[konkey00]

Leaving the house;
Took the car for a test drive just now. I’m starting to suspect that the Plenum was just dirty. Once I got on the road for a minute it started running much smoother. It’s still seems to stagger when letting off the throttle so I think it’s still misfiring. I was scared before because last night and today, the intake was making noises like it did before when it was backfiring and I had coil packs 2 and 3 swapped. When I’m on the road now, I’ve found that it’s not backfiring noises, but actually just sucking in air.

Got back home;
I had a hard time starting the car at the store. It ran well on the drive home but as it sits here and idles it misfires consistently. I got a code for cylinder 4 misfire. I tried spraying sea foam through the brake booster vacuum port for a couple minutes to see if anything would change, but no luck. I’ve swapped the old coil pack on cylinder 4 to another old coil pack, but that doesn’t seem to have changed anything either. I cleared the codes and let the car idle with the AC on. It’ll run smooth with AC until the radiator fans cut off, then it seems to stumble and almost die.

 

[CrickiKaze]

When was the last time you checked valve clearance?

 

[konkey00]

When was the last time you checked valve clearance?

I checked it with a feeler gauge when I installed the BC springs and retainers. I didn’t make any record, but I believe they were all correct according to the JWT camshaft install instruction sheet.

Edit;
I also made marks on the cam gears and chain before beginning on that Spring/Retainer job. Pretty sure it should be correct there, but I can take that small front cover off in the future and double check just to be sure.

 

[konkey00]

Just out of curiosity, would the position of the throttle body affect idle? Perhaps turning it clockwise or counterclockwise on the plenum/spacer would help? This is my setup as of right now.

 

[CrickiKaze]

That's a good question...I have mine in the oem orientation.

 

[SKILLET]

Just got back from pull a part. 2 of the cars they still don't have on the lot for me to take parts off. The two on the lot are destroyed. One looks like it burned to the ground. I'll check back there in a few days.

 

[konkey00]

Alright, I think my car is finally running right. I’ve been meaning to make a new post here to update what’s been going on with my build, but it seems like every time I cut out a problem, two more take its place.
I decided to do a front end swap (04-06 to 02-03) while I was brainstorming and troubleshooting the main issues the car was having. Here’s how it’s turned out so far:

I may continue to paint more parts of the car in this blue in the future if I’ve got nothing better to do. It’s a real mess with 6 different colors at the moment lol. The hood scoop is just an aluminum vent air diverter that I attached to make clearance for the rogue intake manifold plenum. I want to believe that cold air on the intake manifold may cool down intake temperatures but it probably won’t make a measurable performance benefit.

Here is a picture of my engine bay as of today, it will help visualize everything I’m talking about in the next troubleshooting part of my post;

I chased my tail around for a while trying to diagnose the poor idle and misfire code. I first tried installing an OEM hitachi coil only on cylinder 4 but it didn’t seem to change much. I also added a large size cable from the alternator to the battery to improve voltage consistency at idle, but it didn’t fix any issues yet. The next thing I did was install a new baffled oil catch can between the PCV and intake manifold (The black mishimoto can on the firewall). At first the engine started running much smoother, but unbeknownst to me, this catch can immediately started filling up with oil. I didn’t notice until my car started having stalling and starting issues, so I (falsely) associated these issues with each other. Several ounces of oil would be sucked into the catch can on every 20-30 minute trip, so at first I kept a waste oil container in the trunk to empty the catch can between each trip. I fixed the catch can issue by installing a breather filter on the outlet of the catch can and plugging the intake manifold. The crankcase should still have vacuum on it from the vent to intake line, so I believe having the PCV venting to the catch can at atmospheric pressure should be fine. The crankcase vent to intake line also has a catch can installed (The red mishimoto can on the red bracket), so oil consumption is minimized and my engine is running smoother as a result.

I fixed the catch can oil issue and still had problems with starting and stalling, so I went back to square one. On cold start and warming up to operating temperature, the car would have zero issues. It also never had issues as long as the car was moving. After warming up to operating temperature, idle would steadily become more rough and stall if I didn’t blip the throttle to keep engine rpm’s up. If I let the engine stall or shut it off after warming up, it would refuse to start unless I waited to it to cool off or spray motor starter fluid into the intake to force it to start. The engine would also still have issues stumbling or dying when turning the AC on or off.

