Lowest settings but still boosting over 16psi

Re: Lowest settings but still boosting over 16psi (petmr2)

Mon, 02 Nov 2015 11:30:40 GMT

Yep just found another article form twosrus stating the same thing... http://www.twosrus.com/Articles/Installation_Instructions/MBCinstructions.PDF

Re: Lowest settings but still boosting over 16psi (petmr2)

Mon, 02 Nov 2015 10:50:05 GMT

Thanks... I'll need to have a look when I get home. From memory all he did was disconnect the hose from the wastegate and connected the hose for the solenoid and boost gauge. I'm confident he did not block it off... And yeah I think the hose to the T-VSV is still connected... really hope this is causing the issue.

Re: Lowest settings but still boosting over 16psi (Mrskylighter)

Mon, 02 Nov 2015 10:21:42 GMT

petmr2
Can anyone shed some light on this? When the shop was installing the electronic boost controller, I don't recall him doing this..

http://www.turbomr2.com/MR2/HowTo/AP...%20AVCR-02.htm

In this article it states "Cap both ends. You must securely clamp the cap on the wastegate actuator nipple, or you will experience uncontrolled boost (as I learned firsthand). Here's a photo of the rubber hose plugs I used, before they were clamped down:"

He didn't do this... Do I have to do this as well?

If it hasn't been done then yes you need to cap them. When you look at the wastegate what is happening with the second port? Is the hose to the T-VSV still connected?

Re: Lowest settings but still boosting over 16psi (petmr2)

Mon, 02 Nov 2015 09:50:40 GMT

Can anyone shed some light on this? When the shop was installing the electronic boost controller, I don't recall him doing this..

http://www.turbomr2.com/MR2/HowTo/AP...%20AVCR-02.htm

In this article it states "Cap both ends. You must securely clamp the cap on the wastegate actuator nipple, or you will experience uncontrolled boost (as I learned firsthand). Here's a photo of the rubber hose plugs I used, before they were clamped down:"

He didn't do this... Do I have to do this as well?

Re: Lowest settings but still boosting over 16psi (92 Hard Top)

Mon, 26 Oct 2015 21:34:11 GMT

Steve_A
EssDub
If your exhaust is flowing too well, you will likely find that you are getting the overboost issues that plague these cars. Basically, the exhaust flows far too well for its own good and the wastegate simply can't cope with the gas flow, thus letting the rest go through the turbine, creating the excess boost. The fix? Either a big single external gate, or two smaller ones, one on each scroll.

If the vsv isnt the cause then this is very likely the problem. I have a ct26 with 3 inch dump and it will boost to 18psi. This is with no boost control, just the stock wastegate spring which is 7psi.

This is a fairly common problem when using a 3 inch dump and an easy way to tell if this is your problem is to disconnect your boost controller (including the vsv if it isnt already) so your just running the wastegate spring, limiting you to 7psi.

Then go for a drive and have a mate keep an eye on your boost gauge while you do a good pull. You should hit 7psi quickly and then, if your wastegate isn't able to keep up, the boost should continue to climb at a slower rate i,e creep.

If this confirms your issue then there a couple of options. Firstly as EssDub said you could install external gates, this will work but will cost $$$ and is probably a waste of money with a ct26 IMO. Another option is to reduce the flow of your exhaust system either by reducing the size from the dump back or putting in a secondary cat (higher cell count is better in this situation). This will be way cheaper then external gates but kinda defeats the purpose of using the 3 inch dump in the first place....

I would suggest tuning for the higher boost and make sure you have the enough fuel to cope!

I agree this approach.

Re: Lowest settings but still boosting over 16psi (Steve_A)

Mon, 26 Oct 2015 21:12:15 GMT

EssDub
If your exhaust is flowing too well, you will likely find that you are getting the overboost issues that plague these cars. Basically, the exhaust flows far too well for its own good and the wastegate simply can't cope with the gas flow, thus letting the rest go through the turbine, creating the excess boost. The fix? Either a big single external gate, or two smaller ones, one on each scroll.

If the vsv isnt the cause then this is very likely the problem. I have a ct26 with 3 inch dump and it will boost to 18psi. This is with no boost control, just the stock wastegate spring which is 7psi.

This is a fairly common problem when using a 3 inch dump and an easy way to tell if this is your problem is to disconnect your boost controller (including the vsv if it isnt already) so your just running the wastegate spring, limiting you to 7psi.

Then go for a drive and have a mate keep an eye on your boost gauge while you do a good pull. You should hit 7psi quickly and then, if your wastegate isn't able to keep up, the boost should continue to climb at a slower rate i,e creep.

If this confirms your issue then there a couple of options. Firstly as EssDub said you could install external gates, this will work but will cost $$$ and is probably a waste of money with a ct26 IMO. Another option is to reduce the flow of your exhaust system either by reducing the size from the dump back or putting in a secondary cat (higher cell count is better in this situation). This will be way cheaper then external gates but kinda defeats the purpose of using the 3 inch dump in the first place....

I would suggest tuning for the higher boost and make sure you have the enough fuel to cope!

Re: Lowest settings but still boosting over 16psi (Mrskylighter)

Mon, 26 Oct 2015 19:01:08 GMT

Rob
need to disconnect the oem boost thingamajig on the rear fire wall

The OEM boost control is located under the inlet manifold. On the rear firewall you might be thinking of the A/C VSV?

OP, have you plugged the second port on the wastegate? (which goes the OEM T-VSV)

Re: Lowest settings but still boosting over 16psi (Rob)

Mon, 26 Oct 2015 17:11:15 GMT

need to disconnect the oem boost thingamajig on the rear fire wall

Re: Lowest settings but still boosting over 16psi (jason_2901)

Mon, 26 Oct 2015 15:20:44 GMT

On a ct26? Seems excessive lol

Re: Lowest settings but still boosting over 16psi (EssDub)

Mon, 26 Oct 2015 13:18:29 GMT

If your exhaust is flowing too well, you will likely find that you are getting the overboost issues that plague these cars. Basically, the exhaust flows far too well for its own good and the wastegate simply can't cope with the gas flow, thus letting the rest go through the turbine, creating the excess boost. The fix? Either a big single external gate, or two smaller ones, one on each scroll.

Re: Lowest settings but still boosting over 16psi (jason_2901)

Mon, 26 Oct 2015 11:04:44 GMT

Vsv is the stock ecus way of control boost, if its stll working it will probably add another 4psi or so, just do an Internet search for details

Re: Lowest settings but still boosting over 16psi (petmr2)

Sat, 24 Oct 2015 11:15:12 GMT

I didn't install it myself. Paid someone to do it... Do you have a pic of this VSV?

On another note, there are 2 knobs on the HDI boost controller. Low and High. On the lowest setting for low it's boosting at 14.5psi... On the high knob on the lowest setting it's boosting at 16.5psi... I've just left it on the lowest setting on low for now

Re: Lowest settings but still boosting over 16psi (jason_2901)

Sat, 24 Oct 2015 11:10:53 GMT

When you installed the boost controller did you block of the vsv?

Re: Lowest settings but still boosting over 16psi (petmr2)

Fri, 23 Oct 2015 20:22:07 GMT

The dump was installed a month back... It holds for as long as I keep the accelerator down. I don't have a rev tacho so it's as close to redline as possible

Re: Lowest settings but still boosting over 16psi (just_ace)

Fri, 23 Oct 2015 20:19:14 GMT

Does it spike to 16 then drop back down or hold till redline.

Also, was the dump installed at the same time? If so, its possible its just the dump not allowing the gate to open properly.