS II will come in handy for other things. I might have misspoke. When I said butterfly valves I meant those lower intake power valves that famously eject screws. Is there a another set below them or just the one set?

Hey [mention=36148]hawairish[/mention] can you read “misfire count” through mode 6 for individual cylinders in NDS II. Also what year is your Pathy? Looks like Bluedriver’s mode 6 is pretty limited. Need to figure out what the TID codes mean but it only lists pass or fail. Sent from my iPhone using Tapatalk

Here is the linkage for the vacuum actuator of the butterfly valves. The red circle shows where you can move that link to open the valves I believe. Sent from my iPhone using Tapatalk

Thanks guys for the help I'm making some headway. So I've discovered some things that can help me understand what's going on. Firstly I tried smoking the exhaust and intake again last night to no avail. The machine like it always does starts spitting mineral oil again so I stopped after a few minutes. I definitely was getting a good amount of smoke into the intake and saw no leaks. I'm now in contact with the company and I believe they will be sending me a new one. The problem is we have that butterfly valve within the plenum which is closed with the engine off; can I manually prop it open by using that linkage on the vacuum actuator so the smoke can get to that lower plenum intake? When starting my engine in the cold I said what the hell and got under to the vehicle to find condensation pooling at the lower 3rd bolt/nut on the exhaust that mounts to the back of the pre-cats. Saw condensation vapor coming through it too. Almost looked like when the exhaust warmed up the seam closed up and no more condensation vapor. I'm going to get someone to accelerate the engine in park while I'm under there to see if I can see a visible stream. The leak would be just before the downstream O2 sensor and right after the pre-cat, and its exactly the same on both banks. I'm assuming this would definitely contribute to my P0430/P0420 codes. But I would think it would not hurt my gas milage. Now this isn't a definite answer as I'm now curious if there are any more leaks I can't see not to mention its quite interesting both banks are leaking in the exact same place. Could my cats be clogging up and the buildup of pressure forced an opening in the same place on either bank? Fixing the leak could then cause the pressure buildup to get worse. Is the only real way to check if you have a clogged cat by removing them and looking inside? Lastly I recently discovered from another thread on here that through Mode 6 we should be able to read misfire count on a particular cylinder which will definitely help. Bluedriver has a Mode 6 reader so hopefully I'll be able to get some data on whether I am actually misfiring or not. Read online its rare but sometimes misfiring with no CEL codes are possible if its intermittent. Since I have new spark plugs I would imagine if I find any misfires its either a failing coil, dielectric grease causing issue, clogged injector or harness related.

