Jump to content
HybridZ

Recommended Posts

It's on the right side of the throttle body (inboard).  It comes up thru the body and serves as a "stop" to a little flange on the throttle linkage.  There's a screw with a lock nut under there.  Hard to get to as it's all "upside down".  Not your problem, but everything you learn about your engine is a good thing...

 

Your problem is still likely electrical.  Wiring and connectors.  

 

Don't forget the problem I had with random shutoffs years back:  Broken solder joint on the C.A.S. connector spades.  May or may not be an issue, something to check if all else proves good.  (Made the ECU lose the CAS signal and shut down - problem was fairly random but heat seemed to affect it as well...)  You'd need a "new" optical module to check that out unless you can do board level repairs on the optical module circuit board...  Get one from a 90's distributor type VG30E - Maxima, M30, Z31.  You don't need the whole distributor, just the black optical module (CAS).

 

Are you using the Air Control Valve (Air Regulator '82 280ZX FSM - EF&EC-page 55)?  Have you verified that it works (test listed in the FSM)?  It should get battery voltage at IGN ON continuously until IGN OFF.  There's a bi-metal in there that opens and closes a shutter.  It's a very simple part, but the shutter needs to open and close smoothly.  You can pull the air hose from one side, turn the ignition to ON and watch the thing slowly open - it should take a couple of minutes.  Fully described in the FSM (which is much better than my memory).

Share this post


Link to post
Share on other sites

Thanks for the advice, cgsheen.

 

I'm using the stock manifold and stock setup, minus the EGR and pop-off valve (I know it's there for safety, but with boost levels barely above stock my research determined it would cause issues on boost). I'll test the air control valve when I get the chance.

 

Turns out I'm pretty dumb. I got exhaust done yesterday and upon inspecting it found that the vacuum line for the wastegate has been disconnected. Huge vacuum leak. I should have realized when my boost gauge showed -6 psi at idle but never really bothered to look at the conversion to inHg. With the line plugged in vacuum is at -9/10psi cold, which seems right where it should be. Idle went from 1400 rpm to 900 rpm and the car runs heaps better. But of course, not everything is butterflies and rainbows. I'm still getting a random stumble and dying. Came up to a light after driving for ~10 minutes, clutch in to neutral and the car just died. Sitting at a light later in neutral and the car starts to hesitate so I give it gas to keep it alive. Sitting outside my friend's house and the same thing happens. Slowing down into a turn and downshifting to 4th and the car dies. Most of the time it's fine, and then sometimes it just doesn't want to cooperate.

 

TL;DR- huge vacuum leak which when fixed made the car run awesome. Car still randomly stumbles and dies when sitting or when depressing the clutch.

 

Still have some gremlins to track down I guess, but a huge step forward.

Share this post


Link to post
Share on other sites

Been driving the car a bit but getting what seems to be pretty shitty gas mileage. Speedometer doesn't work and I can't really determine why so I'll probably have to unbolt the cable, see if the gear is spinning, and if it is then my issue would likely be the drive cable itself.

 

The car is running pig rich. I got some more posi-taps yesterday and hooked up the O2 sensor to my AFR gauge and it isn't even registering most of the time. I get a single block of red every once in a while. Drove it around the neighborhood and put it under some boost as well and nothing changed. This rich condition, paired with my previously quiet fuel pump screaming at me and the occasional stalls when putting in the clutch and/or shifting into neutral leads me to believe that the stalling is being caused by the excessively rich condition, and my fuel pressure is suspect.

 

The CHTS is brand new and, while I have not actually tested it, did not make a difference in the running condition of my car once I replaced it.

 

Other than that, my setup for idle air is suspect as well. Research points me to a bad/improperly set up IAC/Air Regulator as cgsheen suggested, or possibly even my AAC valve setup. I'll have to do some more research and reading up in the FSM to determine how they function and if how they're set up right now could cause an issue.

Share this post


Link to post
Share on other sites

At this point I'm basically talking to myself, but the goal of this thread is really just to provide a recent chronicling of the classic L28ET swap so hopefully continuing to tack stuff on won't hurt.

 

In the spirit of actually doing diagnosis, I hooked up a fuel pressure gauge between the filter and the fuel rail and ended up with a reading of 70 psi while priming and a severely erratic needle jumping between ~60-80 psi at idle. Removing the vacuum line had no effect. 

 

I didn't have this issue before, and I know my fuel pressure was not that high with the original engine. At this point my suspicions seem to be confirmed- the fuel pressure is excessively high, causing the fuel pump to be noisy due to strain. And given the consistency of my unreadable rich condition, I can only come to the conclusion that the high fuel pressure is also causing me to run extremely rich.

Share this post


Link to post
Share on other sites

I suppose you've already checked the fuel return line all the way back to the tank.  Just go back over your fuel connections and tubing.  Verify that you have the supply and return lines are connected correctly to the fuel rail.  Make sure the fuel rail doesn't have a blockage.  I always find it easiest to start at the source and follow the path it takes back to the tank...

