[mattk408]

Hello all,

I have a question that I am sure all of you can answer.... I own a 1991 Stealth Twin Turbo AWD with 67k miles and am looking to buy a blow off valve. I was wondering where the (stock) blow off valve is located. Is the stock blow off valve called a wastegate? If not, what is a wastegate? Also, I am experiencing lag at the high end that I especially notice when in the high end of 1st and 2nd gear....can anyone help me with suggestions on what to check? I had the wires/plugs changed about a year ago, am currently having a water pump and timing belt installed, just had a rebuilt tranny in it, new clutch, new borla exhaust, HKS boost controller, new left front intercooler, and GT1 18" wheels (check out the attached picture!) ....PLEASE HELP! It's really weird too, because the lag at the top end doesn't happen all the time....when it does, it sucks! Please help me out....I do not always check the message boards here, so I am in dire need for you guys to email me! My email is [email protected]. Thanks!

Matt
Valparaiso, IN

 

[blkstealth]

Hmm, could it be fuel cut? If you have a boost controller I believe it's possible. I do NOT own a turbo (yet) but maybe I can help you.

In all of the pictures that I've seen of the turbo engine bay, the BOV is located off of the Y-pipe (which is connected to the intake) on the left upper portion of your engine. I don't know what a stock one looks like, so I can't help you there.. I'm guessing its a black rubber piece that is kinda conical-shaped. It should hook into a nipple (hehehe) in the Y-pipe.

As far as a wastegate goes, I don't know how one works, but a wastegate is the stock boost controller in a sense, i believe it allows so much PSI of pressure to bleed out (9psi stock for 1st gen), and aftermarket boost controllers basically manipulate the boost from the wastegate (am I correct? please don't flame, im a turbo noob)

 

[billvp]

your car looks nice


The stock blowoff valve (bypass valve actually) is off a hose that comes out of the black rubber piece (that has a split off to each side) that is after the airbox/intake.

The bypass valve is not the wastegate. The wastegate regulates the amount of boost that the car uses to make extra power, and anything over that amount is bled off. The bypass valve just stops boost from being forced backwards when the throttle is closed (and therefore there is nowhere for the boost to go) and the turbos are still spinning out boost.

You did not say what boost you are running. If you do not have an aftermarket boost gauge, then get one, as the stock one is not accurate for boost. Did the problem with high rpm power start since the boost controller was installed or before that? If it is just since then, your plugs may need to be gapped down to around the 0.32 range.

 

[mattk408]

Here's my reply

Hey guys,

I believe I am running the stock amount of boost (9psi?) and yes, I do have an aftermarket boost guage.....I haven't driven the car in about a good month, due to back in July a technician at a local tranny shop, went 60mph in it around a turn and wrecked it! So, it has actually been in the process of getting fixed all since july! Now, I have a guy replacing the wate rpump and timing belt due to a nasty coolant leak (was the water pump). Maybe I can have my guy check the gap on the plugs as you suggested....anything else? The lag at the top end is really annoying and prevents me from getting that "go-fast" feeling everytime.....it really is a drag because it doesn't happen all the time - only about 60 percent of the time.....could it be the plugs? Can I regap my current ones? I do notice that with the boost controller active, the lag is present all the time...... I am not even sure what model HKS boost contorller I have...It was in the car when I bought it....all other stuff I did....anyways, I am trying to get info on the boost controller, but can't, due to it being mounted in the glove box, with no show of stickers/tags for the model number.......it has Low/High/Manual buttons, along with a dial to the right of the buttons that requires the Manual button be pressed in to use......please help if you know anything about this boost controller, and if so, what are the settings for (Low/high/Manual)? Forgive me, but I know little about these cars and am learning daily! Please let me know!!

Matt

 

[blkstealth]

Go here to see what boost controller you have:
http://www.dynamicracing.com/customer/home.php?cat=4&PHPSESSID=de0f938b3c3da72296b949547c76e28c

You should be able to tell by the picture. As far as how to mess with it, use the search feature up top.

Your problem sounds like spark blowout, which happens when your plugs aren't gapped low enough.. you need to regap them down to .032 as someone else has said... check them, though.. you may need new ones. Do a search on spark blowout and you will learn a lot..

 

[ReaperTT]

Matt, I noticed that you're in Indiana. Could you point me into the direction of the shop/mechanic that rebuilt your tranny? I have a '92 that needs work, and it's hard to find one here in Cinti. Also, how much did he charge (parts and labor)? Thanks.

 

[EVILTWIN]

If your car is still equipped with stock turbos, they do not hold boost all the way to redline. This may be what you are feeling, and it may not. Usually after about 5000/5500 rpms, the boost will drop down a tad. So if your boosting around 12psi, it will drop down to about 10ish after 5500rpms.

It could be because the boost is too high for the plug gap, requiring you to re-gap the spark plugs....some people get away with not having to when boost is raised, others have to.

If your not familiar with the boost controller you have, I'd suggest you read up, and educate yourself on how it works, and how to tune it. You don't want to go blowing up an engine because the controller is dialed in improperly. Too much boost on stock fuel system can be extrememly expensive.

If you havn't found the BOV from what others have told you, try tracing the rubber hose near the Ypipe, that leads down beneath the Airbox/filter. It should be right there.

Here is a great site to get you started. www.stealth316.com
You will find the do's and do not's, as well as maintanace tips. Lots of upgrades, with how to's and pictures to help you along.

Enjoy your new ride when you get it back, and boost safely!

 

[mattk408]

Update........

Thanks for the pics and info, guys! I am curous as to how long it would take me, a novice on engine work, to replace a blowoff valve, or if you think I shouldn't even attempt it myself? Let me know.....Also, what would you suggest I get for my car as far as a blowoff valve?? I forgot to say also I have an HKS Dual Intake Air Inlet System (Dual green air filters), so I believe the blowoff valve should still be in the same spot as your pics, correct? And you said .32 on the spark plugs, right? Any suggestions on new and a good price??

Matt
Valparaiso, IN