Turbo spoolup upon start up

[Craigthenormal]

Hello,

I am new to posting here at dsm. I come to you with a problem that i cannot find simular symptoms to on other threads. the problem is i get the turbo spooling up as soona i turn the car on @ idle its about 0-3 psi boost not vacum, it runs horrible and stalls a lot, @ 1100 rps it is at 3-7 psi, @ 2000 rpm it is 12-14 psi. i will explain firther after i tell you more about the car. if you jsut want the problem skip to the LAST PARAGRAPH
The back ground of tthe car: it was complety stock
Its a 1990 talon tsi awd, i bought the car with a bad head( timing belt broke) I took the old head off, replacing the whole thing, along with the head i replaced water pump, starter, all belts, hedders(stock one).
After the 3rd attempt of timing it we finally got it right, its @ 4-6 degrees before TDC, w/o adjusting the CAS.
About the problem:
When first rebuilt, i had a slight missfire with rpm over 1500 rpm, but the turbo did not spool up until 3-4k rpm range, when at idle then i had a vaccum of 7-9 ( dont know if that was psi or hg, it said 7 on the stock gauge).
The problem came the next day we went to start it and as soon as i turned it on , we heard a winding and i looked at the gauge and we had boost.
All the lines are tight and sealed, turbo is still good, wategate moves. I then replaced the BOV becouse it wasnt functioning after i ran vaccum tests on it. that didnt fix anything. the new BOV vented into the atmosphere, so i didnt have the return line, i forgot to plug the hole.
That solved my problem no more eirly turbo spooling! but as soon as i plugged the hole it started to spool. My next thought it must not be getting enought air, i got the air intake set up, 3" intake pipe, filter, and GM MAF, thikning it was an air obstrubvtion some where in the old box. Installed the new components, boost porblem still there. Then went and replaced enbtire exaust... that didnt need to be done but i wanted a new exaust. it is a 3" apexi, from down pipe to the tip.

After replacing all the parts, intake, exaust, and BOV i still ahve the problem, The Turbo is spooling up at idle and running horribly like only 2 cylinders are firing, it didnt spool when i had the BOV return line cap was off on the intake. please help.... if you can send pictures, if not i'm happy with words. oh yeah i ordered a new boost controller, i didnt know if the stock one was bad could have caused it.

 

[mnexcited]

I dont understand why you think installing a boost gauge is going to fix the problem. Also a boost gauge should be tapped off your Fuel Regulator Selinoid. Check your time belt specifically the exhaust side.

 

[kronus]

*resisiting urge to say something stupid*

your ecu cant leak... its a peice of bread board with stuff on it. its a little computer. its electric. im not sure what he means about leaking caps, but i would run a boost leak check if you havent yet. also, the sound you hear at startup might be some sort of leak in your intake tract, not the turbo. definately worth looking in to.

Ummmmmmm, careful...

Taken from vfaq.com

"What is an Electrolytic Capacitor?

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A capacitor is generally used in an electronic circuit to filter out unwanted signals. The electrolytic capacitors in the DSM ECU are used to filter the power supply. An automobile is an extremely hostile place for electronics. The output of the alternator isn't all that pretty to begin with. Couple that with the spark plug high voltage firing, the radiator fans, the interior fan, turn signals going on and off... the +12VDC main power line gets a lot of crud on it.

Which capacitor to choose? There are a lot of different types out there - some large, some small, some really accurate, some "cleaner" for low noise applications, etc. For power supply filtering, electrolytics are almost always used. Power supplies generally require a large capacitor to absorb spikes and dips. You can't afford not to have a steady power supply line inside of a computer - the microcontroller might act erratically or reboot. Electrolytics are chosen because they provide a lot of filtering for their small size. They are also very cheap.


--------------------------------------------------------------------------------

The Problem
Electrolytic capacitors do have a downside, though. They tend to leak with age when exposed to heat and many power cycles. The electrolyte that leaks out is very harmful to PC boards. It can actually eat the copper traces, eventually making a short on the board. When that happens, the ECU will either stop working altogether or act very erratically. As the capacitor leaks, it will also lose its filtering properties, allowing possibly harmful spikes into the ECU.

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"

Yeah, the little cylinders that are circled; those are caps. They do leak. Check VFAQ for the rest of that.

-Kevin-