I'm quite new to Turbo's, so I am not 100% sure of what the problem could be, so I will ask here. When I give the car a hard accelerate, the turbo kicks in and if I keep giving it a bit, once the turbo reaches ~10 psi, and I am in high revs, it will stutter and hiss like a rattle snake, it deeply eats away my performance, and if I don't back off the gas, it will just give me little acceleration. But if I ease my way up to 10 psi, it will be fine. Say if I am in 2nd doing 50 or so, and then open it up, the car goes to take off quickly the turbo will then hit 10 psi and stutter and hiss. Any ideas would be great, I have the car in pieces due to changing the clutch, so I can access quite a few points of it.
First turn your boost back down to stock... Are you running 10psi with the factory POV still in place? (look for a valve on the front of the plenum) If so that'll bleed off boost at around 8psi or so and will cause the problems like you describe. You'll need install a BOV and plug up the factory POV to increase the boost above stock. It's a safety device to prevent accidental overboosting. Other than that it could be a simple boost leak but the "stutter" you describe could be pinging or spark blow out aswell. You're scaring me, seriously turn the boost down before doing anything else! lol I would inspect the fuel system aswell, and make sure that it is up to scratch. Do not run 10psi of boost with the stock fuel pump, you want to upgrade to a high flow pump like a Walbro 255lph pump or something similar. You "can" run 10psi boost on the stock pump, but I wouldn't recommend it for long periods of time as 20 year old pumps aren't always pumping adequate pressure and a fuel pump failure at wide open throttle at 10psi is bad, very bad... Being quite new to turbos, I suggest you take a step back and do some research about what it is you're toying with before you blow it up. Print this out and read it, http://www.redz31.com/turbofaq/turbo.faq.htm and when you're done read it again and then again. Feel free to ask any other questions, but do becareful. This is where people go wrong, you need to understand the system as a whole to fully grasp how turbo cars work. You cant just turn up the boost and go nuts...
I turn it down by adjusting the "manual boost controller"? I haven't touched the car since I brought it, and have been running it like that for some time. So I will turn it down, I am not sure of what the previous owner had done to it. The only thing I can see is the manual boost controller. Im not sure if the rest of it is stock or what, I don't know the point of putting the controller on with stock everything else.
Yeah this is common, you've bought the car from a weekend warrior who knows how to turn the boost up but nothing else. I see this all the time, you're not alone dont worry. Seeing as you bought the car like that, you're off the hook! lol You wouldn't believe some of the dodgy shit people do with turbo cars, this is how engines blow up due to no fault of their own. So yes, turn the boost down for now or better yet while you check the car out you could simple remove it and just join the vacuum lines together or just turn it down to 6-7psi. Your car will feel slow after running at 10psi, but trust me it's best for the moment. Have you given the car a service/tune since you got it? If not, do it. Replace the stock airbox with a K&N filter (part number RE-0810) replace the spark leads with new ones, do the spark plugs while you're there (part number NGK BCPR6E-11) also do the distributor cap and rotor, goto Nissan for these. Along with that, oil filter and fuel filter will be needed. Inspect the condition of your fuel injectors, look AND SMELL for leaks. Alot of Z31's are neglected, especially by idiot previous owners who dunno wtf they're doing so go over the fuel system completely. Look for any cracked/split injector hoses, aswell as the lines to/from the fuel pressure regulator (round metal thing at the front of the fuel rail). Boost leaks, here's a vacuum line diagram that will help alot! http://www.thumper300zx.com/z31/vacuum/vacuum.htm Buy yourself a Haynes manual and read it, read all of it! Great dunny reading material and a brilliant way to learn about your car. That's all I can think of right now, just make sure EVERYTHING is 100% before you turn the boost up. These cars can run 10psi unintercooled all day no problems, aslong as everything is good which is often not the case. So just go over it all, upgrade your fuel pump which is cheap like $100 and there's a write up here on how to do it aswell. Once your car is performing perfectly in stock form, AND you have upgraded the exhaust to 3" all the way if it hasn't been done already then you're good to go for 10psi unintercooled safely. It's not a good idea to run 10psi on the stock exhaust, it's just too restrictive. You will see a big improvement with a full 3" mandrel bent system. Definately the first mod you should do on a Z31...
