It's gotta be pre-turbo...UP maybe.

There is no way your boost would be limited by any sort of leak post-turbo. People take off their exhausts to gain better performance at the track (on a turbo car). Like I said, it either has to be a manifold problem or wastegate problem... or just a buggy-eye problem.

Check your wastegate - it could be malfunctioning and opening early. You could also check your boost controller itself - that could be off.

I've had my turbo/manifold gasket become vapor (it boke apart and nothing was left) before without having it effect my boost.

Wouldn't a turbo/manifold gasket be pre turbo? ...and it didn't effect boost? :?:

Not totally true. If the wastegate efficiency were dramatically increased, as soon as the ECU opens the wastegate just a tiny bit, it might drop the boost dramatically, making the wastegate unable to properly regulate the boost. I'm not saying that's likely or my issue, but it is possible.

Also, taking off my exhaust would certainly *not* help my performance, unless melting wiring and setting the car on fire w/ 1000F exhaust gases blowing directly into the firewall/wiring harness is the new JDM way to go faster. :P

My boost controller is the stock ECU. I highly doubt the electrons in the ECU are broken... especially when my issues appeared just as my exhaust leak got louder.

The most likely culprit is that my header/up-pipe gasket has failed. I've had that happen before, and the result was the same loud exhaust and limited boost. Nothing that a quick trip to Litha and 10 minutes under the car won't fix.

I'm 99% this won't help, but I do have a Cu-Seal Copper gasket for the DP to turbo joint if you need it and it would even fit your car.

I don't know what I need yet... chances are a new stock gasket (or simply tightening things up) is all I need. I think my leak is simply due to the huge heat cycles my car went through at the Friday test day...

I was seeing 1900F EGTs because I had my skid plate installed and it was retaining too much heat from the headers. Getting everything that hot, then letting it cool, and repeating like 10 times over the weekend probably just loosened up the bolts in my exhaust system.

That's hot.

Then that would be a problem at the wastegate itself.

I just dont see how an exhaust leak AFTER the turbo would effect boost like its doing in your case. Why dont you slap a boost controller on there?

If you take it to Lithia and they fix your leak, let me know. I'm interested if that will cure your boost problem.

Classic! Have you seen Scott's engine area?

The wastegate is built into the turbo and controlled by the ECU. If the map on the ECU is tuned with an expected backpressure due the exhaust, and that changes, then there could potentially be boost control issues that have nothing to do w/ the wastegate and everything to do with the messed up exhaust after the turbo.

I don't slap a boost controller on my car because I'd rather not blow up another motor. I figure the ECU and EBC already built into the car were engineered far better than a spring and ball bearing. Though, if you'd like one, I've got a TurboXS MBC sitting in a drawer in my garage.

Lithia won't ever touch my car. Not just because they wouldn't have a clue what to do after popping the hood, but because I barely trust professional race car builders w/ it, let alone some yahoo techs. The only reason I'd go to Lithia is to buy a new gasket that I'd install myself, in my garage... it takes like 10 minutes.

How much you want for the MBC?

Um... twenty bucks?

No shit on that one! My buddy and his friend who both work down there came here yesterday, (the yellow MR2 and the red L with the green door from auto-x) and they were looking at the Z racecar I've got sitting here. They both turned green in the face looking at that thing! Those guys are TERRIFIED by aftermarket goodies. Something as modified as your car would make them water their pants!

Thanks for the offer, but I already have a decent electronic boost controller.

What kind of sensor does the car have to measure pressure in the exhaust system?

A pressure sensor. ;) :P

No really, the car uses both Mass Airflow and Manifold Absolute Pressure sensors to determine the load/pressure on the car. I assume the MAP sensor works fine as input for the ECU to allow it to properly control the turbo's wastegate.

Also, I figured out the leak. The flex joint on my up-pipe has a hole in it:



While I was under there, I also noticed that my timing belt cover didn't quite like the heat from my headers:



I ordered a Bosal uppipe, since it's got the heatshields on it... hopefully it's not a total piece of junk. And depending on how hard the timing cover replacement job is, I'm either gonna hit up Lithia for a new one and do the install myself, or haul the car back down to Gruppe-S for a repair.

Now the question is, what caused the up-pipe flex joint to fail? Was it debris? I've got a skid plate I was hoping to use to protect the underside of the car, but I think it was the skid plate reflecting all the heat from the headers that melted the timing cover. At least taking the skid plate off was good for lowering my EGT's by 200F... so it's certainly having a major effect on the under-hood temps. I wonder if there's a way to use the skid plate with some ventilation to keep things cool... 'course if the problem is radiant heat, no amount of ventilation is really going to make a big difference. :(

Flex joints will fail.

Very good point. :(

FTW? :P

That does suck though Scott. The one UP install I've done (on my car) was time consuming.

Yeah, thats what I've always heard. Maybe 2-3 years out of a flex joint sometimes.

If I recall correctly, one half of the timing cover is hard to replace, and the other is pretty easy, but I can't remember which is which... Helps a lot huh? :lol:

Maybe having some louvers pressed into the skid plate to help direct some air in there, while still providing impact protection would help. Even if radiant heat is the problem, the cool(er) air being forced in while the car's in motion would likely still drop the temps some. (?)

Yeah, I was thinking about the louvers too.......there's enough street rod shops that someone should be able to bust it out pretty easily, but that' snormally in thin sheetmetal, not 3/16" aluminum plate.

Plus, having the louvers facing forward would be better for cooling, but will also scoop up water and catch other stuff as well...


Scott, you need a 1/2" holesaw. Speedholes FTW!

Yeah, I thought of the catching water and crap. Kinda shoots it in the foot. I wasn't sure how thick that skid plate was either, and that's def. an issue! I dunno, just throwing ideas out there!

I was thinking about some brake-duct like ducts sending air over the headers... but I think I'm probably just going to run w/o the skid plate. It's heavy and hot... and there's not that much debris on the track, unless I go off. :lol:

If anyone wants a nice Primitive skid plate, let me know! It's only been used for about 20 track miles. :lol:

As far as the timing cover. The outter cover is a breeze to install. The inner cover requires taking off the timing belt and cam gears. :( I was just at Lithia ordering the parts. I'm gonna try to do the repair myself, since I can't get down to Gruppe-S easily and since they can't get me in until the end of next week, which will cut it too close to the autocross. The parts aren't expensive, unless of course I botch the timing belt install... in which case it will be extremely expensive. :lol:

Hey Cory, you got time to lend me some expertice? :)

When are you doing it dude? I can probably swing by and give a hand! Give me a call if you need!

Parts should be in on Monday... so some evening next week... like Monday or Tuesday night, hopefully.