Boost problems with FC3S

[Iwan]

Hello,

well, I'm not only working on my FD. I have also a Problem with FC3S.

The car was at Mazda dealer for engin rebuild. After that, the car was not running any more.....

I have checked the engine, and build everything together. Now the car is running, but with a smal problem. There is not this "wow" of boost any more. By doing the engine, I replaced the turbo charger (the car has over 140.000km on it) couse the charger has had a deffectiv turbowheel. I have also removed both catalytic converter. Now the car is running well, but depending on the "new" car, there is not so much boost on it any more.
By looking at the boost gauge, the pointer point to about 3 mm befor the maximum. (+40 on display). I conclude, that there is enough of boost from turbo charger. But the boost as it was presented befor is not there any more.

I checked the trotel sensor, but it is OK and working well. Vakuum tubes are OK to. (checked them all)

Do you have an idea, what I should look after next?

Regards
Iwan

[alistair bridge]

hi iwan.

I helped a guy with his fc turbo 2. he had a similar problem. turns out the the c-clip had come off the wastegate actuator and it was no longer connected to the wastegate. it built high boost at high speeds but with the wastegate flapping about it took ages to build.

i doubt that this would be the case with you as you've just had a new turbo fitted. might be worth a check though. you can get at it from under the car if you bend the heat shield a little (lots).

the car definitely had a kick when the turbo got up to speed, 2.500-3000rpm.

cheers

alistair

[tsh]

If the gauge is getting towards +40 ish soon after 2500 rpm, then you're getting enough boost to the engine. Have you checked the hose from the intercooler on the left hand side? These fail quite often...

The other thing to check is the timing. Seems like I got mine wrong when I replaced my engine, somehow the timing marks don't line up any more, but it's running better!

You can reach the wastegate actuator frim above - if you can move the bar avout, it's probalby not attached at the other end!

Sean

[Iwan]

Hi Sean, hi Alistair,

I checked one of the end to the wastegate actuator just after turbo replacemant. I will check the other end today.

Intercooler was also checked as first. But without success.

Regards
Iwan

[Iwan]

back from garage.....

I have checked the other end and it is connected properly to the twin scroll turbocharger (tst) solenoid valve.
I checked the operation of the valve: folowing I could found out:
at idle speed there is about 1.4 V on the connector, wich is normal at idle speed. By going to about 3000RPM the voltage is incease to about 13V.
I have checked the function of the switching actuator. It works fine. Everything seems to be OK. By remooving the connector from the tst solenoid valve, the actuator moves back, putting the connector back, the actuator moves. By going to about 3000 RPM the actuator moves back.

I was also checked the ignition. I was not able to check ignition from the trailing ignition coil. Maybe thats the problem. Leading ignition coil works fine and ignition timings are correct.

But, the problem is still there.... I will check the trailing ignition coil, maybe thats the problem, but, I'm not shure.

Regards

Iwan

[j9fd3s]

if its got high mileage you might want to make sure the throttle plates are opening all the way, it uses a complex linkage and sometimes it doesnt work right

mike