Arcayne

Had a wee search and didn't seem a problem that matched mine.

My car stock 93 has been in at a good Garage for about a week now. I should hopefully be picking it up today, when I was talking to the guy he said they cured my main boost leaks and got me a solid 10 psi on the primary and secondary, but haven't been able to cure my transition problem.
The boost tends to drop away on transition but goes back up to 10psi, sometimes less, on the second. If you don't get 10psi you can lift off a little on the secondary and floor it again you get a solid 10psi. All of the hosing seems to be okay and they have replaced 1 or 2 split hoses. We reckon it could be down to the solenoid rack. Any help would be greatly appreciated.


Cheers
Bob

Mahjik

iTrader: (1)

What exactly is your boost pattern?

http://www.scuderiaciriani.com/rx7/boost_test.html

Herblenny

iTrader: (13)

during transition, you would get a dip.. 8lb is normal.. you shouldn't get 0.. if so, I would go thru some hose checking.. but I think you are ok.. since you are getting 10lb on both primary and secondary..

911GT2

Sounds exactly like what would happen with a malfunctioning TCA (turbo control actuator) It lets exhaust gas vent to the secondary turbo to pre-spool it, so the dip at transition isn't so bad. If the vacuum side of it isn't functioning properly, it will sometimes not pre-spool, but taking your foot off the gas (i.e., creating vacuum) and then flooring it will result in 10 psi on the secondary.

Check here for fixes for it. http://www.autosportracetech.com/RX-...leshooting.htm

If it's your TCA thats broken, I have one to sell you. Most of the time it's one of the check valves or vacuum chamber hoses thats broken, and not the TCA itself.

Arcayne

Having driven the car back from the garage tonight.

10 psi on primary
Dies going into transition doesn't come back on.
They glued the check valve to the Y-pipe from the pressure chamber that had split. One of the clips holding the crossover pipe had slid off. That sorted. The hoses in the rats-nest look okay. relaced 1 or 2 that had split. Checked the solenoid rack with a multimeter they all checked out okay, don't know if this means anything. Plug for the FPS has some damage but is still a good fit.
I don't know if they reset the stock ECU. Would the ecu prevent transition if there had been a problem?

The bit that confuses me is that the primary turbo doesn't put in any effort during or after transition. I thought that it would still generate some pressure.

On the up side I did get the UIM polished while it was off.

Mahjik

iTrader: (1)

My money would be on the check valve that they glue which goes to the pressure chamber. Try replacing that check valve. It's about $20 from Malloy Mazda 1-888-533-3400, Talk to Ray Crowe.

Arcayne

Mahjik thanks !
I think I am going to bite the bullet and do a hose job, Will probably do all the valves while I am in there.

Oh I am in Scotland so I might not phone Malloy.

Herblenny

iTrader: (13)

FYI.. you could also use check valves from T2.. since they are more available and cheaper at the junk yard..

Arcayne

Well the quest goes on. I am still getting 10 on primary then falls away to 0 during transition, and doesn't rcover. I have checked all of the hoses and valves and they are operating in the correct direction. The charge control acuator was a bit sticky so I have oiled it.
While driving if I am idling down I can here what sounds like a ratcheting noise.
Any thoughts?

Arcayne

I can't get under the car to have a look for the ratcheting sound. Any thoughts?

SleepR1

Replace the vacuum chamber check valve. It's also green and black. The one you repaired was the pressure chamber check valve (responsible for low primary boost problems). Also check for oil in your vacuum chamber. If it's full of oil, you will have no vacuum supply for the TCA solenoids (there are two, one in the rack, and the other by the ACV), and the TCA itself.