Hi guys, so my 1989 FC Turbo2 recently developed a bunch of problems in one day after a short run . It's a long story so I guess I will try to make it as easy as possible for you to read.

Prior to the incident when car was still running fine,
Engine was rebuilt 25000km ago.
Car starts with 2 cranks no matter what temperature, cold start, hot start.
Maximum boost attained is 1.16Kg/cm^2, about 16psi.
Normally would boost to 0.61Kg/cm^2 (8.7psi) when accelerating normally on the streets.
Idles around 800-850rpm when warm.

What happened:
Was running on 4th gear 6-7000 rpm at full boost(16psi) and then shifted into 5th and continued to accelerate until I heard something hit the underbody of the car. It didn't sound like something big but it did clunk a few times.
I was worried so I slowed down my pace.
The car started to have weird idle noises and had rough idle.
The car would not boost while in second gear, it felt like an NA car.
The car would start in a breeze when cold, much like before the incident. But would have a hard time cranking when it is warm engine.
The car would idle low after it slows down from boost.
The car now only achieves 0.91kg/cm^2 (13psi) as full boost.
The car does not boost or very little when accelerating normally on the streets.
The car vibrates and shakes aggressively when stopped and idling.

I brought it to a mechanic friend(not rotary specialist) to have somethings checked,
He said that the bolts on the down pipe are all loose
compression test shows 120psi for the first housing and 110psi for the second.
The first spark plug burns cleanly, while the second has some black carbon building up.
I speculated that there might be vacuum leak, but he said he cannot hear any hissing.
The car still runs, does not stall but hard to crank when engine is still warm, vibrates violently after startup , and does not reach its original boost level.

So a large number of symptoms showed up after a short aggressive run. It pretty much turned a healthy, aggressive and reliable track car into a crippled pony.
So if you have any idea what is wrong, or if you can suggest what else I should check for please let me know. I love this car and wish to have it running healthy and smooth.
Thank you very much.

 

Is this car stock and you are boosting 16psi on a stock turbo?

 

Stock engine, JDM turbo. ECU remapped by Rtek, ported wastegates.
The car was boosting 16psi when I bought it and I couldn't figure how to lower to boost on the AVC-R.

 

Avcr is not a good tuning tool

 

If its a stock Turbo 16psi will blow it up, just because its jdm doesn't mean it can handle 16 psi.

That loud clunk may have been your turbo, never take a stock turbo above 12 psi, it's not efficient after 12psi.

Also if your fuel system/ecu is stock then you shouldn't be running any more then 9psi , i know you have the rtek ecu but even with an rtek 1.7 you'll still need an upgraded fuel pump and 720cc secondary injectors to run 12 psi nevermind 16psi.


Rotary >Pistons

 

So the blown turbo is causing the hot start issues and the rough idle? The turbo is still boosting strong right now, just not as much as before.
Thanks.

 

A blown turbo that throws shrapnel under the car is not going to make 12 psi. I know you did a compression test, but they are a bit different for rotaries. You need to check for 3 even pulses per rotor. The single max number can be misleading. Here is more info on compression testing. Is My Engine Blown?

If that tests good, start checking for vacuum/boost leak that would cause your starting and idle issues.

As stated before, 16 psi on a stock turbo is a very bad idea for turbo life and creates dangerously high intake temps. A modified one may be alright, but it's impossible to know what is safe without knowing what is in there. If you can't figure out how to lower the boost using the AVC-R, take it out. There is no danger to running lower boost....except boredome.

 

Thanks for the input guys. Just got it checked by a rotary specialist. 90-20-20 compression on rear housing. Turned back down to stock boost. 16psi was fun while it lasted though.
Thanks everyone.

 

That sucks, I plan on running my car as conservatively as I can until I have proper mods for higher boost.

Hope you can get it back to running right, sounds like the rear needs new apex seals.

Rotary >Pistons