Low Secondary Boost
 

Did the following tests for trouble shooting but did not see any reaction to the turbo control actuator when doing the KoKO so what does this imply. My boost pattern is 12-5-5.

5) Check vacuum chamber's storage ability with engine off

Pull off vacuum hose at Charge Relief Actuator
Should hear air entering hose vacuum, re-attach hose
Start engine - briefly accelerate engine to WOT in neutral again
Turn engine off - KOKO 6 TIMES
Watch Charge Control Actuator work each time
Watch Turbo Control Actuator work each time, (need to crawl under the car to see this one)

Thanks !

what?
 

So what does this mean ? The vacuum storage tank or check valve is bad ??

swap to single....done!

Was the CRV held open with the engine off? I can't tell from the post.
Does the Pressure reserve hold pressure with the engine turned off?

rph

yes the CRV is held open with engine off and the pressure tank is holds ! The crv moves in and out when the key is turned of and on but I dont see the TURBO CONTROL ACTUATOR do any thing so I was wondering what this implies is wrong.

bump

Is the TCA the problem, is it suppose to move closed or open?

It moves only briefly. You need a second person to verify TCA operation.

David

I here noise while under the car but I do not see the actuator show any movement ???

If you actually watched it and it didn't move, then you probably found an issue.

Did you get any pressure in the pressure tank?

Yes there is pressure in the pressure tank!

It wouldn't be the first time that one or both of the turbo control solenoids was in need of replacement.

So you don,t believe it might be the TCA ?

The solenoids, one of the vacuum lines leading to it, or the TCA itself.

David

Could it be a clogged pre-cat ???

If you still have a stock pre-cat, I would change it for a downpipe. But that's not necessarily the cause of your boost problem.

I have done everything, except change out the cats, replaced all turbo control solenoids with custom set, replaced all vacuum lines with silicone, tested the CCV, CRV, BOV, TCA with mytivac numerous times, tee'd in a vacuum gage between the TCA, the CCV and the CRV and made numerous runs and they all are turning on and off at the required 4500 and 3000 rpm settings.

Currently running with the waste gate solenoid disconnected and getting 8-5-5 boost pattern. With the wastegate solenoid plugged in I get 12,13-5-5.

My Turbo is the newer version with the restrictors built into the manifold nipples.

Some people on the forum say it could be a clogged cat and others say if I get the primary boost of 12 to 13 that I am getting the cats are not clogged and it is something else!

So I am leaning now to plugged Pre- Cat! I just do not know I have tested and tested.

I just wish there was a way to test the exhaust out put to see if there is a restriction giving evidence of a clogged cat.

I always recommend verifying the correct plugs are on the right solenoids. Verify by checking the wire colors against the diagram.

Tcav, precontrol, and wastegate have the same plug, but different wire colors

yes! I even tried changing the waste-gate and pre-control solenoid electrical connections, still did not solve issue!

U get 12-5-5 in all gears?

My boost problem is that secondary doesn't come on but doesn't affect the primary either, so my boost stays at 10 all the way from 3000 to 6000 rpm. Anyone know Where should I start checking? I think it could be charge control or charge relief since they control the transition.

If you have 10psi at 6K, you are getting secondary boost. The primary turbo cant supply enough volume to keep 10 psi at high rpm

Exactly right. If you HAVE 10psi past 4500rpm, then you can assume that both primary and secondary turbos are boosting, with a stock car.

The logic being (as Adam stated) that the primary turbo on its own will not supply 10psi through the entire rpm range. Its just not big enough on its own.

(If the primary could do that, there would be no need for twin turbos)
It takes two turbos to maintain 10 psi after 4500rpm.

thanks guys. that does make sense. But I don't have a "dip" at the transition and I don't feel that there is a "pull" when the secondary kicks in at 4500 rpm. My car used to have the 10-8-10 and I used to be able to feel the secondary kicking in right after the dip but oddly it's gone now.

On a different boost issue though, I know I get no boost at all in first gear and in 2nd there is boost ONLY if i WOT. from 3rd and on boost kicks in between 2000-3000 rpm like it should and I know this could be a faulty TCA solenoid after some research on the forum (bought one from Ray but haven't install). Well, the interesting thing is I just started DD my FD and I found out ONLY when it's about 80F out and after I drive the car 20 mins or so when the water temp gets to 195-200 F, the car boosts perfectly and I start getting boost in lower rpm range like it should even in first gear (but still no full 10psi in 1st ever). and I do eventually get the dip from "10-8-10" so this leads me into thinking what in the turbo control system is temperature dependent and will only work well when the car is hot. Or maybe I have a clogged pre cat? I still have the stock precat for this 94 touring with 110K miles on precat. (sounds like a nightmare)

Car is all stock except for RB cat back