What in the Wild Wild World of Sports is going on around here!

[J57ltr]

I'm just trying to lay down some boost here and the car is not letting me.

05' GTP had several problems most of which I have solved or am in the midst of solving. My scanner was supposed to be here a week ago so don't be too hard on me about it.

Basically I had a 3.4" pulley on the car when I bought it and recently changed to a 3.6" since I wasn't able to get a 3.8". The car has 2.5" from the manifold to the stock Y and a set of 2.5" 2 chamber flowmasters on it.

I added a air intake and new plugs and wires, original Platinum plugs then on advise I used AC copper 606's gapped at .050"

At this time I was able to get up to 10psi (before I changed pulleys), then all of a sudden this started happening.

I don't hear any detonation at all, I'm running 93-94 octane.

I added a boost gauge and a fuel pressure gauge. Fuel pressure is about 60-65 all the time regardless of engine load.

If I lay into the throttle from a stop the car comes alive until it reaches "0" then it seems to just go flat like there isn't any more power. The boost gauge will not go any higher.

If I roll onto the throttle from say 40 and slowly accelerate easing the needle into the boost area I can get it to 5 psi then it will hold there as long as I slowly apply throttle.

If I do the same and get to 5 psi then press a little harder the needle drops back to 0.

If I am rolling about 40 and press on the gas until I start getting into boost it will downshift and the gauge will drop to 0.

If I take it easy and start getting into boost 5psi is as high as it will allow.

My theory is that there is something that is causing the boost solenoid to kick in and bypassing it, or the throttle is limiting the intake of air to keep the car out of boost. Those are the only things that make any sort of sense to me. I am sure that the coupler drive to drive shaft has not failed and there isn't a way to limit boost any other way than having the bypass open and limiting the throttle opening.

I'm pulling my hair out over here.

Thanks,

Jeff

[bandook]

Your belt and tensioner good? Not slipping?

[J57ltr]

Yup, in fact I left the belt that I had for the 3.4" on when I switched to the 3.6" now I have a tensioner squealing, so it's a little on the tight side. and no dust from the belt on the snout or anywhere else.

It's a 660 length, btw

Jeff

[99GT2dr]

Maybe try venting the bbv to atmosphere to rule out the pcm doing anything to pull boost.

[bandook]

Yup, in fact I left the belt that I had for the 3.4" on when I switched to the 3.6" now I have a tensioner squealing, so it's a little on the tight side. and no dust from the belt on the snout or anywhere else.

It's a 660 length, btw

Jeff

Have you looked in to your other theories? I think you can just unplug your boost selenoid to rule that out. The way I understand it the pcm activates the selonoid under certain conditions. Or you could just unplug the top vacuum tube on the boost bypass valave actuator so that the valve remains closed at all times. These are just my thoughts but I don't have my blower installed yet so I don't know if I'm missing something here.

Your second theory about the throttle limiting air is unlikely, I would think. Unless your throttle cable is binding or something I don't think its possible. I guess you could take the intake off completely, double check that the butterfly is opening 100% and run it. But I don't think this would cause a sudden drop in boost anyways. I'd examine the selenoid first, then the belt again as well as all idler pulleys. Does the pulley spin easily on the blower with belt off?

Other than that maybe you have an exhaust restriction? You really need to scan to see what's going on. Even a cheap Bluetooth obdII using the Torque app will tell you a lot. Detonation is not something you can always here. Just to know KR is worth the 20 bucks for a cheap obdII and app.


Edit: you said the tensioner is squealing? The belt you have should be good up to a 3.7" blower pulley. Your idler on the tensioner could be bad. Or you have an oversized idler somewhere that is making things too tight? If the bearings are bad on one of them it could cause them to bind, which causes more restriction and allows the blower pulley to slip?

[J57ltr]

Well I did try to investigate the bypass not closing or the pcm kicking it open, but that didn't end well and caused the car to go into reduced power mode, turn off traction control and shut the throttle out completely and causing the computer to set some kind of default idle that caused the engine to run rough. I had to coast into a parking lot and shut the car off open the door and then restart it. It ran normally. I ended up putting the hose back on the solenoid and driving home.

