Possible fueling issues?

DIGItonium

I read some people got the code after cleaning the throttles, but since I did more than that I was pretty nervous about the leaks. I cleared the code and did the relearn again. This morning I redid the zip ties to make them as tight as possible, and replaced a hose that didn't fit the barb all the way through. I warmed up the car and didn't notice any idle surge. After a test drive with A/C the idle was tiny bit jumpy, but stooped climbing to 1k and throwing a code. So far so good! A little more work and early oil change to rid the fuel smelling one, and I should be good to go. Still no raw fuel smell or condensation build up on the exhaust tips, so I must be doing something right.

__________________

DIGItonium

I took a quick drive to my friend's house while treating the car like it is in the break-in period and boost no higher than 2 PSI, half throttle, and keeping the revs below 4k RPM.
https://drive.google.com/open?id=0B1...UjA&authuser=0

For comparision, here's a log taken BEFORE the maintenance work was performed.
https://drive.google.com/open?id=0B1...XzQ&authuser=0

From brief observation, post-maintenance engine idle is a bit higher between 725-800 RPM on average. However, A/F correction seems to be greatly improved (around 105% or so) after about 25 miles total driving. Slight idle bounce exists, but it doesn't seem severe enough to throw a code. There's absolutely no roughness, so engine feels pretty smooth.


Before maintenance, the engine idle was intermittently rough (felt like misfire) and shows up as slight bounce. I was already wondering about potential leaks before performing the work.

__________________

DIGItonium

Sunday I checked some vacuum lines. The OEM hoses clamped near the throttle body was easy to twist and pull off, so I added zip ties. The brake booster hose was also a bit loose, so I switched to a screw clamp. I also went ahead and ordered a Z1 brake booster hose. Idle surge was a bit better, but not entirely. At least it's not stuck at 1200 RPM at times or throwing a code.

Last night I grabbed TB cleaner and sprayed around the lines. When I sprayed one side of the intake plenum the engine started stalling. In a span of 3 hours I quickly loosened the pipes, throttles, and removed the intake plenum for inspection. The gasket wasn't even dislodged or deformed. There was a little bit of oil collecting, which was from 25 miles before I installed the catch cans. Nothing seem seeped out of the gasket. At this point I may have messed up torquing the plenum.

It was suggested that the gasket must installed dry with no lubrication despite recalling some sort of jelly (petroleum or silicone) in the grooves before maintenance work (tech who installed my kit must have used it). Anyhow, I washed it and wiped the surfaces clean. Today I spent another 3 hours carefully seating the gasket and intake plenum, hand tightened the bolts in the correct order, and then set the torque wrench at 5 lbs. I wasn't confident and was afraid of over torquing. One of the standoffs in the plenum was loose from the beginning, but it didn't have any major effects. All but #1 bolt seem to hit the torque limit, but I didn't want to push my luck.

After carefully tightening all of the bolts, I plugged the battery in and did all of the relearn process. Engine would still stall if I sprayed the same area. Then I continued carefully tightening the bolts near 8 lbs. Overall I may have spent more time torquing the bolts than I did Saturday.

Only once after startup it would briefly rise to 1200 RPM, but falls back to 600-650 RPM. After awhile it would idle hunt around 700-800 RPM. With the A/C running, idle hovers at 900 RPM. I took it for an easy test drive and freeway driving. Throttle response was better, though it was nice and cool out. It was eager to start boosting. At the light it would still idle hunt. So far no codes. Surging isn't too extreme, but quite annoying. I drove home and tightened up the bolts a bit more and called it a night.

__________________

Rusty

If you think you have a leak any where in the intake. Use starting fluid. Put a nozzle on the can that you can put a plastic tube into. With this, you can pin point the leak when the rpms rise up. Spray small sections at a time. Long as you are pulling vacuum and not boost.

Used this trick when I was rebuilding old carbs that I thought had worn base plates where the throttle blade shaft went through.

__________________

浪人 - 殺し屋
"The Difficult Anytime, The Impossible By Appointment Only"
http://www.the370z.com/members-370z-...o-journal.html

DIGItonium

Yea, I did some reading about it. I didn't have any on hand and figured TB cleaner wouldn't hurt, and I was worried about making a mess. But it definitely made the engine bog. I'm not sure if it's related to the leak. I'll try the proper fluid later this week.

__________________

VSS370z

I need to do some checking as well. I tried all the realearn stuff and no luck. That idle surge at first i could deal with it but now is driving me nutts.

DIGItonium

@VSS370z, can you list the work you done recently?

How's brake pedal pressure? Mine was pretty tight while idling, and it would easily affect engine idle from pressing it down. So far it seems to feel a bit better this time around.

