boost leak maybe?

[eclipseb0y]

i recently got a 91 twin turbo z, well other than the power, the car is great, lets get to the problem...whats the average psi z's get cause i usually around 12 and when the car is really warmed up i get the full 14, then there are days i only get 6 then 2nd shift 12 or 14...do i have a boost leak? or does this sound normal for a z thats cold not to get the full 14 or do they average around 12? thanks for the help, no boost controller either.

[Broke_as_****]

Well first off your car is not stock because stock Zs run 9 psi. The previous owner probably put a set of boost jets in the car and left it at that. If you are refering to only getting 6 psi in first gear that may be because you aren't really in first gear long enough to make full boost. But then as you get to higher rpms and shift to second the turbos spool up to full.

If you look under the boost piping coming from the intercoolers to the throttle bodies you should see a little 1/4" rubber hose coming off the bottom. Those feed the wastegate acuators and control boost level. If you pull the hose off the pipe and look inside, if you see a little metal bit in there, that would be a boost jet. Might want to check the ECU to see if its an aftermarket piece as well.

To do that: Pull back the carpeting on the passenger side footwell in the car. You'll see a piece of wood, remove it. Under that is the ECU. Most aftermarket ECUs will have some sort of sticker on the outside that you can see. If not you'll have to remove the ECU from its little metal bracket and open it up. Don't bother removing the wiring harness off it, you can open the lid with it still attached. Just be very careful and make sure you aren't using a magnetized screw driver. Anyway, once you have the lid off the ECU you'll see two circuit boards a smaller one over a larger one. The larger one fits into the bottom. If all you see is the bottom of the larger one, take off the other sides lid. now you can remove the 4 screws holding in the small circuit board. Again, be very careful. In back corner of the larger board, that was under the smaller board, you'll see a large chip, about twice as long as it is wide. If there is no socket under the chip, its stock. Almost all aftermarket ECUs remove the stock chip from the board, put a socket in, then snap the performance chip into the socket.

Here is a better explaination with pictures to boot

[JCCR]

my z also pushes 12 to 14psi on my stock boost gauge but some one here said that is not acuarate. the gauge is only to see if your turbos are working or not.

[eclipseb0y]

when i bought the car it had a stillen exhaust system and a ecu computer chip upgrade...so it does have a ecu upgrade.

[Broke_as_****]

Part of just about every ECU kit I've ever seen is a set of boost jets so thats what that is. I would recommend you get a boost gauge and controller to more accurately control the boost in your car. All told it will probably run you about 150-250 dollars depending on what type of controller you want. The best that have many intergrated engine monitoring functions can run upwards of $600, but thats mostly overkill unless you are seriously tuning your car. Also I would recommend a JWT popcharger intake if your car doesn't already have one you are unaware of. That will give you your basic stage 3 Z, good for upwards of 340rwhp.

[eclipseb0y]

where do you guys shop for your z, cause i cant find crap for them? ebay barely has things too.

[longlivetheZ]

Check the sticky for parts.

Hey broke...you think maybe he's pinging in first gear and running into safety boost?

[Broke_as_****]

Ebay is a bad place to shop unless you are getting something like strut braces.

Look under the "Good Z resources" sticky. Just make sure your eyes don't get bigger than your wallet. My engine blew so I was going to get some down pipes while I put the new engine in. Now I'm going for ball bearing turbos, cams, $1900 exhaust manifolds made from exotic metal, dual intake, 555ccs...you get the idea.

EDIT:

Hey broke...you think maybe he's pinging in first gear and running into safety boost?

I don't think so. Safety boost is 3 psi anyway, maybe his ECU is different. But that might be the case, detonation can caused by stomping on the gas at low rpms. But really I think it just might be the stock lag from the turbos considering he says he only has an exhaust system on the car. By the time hes run hard enough to shift to second the turbos would be spooling harder. Only a more accurate boost gauge would give you any more insight I would think.

[eclipseb0y]

whats safety boost? and whats pingable lol im no mechanic, i just got the money to fix it.

[longlivetheZ]

Pinging...aka detonation or knock...is an uncontrolled flame front in your cylinders. Lammens terms...fuel/air mix burning when it's not supposed to. The Z32 has knock sensors that detect this and will take corrective actions...safety boost...retard the timing...etc.

I doubt this is your problem cuz safety boost doesn't revert back to stock boost until the ignition is cycled (turn the car off, then back on). It was ust a thought.

[Broke_as_****]

Pinging is when the gas in the cylinder explodes before the piston is in the right place. This can destroy an engine. A car with a turbo running alot of boost on low grade gas, hot intake air or a few other things can cause this to happen. So turbo cars are fitted with sensors to detect this and automatically open the wastegates so the turbos stop making pressure. When a TT Z is in "safety boost" mode, it won't make more than 3 psi of boost. Thats with a stock ECU anyway.

Anyway, if your stock boost gauge is correct and you are running 12 psi with spikes to 14 psi, I would strongly recommend getting a boost controller to more accurately control your boost levels. And tone them down a bit to 12-13 psi. Get much past that and the stock fuel injectors will start running lean at higher rpms, leading to pinging. Also, I suggest you go to www.twinturbo.net, go to their FAQs section and study up on your car.