Turbo Problem

[Cyto]

I'm pretty sure somewhere out there, there is a thread already about this, but I don't care...because its 8 am, and I haven't been to sleep.

My 88 Supurbo yes I combined them. Is not wanting to release the pressure built up by the turbo. Which means, I have tons of acceleration, but it's a horrible air/gas ratio, and the engine isn't wanting to spit out as much gas as the turbo is air. It's going to 8 psi and dumping, then itll repeat until i let the gas off. No I don't sit there and do that...I rarely get it up to 8, but I can't do anything for real in it.

I think the wastegate might be stuck, if so I'm going to order a new wastegate...so if anyone could help me with this problem I would be glad to say thanks, and help out with what knowledge i have.

If it is the wastegate, what is the site that offers stock supra parts and OEM ones. It's not a very well built website, but it is high trusted and I can't find it anymore... =(

[dunewarz]

Mklll don't come with wastegates. I think you're referring to a blow off valve. It could be stuck closed which will cause a large amount of pressure build up in your pipes.

[cre]

Originally Posted by dunewarz

Mklll don't come with wastegates. I think you're referring to a blow off valve. It could be stuck closed which will cause a large amount of pressure build up in your pipes.

You are dead wrong.... the CT-26 uses and internal wastegate. The wastegate actuator is the round metal can with the rod coming out that is mounted to the CT-26.

BOVs do not vent from boost; They vent when the actuator sees vacuum. They are not a device for controlling boost levels.

Cyto, wastegate actuators are generally not cheap. I would start with trying to find a used one to swap in. Have you actually tested the wastegate to see if it is likely that it's sticking?

[Cyto]

When the HG blew, he had to take everything off, when he put it back together, he found out that water had gotten in the exhaust and melted the honeycomb in the Cat, at first he thought it was the wastegate. The problem: not wanting to rev up.
Solution: Gutting the Cat of everything(straight pipe down the back now).

[cre]

Originally Posted by Cyto

water had gotten in the exhaust and melted the honeycomb

Utter bullshit. Water is always flowing past the cat, it's a natural byproduct of the combustion process... besides, ceramic, platinum, manganese, iron, nickel, palladium and rhodium are not water soluble and all have a much higher melting/burning point than water could ever achieve...

[Cyto]

Originally Posted by cre

Utter bullshit. Water is always flowing past the cat, it's a natural byproduct of the combustion process... besides, ceramic, platinum, manganese, iron, nickel, palladium and rhodium are not water soluble and all have a much higher melting/burning point than water could ever achieve...

All that was said by a local mechanic, I figured it was stupid. I didn't question it though, however; he did completely strip everything out of the converter.
I'm not too car savvy, so bare with me? lol

[dunewarz]

Originally Posted by cre

You are dead wrong.... the CT-26 uses and internal wastegate. The wastegate actuator is the round metal can with the rod coming out that is mounted to the CT-26.

BOVs do not vent from boost; They vent when the actuator sees vacuum. They are not a device for controlling boost levels.

Cyto, wastegate actuators are generally not cheap. I would start with trying to find a used one to swap in. Have you actually tested the wastegate to see if it is likely that it's sticking?

Actually BOVs do vent boost. Waste gates prevents boost from occurring by venting exhaust gas from the turbo fin.

[dunewarz]

You'd have high boost lag if your turbo was running full boost. You'd have high acceleration if your BOV was stuck closed.

[rob87]

What about the other way around to the original posting. No turbo boosting or very little according to the gauge and hearing a whining pitch sound when you should be getting boost from the turbo?

Would it be a bad turbo unit, wastegate or BOV?

This just started happening to me and not sure what to tackle or look for to confirm what is wrong.


87 turbo manual trans
rob87

[cre]

Let's review... you've apparently misread or misunderstood or both.

This:

Originally Posted by dunewarz

Mklll don't come with wastegates.

Equals:

Originally Posted by cre

You are dead wrong.... the CT-26 uses an internal wastegate. The wastegate actuator is the round metal can with the rod coming out that is mounted to the CT-26.

This:

Originally Posted by dunewarz

[a stuck BOV]...will cause a large amount of pressure build up in your pipes.

(Close, but not quite... you'll only see a little more pressure than normal.)

Equals:

Originally Posted by cre

BOVs do not vent from boost; They vent when the actuator sees vacuum. They are not a device for controlling boost levels.

Lets examine this statement further: "They are not a device for controlling boost levels."

Nowhere did I say they do not vent boost... I said they are not triggered or caused to open from boost (a requirement of any device which is supposed to open to release excess boost).

The BOV is used to flat out DUMP the pressurized air within the intake in order to prevent the turbo's inducer and shaft from absorbing a shock and possibly spinning backward due to the repercussive surge which follows the closing of the throttle plate.

When you release the throttle the intake plenum after the throttle plate goes into a state of vacuum, the turbo's impeller is (due to a neato thing called inertia) still spinning and the air is smacking the throttle plate and bouncing backward. To prevent this shockwave from reaching the turbo and thus extending the turbo's life (also to help the turbo spool up faster by preventing the need for the incuder to reverse direction yet again) a blow off valve or a bypass valve (there is a difference and each has its own benefits and downfalls) is employed to dump as much pressure as possible. This valve is opened by using the vacuum pressure when the throttle is closed to pull open the valve.

A wastegate is driven by the pressure level of the intake manifold. There is a spring inside which prevents it from opening below a certain level... this is the reference load. In order for a wastegate to open the signal load must be higher than the reference load. Once the manifold reaches the a point above that level the wastegate slowly opens allowing the exducer to slow but just until the reference level is again higher... it's a balancing act. The wastegate keeps the pressure constant, not the BOV which simply dumps as much as it can.


You can run a car without a BOV or BPV; You can't or at least definitely shouldn't run without a wastegate.

Originally Posted by dunewarz

Actually BOVs do vent boost. Waste gates prevents boost from occurring by venting exhaust gas from the turbo fin.

Yes, right on both counts... which has me wondering how it is you fail to understand what their purposes are.

Originally Posted by dunewarz

You'd have high boost lag if your turbo was running full boost. You'd have high acceleration if your BOV was stuck closed.

Wrong... you've got it backward. If the waste gate is stuck closed you'd overboost; The waste gate is the pressure regulation device. Stuck BOV or BPV = lag and potential damage to the inducer and shaft.