I spent more time carefully torquing each bolt close to 8 lbs than I did Saturday because I was too scared to break things. So far no codes because it's not surging by 200 RPM anywhere near as often as before. The engine isn't freaking out as much as before, and it actually idles a bit lower. I guess that's progress as the bolts are further tightened. It's just #1 that doesn't seem to be hitting the torque limit, which is the same side engine stalls if I spray underneath it. I'm getting brake cleaner spray this afternoon. Hopefully all goes well. If it's still hunting, I'm going to guess it's the MAP sensor at this point. I read a failed MAP sensor could cause the same issues.

Funny thing with the idle hunting is that the engine is actually running smooth and not misfiring. Idle isn't rough.

__________________

Spooler

If you are spraying carb cleaner or throttle body cleaner on the outside of the intake and the engine bogs, you have found a vaccum leak. Address the leak. Look for a sealing issue or a cracked manifold. I would get a new gasket. Silicone is not normally needed on Nissan intakes. You found your issue, now you just have to get it fixed.


Side note: you want to use carb cleaner or throttle body cleaner. Don't use brake cleaner. You want it to burn if it gets into the cylinder.

DIGItonium

That's good to know. I didn't want to make a mess and used TB cleaner. The gasket is brand new, and it is not deformed. I thought it was dislodged when I put the intake manifold on the first time, but it looked fine. I took it out and washed it with dish soap and cleaned the intake manifold. I didn't see any visible cracks either.

Last night I made sure to be extra careful and started off hand tightening the bolts in specific order. Then started tightening at 5 ft-lb. I did the test, and the same side bogged the engine, but it seem to idle a bit lower before hunting. Then near 7-8 ft-lb before reaching the "clicking" point, things seem to improve a little bit. While all the bolts are very tight, and I'm carefully turning by 30 deg at a time, #1 hasn't hit the 8 ft-lb limit of the wrench. That's the same side where the possible leak is at. I sprayed the driver side, and it didn't seem to bother. Bolts on the driver side is hitting the limit on the wrench. #7 and #8 was already very tight a bit earlier on. I'm just a little nervous continuing to tighten bolt #1. Before tightening once more and calling it a night, idle was a bit lower and hunting range was probably close to 50 RPM or less. It was less likely affected when I pressed the brakes. So hopefully there's some progress.

I'm going to take a look at it again tonight after replacing the brake booster hose.

__________________

DIGItonium

Game over. I've completely given up. It was still idle hunting. So I tightened up a bit more and #1 bolt broke off. It's still drivable.

Wish I had professional help to make it right. I'm exhausted.

__________________

phunk

What were you tightening that broke? The intake manifold bolts? If so, there is no point to torquing then any tighter than stock. Tighter does not make it seal better or seat down any tighter, its just more torque on the bolts, and that is it. There are steel sleeves seated in the manifold that touch down to the LIM and take all the torque load. They have a step machined in them to hold the manifold down. You would have to torque so tight that the steel sleeves deform (not going to happen) before it held the manifold any tighter than standard touch-down.

You just need to make sure the gasket is in good shape. O-ring style gasket, it should be bulging out from the flange and take some decent pressure with your finger to get it to be flush with the plastic flange. If its pre-compressed flat, it needs to be replaced, but I expect that to be very old by then. I just looked at mine with over 60K on it and its a 2009, gasket is still good to go for years to come.

__________________

phunk

Its most likely a tune issue... either tune or throttle bodies. Assuming you do have an intake manifold leak, while this would increase engine speed and lean out A/F a little at idle (o2 feedback should correct for this though, and show up as heavier o2 compensation that could be logged), I see no reason the engine speed should not be able to remain stable... for an intake leak is accomplishing the same thing as increasing throttle a tiny tiny bit. It shouldnt struggle to accommodate tiny intake leaks... Think of the PCV system, essentially an un-metered intake leak right there - sucking in that crankcase air.

__________________

phunk

If I was trying to diagnose it, I would get into the UpRev and start by watching MAF voltages and o2 corrections, and seeing what the ignition timing is doing. Goofy ignition timing tuning can cause idle speed to bounce because, all things equal, if you add timing, engine speed goes up... if timing isnt pretty steady at idle, idle wont be steady.

Sorry if some of this was gone over, I didnt read the entire thread.

__________________

DIGItonium

@phunk, I added links to Cipher logs. Right now I'm looking for someone local to help me out. I've been working alone on this too long and don't have the patience anymore.

The engine would bog if I sprayed the passenger sidea underneath the intake plenum. With the torque wrench I had trouble feeling the clicks. I had it at 5 lbs when the bolt snapped. It's #1, which is same side I sprayed causing the engine to bog.

__________________

phunk

I would probably pull the manifold back off and examine it in great detail for any cracks or problems with the gasket.

If that bolt snapped at only 5lbs - either that torque wrench is broken or I dont know LOL

__________________