The kind of pressure gauge and firmness of hose can affect the needle movement, I'd imagine. So compare the wg duty control with the pc duty control to find the pattern.

 

Ok this morning I teed into the vac line between the precontrol actuator and precontrol solenoid, closer to the solenoid.

Didn't get much of a chance to do WOT runs because there was a bit of traffic on the way to work, but I did get a little but of info.

Below transition, 7.5psi, and NO bouncing of the needle. At the transition, a sharp drop to 5psi, which held. In other words, it was almost identical to when I have my boost gauge plugged into the UIM, but without the vac reading at idle.

So to recap - I'm not seeing any bouncing of the needle ever. The vac line between wastegate actuator and wastegate solenoid sees roughly 0psi untill about 4500rpm, then solid 5psi (the same as my boost reading post 4500rpm taken at the UIM nipple). The vac line between the precontrol actuator and precontrol solenoid reads 7.5psi until 4500rpm, then 5psi after 4500rpm. This is identical to my boost readings from the UIM, but obviously without the vacuum at idle.

I'll get there one day!

 

Today I ran a few more tests. I finally decided to WOT in neutral (hadn't done it yet) and I scored 4psi in the upper revs, and was able to see the pre-control actuator move.

I've done the KOKO before (not turning the engine on) and I can get 10-15 cycles on the CCA so I know my vac chamber and CCA are probably OK.

Today I did the KOKO to test the TCA. I gathered from searching that to test the TCA you need to KOKO but actually turn the engine on, and you should see the TCA move in, and then snap back out again straight away.

Well I WOT the beast a few times in neutral to make sure I've got at least a bit of pressure and plenty of vacuum, turn the car off, then KOKO and could only see a small jiggling of the TCA, it didn't move in so to speak just kind of shook. It could have been the vibrations of starting the engine for all I know. I certainly didn't see what I was expecting (sorry, HOPING)

OK so it looks like my TCA isn't moving, possibly caused by a dud TCS. That would explain my low secondary boost.

But I'm still missing out on some primary boost too!!!! Unless the TCA isn't adjusted right, so that the valve is leaking some exhaust to the secondary.......

But WHAT could be causing my sharp drop 7psi to 5psi at the transition though, if the TCA isn't operating correctly?

 

Update:

Haven't worked on my boostage issue for a while, been a bit too busy. My idle has been getting lumpy courtesy of a LIM gasket (last service they spotted a torn bit of it sticking out and warned me that my idle would start getting rough when it started to give way properly). Anyway so I'm taking it in to have the LIM gasket fixed on Wednesday, so while their doing that I'll get them to check the TC solenoids and actuator, and their respective hoses.

 

Well I had the LIM gasket fixed at rather great $$. The shop I took it to found a number of issues, some hoses had popped off under the UIM (they couldnt remember which ones) my O2 sensor was toast and some bolts were missing from the exhaust manifold.

Getting it back from that work, the engine was smoooooth as but unfortunately my boost pattern was still the same.

That was about a month ago, I haven't done much since then. The good news is I FINALLY found an Aussie distributor of Mityvac products so at lunchtime today I ducked outta work to go get my brand new Silverline Plus Automotive Test Kit (vac/pressure pump). I was looking for similar products all over the place, in the Auto parts stores and hardware stores to no avail. Thank god I found one! Troubleshooting without the right tools just wasn't working.

First steps: Check boost gauge accuracy - verify correct operation of wg/pc solenoids and actuators.

Let the fun begin............

 

"WANTED
10PSI BOOST
$1'000'000 REWARD"

Is this offer still good?

 

Haha

Not if it's my own stupidity that's causing the low boost......tried to check accuracy of my autometer boost gauge last night. Pulled the hose off the UIM nipple, connected up my new MityVac and discovered that the line to the boost gauge won't hold pressure......I wish I had the mityvac when I put that sucker in so I could have tested the lines.

 

The UIM nipple is part of the intake piping - it should leak. Ideally it should leak really well if your IC losses and intake resistance is low.

As a starting point, tee into one of the lines leading to the pressure tank (on top of the engine), and the vacuum tank (below the alternator and PSP). Test those for leaks.

Dave

 

no no i meant I pulled the line to the boost gauge off, and hooked up the mityvac to that line. I think that I may not have connected the vac tube to the back of the gauge properly, causing it to leak at the gauge. I need to pull it out of the A-trim pillar mount and make sure the connection is secure.

I'll be going nuts probably on sunday with the mityvac testing EVERYthing

 

i recken them wastegate actuators-thingymajiks are going south of the mississipi!

 

Tried to search but I have been getting these weird proxy errors when searching lately, not sure whats going on with that.

I am testing the check valve in the line between the y-pipe and pressure tank.

If I do this (arrow representing the check valve)


open to air -----------> pressure


It will hold pressure fine. If I do this


pressure --------------> open to air


I can hear air passing through the valve.


vac --------------> open to air


It won't hold a vacuum, ie: air will flow against the arrow direction. http://www.autosportracetech.com/RX-...leshooting.htm calles these "pressure" check valves so I'm thinking that's normal operation but just want to make sure. Can't seem to find anything in the FSM but I might not be looking hard enough.

 

OK well I'm starting to get lost and a little confused.....

I've now tested the WG/PC solenoids and actuators to the specs in the FSM. (On a side note, the FSM says the actuators should move at 10-14psi and I *thought* it was supposed to be around 7psi. I'm guessing that if the actuators move at 10psi then you would probably only see 7psi or so at the UIM after losing some pressure through the IC?)

Pressure tank is holding pressure, as is the check valve (see above post, don't think the vac issue is important as it theoretically should never be in that situation)

My boost pattern is 7.5 - 5 - 5 and I have now tested the following to try and find the reason for my low primary boost.

