Toby Van Horn

okay so I decided to take the advise of some fellow members to solve my maggie troubles. It does not idle well, and does not want to go when given gas (boost gauge shutters up to 8-9 where before it shot straight to 10) and there is not much power to it at all. My rear belt has been showing wear (shredding) so I decided to take this time to replace it.
I went to take the belt off the front to check for possible vac leaks. On the bottom of the throttle body there is a pipe coming off it, and it did not have anything hooked up to it. I am hunting everywhere to see if a hose came off while replacing the belt, but could not find one.

I have two questions.
First, does that pipe get plugged, or does a hose run to it?

If a hose runs to it is there a place that it typically somes from?

Its getting a little late and I do not think that my neighbors would like it if I start it up tonight to check it out further, but any suggestions would be great.

Thanks
Toby

BLOWNBLUEZ06

That pipe needs nothing connected. It is for running coolant through it. Don't worry, you're good.

Toby Van Horn

got ecs tensioner on and seems to be no belt slipping, but the car runs about the same. I am hunting for some vacuum leaks and what I can tell round the supercharger nothing seems to be leaking.

One thing I thought of is a few weeks before this occured I got a code P0440 which I guesse has to do with an EVAP leak. Is this something that could be connected?

Is there a possibility that a vacuum leak going to the EVAP system could cause it to run so poorly?

I have also read about some CATS going bad, do they go bad quickly sometimes and give you lack of power and restriction of boost?

Rob's 73

Vacuum leaks can cause problems on all cars. I would think that it cause havoc with the maggie if it is severe enough for the bypass valve to move. This could be causing you to boost as soon as you give it throttle. Try just capping the evap connection. The boost bypass modulator (can't remember what they are called) has been known to go bad.

BLOWNBLUEZ06

Toby, Do me a favor and take a picture of the driver side of your blower and post it up or e-mail it to me. Don't re-size or shrink it much if any. I'll pm you my email address if you want to send the pic directly.

Regarding your cats, I raced a guy and the car was running fine. I changed cams and the car wouldn't run on first start. I couldn't tune past the problem and while troubleshooting, I revved the engine and blew the cat out the back of the car. It was like a stroke. Fine one minute and toast the next. That's how fast cats can fail. I had the Dynatech cats.

I mentioned a while ago to make sure the bypass valve actuator is free of any obstruction and never heard that you checked it. The vacuum lines that run off the throttle body on the driver side can easily interfere with the proper operation of the actuator. You can manually operate the actuator with your hands to verify it is operating with no interference from the lines that must pass it. One of those vacuum lines goes to the actuator and the other goes to your evap circuit. Check it closely.

Toby Van Horn

Toby Van Horn

"This could be causing you to boost as soon as you give it throttle."



I will try to cap some of those vacuum lines, and I assume you are saying that it can cause you to lose boost? Thanks for all the input I will find out the problam soon (I hope).

BLOWNBLUEZ06

The lines under the throttle body are coolant lines, so not to worry about those. I can't see the vacuum line connections very well other than the evap line touching the boost bypass actuator. Do you have a boost/vacuum gauge or just a boost gauge that doesn't show vacuum? If it shows vacuum, what's your vacuum at idle? What is it usually? You can raise your hood and with the door open and engine running, verify the boost bypass actuator is closing at WOT. I also need you to manually operate it by turning it end to end. Making sure the actuator isn't stuck partly open or closed. In case you're not familiar with the boost bypass actuator, it is mounted on the front driver side of the blower where the inlet meets the body and has a vacuum line going to it's black base with a little silver arm that turns a shaft going into the blower body. I see a small possibility that something could interfere with full operation of the bypass valve and if it doesn't close 100% at WOT, you'll lose boost. Make sure all of those vacuum lines coming off the driver side make it to their destination with no cuts or possibility of the loss of vacuum.

Toby Van Horn

at idle it seems to be around 14 in of vacuum, and that was what it was all the time that I can remember. When I first had a problem a few weeks ago I would see vacuum around 22-24 at idle which was a lot more than I remember it.

It wont damage the bypass actuator by moving it by hand?

And what does this actuator do?

BLOWNBLUEZ06

It won't damage the actuator to move it by hand. It's simply a diaphragm that moves that arm that opens and closes a butterfly valve located in the base of the blower just before the air hits the rotors, allowing the air to bypass the rotors entirely in low load/throttle conditions. It improves efficiency in those conditions. If it doesn't close, it will drop your boost a great amount by preventing the air from being moved by the rotors and going straight into the lower manifold. It won't affect your idle vacuum though. Just in case it hasn't been mentioned, make sure all of your bolts are tight. When I say tight, I mean roughly 15ftlbs, which is maybe a little more than wrist tight. You may want to pull the blower off to check for cracks and too, but check the simple stuff first. You may want to try capping off all or one vacuum line at a time to see if your vacuum improves and to help isolate your leak. If you cap them all off except for your boost/vacuum gauge and still have low vacuum, then I'll have more suspicion of something in the Maggie unit leaking. The Maggie is not difficult to remove or disassemble the lower manifold if needed. With hand tools, I was able to remove it in approx. 30 mins. I wish you lived closer, I would come over and dig into this problem myself. I'm almost losing sleep over it and it's not even my car.
If I remember correctly, the vacuum will go down with clogged cats but the boost will go up.

RED99

Is this vaccum gauge a boost/vaccum gauge mounted inside the car? If it is, then check the line for a leak.
If your vaccum gauge is correct, then you can try using some propane or a can of starting fluid and spray it around every place that could leak vaccum and see if your idle goes up. If you use to starting fluid, just do a little at a time and don't soak the motor all at once and give it a chance to evaporate. This is an old trick thats been done thousnds of times. But I would suggest to have a fire extenguisher close by for those 1 in a million chances.

Toby Van Horn

So a small update, I traced what I could for a vacuum leak and it still has a decent miss, in the time that I have been double checking things I have developed a upper end noise, along with the miss, I took a stethiscope and it sounds like it is coming from the top of the rear cyl on the driver side. I will be taking off the valve cover to see if there is anything visable.... Anyway thanks for all the input and if anyone has advise of what to look for specifically that would be great. I am going to do a compression check on each cyl to see that the outcome is.

Toby Van Horn

at least my maggie has a new ECS tensioner out of the deal.

Vega$Vette

My guess is your burned #7

Do a compression test and you'll have your answer