My 1990 300zx Twin Turbo build by megaDan

11 minute(s) of a 731 minute read

Yet another update! You can tell I want to get this done because updates are more frequent.

I had another large group of tasks yesterday. First of all, I got some generic 2.5" test pipe gaskets yesterday at Advance Auto Parts so I could make a bit of an adapter between my test pipes and my H pipe. As I mentioned earlier, for some reason my test pipes were mismatched lengthwise by a little less than .250". They were great last year, but nothing I did would get them flush, so I stacked a few gaskets on the shorter one and bolted everything together. The exhaust has never been a PERFECT fit, it always took a little force to get everything lined up, and this was no exception. But I was comfortable with how it all ended up.

Afterwards I needed to reinstall all the AC piping and etc in the interior, I had never reassembled it after my heater core replacement last year. (Big mistake) I found 5 of the plugs, but couldn't figure out where the last 2 go. And nothing works unless its ALL plugged in (so I am told) and I need to have the climate control working so I can bleed the air out of the cooling system. Once I realized I was missing a large section of the plumbing (I tossed it in the hatch) I saw it had 2 connectors. Figuring out how to install it was a pain in the ass. It only took about 10 minutes, but theres no good way to do it by yourself. It consistes of two plastic...tubes...I guess, which are loosely connected, and they have to be installed at the same time. You have to get them in position while lying on your back, and then with one hand hold them in place, get back up in the drivers seat, and stick a screwdriver through the center console and pry them into place and make sure they fit right. It took a while to figure that out. Again...another pain but got it sorted out.

Lastly I filled the radiator with coolant and tried to start the car yet again. No luck. Still can't build pressure in the intake system and cant hear any source of leaks. Even with my compressor regulator set at 60psi. Unfortunately after ALL of the times I have tried to start it so far, I have forgotten to pull codes every time. Damnit. Anyway, it still failed to run pro

perly. It stumbled quite a bit, seemed to be misfiring, and ran very lean according to the WBO2 (hard to tell, have a bad ground with my gages now).

Last thing I did was start to pull the plenum. Thankfully with my top feed injectors a plenum pull takes all of 10 minutes. Tonight I will be removing all the intake plumbing (that we have touched during this project) and reinstalling EVERYTHING one piece at a time making sure it is all clamped down. I'm sure we missed a hose or something. I hope thats all it is. 

Every night the car doesn't start I get discouraged and I'm stressed out. But by the time I stop thinking about it and wake up in the morning I realize I'm really close and its just a little bit more and I'll be there. 

I JUST WANT TO BE DONE!!!!!!! Yay. Ugh. Maybe this weekend. Car goes back on insurace today (in case I get everything sorted out and drive it this weekend) and collectors plate paperwork gets filed on Monday.

Workspace:

New rad installed. Look how high it looks! Luckliy the hood closes.

3/24/2012

Last night I pulled the plenum again, determined to find whatever could be causing a massive vacuum leak. Sadly, it looks like this was my fault. The passenger side accordion pipe was loose to the turbo inlet. The driver side didn't budge when I pushed on it. While I was in there I rerouted much of the wiring harness and vacuum lines to the boost solenoids. We tossed everything together pretty quickly the first time, so vacuum lines weren't tucked properly and everything was pretty much a cluster. I stuck the solenoids under the battery and BMC, and ran all the vacuum lines under all the intake hoses. Much nicer.

I tightened EVERY clamp from the turbos forward and put everything back together. Luckily with my top feed setup I can do a full teardown and rebuild of the plenum and intake pipes in a little over an hour.

I think we missed a ground on the first attempt because when I started it up it sounded like it was running on 3 cylinders. Code 42, forgot to plug in the fuel temp sensor. Tried again, still 3 cylinders. Code 42 and 21. I swapped PTU's to a spare, and it ran much better. Unfortunately this time cylinder 2 wasn't firing. I swapped coilpacks with no luck.

Gonna run through code 21 diagnostics today after I visually check for spark. SO SO SO close. I do still have a small vacuum leak for some reason, at the back of the motor, I can hear it whistling. The GF is gone for the weekend so I'll be looking for parts on craigslist nearby (shh don't tell her) and trying to troubleshoot these issues. I forgot to get insurance put on the car yesterday, and its raining so I can't do much driving with the Z anyway.