 

( you can disconnect the return tubing at the frame rail and run it into a container.  You should have very good fuel flow - the FPR will "back up" the fuel to maintain a certain pressure, but then the entire output of the fuel pump will flow out the return line to be returned to the tank. )

 

You know how much fuel pressure you should have - ~36.3 PSI with the engine not running - ~36.3 PSI MINUS your manifold vacuum when it is running (unless you're in boost :) ). That's what the stock ECCS is expecting.  My manifold vacuum is usually 10-11 PSI (maybe 11-12) at idle.

 

And...  you can always run an aftermarket FPR...

Edited by cgsheen

Share this post


Link to post
Share on other sites

That's the plan, sheen. I did make sure the lines are corrected right. I do have fuel in the return line, so if it is in fact a blockage my guess would be it's in the fuel rail since I didn't have an issue before.

 

New FPR is on the way and it's adjustable with a pressure gauge built in. Worst case scenario, I end up with an adjustable FPR. We'll see how the car behaves after replacing it, I really haven't had the time to work on it (just started a new job yesterday).

Share this post


Link to post
Share on other sites

Well, the new FPR definitely helped a lot. Of course the car still isn't running right... And it turns out I'm a dummy and don't know how narrowband AFR gauges work. What I thought was rich is lean and vice versa. 

 

Fuel pressure is where it should be but the gauge is very erratic with the car running. Not sure if that's normal. With my new knowledge I know that the idle is lean, not rich. FPR has helped a little but not much it seems. So knowing now that the idle is lean I have to completely change my way of thinking. Under boost the AFR gets richer so that's a good sign.. 

 

Here's the kicker- while coasting down a hill at a constant speed I can turn my headlights on and the AFR gauge will immediately change with it, going leaner. I'm also getting a constant popping noise from my speakers every couple of seconds. I'm wondering if my ground circuit isn't actually grounded very well.

Share this post


Link to post
Share on other sites

Haven't done much to it for a while until recently. I bought an intercooler so I've been working on getting that to fit well. I've got the outlet->intake mocked up but the turbo->inlet is proving to be much trickier. I managed to get my AFM situation figured out- had to relocate it because the intake pipe/filter went through the core support on the driver side but I'm using that space for the intercooler piping.

 

I also added some extra grounds to see if the car would react at all... nothing. There's something funky with my electrical system, at least for my gauges. My oil pressure gauge reads low, my temperature gauge reads low, and my AFR gauge reads weird as well and the reading changes when I turn the headlights off or on. I'm still trying to figure out what could be causing it and the only thing I can really come up with is a low voltage signal to the gauges. I'll have to check what they're getting at some point.

 

I decided to verify my oil pressure with a regular needle gauge which I screwed in place of the stock oil pressure sender unit. Mechanical gauge read ~40 psi at idle after a dead cold start. Not sure if that's too much... I didn't get a chance to warm it up and see if it dropped. At least I know that I don't have low oil pressure, but I wouldn't have guessed I'd be worried about the polar opposite.

 

I still need to drop my transmission and inspect/replace the rear main seal and/or oil pan gasket at the back as well as figure out my dump pipe situation. I think I'll just have to take it into the exhaust shop... much easier that way.

Share this post


Link to post
Share on other sites

Did you ever resolve the trans mount issue on page 2?  There is a different mount for a turbo trans and it has a swap in it so the motor stays where it was originally and everything bolts together with stock parts. Swap the front yolk on your original drive shaft to the turbo and your good to go.

 

Disreguard if you have figured this out already. If not let m,e know I have a couple extra turbo trans mounts.

Share this post


Link to post
Share on other sites

Did you ever resolve the trans mount issue on page 2?  There is a different mount for a turbo trans and it has a swap in it so the motor stays where it was originally and everything bolts together with stock parts. Swap the front yolk on your original drive shaft to the turbo and your good to go.

 

Disreguard if you have figured this out already. If not let m,e know I have a couple extra turbo trans mounts.

 

I wasn't aware of this... do you mean the rubber mount itself is different? I ended up getting a transmission crossmember from a 280zx turbo which has a little hump that moves the mount back 15mm. From research I discovered that the l28et t5 mount sits back 30mm, so I had a local guy cut and weld the middle section back an additional 15mm and it worked perfectly. Got a brand new custom driveshaft from Powertrain Industries with serviceable zerk fitting u joints for just shy of $300 shipped to my door. With the amount that the only local driveshaft shop wanted to set me up with what I needed, I still came out better.

 

 

Any pictures of how you mounted the AFM? I see you used flexible hose to locate the air filter. Did ou have to cut the rubber boot to the turbo?

 

I don't think I have any good pictures of it all put together... it went (Turbo)>(3 1/8" [or 80mm] silicone hose w/fitting for PCV)>(AFM)>(3 1/8" to 3" silicone adapter)>(3" aluminum pipe)>(flexible intake ducting)>(3" aluminum pipe)>(3" air filter)

Share this post


Link to post
Share on other sites

That idle adjustment is a pretty good sized bolt with a spring on it. You could try that, but I've read lots of places that you shouldn't ever need to touch it unless someone already fiddled with it.

 

I'd look more into what parameters change when the temp sensor decides the engine is warmed up vs cold...but that's just me.

Share this post


Link to post
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.


×
×
  • Create New...