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Xterra supercharger on a VG30 project


JHine5588

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Now that you've seen it I can't get flamage, thanks :)

 

And the questions begin! I'll go first...

 

This car will NOT rev past 2K rpm's. Now I know the plugs, wires, cap and rotor are all old along with the gas that is in the car. I'm actually trying to run it out of gas and put some good stuff in it. I'm under the assumption that it is blowing spark out because it just isn't hot enough and yes, it does it even when the supercharger belts aren't on. I have NOT gapped the plugs down yet nor have I stuck a timing light on it after doing a cam swap. I haven't a clue what the cams are; this is my buddies car I'm building for him while he's in Afghanistan. It has a turbo ECU and currently no idle valve is hooked up (questions on that after this). I tried to read and understand the process of checking the codes but the thing flashes at me so much idk what I'm looking at LOL. The book says it flashes a 23, 24 and 31 but if not write down the trouble codes... So it flashes a 23, 24, 44 and 55 where if I remember right one is a crank position sensor (CKP) yet the other is everything is fine?!? I'm lost on that honestly...

 

 

 

Jeremy

Edited by JHine5588
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As for the idle valve issue, I obviously can't use the stock one so I'm using the Xterra supercharger one. The problem is the 300zx books I have do not tell me which valves are the fast idle and which is the stepper valve. If I were to guess the larger of the two would be the stepper valve. Also, I haven't a clue which one is which on the Xterra setup either so I'm hoping someone can help me with this. Now, it is installed (and the car idles remarkably well even without it hooked up) but I'd like to get it hooked up and done correctly.

 

I have gotten rid of things such as the AAI valve (I think that's what it was up behind the drivers side headlight and disconnected the solenoid going to it) but I do have the solenoid for the FPR hooked up. Also the little valve on the passenger side of the plenum is no longer hooked up... I believe it was an air bypass valve is what they called it, and along with the EGR valve and solenoid are gone. Could this be causing my lack of RPM's noted in the last post?

 

Thanks guys, any help will be appreciated because I know nothing about these motors!!

 

 

 

Jeremy

 

P.S. In these videos it is running on the stock injectors. We have a set of turbo injectors but all of them seem to be DOA... I bench tested them and apparently they are all stuck closed. I haven't tried soaking them to get them freed up yet.

Edited by JHine5588
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Well, I'm not real certain about the supercharger/xterra stuff, but usually if you're not able to rev past 2K then the engine is in Limp mode. Does it seem really rich at >2K rpm? If that's the case, then either your AFM is bad, or not being read correctly. You really need to get the FSM for the Xterra so you can try to figure more about what you're looking at. As for the injectors being too small, that shouldn't be stopping you from revving, it's just going to limit your power at higher RPM. since it's running you might see if you can find a Consult III that could read the actual codes and interpret for you. I assume you're using the stock Xterra harness / ECU etc too right?

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We're using all turbo Z stuff, ecu and harness. Nissan didn't change much (i.e. the closed throttle/WOT switch and the 2 wire fast idle/stepper idle valve) so all i'm doing is wiring up the Xterra stuff to the stock Z harness. Someone else told me it sounds like limp mode and yes, it is very rich. I agree with the injectors not allowing it to rev but these are also the big Jim Wolf valves without the spacers installed on top of the valves... My buddy ordered them not knowing the springs and spacers were needed.

 

Like you said, once I get a service manual I can figure the rest out. I've read a couple different ways to test the codes so I'll do that sometime soon. I am starting to believe it is this limp mode so now I just need to figure out what will cause it, besides the MAF... Would a faulty crank angle sensor do so? I think it threw that code.

 

 

 

Jeremy

Edited by JHine5588
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We're using all turbo Z stuff, ecu and harness. Nissan didn't change much (i.e. the closed throttle/WOT switch and the 2 wire fast idle/stepper idle valve) so all i'm doing is wiring up the Xterra stuff to the stock Z harness. Someone else told me it sounds like limp mode and yes, it is very rich. I agree with the injectors not allowing it to rev but these are also the big Jim Wolf valves without the spacers installed on top of the valves... My buddy ordered them not knowing the springs and spacers were needed.

