MR2 Turbo Gen 3 whistle and over fueling

 
Okay after my last track event I've developed some more issues that are driving me nuts. The first is a whistle that comes on under boost. It sounds like its comming from the intercooler but I can't find any holes. Car still makes full boost without issue. I tried my own pressure test on it and it didn't seem to have any holes. Could it be a small hole in the exhaust instead? Anyone had a small hole in the exhaust before, does it make a whistle sound when loaded?
 
The other bigger issue is the car is running very rich at start up and idle. I have done a diagnostic check and there are no error codes. Being a gen 3 I'm led to believe there is no cold start injector. The car will shut off at idle sometimes unless I feather the throttle. If I drive it off boost it seems to be able to idle when I lift off the accelerator but if I floor it and let it boost through the gears, when I lift and stop the car wont idle, it will just stall unless I feather the throttle. It seems like its running rich at partcial throttle also and even under boost as I can hear extra fuel backfiring in the exhaust but the car drives with the same power it always had so its not like its dropping power under acceleration, just a bit too miuch fuel. What i've checked so far is the ecu for error codes which came back all clear. The spark plugs aren't going black if I turn the car off after driving. They are all comming out brown, so I don't think an injector is stuck open as I would expect that cylinders spark plug to be black. The ignition is all brand new, no misfires at full boost. All I can think is maybe the O2 sensor is bad but with no fault code on the ecu? Also the fact it idle sometimes but not after full boost is odd. Anyone got any ideas?

It has a mines chipped ECU so basically standard at start etc....
I have reset the ECU just recently as the battery died and I had to fit a new one. As the car isn't street registered I haven't driven it more then maybe 1km as it has that idle issue.

I've checked the vacuum lines and they all seem good. If there is a vacuum leak ater the MAP sensor however it should technically run lean not rich as it will drawn in air after the sensor. That's why I'm leaning towards the O2 sensor as it looks most liekly to occur during closed loop but Toyota say if there is a problem with the O2 sensor it ALWAYS will be picked up by the ecu and register a fault code. It's very odd becuase it does start idling properly but if I let it boost up immediately after it wont idle. Apparently the O2 sesor doesn't kick in till it is warm which doesn't explain the over fueling during start up either.

Sounds vac related to me. Check for small splits on the ends. It's been a common problem for me over the years.

Just as an update I reckon I know what the issue is. I reckon I have an exhaust leak from the dump pipe somewhere. This would explain the whistle under boost and also at idle it will get extra oxegon into the exhaust system causing the idle to run rich from the o2 sensor.......only problem is I haven't been able to spot where the leak is yet.

Not sure what exhaust it is. Looks like a custom job. I'll take a look around this wekeend and report back but I'm fairly confident its a hole soemwhere in the exhaust near the O2 sensor. I've never had a hole int he exuast so I didn't know if it makes a whistle sound as it sounds a lot liek an intake leak. I read on Suby forums though that when they get holes in the up pipe to the turbo it makes a whistle sound liek the turbo spooling.

Yeah I'll be looking for the carbon stains if its leaving any. Otherwise I'll try a few other tricks to locate it. Worste case it will go on a smoke machine. O2 sensors are very sensitive so if the leak is anywhere near it will detect extra oxegon. It will keep adding more fuel till it doesn't detect any excess but this will never happen, thus runs very rich. Anyway finding this leak will not be fun. Both exhuast brackets have snapped after the last race so need it rewelded. If those broke i'm not suprised there could be a crack somewhere else.

I'm fairly confident in the exhaust leak so i'll sort it out thanks anway. Smoke testers make for the easiest diagnostic for vacume and exhaust leaks. Just don't want to have to take it to a shop with a smoke machine if I don't have to.
On a modified turbo you have a lot of noises going on. Also exhausts will drawn in air on the pulse, hence why a hole will cause problems especially near the the sensor. When tuning EFI systems on previous race cars even we wouldn't use the O2 sesors you can hook into the back of the exhaust as we found them inacurate. Instead would use a drilled bung much like a factory O2 sensor bung to take the readings and that wasn't just for idle, thats for full dyno tuning runs. Thanks anyway, I'm 90% sure I'll be able to find a leak and get the car ready for its next track event.