I read that too somewhere, cool stuff! Totally explains why my intake was beautiful when I took it off despite some oily walls from the PCV system. Next to no carbon buildup on the runners at 220k miles unlike modern EGR equipped direct injected motors. You're absolutely right! Don't know why I didn't think about this. Since it's in Open Loop to start out with its not reading from sensors but from predetermined parameters set by Nissan. Only trick is to figure out if the vibration is gone because its in Open Loop or because the RPMs are up. As far as Nissan Data Scan II those guys know what they're doing. I looked into it a little while ago to see if I can read the Trans Temp sensor live data but Nissan really screwed us on that one. From what I could find in the FSM and communicating with them our system uses a combination of OBD2 and OBD1 or DDL2 and DDL1. The TCM primarily uses DDL1 communication while the ECU uses DDL2. The problem comes when you need a scanner that can communicate using both. NDS1 doesn't communicate with transmissions apparently because you need to simultaneously be able to communicate through DDL2 too. "ConZult" also told me their platform won't work either so instead I found in the manual how to read my A/T Temp sensor using a multimeter and extrapolated their provided (simplistic) plot in google sheets. Now I just plug in the voltage I read with my DMM into the plot and it spits out the corresponding temp (very crude but usable). Had to use like a 6th order polynomial to try and match the slope of the provided plot. And yes I also looked into adding an aftermarket temp sensor but I had already dropped my pan a while ago and was not looking to go through that again. Drain plug sensor worries me for the possibility of a branch getting ahold of the sensor wire offroad and ripping out causing a leak without me even knowing. An aftermarket sensor in the pan also might read slightly different than the factory sensor on the valve-body. Thought about making an individual post about this but was unsure if at this point anyone really would be interested. I'm sure by now everyone has figured out their own way on checking trans level and read temps. My Bluedriver can read Short term and long term fuel trims as well for both banks its just deciphering it being the task. I'll try to time it like you suggested @hawairish. You're absolutely right. I have found that the actual MAF body is like plastic welded into that intake shroud even with removing the securing bolts. So instead I remove the entire shroud off the intake box and clean it that way. I have only ever sprayed MAF sensor cleaner and have only wiped the flat backside (spine) of the MAF body where there was accumulation of gunk but I have never gone near the wire with anything. I'm unsure what you mean by where you are cleaning with a q tip as the metal wire is all that matters and you wouldn't want to touch that with a q tip right? I actually got a little $100 smoke machine maybe 4 years ago from Amazon to test for leaks in my exhaust as I would always hear a faint high pitched whistling at start up. The damn thing works for maybe a few minutes then starts spewing glycerin (baby oil) through the nozzle so I stopped using it. I assumed they just all were temperamental unless you were to spring for a shop level unit. Maybe I'll get in contact with the brand and try for some trouble shooting with that. Its just the thought of shooting baby oil into my intake or exhaust doesn't fill me with joy haha.

I’m think you’re exactly right. Going through the rest of that section makes it clear the system is constantly monitoring the health of the sensors as well. Seems more intelligent than I initially thought for an older Lambda system. It has different conditions and thresholds for both the sensors monitoring and the sensor condition itself. It monitors the health of the sensor in more than a couple ways too. I doubt it covers every failure possibility though so there’s always a possible anomaly where it’s bad without triggering a CEL. That section of the FSM is also constantly mentioning the O2 sensor heater. I’m guessing it’s built into the O2 sensor itself as I believe one of the O2 sensor wires is the heater wire. One thing that dawned on me is the possibility of a clogged EGR system. But to my knowledge most VQ35s didn’t use EGR? I don’t think the 2002 ever had one. There is a vapor canister vent solenoid on top of the engine that I think gets confused a lot for an EGR solenoid. One final thing I’ll note since I forgot to mention earlier; not sure if this will help diagnosing but when the engine is cold and warming up there is no vibration in gear at idle. Not sure if that’s because the RPMs are up as the engine warms or something else I’m missing. I know bad ECT sensors do weird things for most vehicles. After starting the vehicle with a cold engine and putting it in gear after a minute or so, the RPMs only drop to about 800-850 instead of the 650 when warmed up. Obviously thats because the engine is conditioned to increase rpms when warming but something to note, zero shaking. Sent from my iPhone using Tapatalk

Yeah I’m used to 19 highway lol. I used to get 15mpg city but now it’s closer to like 10-12mpg city. The weird thing is P0430 comes back more frequently than P0420 too. I definitely had some of the O2 sensors replaced by a shop probably around 4-5 years ago. Don’t remember which ones. I’m not getting any other codes, no O2 sensor related codes or misfire codes, just the low catalyst efficiency codes. What I’ve been told is when that happens 90% of the time it is a bad cat. I’ll definitely try replacing the O2 sensors and check for any exhaust leaks before getting new cats. Based on what the manual says; it sounds like the upstream sensor is the only sensor that will change the air fuel ratio based on its reading. In the FSM it says under normal operating conditions sensor 2 (downstream) does not affect the air fuel mixture. But there is one phrase that confuses me. I’ll attach below. How hard is it to get to the cat bolts and remove them? I still feel like the car is exhibiting a lean condition based on its behavior. Also the stumbling after a hard drive feels like a miss but I can’t be sure. It’s like the car is bouncing rhythmically at idle. Not the same shaking/vibration that is normally exhibited when in gear at idle. Maybe my MAF is going. I’ve always cleaned it with MAF sensor cleaner like you’re supposed to but I’ve also heard they can be so temperamental. I’d always let it dry for an hour or more before energizing it again. Sent from my iPhone using Tapatalk

