Only getting 4PSI - (also posted in EManaged Section for wider potential advice)
 

Hi all,

Just finished my install, but at the moment I'm only getting about 4psi of boost. 4sfed5 suggested yesterday in another thread that I needed to move the actuator trigger hose to the plenum side of the IC - did that - no change.

I think the turbo itself is a TD04 13G - its not a big turbo - could it be running out of puff, or does anyone know where I can check the model numbers and specs of various TD04 models?

Could it be leaking at the BOV?

If I was getting boost leak, I'm thinking I'd know it very quickly from how it runs? At the moment, it idles, runs, and purrs like a kitten - actually I'm getting better driveability than I had with the NA system.

I've ordered a manual boost controller which will arrive soon, but I'm wondering what else it might be, and if it is something simple. I'd just like to sort out/elliminate the simple options/fixes first.........

It could be a loose coupling that only blows open under boost. Or cracks in the accordian if you are using the stock crossover.

Full SS system - from the turbo across the IC to the plenum.

What's the easiest way to actually test/check it, or to accurately diagnose the/any problem?

With my first turbo, the wastegate acutator itself was shot. How easy is it to pull the actuator open? If you can easily pull the arm out with little strength, then it's shot. If you have to grip hard and put some muscle into it, then it's probably fine.

The best way to check is to attach a hand pump with a gauge and measure when it opens.

If the actuator itself has gone bad, you'll probably see the same amount of boost with the boost source disconnected from the actuator. You can test that by simply disconnecting the boost line and go for a drive. BE CAREFUL: if your actuator is good, you'll build boost unrestricted. Just ease into the throttle lighly a couple times and watch your gauge. If keep giving it more and more throttle and you're at WOT and only making 4psi with the boost line removed, it's shot.

Other considerations... is the flapper door completely closed? The wastegate rod should be pretensioned slightly... ie, the wastegate spring should be forcing the flapper closed, but just barely... NO SLOP IN THE FLAPPER.

Where are you getting your mani pressure reading from? Mechanical gauge or MAP sensor?

Also, why do you think it's a problem? The WG can might have a low boost spring in it.

You could pull the hose off the wg actuator, and go for a ride. Be careful, as the actuator will never open the wastegate. Throttle up in 4th or 5th and see what your boost gauge does. Just be careful.

Mechanical gauge but my first EManage log file also confirms boost peak at just under 4 PSI from the voltage measured at the MAP sensor.

I can pull the wastegate open with a little force, but it is pretty easy - I've been suggested to try a pump with a gauge to check the opening pressure - I'll give that a go first.

I have the wastegate arm/wastegate 'loaded' with a little bit of pretension, so the wastegate is definitely closed to begin with.

I also tightened up the BOV setting a little bit last night, but I suppose I could also pressurise the intake system using a pump and gauge (with the turbo outlet closed off) and that should tell me if the BOV is leaking???

sounds like actuator is shot.

Shouldn't be :vash: - it was bought brand spanking new and sat on my workshop shelf attached to the turbo for a couple of months.

Might have to look at a warrantee replacement.

are you saying that there is NO difference AT ALL between the pre and post I/C boost pressure??? thats not right, somethings amiss there....where is your map sensor located and where does it get its signal from?

Boost pressure for MAP sensor AND boost gauge is now being read at the two nipples on the front of throttle body - same place for both.

And yes - I found almost no change in boost pressure when I swapped the actuator line location. I'm only running a small RX7 topmount as my FMIC so I wouldn't expect much loss across it.

So now I'll reset the BOV (although I firmed up the spring tension last night) and test the pressure at which the WG actuator actuates.

Tested the wastegate actuator just now - it looks like it's going early. I'll try the clip off version tomorrow to make sure.

It's confirmed - I removed the wastegate actuator hose - a quick drive round the roundabout at the top of the street, and it is definitely boosting beyond the current 3-4 psi on moderate throttle application - it actually came up so quick it popped a loose silicone hose joiner off it's respective pipe when I backed off - which I found after a very quick limp home. Started it up but no harm done by the sounds of it and the way it's running (normal) this morning, although the plugs are already looking quite carboned up.

So a boost controller is going in - I'll probably retain the existing wastegate actuator - which gives me a very soft and driveable base level of boost that I can build up from - thanks for the suggestions guys.

....and T25Miata..... the BOV is loud.

:gay: Ricer! :gay:

Can't wait to see it with the boost controller in!

I know you said you solved the problem, but just throwing this out there. My Greddy system only made 3psi when I first put it on. The manifold gasket was leaking. Shortly after the turbo to manifold bolts became loose and let air out of that joint. Might want to check the torque on all those bolts. Just something to check, it's really obvious as it flutters under boost.

I've started another thread because I freaked myself out diagnosing the problem - I removed the WG actuator hose last night and it boosted like a total mo-fo. So I'm pretty sure that although it'sis fluttering quite a bit on throttle lift off, I've got a low level actuator (I ordered a 7psi one, but it seems much less than that)