Also I got myself a cheap OBDII bluetooth transmitter which I intend to play with in my Golf today. If anyone has any idea why just one cylinder won't fire with what looks to be a good PTU, I'm all ears. 

4/9/2012

I've been avoiding this thread because its been nothing but bad news. But after last night I guess I'm ready for an update.

No spark was caused by a loose PTU connector it seems. That has been sorted out. 

The vacuum leak and inability to build pressure with a boost leak test is another story. I put worm gear hose clamps on every hose instead of the nissan OEM clamps to try and stop the leaks. No go, found one of my injector rings leaking. Took care of that, and the leak jumped to the upper plenum gasket, and after that was taken care of.....................it moved to the lower intake manifold gaskets. 

More on that in a second. I did manage to get it running decently (it seemed so at least) and I drove it 5 miles down the street to test out everything without power steering. Big mistake. And after I pulled out of the garage I noticed puddles of water under the exhaust, and a small puddle of oil at the rear of the engine where it mates with the trans. I was pretty upset at that point. And to top it off halfway through the drive I noticed the heater core was leaking and there was a loud ticking noise coming from the engine bay AND it was misfiring because of a lean condition. I was pretty upset. This would be the reason for no update in 2+ weeks.

Back to the solutions:

I pulled everything to retorque the head studs, and found a few that were LOOSE. Retightened everything and hoped that was the source of the water out the exhaust. The plenum came on and off about 5x trying to hunt down vacuum leaks.

After that I tried eliminating my injector vacuum leaks, but the lower manifold I'm using had two stripped holes in the center (which I didn't notice until the car was practically done). I had to drill them out and helicoil them, which worked fantastically........but didn't help with the leak.

Why the @!#$% did I use the intake manifold gaskets I installed? I had a set of the bronzeish colored metal gaskets with rubber inserts lying around, and I used the ones made out of exhaust gasket material. WHY?! I'll post pictures later. 

Sooo I was hoping I could pull the lower plenum without resetting the timing, we had the timing belt clamped and ziptied in place, with people on each gear holding them so they didn't move. It didn't matter, the belt still jumped. Which also didn't matter because I forgot about the rear timing cover on the passenger side which goes around the idler stud on the lower intake manifold. 

Lucky me. So as of Thursday night I was in for a weekend of tearing everything down so I could reset the timing. Luckily I had no work Friday so I spent the day in the garage, with the exception of lunch. My girlfriend was stuck working so I delivered some Panera. Mmmm.

I had pretty much everything together by Friday night, I just needed the right size power steering belt to match my crank pulley. It only took 3 trips to autozone to get it right. 

After checking everything and checking again, I FINALLLLLY tried to start the car again at about 6pm Sunday. Before the initial crank however, I gave her one last boost leak test. Lower intake manfiold: Sealed. Injectors: Sealed. Upper intake manifold: Sealed. Balance tube: forgot to bolt down. Oops. What I don't get is despite not having any leaks...I still can't build any pressure in the system. The car ran great (minus the 02 sensor issue I've been having. More on that later also), pulled 22mm/hg vacuum at idle and despite a full bottle of soap and water I couldn't find a single leak. I can hear air flowing what sounds like inside the plenum, but no leaks. And nothing out the exhaust according to my ears. 

As I said the car ran great, until it reached 167*F. At whichpoint the RH 02 sensor would peg at 1v, then slowly reach stoich, then peg at 1v, and repeat. And while its doing this it would rev higher, and sputter back down, and run real lean when gently cruising. I tested my 02 sensor theory by forcing the ECU to run in closed loop mode (fuel maps only) by unplugging my wideband 02 from the wiring harness (yes I'm using the 1v output from the LC-1). After that it ran MUCH better. Still slightly lean, but not to the point it was misfiring. 

No leaks from the heater core, no leaks from the engine bay that I can see, and nothing from the exhaust. I'm starting to feel better. Tonight my Z gets its face back! First time in 13 months. Then its another drive to get me near 50 miles and another oil change. Gotta put 500 miles on this as quicky as possible so I can get it tuned in Cincinatti in May. 

In the meantime I need to teach myself Nistune so I can set up my spare ECU and fiddle around to see if I can figure out what's going on with my 02 feedback. I was thinking of getting 2 new OEM sensors and relocating the wideband to see if that helps. I'm kind of stumped at the moment.

Pics are boring for this post. Shows my retapping setup for the lower intake manifold along with the finished result.