Sounds like my best course of action is to get a smoke test done on the intake and exhaust. I need to tear into my intake plenums again anyways to replace my valve covers, I can address whatever leaks they find if any then. I’ll clean the plugs and coils of any dielectric grease I used last time as it really is a scam. Anyway to know if a coil is going bad even without misfire codes? This is a coil on plug setup. In the meantime I think I’ll also look into engine and transmission mounts as well because I know for a fact my Transfer-case has movement, found out when I pushed up on my rear driveshaft yoke where it connects to the t-case; proceeded to see the entire T-case move up and down very slightly. Looks like a little movement is normal from what I can find online for that T-case bushing. If none of that fixes my issues I’ll move onto probably replacing the IACV to rule that out and take a look at getting my cats replaced if they are still throwing codes and my mpg is still bad. Got 15.5mpg the other day purely highway driving on a long trip at 70 mph most of the way. I should note I have a BlueDriver OBD2 scanner that can read some parameters and what I found is the long term and short term fuel trims for both banks is not that bad. Always less than 10% but there has been times where it gets pretty close. Holding at 2500 rpms gets you closer to 0% but at idle it’s usually a little bit higher but still under 10% Sent from my iPhone using Tapatalk

Thanks hawairish; seems like your issue pretty much aligns with mine. Something new to note I was in the mountains today for a trip. I pulled up on a pretty steep incline, parked and turned the car off on the forest road I was on. After 20 minutes I went to start the car and back down the incline; immediately after sticking it in reverse the RPMs dropped to 500 and for the first time it felt like the car was about to stall. Never had it happen before until then. It did not stall but came close. I’m definitely scheduling an appointment for a smoke test but I have a sneaking suspicion my IACV might be having hiccups. When I disassembled it to clean it and replace the gaskets I noticed evidence of coolant seeping into the housing. I thought it was functioning fine still as I never had any rpm surges etc. guess it’s not always necessarily just working or not working. Might be working only in a certain capacity but not in another. Any chance if I do in fact have a clogged/bad catalytic converter from those P0420/430 codes that could be causing the shake? I wouldn’t think they are directly related as the vibration has been there even before catalytic converter codes but maybe it exacerbates the vibration. Sent from my iPhone using Tapatalk

Thanks guys, based on research something like this does sound like it can be anything from a bad coil to the IACV. What I should mention is like I’ve said this has been going on seemingly since I owned the car. It has gotten slightly worse over the years but was always there in some capacity. I’ve cleaned the MAF sensor close to 5-10 times over the years. I’ve taken apart my IACV to replace the gaskets as a preventative maintenance for that dreaded coolant leak issue. I guess the IACV itself could still be bad. When I replaced my PCV valve and spark plugs I cleaned my throttle body and reset the Idle relearn procedure after assembly (drive by cable). Now I do believe there is a potential vacuum leak somewhere possible from my assembly of the plenums but this didn’t affect the vibration post assembly. Vibration remained in the same capacity before and after that job. I should say since I did that job of replacing the spark plugs etc i started to get P0420 and P0430 codes and have yet to address. My assumption was since they started right after I did the work they are likely being triggered because of a vacuum leak or a bad ignition coil etc something I moved around while I was in there. Takes about a month for the code to come back usually. No misfire codes or O2 sensor codes. I have noted stumbling though when at idle right after a hard drive on the highway if I gun it pretty hard. I definitely think I used too much dielectric grease when installing the spark plugs but I see no misfire codes. Ever since those codes started showing up my gas milage has been terrible. I’m going to get a smoke test done soon on the intake and exhaust just to rule those things out as there’s more than likely a few leaks here and there regardless of what I have touched. Should I stay away from those Firestone places for something as simple as a smoke test haha? There’s one near me that has been pretty good with the manager being a classic JDM guy who’s owned them all. Not sure what the mechanics are like though I’ve only had an alignment done by them. Sent from my iPhone using Tapatalk

