Hypforlife32

iTrader: (5)

whats up guys, So i am having an issue with my car and cant seem to find it. its a 408ci, s484 setup in my 99 f body on e85. On 11lbs through a th400 the car made 716whp after about 2 pulls and 14 degrees of timing. the graph at a normal arch to it when boost built. We added 3 lbs of boost to abotu 14 psi. it made about 765 and the graph dropped off on a downward slope which my tuner and i both found extremely odd. He said it felt like spark blow out. We changed the plugs and turned the boost controller back off so its back to 11.5 lbs now which it was at orginally...now the entire way the car makes power is different. no more arch to the graph. it almost like flatlines in power and makes 588? and 570whp...I have no smoke coming from anywhere out of the ehxaust, not even a haze. no blow by or anything. I am kind of at a loss for words. Could any one shed some light as to what it could possibly be? I am personally leaning towards torque converter. The stall speed of the converter was supposed to be around 4500rpm but i cant get it to go past around 3400ish before it actually starts to build boost off the brake...I havent tried the transbrake before this problem actually occurred. Seems like an odd problem for sure. Thanks in advance!

ls3fox

Did you log the mph that would tell you if it did 140 on the first pull and now only does 120 you know the converter took a dump

Hypforlife32

iTrader: (5)

Trying to get my tuner to send me the good runs vs the flat line runs. Even though it should measure wheel speed. My speedo doesn't work in the car.

ls3fox

Yea you should be able to change it from graph by rpm to graph by speed

Hypforlife32

iTrader: (5)

I have been leaning towards the converter and when I pulled the trans the fluid that came out was pretty damn black. 150 miles of street time and couple hours dyno time. With trans cooler.

ls3fox

Yea when I first read it i thought converter

Hypforlife32

iTrader: (5)

Also when it originally made 11.5 lbs then the issue occurred. Turning the control back to off which was on 11.5 lbs before is now like 10.5ish. Almost like Load change? But not sure if it works like that in a turbo car.

6669camaro

iTrader: (1)

If not the converter, make sure you don't have a restriction in the exhaust, like a collapsed section of flex pipe.

Hypforlife32

iTrader: (5)

My exhaust is 5 inches and 3 -4 ft long lol. 0 restriction.

6669camaro

iTrader: (1)

I was taking about the pipes that are pre turbo. Do you have a flex pipe before the turbo? I've seen those collapse and kill power.

Hypforlife32

iTrader: (5)

Oh yes! I do. Hmm. Never thought about that. Would you see it collapse from the outside? Or an internal thing

6669camaro

iTrader: (1)

Usually you can't see it till you take it apart and look down the inside. The cheap ones are really know for collapsing. If you have an o2 sensor before it you can take it out and install a pressure gauge and see what you have. You should have very little back pressure like maybe 1psi. Just something else to check. and a little easier to check, if the converter is ok.

Hypforlife32

iTrader: (5)

I'll have to check. I do have an 02 sensor not far from the flex pipe at all. Actually very easy to access.

forcd ind

iTrader: (7)

Trans builders will usually tell you high stalls and dyno's are not a good match-my buddy tells me its one of the complaints they get, but its fine at the track-its a possibility you over heated the trans, but did you mont. trans temps
I have experienced intake tubes cols. also, and boost side pipes pulling under boost, then going back together-that one drove me crazy
You are making power though

Hypforlife32

iTrader: (5)

I am a firm believer in high stalls not making power on the dyno but when the graph changes usually there is an issue

Hypforlife32

iTrader: (5)

The trans shop called me back today and said the transmission is perfectly fine. he went through it and dyno tested it. All looked great. does any one have any other ideas of what it could be.

ls3fox

Did you have the converter checked?

Hypforlife32

iTrader: (5)

He said he doesn't think anything is wrong with it. But gonna charge me 285 to open and close it IF nothing is wrong. So he is gonna open it up

ken6881

You need a new converter guy. That's expensive to just cut it open and weld it back shut.

Hypforlife32

iTrader: (5)

Whats average pricing for something like that? Also it was a brand new converter when it went in. Sucks.