[Mk2] [Turbo] Boost Problems! 1995 Rev 3 Turbo

[danwarwick]

Hi all, not getting much time to do anything with my car recently due to other commitments but I want to slowly make it perfect again. It's going to be a long term project!

The first thing I want to sort out is the problem i'm having with the boost. A few months back (taken me a long time to find the time to start investigating!) the boost pressure dropped from standard to never reaching more than 0.4 Bar. It recently seems to have dropped off slightly more.

At the same time the Blitz SSQV dump valve started to make a fluttering noise rather than the assertive hiss it was making previously and the standard boost gauge began flickering under full acceleration. The standard boost gauge had never previously moved before as it's fitted with an aftermarket gauge elsewhere.

My first thoughts were a leak in a hose but I can't see anything obvious. There is no sign of any smoke when I check the mirrors while accelerating and the car doesn't use any oil.

Any help would be much appreciated as it's driving me mad having next to no power anymore!

[b4nk51e]

The dump valve won't go off properly if there's not enough boost to open it. Does the car idle ok? could be a vacuum hose or even a leaking dump valve I had the latter with a cheepo ebay ssqv so binned it

[gerbil1028]

Dump valve failed and causing a leak ??

[danwarwick]

I had suspected the dump valve was a possibility, I have the original Toyota valve which I was thinking of putting back on as I'm not bothered about losing the hiss between gears.

Is it hard to replace the HKS back to the stock valve?

[danwarwick]

The dump valve won't go off properly if there's not enough boost to open it. Does the car idle ok?

The car idles perfectly and seems to run fine apart from being massively down on power.

[samgpr50]

I would say faulty dump valve. I see you are in Cheshire. If you need a hand I'm happy to help out where I can.

Sam

[gerbil1028]

I live the spirit of this club

Anyone want to give me a rev3 tubby conversion package

[Peter Gidden]

The dump valve won't go off properly if there's not enough boost to open it. Does the car idle ok?

The car idles perfectly and seems to run fine apart from being massively down on power.

A Rev3-5 will idle properly even if you remove the dump valve and leave a gaping great hole. It'll run with all the intake pipes missing. Because they're MAP sensor based.

A Rev1-2 will not idle with any leaks in the intake system.

[gerbil1028]

Come on peter offer me a free rev3 package lol

[danwarwick]

I would say faulty dump valve. I see you are in Cheshire. If you need a hand I'm happy to help out where I can.

Sam

That's a very kind offer which I'd love to take you up on when I have the time, I'm only over in Congleton so not far at all!

[samgpr50]

No problem at all. I'm actually in congleton as I type this! Let me know when you want me to pop over. I'm only in Alsager.

Sam

[danwarwick]

Brilliant, any time in the evening during next week would be perfect, unfortunately I'm away every weekend.

[samgpr50]

I will ok you my number later and just call or text me when you are ready.

Sam

[danwarwick]

Brilliant, thank you very much!

[nathan.z]

I had a similar problem with my rev 2 a few months back, the problem initially progressed until the point of where no boost was created. In the end the boost controller was replaced with a manual boost controller. The turbo was still intact, there were no leaks and the actuator was tested to operate at the right boost level.

The manual boost controller instalment worked, however it temporarily will not reach full boost depending on how it's feeling on the day. It's much better when it is operating. I'd say 80% of the time.

Bit of a gremlin but I don't have the time to dive into it any more until summer.

[danwarwick]

Was yours an aftermarket ebc nathan? My car is just on the factory boost control.

[nathan.z]

Mine was factory too! I have a feeling we're encountering the same issue.

[danwarwick]

Possibly so. I think it's one of the most annoying problems I've ever had with a car, knowing how potentially quick it is and not knowing why it won't produce the power is infuriating!

[danwarwick]

Possibly so. I think it's one of the most annoying problems I've ever had with a car, knowing how potentially quick it is and not knowing why it won't produce the power is infuriating!

[Peter Gidden]

This is not a difficult problem to diagnose.

Providing the turbo is operating correctly, it must be producing boost.

Therefore either the turbo is not operating correctly, or the boost is being lost.

An hour at the most in my workshop.