I found that when the engine was stumbling or stalling, it was always when the radiator fans turned on. I assumed the problem was electrical so I started by checking the relays since the AC and radiator fans both were powered with relays in their circuits and both were affecting the engine idle negatively. All of the relay contacts functioned when applying 12 volts, so I could rule them out as causing the issue. The radiator fans and AC were functional when voltage level was good, so my next guess was that there was a high resistance connection somewhere. I added a grounding jumper from the relay grounding point to the alternator grounding point (it’s a blue cable that’s going over the coolant reservoir), which is also jumped to the engine front cover and then jumped to the negative battery terminal. The stalling issue was improved but not fixed; the engine would stumble when the radiator fans turned on and recover more often but it would still eventually stall. I used Uprev to watch the voltage level when this was happening and the voltage would drop from 14V to 12.5V without dying when the fans turned on, but if voltage level was at or below 13.8 bolts before the fans turned on then it would kill it. I then added another jumper from the grounding point on the chassis behind the intake pipe (I believe this is where the fans are grounded. It’s a red cable.) to the negative battery terminal, and I have not had any stalling or starting issues since. When the fans turn on, they will typically drop voltage from about 14V to 12.8V which seems to be plenty enough to keep the engine running so far.

I think I will go ahead and add more grounding jumpers with the excess cable I have left from any remaining grounding points I may have missed. I don’t think that I really NEED to replace my radiator fans yet, but I think it would definitely help to have fans that have less current draw (that causes voltage drop) on startup.

I hate the stock wiring harness and grounding so much lol. All of the mods on the car are kinda fucking useless if I can’t drive it reliably, so I would say adding big cables to all the ground points on this shitbox is probably the most important thing anyone needs to do to it. Hopefully my car stays running right this time lol.

 

[konkey00]

I decided to go ahead and get a new Megan radiator, mishimoto fan shroud, and 2JR’s plug and play wiring kit. I probably didn’t really need these things since I’m not having the starting or stalling issues anymore, but the engine still stumbles when the fans come on. I’d rather have peace of mind and know everything’s working as it should rather than wait for things to get worse. I got the Megan radiator as a precautionary upgrade since I plan to autocross next year. It’s a little bigger than the stock radiator, so the slim mishimoto fan shroud is still pretty close to my eBay exhaust manifold. I’d be willing to bet that I’d need to go back to the stock size radiator if I had a Medusa header or a turbo. The fans kinda freaked me out when they first came on because they sounds so different from the stock ones. It caught me off guard since I was listening for the engine to stumble, but instead it started sounding like an airplane when the fans came on.

I also decided to add another grounding jumper from the transmission ground to the battery. I can’t tell how much it’s helping since I added it the same time as these fans. I’ve only idled the car once after install, but it’s acting better than it did yesterday.

 

[konkey00]

I’m still having issues with the car the past couple months, I’ve gotten to a point where I feel pretty stumped. The issues I’m getting are pretty consistent and repeatable;

When I cold start it, it’ll start up fine. Driving it around before it gets up to operating temperature is good. As it idles, warms up, and adjusts fuel and timing it starts running richer the longer it sits. It’ll go down to 10 on my wideband and idle shitty when it’s fully warmed up. If I turn it off it will not start. I have to wait at least 15-20 minutes for it to cool down some before it’ll start again. If I do start it again before it completely cools off, then it’ll idle at about 14-15 on the wideband gauge, but the timing is bad. It will misfire at idle and the check engine light blinks while driving. The CEH code will usually be a random misfire and occasionally a cylinder 3 misfire.

I replaced the upstream A/F narrowband sensor with an NGK in January, but it made no difference. I also disconnected my grounding jumpers to see if that was causing the issue but it didn’t seem to make a difference either. I haven’t tried anything since then because I didn’t want to introduce new issues or unnecessarily replace things. I still haven’t pulled the cover from the cam gears to make double check timing is correct so I’ll probably check that this weekend. Almost every sensor has been replaced within the last year so I’m suspicious that something could be wrong with the ECU if the timing is correct, so I might have to search out an 04-05 ecu if that’s the case.

 

[Tritton]

Blown head gasket. Pull the head, have it decked, use arp studs with new gasket.

If you do this consistently check you fluid levels, you'd be running low here and there.

I had the exact same symptoms and a new hg fixed my turn off will not start. Basically the motor is tweaking under heat and allowing water to flow into the cylinders which then hydro lock when you turn the motor off. You have to wait for the system to depressurize before it'll start again.

 

[konkey00]

Blown head gasket. Pull the head, have it decked, use arp studs with new gasket.

