saxyman990

Alrighty fellas, I know, I'm just as tired as all of you of hearing about boost problems. But at the same time, I've been dealing with this problem for a little while now, and I've been searching the forum everyday like it was my job. Unfortunately, I couldn't quite come up with the answers that I was looking for, so I thought I'd ask for help

Here's the symptoms:

Idle @ approximately 5-600
Vacuum at idle: ~11 in Hg
Boost pattern: 11-6-slow rise to 9

primary boost is great, transition is a little low, and then it takes a while to build it back up (usually by redline it is at full boost). Also, the problem seems to get worse as the car gets hotter (shortly after startup my boost pattern is not perfect, but it is okay, but after 30-45 minutes of driving, it gets a lot worse). This leads me to believe it is a problem with the TCA. I visually checked the TCA and the lines running to/from. all the hoses seem to be connected fine. Couldn't visually find another boost leak anywhere else in the system.

Vacuum seems really low, so it appears I have a boost leak. Could this be the cause of my low idle as well? What about the secondary turbo being slow as hell?

I know that I really need to do a hose job. But will that fix the problem with the secondary? Could it be a check valve, or the TCA itself?

What is the procedure to check the TCA and the lines to make sure everything is working fine?

Just racking off some ideas here guys. Please let me know your thoughts. I really need some help


Rob

saxyman990

Oh yeah, one more thing: while messing around with the hoses I noticed that I have a little blue electrical plug that is not conneted to anything. It is located underneath the pressure tank (right next to the wire connector for the air pump). I'll post a pic tonight or tomorrow of this.

I know it sounds like a really dumb question, but I have a tendancy to be dumb. Does anyone have an idea of what this is for?

Thanks again
Rob

saxyman990

Please help guys. I know you're tired of dealing with boost issues, but I'm really stuck on this one.

I've had a couple people tell me to just go non-seq, cause then I won't get these problems, but I like the feel on seq when its working right. So that is pretty much out of the picture.

How should I properly test the solenoids and valves??

Again, please just shoot me some ideas. Thanks

Snook

iTrader: (12)

ttt

help the man

spooledUP7

Ok, if you did search like you said you did, then you surly came across the secondary related to heat issue. Most likely in your case you have a bad TCA solenoid (vacuum side). These are mounted directly to a heat sink, I mean ACV, and tend to break from the constant heat cycling. You can confirm this by removing the UIM and pulling out the solenoid and heat it up with hot water. Using an ohm meter with aligator clips to the solenoid terminals, you should see the resistance fall off when it heats up. This is a bad solenoid. Replace it, or cheat like I did and still the guts from the purge control solenoid. Either way, you need to replace it to get your secondary boost back online.

johnchabin

iTrader: (2)

Do the following. You may have tried some of this, but I can't assume what you know:

1. Under the pressure chamber there are the two hard pipes that go down to the TCA. It's clear on the vacuum hose routing diagram on page F-10. One is for the Pressure side of the TCA, and one for the vacuum side. Pull the short hoses off the hard pipes and use you Mity-Vac to produce pressure/vacuum where appropriate into the hard pipes. Lay on the ground and watch the TCA while pumping up the Mity-Vac. This is just to verify the TCA is working on both the vacuum and pressure sides (and the hoses down below aren't leaking).

2. Replace one of these hoses and T into the other. Drive past transition. Depending on which one you pulled, you will see either 0 psi ---> + 10 psi or 0 psi ---> - 10 psi. Switch to check the other one. Whichever you don't see is the problem side of the TCA. Mine was the pressure side and I had the same boost pattern. Pressure was never getting to the TCA so it was lazy opening, producing bad transition and slow build.

Good luck.

John

johnchabin

iTrader: (2)

Oh, I check my solenoids with the Mity-Vac and by applying voltage to the unplugged harness at the ECU. You just have to emulate the SINKING outputs of the ECU.

You can do this with the engine hot or cold.

rpm_pwr

Your low vacuum is because you're idling so low. And that is a MAP sensor / idle control valve issue. Maybe a manifold leak but that's less likely.

Easiest way to check if the TCA is working:
1. The change in exhaust pitch. When in secondary mode the exhaust is noticably louder and lower pitched. It really should be obvious.

2. Pull the CRV valve off the air box and floor the car from 3500rpm to 6000rpm. On a perfect car you hear a rush of air from 3500 to 4500 and then it just roars as the TCA kicks over. It should be so loud you can do this test with the stereo on!

-pete

saxyman990

thanks for your input guys. Definately appreciated, and should help me get on the right track.

spooledUP7: During my searching, I actually did run across that thread. But for some reason, I was really not thinking that it was related to my problem, so I just kind of blew it off. Now that you mention it, I have no clue what the hell I was thinking. That definately could be a cause of the mishappenings.

rpm_pwr: I don't think the vacuum problem is just due to the low idle, because when I flick on the lights or hit the AC, the idle jumps up a couple hundred RPM like its supposed to, and the vacuum raises accordingly. However, when idle is at 900 (due to the lights, and AC), vacuum is still only at 11-12 in.

Could the bad solenoid be a cause of my low idle and vacuum? Or do I have another problem associated with this.

After I remove the UIM, can I just take out the solenoid, or am I gonna have to remove the whole rack?

M104-AMG

iTrader: (8)

I pulled CRV off the air box, and from 3500 to redline, I did NOT hear any roar.
The CRV tests fine, so do I assume the solenoid is bad ?

My boost pattern is 10-8-0 and it doesn't return even after I lift for awhile to recharge the vaccuum chamber.

TIA,
:-) neil

Mahjik

iTrader: (1)

It's not really a "roar" you'll hear of the CRV isn't closing; it will sound like your BOV but constant (as if your BOV isn't closing).

If your CRV is fine and you are still having this problem, it points to either a hose mis-route or a check-valve problem.