cal-x

Neither my mechanics or myself has got any ideas... pls help!

I have a 96 4th series 16bit ecu, stock turbos.

Every morning's first start up is fine. Normal boost, normal start, normal drive, normal revving. Until i turn it off to start again (say i go get gas, or turn off my vehicle to get a soda) , then it wont go into boost.
Doesn't matter how long i drive for upon my first start, as long as i dont turn it off then restart the car, it runs fine.
BUT! As soon as i turn it off, restart the car, then i have no boost. When i try to force it to rev up quickly, once vacuum reaches zero, it would keep backfiring until i let off the gas.

Here's the REALLY weird part. I let it park for few hours, close or at complete cool engine, everything is fine! ... until i turn it off, then restart the car. And the problem goes again.

Mahjik

iTrader: (1)

If you have the OEM ECU, start by checking for codes:

https://www.rx7club.com/3rd-gen-arch...ut-ecl-238994/

96fd3s

a 96 car with 16bit ECU is a series 7, not a series 4.
anyway sounds to me like a solenoid is malfunctioning while warm..
its not uncommon for them to act fine while cold ,then stick or stop working when warm.

cal-x

Thanks very much to both of you!

Yes, i have OEM ecu, and maybe its different series for different years? I have a rhd.

Which solenoid are we talking about?
Do you have a picture of it?

Also, is this solenoid same through l the years?

Mahjik

iTrader: (1)

He's suggesting a boost solenoid failing once it's warm. This can definitely happen, but typically you don't hear the car backfiring when this happens; you simply don't have boost. This sounds like something else is going on, possibly putting the car into limp mode which is why I suggest you check to see if you have any codes stored.

cal-x

Finally got a chance to have a ecu code read. It shows code 45 charge control solenoid valve.

On a 4th serie engine (jdm 96'), where is that located?

rollcoal

iTrader: (5)

i can sell one to you for 40$ shipped
.. you have to take off your upper intake manifold (uim) an its under there.. but theres a big mess under there so you're gonna have to do some searching.. type in "twin turbo vac lines" and usually they have some diagrams and label which solenoid is what

rollcoal

iTrader: (5)

https://www.rx7club.com/3rd-generati...-turbo-749702/

look in those diagrams on the first page

R-R-Rx7

iTrader: (24)

Last post completely useless

Does it hesitate revving after 3k rpm while in gear and wot?

cal-x

As i said... perfect power and boost at first start up... no matter how long i drive it for.

Only issue is when 2nd start up, couldnt go into boost at all.

R-R-Rx7

iTrader: (24)

So let me rephrase.
When it does it.. does it hesitate to go over 3k rpm at wot?

cal-x

Well, its not a hesitation.
No matter what rpm, i get no boost at all. When i try to punch it hard , i get backfire (popping sound from exhaust ) until i let of the throttle.

So it doesnt happen at a certain rpm.. it happens through all rpm.

Mahjik

iTrader: (1)

Turbocharger Overview

If the Charge Control isn't working properly, it will vent all of the primary turbo flow over to the secondary, which is venting out through the Charge Relief under 4200 rpms. That should effectively provide no boost. I would start with checking/fixing that solenoid first and then re-evaluate your symptoms.

R-R-Rx7

iTrader: (24)

This is a common problem with the black box.. one of the valves is acting up. If i remember correctly is the top left one.

rollcoal

iTrader: (5)

why do you think i posted the link to the diagram.. how was my comment useless? the diagram shows where the valve is... at least gives a general idea

R-R-Rx7

iTrader: (24)

Because this is a pre 96 turbo solenoid system. Nothing in common with the 96+. The black box contains all the valves.. the pre 96 system are independent valves and separated

rollcoal

iTrader: (5)

oh whoops didn't even read 96.. my bad