Wow thanks so much for all the helpfull information, haha off to turn it down right now, I might just even connect it back together (I have a feeling it was that shit with 10psi, that it might run better at 6-7) I'll have a read through those links and let you know if I have any other questions, but thanks for the fast reply too.
No probs, these cars are VERY reliable and VERY quick if you do the right things and look after it. I've never had a single engine problem out of three Z31s, and I dont exactly drive like an old lady! lol The VG30ET loves to be thrashed, aslong as it has to the fuel to feed it and everything else is up to scratch you wont have a problem. If the factory pov is still in place, you cant run higher than 8psi without it bleeding off the boost. See the blue thing at the front of the plenum? Yours wont be blue as thats an aftermarket one, it will be silver/brass in colour. If that's already plugged up then it'll be a boost leak...
Ok mine looks nothing like that... I will post some pics of it, since I don't want to do any damage to the thing, and maybe you could notice somethings. Exscuse the quality, don't have anything but my nokia 6120, and its nightish. Just don't laugh at it too much, lol.
Just as I suspected, the pov is still in place. The guy you got this car from was a real knob head... That is the pov, the round metal piece on the front side of the plenum. It's impossible to increase the boost and have it hold steady with that in place, it simply wont let you. When it's time that'll need to be removed, and a bov installed on the charge pipe just before the throttle body. Missing wire, that's the fuel temp sensor. Dont worry about that, it's mainly for REALLY cold starts like freezing temps experienced in the USA. It doesn't do anything for performance so forget about that. Very common to be broken off... Missing connection, is your car a manual? If so that is the spare connector for the TPS (throttle position sensor) I believe going by that pic and you dont need it. If you have an auto then I would say the wrong TPS is installed. That missing vacuum line is to your carbon canister, you'll want to replace this. Use the thumper300zx.com link I pasted above to fix that. Other than that, going by those photos everything else looks like it's where it should be. That engine bay isn't too bad really, I've seen some real shockers before.
Cool thanks for all that, I will get into upgrading the exhaust and fuel system, I have replaced the thermostat housing and the distributor cap, also the rotor. I will change the fuel lines, and look at changing the POV to a BOV, how much are those going for nowdays? Thanks for all your help 300zxt
A good bov will fetch around $200-$300 or so, GFB are good. I would personally recommend the Mach 1 because it has the plumb back fitting to make it "legal" and silent if the situation arises. Open atmosphere bovs are illegal in all states I believe, although rarely enforced it's still very nice to be able to make legal if need be. And no problems with the help, there's not alot of Z31's around these days so I do my best to keep them on the road thrashing those around it! Hehe!
Wow so I guess I will be looking at about $5-600, thats fine, I will be buying a z32 around the end of jan, but I will keep my z31 as well, the performance it gives for $3500 that I payed for it is crazy. Thanks for all those links too.
Haha, yeah I meant for the upgrading the fuel system and that. I like the site, makes me want them all, haha. --Added:-- Will the BOV from GFB just mount on over the POV? or do I have to install them off one of the lines?
Lol, come and have a look at MY Z31. I send out a message to all Z31 owners. If you think your Z31 is crap, come check out mine.... It'll make you feel better and why not make people feel better
Yours is no worse off as I know the problems with your car, and they are not serious! Nah you block that off, the bov is installed on the charge pipe... I wouldnt go with purple though!
You haven't seen the engine bay tho I may sound like a whining bitch......but I only do because its my way of dealing with not being able to fix the b****...... at this point in time.... Btw zxt, I would love to see more pics of ur ride!
Oh wow thanks for that 300zxt thats an awesome help, now I know exactly how to install it (I might try red). Haha good one NewbieZ31, hows your z31? Is it running, or your building it? and yeah i'd like to see your ride 300zxt.
Oh yeah, its running....barely haha. Injectors leaking (bought a extinguisher btw zxt), paint faded, CHTS busted, interior falling apart, smashed up rear end (a little bit.... lol zxt).....and more i cant think of.
Aww man that sucks, if it makes you feel any better I just found that one of my fuel lines leaking a bit, never noticed that before...
Fix it asap, 20 year old rubber strangely enough doesn't work too well! lol This is why running 10psi is a bad idea off the bat, especially with a fuel leak. That's how you lean out and blow it all to shit or have your car burn to the ground simply because you were stupid! lol My Baby, My Beast, I have another in storage aswell with alot more modifications than the above two cars, but that's a secret for now! lol Not really, just nothing to update until I get it out of storage.