Now as I understand the operation of the bypass on the 05' car is that the top connection is ported to the inlet of the blower after the TB, so that it is either under vacuum or atmospheric pressure (or close to it). The bypass valve actuator has spring pressure to keep it in the closed position. Now the bottom under the diaphragm is ported to the solenoid and when the solenoid is in position 1it shuttles the bypass to atmosphere. In position 2 the port from the bypass is shuttled to the manifold pressure. So with this arrangement if the computer calls for the solenoid to reduce boost it ports manifold pressure to bottom of the bypass forcing it open against the spring pressure. When it allows the solenoid to close it changes to position 1 the pressure trapped in the bypass is then vented to atmosphere.

I say position 1 and 2 because I don't know when it's on or off.

my second theory still could be since the throttle is drive by wire. I have no linkage.

the exhaust cat and resonator have all been recently replaced.

My bluetooth scanner is a week late post office says it's been in Cali the whole week so that's on the way. I have scanned it with other scanners and haven't t seen anything out of the ordinary I have t been able to drive it with the scanner. I have a regular code reader and had a P0068 and traced that to what I think ended up being many small vacuum leaks. Hasn't come back in the last few days.

The tensioner pulley was showing signs of spalling on the surface and I think that the added tension just took it over the edge. Remember this is a car with 136k on it and I'm pretty sure the tensioners are original. The belt is tight but I was able to hold the tensioner and slide the belt over the supercharger pulley and past the first rib to have it align properly (8rib) easily.

Jeff

edit: when I did bypass the bypass I still was not able to get over 0. Today I could repeatedly go to 5psi give it a little and it instantly falls to 0.

[99GT2dr]

I knew there was a reason I never got involved with '04+'s. If it were me, at this point I'd be swapping the bbv with one from one of the other 4 blowers I have sitting in my garage to see what it did. Or figuring out some way force and keep it closed for a test run to see if it builds boost.

[J57ltr]

That's on the list I ran a wire for the sender to measure fuel pressure. Done with that so I'm going to put a micro switch and have it light an led to tell if it's closed or not. That's something I can do at lunch tomorrow. I won't be able to go to my storage until the weekend. Probably have some blowers (ported or not) and cartridges (rotor packs) for sale soon.

Jeff

Edit: 99, I got the 05' specifically because it had the Gen V blower with abraidable coating which was supposed to bump up the efficency by more than the difference between Gen 3 and Gen 4. Now I think I'm going to regret it or batton down the hatches and figure out this fancyfied addin' machine what controls this engine.

[99GT2dr]

Yeah I thought about getting a Gen V, after looking into it decided it wasn't worth the money, unless I got one really cheap from eBay or something. Before I put enough effort in to max out a Gen III, I'd be going turbo anyways.

[J57ltr]

I think it's different how you guys refer to the previous generation as a Gen 3. It's the Gen 4 for the Ford M90. The GM gen 3 inlet and outlet match the Gen 4 Ford M90 that was used from 94-95 the Gen 3 used from 89-93 had a different outlet and inlet configuration and bare rotors. I have some really good tech articles from back when we started porting, airflow and such.

Jeff

[J57ltr]

Just keep a look out and try spelling it wrong like suppercharger or leave out a letter. I found a lady selling 3 Jag XKR M112's for $125 each BIN. They turned out to be dealer takeoffs with failed spring couplers. They were practically brand new I bought one and linked on our forum and another guy bought the others. I would find a lot of good deals that way.

[16MustangVet]

stock gen5 is worth it over even a ported gen3..........

[Booba5185]

We kinda went through the Gen III to Gen V subject in one of my threads, lol. It turned out to be not really worth it. If you are replacing a Gen III for whatever reason it's a good upgrade, but replacing a perfectly good blower just for the Gen V isn't worth it at all.

[J57ltr]

Ok guys I got my BAFX adapter and set it up there are a couple of screen shots in this thread:

http://www.grandprixforums.net/threa...e-WOT-problems

I don't believe that the data is delayed enough to make a difference. I have had a couple of times where the car goes into boost and have hit 8psi and 5 psi but the weird thing is it seems to be knocking even before I get into boost. This isn't possible an 8.5:1 engine should not knock at even the 5 psi level with premium it just doesn't make sense. I think I may have a defective knock sensor if this is happening. Look at the pics and tell me what you think.

thanks.

Jeff