I’ve been dealing with this for a long time; I understand the basic reasons this might be happening but I’m hoping in providing more specific details I can narrow the scope, also hoping somebody has dealt with this exact issue. With the vehicle warmed up, when in Drive or reverse while stopped and idling the whole vehicle shakes. It doesn’t really start until a few seconds after coming to a complete stop and the RPMs fall and settle slightly below 750rpms (around 650rpm). When idling in park or neutral the RPMs are dead at 750, no vibration or shaking. Certain things like using the window regulators or turning the steering wheel while stationary will additionally make the whole vehicle shake and the rpms drop slightly. Now the shaking is pretty aggressive, turns my seat into a massage chair and it’s been doing it seemingly for years. I’ve always thought it was the transmission but it’s lasted tens of thousands of miles like this and shifts beautifully now. I’m starting to think it might be the alternator (never been changed) not supplying enough output to my battery (new) but I would think that should effect the vehicle at idle in park and neutral as well. I think another likely candidate is the IACV crapping out and not reacting correctly when coming back down to idle with a load placed on the engine (in Drive). I’m sure it can be my torque converter going as well but what I’ve noticed is when the car starts to shake and vibrate at a stoplight for example (in Drive), if I turn on the Air-conditioning or heat, the rpms bump up briefly to between 700-750 and the vibration immediately goes away. Then as the ECU gets used to the additional load it settles the rpms back around 650 and the shaking/vibration comes back. Seems to me like maybe the load on the engine at idle in Drive is too much somehow causing the engine to bog, or should 650rpms not cause my car to shake? Whether it be a failing alternator or not enough air getting in through the IACV, the revs drop because the load is slightly too much. In every other case there is no vibration once the revs are at or above about 700rpm. What do you guys think? Sent from my iPhone using Tapatalk

I would go with factory plastic valve covers, you'll likely spend an equivalent amount trying to source the aluminum ones. The originals lasted a good amount of miles in my case and in your case 21 years. The problem with the spark plug tube seals is the act of removing the old valve covers to change the gasket usually does them in even if they weren't leaking before. Like @hawairish said, the spark plug seals are not serviceable unlike the aluminum covers.

I found myself in the exact same situation as you about a year ago Eric. I ended up going your initial route with the rear OME MD springs (2922) and it improved so many aspects of the vehicle I never regretted it. Now I personally kind of like the raked out look combined with the fact that I carry a lot of gear on weekends heading to the mountains it seemed like the perfect solution. Well I will say after installing the MD springs just in the rear, it was too stink bug looking even for me, I didn't let it stay like that for long. With likely sagging front springs as well, the disparagement was too much so after a couple months I decided to put MD springs in the front too. For a while I debated whether to actually do the Light Duty springs over the MD because I liked the raked look. Well I'm very glad I didn't, so much so I also added the Rocky-Road front trim packer with my MD springs because I wasn't happy with just the MD springs up front. Even after the springs settle, with just MD in the rear I think it would be too much of a difference. When people say 2" lift, that's from the sagged out state. It's 0.75" of lift over the stock from the factory height. I'd recommend actually just going ahead and doing the OME 2922s in the rear for now and when the funds permit go with the matching springs in the front. You won't regret it and in the meantime the handling of your Pathfinder will feel like new. Despite what people say, worn out springs also have a huge contributor to body roll and polar moment of inertia. My guess is if you went with a factory like replacement for example from Moog, you'd wished you had gotten a lift.