supak111

iTrader: (3)

Looking to buy my second FD.

Seller claims the car only boosts 6psi (stock ecu, stock twins, aftermarket exhaust, stock besides that) and that the previous owner lowered the boost on purpose. Now as far as I know there is no way to lower the boost on the FD while running the stock ECU, stock twins, especially with aftermarket exhaust, am I correct?

I'm thinking there is something wrong with the engine, turbos, or its simply leaking boost.

Is it possible to lower boost on an FD, stock ecu, stock turbos?
If not and the FD is really only boosting 6psi, usual reasons for this?
MY MAIN QUESTION: Could it be because of bad seals?

Please any help, comments or suggestions much appreciated before I buy this thing. Thanks everyone Sam

jkstill

iTrader: (11)

Does the car have a PFC? Boost can be set down to 6 PSI IIRC.

Otherwise it sounds like the secondary turbo is not boosting.

Been awhile since I had twins, but I seem to recall that 6 was all you could get on the primary.

supak111

iTrader: (3)

so there could just be a problem with the valve that lets the boost in from the secondary turbo (vacuum/boost line)? Any idea if the problem could be the SEALS in the engine? I just don't wanna buy it if the engine needs a rebuild

thatjdmchic

im having similar problems with our new fd. i found this while researching. http://www.youtube.com/watch?v=OfAlNNPGtXo

jmm8904

iTrader: (19)

The stock twins can be put on low boost by looping the vacuum line to from the two turbo control solenoids. My FD was like that when I bought it because it had full exhaust and stock ECU and Petit Racing had put it like that so it would overboost and hurt the engine. I installed a PFC and reconnected the lines at was perfect. Check the turbo control solenoids that are right behind the alternator and see how they are hooked up.

LT8TurboII

iTrader: (2)

My car had a 7 7 7 boost pattern with the pills removed from WG and Pre-Control lines.

Montego

iTrader: (1)

It could be that his gauge is off or something is broken...

When the stock turbo system is working properly the lowest that the boost can be set is 7 psi. That is when the turbos are running off the wastegate spring. The stock turbos have a 7 lb spring which means that it opens at 7 psi when there is no pressure being applied to force the flapper shut. That is how you achieve boost control, basically by forcing the flap shut to a desired level. Thus you can only control boost levels above the wastegate spring not below it.

If you understand how a wastegate works then that should make perfect sense to you. If you don't get it read up on wastegates and you will see.

supraturbo1987

iTrader: (4)

6 is not all you can get on primary..factory boost was a 10-8-10 approx. (10 on primary turbo, dip during transition to 8, then back to 10 when secondary comes online)

Right now, my car is bone stock with no mods whatsoever and I am getting 12-13 on primary, then no transition and the boost dies off (secondary isn't even coming online) and I know it is a problem in combo of the vacuum lines, solenoids and check valves. You can tell the health of your motor pretty quickly by checking how much vacuum it is pulling with a boost gauge. At operating temp, 15-18mmHg is healthy.

Trev

RotaryEvolution

iTrader: (30)

look to see if the lines were replaced(pills missing from the actuator lines) or that they solenoids were bypassed as mentioned. otherwise it could simply have a boost leak. clogged cats will also lower boost.

there's plenty of ways for the boost to be lower than normal you chuckleheads.

supak111

iTrader: (3)

Lot of good info, love this forum. I will have to check some of that stuff quick when I go and look at the car. Glad to hear no one thinks its a motor problem.

DaleClark

iTrader: (55)

Most likely just the pills were removed as stated. It's actually a GOOD thing, that will keep the motor happy until you get everything just so.

Buddy of mine just bought an FD, didn't have the pills in the lines, 7 psi max boost.

Dale

jmadams74

The key is, make sure YOU understand the issue(s) as you are obviously buying from someone who either knows little or nothing about FD's, or is not fully forthcoming with the situation.

MazdaSpeedDan

iTrader: (4)

My money is on turbo pills, I was boosting 7psi with turbo pills you could drive a truck thru. Put new ones in there and was boosting at 10psi.

dgeesaman

iTrader: (7)

I'm short on time but I'll stab at your 3 questions without going through the rest of the thread. FWIW.

It is possible to reduce boost by connecting the boost lines directly to the wastegate actuators. No pills, no solenoids. The result will be wastegate pressure which is about 7-8 psi.

Boost of 6psi across the board might be due to the above setup if the boost gauge is slightly off. Otherwise assume it's a boost leak or other mechanical issue. A clogging cat or other exhuast restriction might also be depressing boost level.

Bad seals in the turbos does not cause low boost. If it's not due to a deliberate setting, it's in the control system not the turbos or engine. To check on the turbo seals you should look for oil (smoke) coming out the exhaust after boost or lots of oil blowing into the intake piping after the comrpessor.

David

limepro

iTrader: (2)

Pettit also did this to mine, different ecu hooked the lines up correctly and have fun.

95WhitePEP

What year is it?

The 93,94 had pills in the lines.

But the 95 had them built into the turbo housing themselves. So if you wanted to change out the pills in the 95 you would have to drill out the casing, then put the modified pills in the lines.

nismosilvia270r

iTrader: (5)

if it isnt the pills, double check that the proper plugs are connected to the precontrol and turbo control solenoids.

with them switched, my car ran 7 psi on primaries and secondaries either bled off or worked normal up to 7 psi. this depended on how fast the actuators were triggered by the wrong signals.

supak111

iTrader: (3)

Well then it sounds like the guy is telling the truth. He said the person he got it from purposely made it boost 6psi to keep the engine healthy since the ECU is stock. I'm guessing because the engine was over boosting since it does have a full exhaust.

I'll check to see if the pills are there. Exact location and what I'm looking for would help, anyone?

Also he said TWINs were upgraded with stock (guessing from a newer RX7 95and up probably). If he got some JDM twin would those have the pills in the turbo housing like mentioned above?