bnr twins seqential
power fc
exhaust
meth

I just put 1200k miles on my rebuilt engine and ive started to get into boost. at 5psi it pulls nice and smooth.

If i give it a little more gas the boost goes down to 2psi and i hear the turbos spool down.

its consistent but i only tried it a few times for a very short period of time.

the bnr twins are as new as the engine.

 

you have a major boost leak , check your intercooler system , the wastegate wont even open until 7 psi based on its spring . so only real explenation is a boost leak when it gets to 5 psi something loosens and leaks all the air out .

 

I drove the car again and started feeling it out and easing into it. if i give it just enough gas the boost will bounce from 5 to 0psi every second back and forth.

I tried almost full gas and it boosted to 8psi no problem and pulled like crazy. these twins seem loudest at atmospheric because they don't hiss above 5psi (im sure you knew that).

I guess there's not a leak if i can hit 8psi. so could it be some sequential vacuum madness?

 

when it jumps from 5 to 0 psi there's barely a change in acceleration. i drove it full throttle and it maxes at 8psi (instead of 10 i guess thats the power fc). i'm beginning to think its normal

 

If you had a Datalogit you could post logs so we can get a better idea of what it's doing

 

ok what kind of boost gauge , like ARGHX said if you had a datalogit and could link the logs

what are your intake air temps .

to remove the doubt that its your boost gauge look at the boost gauge on the PFC ssee if it happwns hte same .

Also after 4k rpms if you are on light throttle it will go from 5 psi to 0 as the secondary turbo opens since it requires more exhaust to spool both then it did the primary to 5psi .

if you are in one of the longer gears and in the RPM range where only the primary turbo is boosting 5 psi wont really be alot of power you also have to remember the BNR's take a bit longer to spool .

 

This is probably what's is happening i haven't driven the car in a year and it had stock two twins then.

Im getting a datalogit as soon as i can it's on my list and it's long.

 

I have similar trouble:

I have the fd3s with mid streed ported 13b-rew 2000 km after rebuild.
Power FC (no datalogit)
Also it's installed tuned dp and all exhaust 76mm with HKS silencer.

All other parts are stock.

Yesterday I've had first boost after rebuild.
I noticed that car have low boost (0.12-0.17) at the 1st gear (I gave 5000 rpm max), later there is two scenarios on the 2nd gear: 1)sometimes boost at 3000-3700 rpm is still low (0.2-0.3) , later it's increase up to 0.77-0.84 (4000-5000 rpm) OR 2)sometimes it's still low - 0.2-0.3 (4000-5000 rpm)

on the 3rd gear usually boost 0.7-0.8 (4000-5000 rpm)
on the 4th and 5th gears boost is the same - 0.7 (4000-5000rpm).

Also I've noticed that when car is running and not driving (stopped , neutral gear) when I push accelerator rpms are increasing slower from 0 to 2000rpm and engine works strange, then rpms increasing more faster (from 2000 to 4000-5000 rpm).

Also I've heard strange noise from the hood space (like airflow don't goes right).


We are suspecting some solenoid valves in this trouble, but there are no error codes displayed.
Or may be I should reset a Power FC ?

 

Charge relief valve not operatibg properly?

 

May be.
We've checked resistance of every valve, turbo control was lower than others , cleared connectors anв resistance become well.

But car is still hesitating

 

it's really make me upset

 

i've also noticed this. i haven't driven the car in so long i thought it was normal but its exactly like you described. a lot of lag from from the pedal to the revs at low rpm.

my problem seems to be effecting the primary turbo only. if im over 4k rpm and at full throttle i hit 7 to 8 psi every time.

 

I have the same with one difference - I have no boost at the 1st gear, time to time at the 2nd , other gears with boost after 4000rpm

 

"The Turbo Control Solenoid / Actuator is one of the more complicated actuators as it requires both vacuum and pressure to operate properly. This actuator is controlled by two solenoids, (both are wired together to the one ECU output) one solenoid applies pressure to one side of the actuator and the other applies vacuum to the other side of the actuator. With pressure on one side and a vacuum on the other side of the actuator, the speed of the actuator is improved. A typical problem is loss of Secondary boost in 1st or 2nd gear at 4,500 RPM, but reliable operation in other gears. This points to one side of the Turbo Control Actuator not getting it's pressure/vacuum, so it will still operate but not quickly enough."

Troubleshooting

 

we have the exact same condition and mods except that i have meth and bnrs. my power fc was installed during the rebuild process was yours? could it be the pfc?

full throttle under 4krpm boosts to 8psi then instantly to 3psi where it remains until it seemingly instantly boost to 8psi kicking me in the back.

in 5th i can get it to boost to 8psi under 4k if i'm not trying. i run out of road before i can get to 4k rpm.

so my boost pattern is 3-3-8 except the first 3 tries to be an 8 and fails (which behaves like a boost leak).

i really just need a datalogit i know.

 

I had the same problem before rebuild, so I don't think the trouble in the Power FC.
I suppose that problem really in the The Turbo Control Solenoid / Actuator, so I'll check it first

 

Check those Turbo control solenoids, they're known to go out.

If you do find out that it was the problem. I have a solution. My custom solenoid kit.

However I am no longer making these anymore. But there is one last kit that's brand new for sale that a member bought from me not too long ago before I decided not to produce these anymore.

The link can be found HERE.

-AzEKnightz

 

that's a rich fix. damn priorities

 

I found this funny.

The first question came in mind, "why do you own a rx7?"

It's a money pit and we all agreed.

Sarcasm aside, if the cost of the kit was expensive, try giving Fritz a PM. He can probably hook u up with some used solenoids for a lot less.

-AzEKnightz

 

Who is Fritz ?

As I know some people use maс solenoids (about $35 per one)

 

Fritz is a member user name.

He sells alot of used parts. He's well know here on the forum. Search him up if you need any used parts. He's quick with communication and provide excellent services.

-AzEKnightz

 

Do you solve the problem?

We've checked it all, but can't find anything work wrong ...

 

haven't looked at it yet. I'm going to have my wankel tech look at it next week.

 

Today I've ride again - the problem is still there.
Low (almost none) boost at the 1st and at the 2nd, and good boost at other gears.
Also I noticed that when I've stopped pushing accelerate pedal a sound like "foooow"appears from the hood space.

We've checked all of acuators and solenoid valves. All are in the working condition.
It's hard to check vacuum lines cause in my car vacuum lines (JDM '99 spec) differ from all I've found (93-95).

Or may be the problem may be in bad spark plugs?

 

Mine used to 'spool down' somewhat and I always thought to a degree it was normal

On twins seq mine would go from 5psi and then drop off as rpms increased during partial throttle. If I let off gas after 4500 in partial id hear whoosh sound which was secondary turbo bleeding off.

Wot, rock solid 10-8-10 or 8-5-8 depending on boost settings.