1) calibrated boost gauge - it's good to within 0.5psi. It actually reads over.

2) checked electrical continuity between ECU pins and WG/PC solenoids. Identified correct electrical connectors for particular solenoids.

3) Checked and re-checked WG/PC vac lines, for kinks and blockages. The pills are in the correct locations (larger diameter for WG)

4) Tested WG/PC solenoids, including baking to ~220F in the oven and applying 15psi pressure before using 12V to open the valve, to see if they stick.

5) Tested WG/PC actuators, blocking outlet port and applying pressure to the inlet port. Both met the FSM spec of the rod moving around 10-14psi.

6) Checked and re-checked IC piping for leaks.

7) disconnected the actuator vac lines from the nipples at the turbo (and plugging the nipples), thereby forcing both WG and PC to stay closed. Could boost to 12psi without going WOT before I chickened out to save my motor. No sound of boost leak.

8) tested the ABV and it is holding pressure when pressure is applied to both the big and small ports. If I dont apply pressure to the small port (vac line from UIM) a small amount of air leaks through.


Do you guys think it's a fair assumption that the issue lies with the WG/PC systems somewhere based on number 7 above? That's kind of my thought train at the moment.

 

When you did number 7 did you go above 4500 rpm? Did you see a transition from single to dual?

You may want to plumb in a couple Home Depot boost controllers to see which actuator is really causing the problem.

It may be that the PC door is venting more than it should as a result of an excessively cracked manifold. It is not uncommon for the precontrol port to develop a large crack.

If that is the case you may need new turbos, but you might be able get a few more miles of normal boost by pinching the PC pressure line a bit with the home depot valve to keep it closed a little longer.

If the PC bypasses too much exhaust to the secondary turbo you may see these low numbers.

 

No, I didn't see a transition. I performed test 7 around 3-4krpm and only poked at the throttle a bit, didn't go WOT.

Next weekend I'm going to plumb into a line that will show me primary boost before the intercooler. That way I should be able to see if there is enough pressure there to be driving the WG/PC actuators. IF theres not then that leaves two scenarios that I can think of. Either my boost is leaking and I'm too dumb to find it (yet) or I have an issue with my internal doors not being closed properly (wastegate/precontrol/charge control/turbo control). What you said about a manifold crack could well be true. I'd hope that it's not, as I had a shop pull my turbos to fix a LIM gasket and you'd want to think they would notice something like that.

I'm also giving some serious thought to going for MBC.

 

Well I was thinking about test 7) above, and a cracked manifold would limit boost regardless of if the hoses were plugged in. As well, the actuator rods must be adjusted properly or close to it, or else they wouldn't keep the doors shut to hit 12psi. So I wouldn't go blaming the turbos yet.

I think the black/green check valve needs replaced (or at least tested). If you can't get new check valves easily, you can try swapping the white/green check valves with them as a test. In any case, a check valve

open to air -----------> pressure
(0 psi)-----------------------(10psi): It will hold pressure fine. (Passes test)

pressure --------------> open to air
(10psi)----------------------(0psi): I can hear air passing through the valve. (Passes test)

vac --------------> open to air
(-10psi)---------------(0psi): air will flow against the arrow direction. (Fails test)

That last statement sums it up: Air should never flow against the arrow direction. In the first and third cases, the valve should perform the same way, because there is roughly the same net pressure over the valve.

Dave

 

Whoa partner........... Did I miss something here? Your doing all this testing and your boost gauge has a leak?

 

Yeah I was confused about this - because somewhere I read it was a "pressure check valve". Either way, I agree with ya, I'll get some check valves from a local parts store when I get a chance.

Unfortunately I'm not doing any testing on my boost issue this weekend - having some issues with my drivers door lock mechanism. Cheers for your posts though

 

Nope you didn't miss anything.

When I installed my boost gauge a few months ago, I obviously didn't tighten up the nut/olive thing enough at the back of the gauge that connects the vac hose. So when I finally got my MityVac and went to check it's calibration, it wouldn't hold pressure.

The leak, however, was insignificant in terms of how much boost it was leaking out. My boost pattern (and vac reading at idle) have not changed one iota since I tightened that nut and fixed the problem.

 

I really should work harder at this. I keep leaving it for a few weekends, and then I've gotta search for my thread to post again.....

On saturday I got under the car and started poking around to see if I can check the adjustment of the actuator rods/doors.

Does anybody have info on how to easily get at these doors and to adjust them while the turbos are still in the car? It's bloody crowded in there.

 

In theory it can be done by only removing the motor mount heat sheild and the lower turbo heat shields.

In practice I always pull the intake hoses and the downpipe. But I work slow and have big hands

Dave

 

Cheers Mate

Somehow I just knew you were going to answer that one!

 

Here, today I just happened to be reinstalling my turbos. I think the downpipe can stay there no problem.

The Vanditmars site suggests putting a prestretch in each actuator rod of a 1/2 pin width. You can see it in the red circled joint. I suspect that the real amount should be just less than that - otherwise the wastegate boost control will be affected a bit. But that's a theory for now.

In this pic, the precontrol is in blue, the wastegate is in red, and turbo control is in green.

 

Thanks Dave, your awesome mate. Love the vanditmars site, great info, but I was a little confused by the words without having a picture to back it up. I haven't as yet seen the rods/doors in close up. That photo really clears it all up for me.

Remind me when you come to Oz so I can buy you beers

 

Searching through for ideas on probably the hardest 2nd turbo boost issue problem I have had to fix & this thread stops before the problem is found...........Damn

Like reading a book with the back pages torn out........

 

Well go over to Perth and find out what happened!!