Decimus Meridias

iTrader: (5)

Hello to the maxima.org community. I have greatly appreciated all of your advice, wisdom, and information in the past and and have a problem that I just can't seem to figure out. This post will probably be long, so apologies in advance. Yes, I have searched...extensively. I may not be the first with this problem, but I don't think it is very common.

BACKSTORY: I have had a 96 nissan maxima 5 speed for the past 7 years and it has been a great car. I have been working as an A&P (aircraft) mechanic for the past 5 years, so I'd like to believe I'm not a complete idiot and have at least some understanding of the way things work with mechanical and electrical systems. This past summer I finally decided to do some of the mods that everyone wants to do b/c I had time, an extra vehicle, etc. I wanted to do an 00vi with VAFC-2, ebay stainless y pipe, etc. I decided to just pull the engine and transmission (I know this is overkill, but I wanted to take everything apart, clean it up, paint valve covers, etc.). My water pump went out (not just the seals, the pump itself seized), so I replaced that.

GENERAL INFO: My 00vi swap used all 5th gen components including Upper and Lower intake, Injectors and fuel rail (with both fpr hooked up correctly to the stock delivery and return fuel lines), rear valve cover with 5th gen coils, 5th gen throttle body with IACV (see below for more info and 4th gen).

PROBLEM: I now have everything back together and my car will not idle. I can get it to start if I push the gas pedal back and forth. In this case it backfires, pops, shakes, and then will run smooth if I keep it above 1500rpm. Below that it will shake and die pretty quickly unless I wiggle the throttle just right. I can drive it around and it has power like normal (no misfiring, all injectors are working), but as soon as I let off the gas completely, then it dies. It starts a little easier when warm compared to being cold, but it will not idle either way unless I hold the throttle at 5% or greater ( I only know % b/c of my vafc2).

SOLUTIONS I HAVE ALREADY TRIED:

- Originally intstalled 5th gen throttle body with IACV attached, but then installed stock 4th gen IACV with BOP and proper hoses to intake. Read info here ( https://maxima.org/forums/4th-genera...on-sensor.html ) that lead me to believe that shouldn't matter.
- Crank position sensor (POS, haven't tried REF yet). I got really excited when I read about possible starting issues with this in the aforementioned thread. I tested mine (12v red, ground black, and 5v white intermittent when you hold a bolt or something close to the magnet, then 0v when you pull it away). I tested mine and it was bad (0v always on white), so I went and got a new one at Oreilley's (it tested bad 5v constant on white), so I went to the junk yard and pulled one and it tested good (5v-0v depending on metal on or off the magnet). I don't think anything can go wrong with the timing ring, because its just a peice of metal with notches, but I may be wrong. Either way I didn't ever remove it from the engine when I had the engine and tranny out of the car).
- Grounding. I have cleaned all grounds and don't believe this to be the issue, but I have recently done some more reading about poor grounding between engine and transmission after reinsall, so I will be adding more grounds soon.
- Reset VAFC-2 settings (I have yet to tune my car, WB02 coming soon), but I was under the impression that our cars will still run with 5th gen injectors, it will just run really rich (as much as 50% rich at WOT from what I hear), but that they will still idle and be driveable below 3000rpm. I can say that mine seems to run just fine between 1500 and 4000. I can drive it around and it seems pretty normal compared to how it was before I modded anything, but as soon as I let off the throttle completely, then it dies.

I will check this often for replies and to answer questions. Any help is greatly appreciated, but posts such as "SEARCH!" and "This question has been answered 1000 times" aren't really very helpful. Also, "Did you make sure your battery is connected" and similar posts just show you didn't actually read mine. SO....

PLEASE READ ALL OF THIS POST BEFORE REPLYING.

Thanks!

Finkle

First thing that comes to mind is vacuum. I had an issue with my old upper IM, turned out the inner two bolts were not tightened down. I could rev it, but it wouldn't start without holding the gas down. Check the vacuum if you can keep it running and see as the rpms drop, the vacuum should go up. It should be around 18-22 at warm idle, granted you can't get down to idle without it dying, but see how close you can get. I have the 5th gen TB on my car with the 4th gen IACV. If you turn the idle set screw on the TB, you really don't need the IACV in there. The car will start then abruptly die unless you hold the gas a little bit when cold. But without an IACV you should be able to hold it at idle.

Have you checked for codes?

Decimus Meridias

iTrader: (5)

Hey thanks for the response. I replaced the upper and lower intake manifold gaskets when I installed them, and just rechecked the bolts on the UIM, so I don't believe I have a vacuum leak. I installed another ground to the engine and removed the 4th gen IACV and reinstalled the 5th gen. I bent the pins a little more and now it idles! It still idles a bit high (1500rpm at start like it should, but only drops to about 1100). Hopefully I can get it back down to 5-600.

I do have three codes. First was a coolant temp sensor that I cleared by plugging it in all the way. Second is an intake air temp sensor that I have checked connections, tested sensor (ohmed resistor), and replaced it with another one, but it still shows up. Third is an 02 sensor that I've been meaning to replace.

I'll continue to try to work out the little bugs and update as I make progress, but at least it is driveable now! Thanks!