Rotaryrockstar

My list of current mods for reference to symptoms
10th AE
Racingbeat Downpipe w/ Presilencer, 50 mm catback
Vac spider/AirPump/ACV/EGR removed, retained twinscroll and Hotstart assist
Injectors serviced by Marren, 3000 miles and 1 year ago
MOP removed and pre-mixing (OF COURSE!)

It's long but, thanks for your time!


Hello again! I just today reassembled my cars internals after monster porting the wastegate. (30mm!) I did remove the hotside during the procedure. This also was the 1st time I dissasembled a turbo. All seemed well with the reassembly, so I am not worried there. When all was back together I started the car, had a coolant leak on the block side of where the line runs from the passenger side of the turbo to the underneath of the (blocked-off) split-air pipe port. While replacing the gasket there, it leaked coolant all over the turbo and exhaust manifold and downpipe.

The wastegate porting; I did myself, with a dremel and a tungsten carbide bit. LONG job, but I got it nice and smooth inside the port however, trying to get the surface where the "flapper w/welded washer" meets the rear of the assembly, wasn't quite as smooth as I had hoped for, consequently, I don't think it seals perfectly, thought not totally bad either.

So, car warmed up and no apparent leaks, the idle was different, it was
"galloping" sparattically between 1000 and 1250 rpms. Not the usual rythmic surging I used to have on occassion. (The last time I tested the BAC valve it was .8 over spec.)
Going down the road some, I stopped at a sign. 1st gear up to 4k, fine... I shift to 2nd and it revved fine for 600 rpms and then it "burped and cut-out" for a second and then resumed 1/4 throttle acceleration as normal. It has NEVER done this before, and I have no idea what that was. 1 mile later, I turn around to come home and go WOT with no problems, acceleration didn't feel any different than what it was before the wastegate port, except maybe just a little slower. I guess it could be increased lag from the imperfect seating of the WG flapper. Just a guess, I am new to this stuff. Also what I experienced during the drive is, the car felt like it was uncomfortable when decelerating in gear... In the way that, there was signifigant popping in the exhaust. My HANES manual reffered to this as "afterburn." Does that sound right?

Finally, I parked after about a 10 minute test drive and there was a good amount of smoke coming from some unsee-able place in the center of the motor and a little towards the passenger side. At first, I panicked and thought it was the fuel pulsation dampener, but there were no flames (thank god!) and the smoke was white, smelled sweet and burned my eyes pretty good. Must be coolant. The smoke "puffs" seemed to be rythmic, indicating a drip perhaps. The only leak I can imagine is that maybe it's the coolant line on the OTHER side of the turbo and it's dripping somewhere close to the exhaust manifold.. Which means take the whole damn thing apart again right?

Last thing. I did not adjust the TPS and throttle cable after reassembly. I used to check the TPS on my old n/a using the LED method all the time. I have a set of LEDs and for the life of me, cannot find the plug to connect them to on my 10th ae!
Could the BAC,TPS and throttle cable be causing this weird popping and rough deceleration and idle? Or is it the wastegate port? *GULP*

Thanx much! Any input would be greatly appreciated!

RotaryEvolution

iTrader: (30)

why would you need to port it 30mm on a stock turbo? that is stage 2 hybrid territory and even a properly ported wastegate wouldn't need to be ported even that large.

my best guess is with the much larger flapper the exhaust is bouncing the flapper door forcing it's way out bypassing the turbo causing the erratic idle. if this is the case then you would need to alter the rod length to put more tension on the wastegate arm from the actuator.

this is the only thing i can think of if it wasn't doing this before the porting. however it isn't exactly an easy repair so i would check out anything else you may have touched while removing/installing the turbo inclduing double and triple checking the idle settings, TPS and timing.

Rotaryrockstar

All the threads I read on porting the s4 waste gate indicated that even with a port as large as I have it now taht they are still prone to boost creep, potentially to dangerous levels. No where was it indicated that one could "overport" the s4 wastegate.
Wouldn't it require boost to actually push the flapper open? I mean, its still attached to the actuator, is the exhaust really pushing that hard at idle?

NZConvertible

If the wastegate isn't sealing properly, boost will build slower. But you're probably also running less boost now because of the bigger wastegate port. That's the whole point remember? You don't mention any before and after boost numbers. I hope you have a boost gauge...

Don't **** around with the lights. Use DMM on the TPS plug. Aim for 1V across the brown/white and black wires.

Because it completely cures boost creep. There is no reason not to do it, and you're set for pretty much any future intake and exhaust mods.

There is absolutely no way a leaking wastegate can affect idle quality.

RETed

Wow long story...

Engine has trouble holding idle implies intake vacuum leak most of the time.

Adjusting the TPS would eliminate one potential problem.


-Ted

Rotaryrockstar

My wife wont allow me the money to get anything else for my car right now! :P
I had a serious exhaust leak right at the turbo, plus I could hear my boost blasting somewhere all over the engine bay. In short, I took everything apart to fix those things. I figured porting was cheap and needed to be done regardless of my lack of decent gauges. Allof my budget thus far has been to make the car safe to drive. I had to get a clutch and clean the injectors and all that jazz. Positivly the next thing I will do is get an aftermarket boost gauge. I am dying to know what I am making.
But as far as the afterburn and popping noises, you think thats a vacuum leak?
And where is the TPS checker plug? I know its dumb that I can't find it.

Rotaryrockstar

One more quick question... Can I run the engine with the intercooler disconnected to check for vacuum and coolant leaks? I thought I saw a guy do this before... Ifso how would I go about that? I'd have to plug some holes with towels right?
Thanx...

NZConvertible

Don't bother with it. Use a DMM on the TPS plug instead like I explained before. It's far more accurate than the lights.

Um, NO!

And then how would air get into the engine?

What you probably remember seeing is someone replacing the IC with a temporary connecting pipe. You can make one of these easily with PVC pipe. It's suitable for idling and even gentle driving. It makes throttle-related adjustments much easier.