If you do this consistently check you fluid levels, you'd be running low here and there.

I had the exact same symptoms and a new hg fixed my turn off will not start. Basically the motor is tweaking under heat and allowing water to flow into the cylinders which then hydro lock when you turn the motor off. You have to wait for the system to depressurize before it'll start again.

I hope that’s not the case. I’ve never noticed my coolant levels getting low or any oil/coolant mixture yet. Coolant in the reservoir hasn’t dropped much since I installed the new radiator. I filled it up all the way, and if anything it’s spit some out through the top of the reservoir. I’ll check under the radiator cap this weekend.

I changed the oil late December or early January and it was just dark in color which seemed normal. Oil level has stayed pretty consistent lately. Last fall oil would get sucked into a catch can because I had a bad PCV, but I replaced it and it’s been fine since.

I believe that when warm, the engine is turning but not starting, but it’s been a minute since I drove it so my memory might not be right.

Might not be a bad idea to do a head gasket job for preventative maintenance anyways especially if I can’t find any other cause for my issues.

I have all the tools to do a leak down test and a compression test so maybe I’ll do that as well once the engine is warmed up.

 

[konkey00]

Blown head gasket. Pull the head, have it decked, use arp studs with new gasket.

If you do this consistently check you fluid levels, you'd be running low here and there.

I had the exact same symptoms and a new hg fixed my turn off will not start. Basically the motor is tweaking under heat and allowing water to flow into the cylinders which then hydro lock when you turn the motor off. You have to wait for the system to depressurize before it'll start again.

I’ve still got my old motor, it would probably be more convenient for me to pull that head, have it decked and then swap them if it comes to that. Might be an opportunity to throw in some S1 or C1 camshafts since I’ll already be that deep into it.

 

[Tritton]

There we go!!!

I’ve still got my old motor, it would probably be more convenient for me to pull that head, have it decked and then swap them if it comes to that. Might be an opportunity to throw in some S1 or C1 camshafts since I’ll already be that deep into it.

 

[todd]

Years ago, my Sentra was bogging down at idle. Later, it started to loose coolant through the head gasket. I did a head job which fixed the coolant issue, but I also did a valve job. The mechanic's machinist said the valves failed their test. After the valve job, the bogging down at idle was fixed.

 

[konkey00]

Years ago, my Sentra was bogging down at idle. Later, it started to loose coolant through the head gasket. I did a head job which fixed the coolant issue, but I also did a valve job. The mechanic's machinist said the valves failed their test. After the valve job, the bogging down at idle was fixed.

That’s interesting, I installed Brian Crower springs and retainers and checked valve lash and it was correct at the time of install. It sounds like maybe yours weren’t sealing to the head properly? Before the head gasket work, did you try a compression or leak down test by any chance?

I haven’t been able to find time to diagnose or repair anything yet. My sister’s Lexus ES300 decided to blow a gasket so I’m swapping that engine for her during my free time. The Sentra has gotten pushed to the back burner by that task and finishing some firearm projects I started on during the winter when it was too cold to work on cars. Not the end of the world really; the wheels/tires I ordered last Black Friday for autocross track days are still on back order so I’m in no rush right now. At this point I’m mentally preparing to have it ready next year.

 

[todd]

I'm not a mechanic but know a little. At the time of repair, my car had all the factory stuff in it. I don't know what you mean by valve lash. My understanding at the time was that there was too much carbon build up in the valves (maybe the carbon build up restricted air flow which maybe later caused too much heat at the gasket causing the leak). Once the carbon was cleaned out and put back together, the engine never bogged down anymore. One thing I had to do after the job though was the throttle body idle air flow relearn (before doing this, after the job was done, the rpm's would sometimes drop rapidly at idle; after the relearn the sudden dropping disappeared).

 

[konkey00]

I'm not a mechanic but know a little. At the time of repair, my car had all the factory stuff in it. I don't know what you mean by valve lash. My understanding at the time was that there was too much carbon build up in the valves (maybe the carbon build up restricted air flow which maybe later caused too much heat at the gasket causing the leak). Once the carbon was cleaned out and put back together, the engine never bogged down anymore. One thing I had to do after the job though was the throttle body idle air flow relearn (before doing this, after the job was done, the rpm's would sometimes drop rapidly at idle; after the relearn the sudden dropping disappeared).

That makes sense, if/when I swap heads I’ll be sure to inspect and take pictures of the condition of the valves.