Car is 1988 S4 TurboII RX-7..

This problem happens on and off. First of all everything is stock except for a pod filter + removal of the vacpot on the 2nd set of secondary butterflies (for easing into full throttle).

Basically boosting and you take the revs over ~4000 as the rpm is shooting up you hear a clank noise sounding like a turbo i think, and it happens again and boost sorta stops for a second as it clanks.. its a pretty worrying sound heh.

I was thinking maybe there is shaft play and the blades are hitting the housings all of a sudden?

Any thoughts would be great, if I left out any necessary info let me know

Cheers

Paul.

 

Is it possible it is either the twin scroll flapper moving, or the wastegate flapper?

Vince

 

Hmm if your hearing that over the exhuast noise... are you sure your not pinging or dentenaing? How are your a/f ratios?

 

i had a sounds similiar to that and it was two of my turbo manifold studs had broken off in the block. when i'd get to high boost everynow and then the manifold would move and make a clunking sound. Boost didn't drop off a noticable amount really. Hope it's not your inducer hitting the housing?

 

You better hope the blades arent hitting the housing. If the metal shavings go into your engine's intake its bye bye FC

 

sounds like it could possibly detonation because the boost fluctuates while accelerating. does the car start to buck or hesitate?

 

It hesitates Really Slightly when it makes the noise -- its just a damn loud noise that sounds like something thats moving pretty fast coming into contact with something...

I don't think its pinging... altho not exactly sure what that sounds like... hmm.. come to think of it, I think it has mainly happened at night, so with headlights on... i could be wrong though.

I guess we really should pull everything off - already done the intake manifold + TB, next up turbo...

Not sure about the twin scroll flapper/waste gate flapper - where are these and why would they make this noise?

I'll try and get a recording but it's not a nice sound and it's hard to convince the driver to push it when he knows its gonna go clank! and that could be the end of the engine heh..

Cheers for the ideas I think best way to go is to pull the turbo + all and inspect everything.

Another thing - when boosting we can often smell fuel :P

Replaced all hoses to the fuel rails so its not them. Injector seals look fine too..

 

Did you replace the FPD when you replace the fuel lines?

 

We did not... I took a few photos perhaps you know what to look for?? It didn't appear crached, but I think there was a little gap on one side of the screw..

http://photos.pw.cx/albums/s4rx7tear...ardown_034.jpg

http://photos.pw.cx/albums/s4rx7tear...ardown_033.jpg

http://photos.pw.cx/albums/s4rx7tear...ardown_029.jpg

Still this doesnt expose the source of the clank noise... maybe its the turbo manifold loose? maybe..