 

Like you said, once I get a service manual I can figure the rest out. I've read a couple different ways to test the codes so I'll do that sometime soon. I am starting to believe it is this limp mode so now I just need to figure out what will cause it, besides the MAF... Would a faulty crank angle sensor do so? I think it threw that code.

 

Jeremy

 

Sounds like limp mode, but that backfire through the intake could be that your dizzy is off a tooth. Or it's just so rich. Or both.

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I haven't put a timing light on it yet but will be soon... I doubt it's too rich because i'm using the stock NA injectors right now. The turbo ones my friend got are shot... all stuck closed. Might try to clean them. Everyone that knows these cars is saying limp mode. I need to try another MAF.

 

 

 

Jeremy

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They are Jim Wolf regrinds and my buddy didn't realize that you needed the spacers and springs. As far as I can tell the cam timing is correct but as I said, there are no spacers installed right now. We should be getting them shortly.

 

 

 

Jeremy

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They are Jim Wolf regrinds and my buddy didn't realize that you needed the spacers and springs. As far as I can tell the cam timing is correct but as I said, there are no spacers installed right now. We should be getting them shortly.

 

 

 

Jeremy

 

You need a tune for those cams, as the stock ECU can't adjust for it and thats most likely the reason why.

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Well I assumed being a MAF setup it can handle the different cams with no major issues. The only thing I would think it would have a problem with is a major displacement jump or raised compression for any additional fuel computations it would have to make.

 

 

 

Jeremy

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The timing is out as I have no timing marks on the crank. I basically have the ignition timing set to where it I pulled the most vacuum then backed it off 1in/Hg. I have a wideband on the car so I will be keeping an eye on AFR's. We'll only be running around 5psi so I'm thinking that what ever ECU we end up with will handle it fine. If not he can get something like that, or I can do a full standalone megasquirt or even just an FMU.

 

 

Jeremy

Edited by JHine5588
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  • 1 month later...

Just remember you need to correct ECU for the cams/mods you have done.

 

The Z31 turbo ECU is more than capable of adjusting for them. You can make anywhere from 170whp to 260whp on the stock Z31 ECU, and it'll still be rich as a pig at high RPMs in boost. But thats the issue, is its rich as **** and can't be relied on for the most power you can get.

 

Did you change the MAF yet like I told him to to tell you before, and like others have told you? Just curious how this thing is coming.

Edited by michaelp
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No, I haven't replaced the MAF yet mainly because he doesn't have another one laying around, but also because the last month and a half I was fixing his Land Rover so he could drive it while on leave. Once we get another I will put that in, and also the JWT chipped ECU in with the turbo injectors... BTW, are the turbo injectors low/high impedance and the NA ones the opposite? Here is the run down because it is a lot easier to explain it this way.

 

Installed the turbo injectors but they wouldn't fire, figured they were junk/stuck

re-installed the NA injectors and they fired fine so I got it running on them

realized the ECU was the stock NA ECU and not the chipped one

 

Therefore I was trying to fire turbo injectors with a NA ECU and they weren't working. I was thinking if the NA ECU fires a low impedance pulse, then it might not be able to trigger the turbo injectors, therefore the injectors may still be good and I just have to swap the ECU's to get them to work.

 

 

 

Jeremy

 

P.S. If anyone has a working MAF laying around they aren't planning on using and wouldn't mind donating it to the project for a United States Combat Medic please feel free to PM me and I'll get you my address. I'll be sure to tell him who gave it to him.

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All 84-87 injectors are low impedance, with 88-89 being High. Low Impedance ECU and trigger high impedance injectors, but if you use high impedance ECU on low impedance injectors you'll fry the Injector Drivers in the ECU.

 

If you're willing to drive to Savannah, NY I'll give you a MAF for it.

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Is there any way of telling which are low and which are high? The only things I can tell you are the car is an 87 and the turbo injectors we were trying to put in are red, the vacuum connector for the fuel pressure regulator points to the drivers side (we installed injectors and fuel rails) and the plug is different from the stock NA injectors (the little protrusion on the outside of the injector doesn't line up with the one on the stock injector plug). That last one will be the give-away I'm sure...

 

I'll be in Cazenovia probably this weekend... I might be able to make a stop over and pick it up on sunday.

 

 

 

Jeremy

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