4000RPM's = Brick Wall???

[mcaracter]

Quote:

Originally Posted by mcaracter Well, then tomorrow after work I think I will double, tripple, and quadrouple check my cam timing. I think I'm also going to remove my Grainger valve and return to computer controlled boost and see if that makes a difference.

Well, some interesting and positive results. I removed my Grainger and returned to computer controlled boost. Yes, the car makes less boost and power, but the usable power band is MUCH nicer! Before, I was having trouble making any real boost in first and second gear. Then, just as I'd start really moving, I'd hit my 4500 RPM ceiling. Now, I build less overall boost, but I build it sooner and I'm able to wind it out to a higher RPM. I've taken it as high as 5000 RPMs and MOST of the time I have no problem. I do occasionally hit the ceiling, but for the most part the car is more drivable than it ever was with the grainger. Also, in relation to another question, I was mistaken, my vacuum at idle is right about 20 inches of mercury, not 15.

Any new suggestions in light of this new evidence? I still haven't been able to check fuel pressure as I lack the necessary tools at the moment.


Thanks!

-Walt

[speeduphoria]

Yep

Now you had a grainger, then went back to stock and everything seems fine, correct?

So that leads me to believe that you did not have an orifice between the grainger and the WG. Is this the case?

If you did have that right then its back to fuel or spark blow out IMO

[mcaracter]

Quote:

Originally Posted by speeduphoria Yep Now you had a grainger, then went back to stock and everything seems fine, correct? So that leads me to believe that you did not have an orifice between the grainger and the WG. Is this the case? If you did have that right then its back to fuel or spark blow out IMO

It was my understanding that the tiny hole in the end of the grainger is the orifice you speak of. If this is the case, then yes I had an orifice between the grainger and the wastegate. Actually, I'm using the gutted grainger as my orifice in the computer controlled set up.

Sounds like I need to check my fuel and spark.

[puppet]

Fault codes?

[1991shelby]

The orifice he is talking about (at least in mine) is a small red piece of plastic with a pin hole that goes inline from the turbo to the wastegate solenoid.
Are you seeing any exhaust smoke from oil? Loss of cylinder pressure at higher rpm from bad rings can cause high end power loss. Just a thought.

[mcaracter]

Quote:

Originally Posted by puppet Fault codes?

Actually I just recently had two separate instances where my car stalled, so I ran codes and sure enough I have a code 54 for the HEP. Definately warrants further investigation.

Quote:

Originally Posted by 1991shelby The orifice he is talking about (at least in mine) is a small red piece of plastic with a pin hole that goes inline from the turbo to the wastegate solenoid. Are you seeing any exhaust smoke from oil? Loss of cylinder pressure at higher rpm from bad rings can cause high end power loss. Just a thought.

I've never seen smoke at high RPM's. I do, on occasion, see smoke when I accelerate hard at wide open throttle from lower speeds, but it's not oil smoke. It's "fuel" smoke. If that makes any sense.

[1991shelby]

Well that sounds normal.
Except for the HEP. I would get that changed before it leaves you stranded some where. Plus that will rule out weak spark.

[boxcar]

My van had a similar problem, good power up to 4000 and then it would nose over badly. Turned out the cam timing was advanced one tooth.

[TonaChris]

Quote:

Originally Posted by mcaracter It was my understanding that the tiny hole in the end of the grainger is the orifice you speak of. If this is the case, then yes I had an orifice between the grainger and the wastegate. Actually, I'm using the gutted grainger as my orifice in the computer controlled set up. Sounds like I need to check my fuel and spark.

Im not sure a gutted grainger would be a small enough orifice. Im using about a .035" welding tip for my orifice in the map signal line.

[TurboDoctah]

hmmm keep the info coming, i have a very simular problem.. but mine i cant rev past 4-4.5k... sigh.

[impuresoul2k3]

turbodoctah have you checked ignition and cam timing, mine would max out around 4500, turns out my ignition timing was sitting at 0* BTDC to maybe 1* ATDC

[TurboDoctah]

Quote:

Originally Posted by impuresoul2k3 turbodoctah have you checked ignition and cam timing, mine would max out around 4500, turns out my ignition timing was sitting at 0* BTDC to maybe 1* ATDC

yep everythings dead on.

[86daytonaZ]

I had the same exact problem after doing a head gasket and turbo replacement in my 88 Daytona. I went over timing probably a good 20 times, dead on every time. Turns out i had a couple of leaky injectors and I couldn't hold decent fuel pressure under boost, the thing would hit a ceiling at 4000 and just sit there and buck. Replaced the injectors and fpr and I was good to go, until I spun a rod bearing lol.

[TurboDoctah]

hmmm i think imma replace my fuel filter.... its probably way past do anyways specialy since iv ran a couple tanks of E85.... its the only part i havent replaced.... litteraly.

[mcaracter]

Quote:

Originally Posted by 1991shelby Well that sounds normal. Except for the HEP. I would get that changed before it leaves you stranded some where. Plus that will rule out weak spark.

Well, it did leave me stranded about a mile from my house. I walked home in the pouring rain to get another car only to have it fire right up when I got back to it. I replaced the HEP the very next day and it starts more easily, idles more smoothly, and is all around much more drivable.

As for my original concern of the 4500 rpm brick wall, with all the changes I've made it has almost disappeared. It is now a random occurrance that I would say happens maybe about a quarter of the time. There have been several instances where I've comfortably revved to about 5000 + rpms. So, I'm still at kind of a loss. I know I still should check fuel pressure and such, but I don't have the necessary guages to do so.