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Old 02-16-2009, 02:45 AM   #1
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Default Anyone running low boost

This may seem like a dumb question to you guys, buttt are turbos running stock wastegates supposed to boost to a certain point (from 3k to 4k for me) and then just stop accelerating? It feels as though when it reaches that point the car is being held back and accelerates less than a naturally aspirated miata would at 5k RPM. I do have a manual boost controller installed but turned down (I'm still trying to run through all my 87 octane and not trying to blow up my car 40 miles from home). I have only just installed my first turbo, so I don't quite know what a low psi turbo'ed car is supposed to feel like, but my friend's evo seems to accelerate all the way to redline. I know thats a big difference but thats how I assumed all turbos would feel.

Because there is a constant increased pressure when the turbo has reached its peak, there shouldn't be any decrease in acceleration, only a stop in increase in acceleration, right? The only way I'm thinking this is possible is if my fuel is maxed out, or if there is a leak in my intercooler piping that somehow gets worse at higher RPMs and fixes itself at low RPMs. I am still running stock injectors and fuel pump but stock wg psi. If thats just how turbos somehow work or if anyone has any ideas, please enlighten me. Thanks in advance.
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Old 02-16-2009, 02:53 AM   #2
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Whatever you're doing just stop driving it until it's sorted out, **** is definitely not running right. Are you even running a wideband? What are you even boosting at? And drain that 87, shame on you.
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Old 02-16-2009, 02:55 AM   #3
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your car is not running right.
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Old 02-16-2009, 02:57 AM   #4
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You should have had 91 in the tank when you installed the turbo, tsk tsk.

Give us some more specifics, starting with what you consider to be "low" boost. FWIW, your friend's EVO runs at least 19 psi, so don't expect to get that same feeling on the stock injectors.
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Old 02-16-2009, 02:59 AM   #5
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no wideband, no gauges yet. I got eager. why would this happen though? I won't be taking my car to a shop so I'm trying to diagnose it and figure out a way to fix it within the week.
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Old 02-16-2009, 03:02 AM   #6
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uhh low boost as in whatever my T3 50 trim stock WG psi is. I believe it came from a 1970's volvo? I could give you specifics about the part number and such if necessary by tomorrow.
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Old 02-16-2009, 03:06 AM   #7
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so it is running great except that at 5k rpm it feels like it just hits a wall?
A few questions:
1. What modifications have you made to your fuel system? From what it sounds like, you have not made any changes at all. That is no bueno.
2. What modifications have you made to your ignition system?

From what I can tell, if you have stock fuel system and no rising rate FPR installed, then you are running out of fuel up there and bogging from being too lean. Dangerous situation, motor could get fucked up doing that.
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Old 02-16-2009, 03:08 AM   #8
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Jesus dude, most people are at least a little cautious about diving right in to the boost, not you apparently. No boost gauge, no wideband?

Part numbers won't help, no one can tell you what psi you're running based on that. Get some gauges so we at least have something to go on. In the meanwhile, get that crap gas out of the tank, check for exhaust leaks and boost leaks, and make sure your fluids are new and that your other maintenance (such as fuel filter) is up to date. I'm guessing (hoping) you've undone the timing bump in your sig?
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Old 02-16-2009, 03:09 AM   #9
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Quote:
Originally Posted by thmharada View Post
uhh low boost as in whatever my T3 50 trim stock WG psi is. I believe it came from a 1970's volvo? I could give you specifics about the part number and such if necessary by tomorrow.
Ok dude, you are on track to ******* up your car seriously with that sort of lax attitude toward the whole thing. Answer the questions i posted above please and we can go from there. Don't drive it in boost anymore until we figure it out.
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Old 02-16-2009, 03:13 AM   #10
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i bet there is no fuel management
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Old 02-16-2009, 03:16 AM   #11
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oh god here we go....if you dont have proper fuel/timing management and are running "whatever wastegate pressure is" on stock injectors with no knowledge of boost or afr's, give yourself a swift kick in the stomach. if you are you need to let us know exactly what you're running
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Old 02-16-2009, 03:19 AM   #12
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so it is running great except that at 5k rpm it feels like it just hits a wall?
few questions:
1. What modifications have you made to your fuel system? From what it sounds like, you have not made any changes at all. That is no bueno.
2. What modifications have you made to your ignition system?

yes, that's the feeling exactly. Sorry, I have a 12:1 vortech FPR. I have NGK blue wires and iridiums.

I have, of course, retarded it to 8. If I've been 87 octane and not knocking with my timing for the past 45 miles, I should be getting away with it. The gauges are currently being shipped to my house. I have replaced all fluids and checked for leaks, 5k miles on the fuel filter. I was a ridiculous and outrageously reckless for having driven the car right when I got it running, but I'm sure you all know the feeling. I do however, know how to maintain my car correctly and have adequate skills and experience, despite my age. not trying to brag, just trying to provide a little more background information

Thanks to everyone for the warnings though
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Old 02-16-2009, 03:22 AM   #13
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guys, could this be a need for an O2 clamp?
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Old 02-16-2009, 03:28 AM   #14
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Most people on stock injectors retard to 6*, run whatever premium is in their area, and have a boost gauge at minimum so they at least know if they're on target or not. It seems like you need to learn to be more patient. No one mentioned anything about your age, but frankly I'm not shocked. Just calm down, keep out of boost for awhile, and no one's engine gets hurt.
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Old 02-16-2009, 03:33 AM   #15
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thanksthanks. but does anyone have any ideas on the diagnosis?
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Old 02-16-2009, 03:48 AM   #16
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You don't have so much as a boost gauge and you want us to diagnose why your car is falling flat on its face? You must be joking. Get a wideband and a boost gauge and spend some time reading the Useful Posts section here, and you'll learn enough to diagnose your own car.
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Old 02-16-2009, 11:05 AM   #17
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Phone conversation:
"Doctor I have a terrible headache! What is wrong with me?"

"Are you running a fever? Did you hit your head? What's your blood pressure? Are you taking any medications? Do you have any other symptoms?"

"I can't tell you any of that, Doc, but you've got to help me."



No gauges, no answers, too many questions, no way to know.
Park it until you equip it with proper diagnostic tools. Wideband o2 sensor is a minimum requirement for a DIY.

And FYI - you typically won't hear knock with the top down.
It will already be too late when you figure out that you've had it.
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Old 02-16-2009, 11:20 AM   #18
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Diagnose your car. Ditto to all the advise given. Nobody on this forum knows what's wrong. You need to get a wideband and boost gauge. Swap in a new set of plugs gapped at 0.020", new wires, and begin diagnosis. Also check fuel pressure.
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Old 02-16-2009, 01:56 PM   #19
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You really should get some kind of engine management. You're being a little over confident in your skills and in the end it's going to trash your motor. Either your ballsy as **** or just ignorant when it comes to this stuff. You really shouldn't have even installed the turbo until you've read all the essential information. Wait for your gauges before you mess with it anymore.
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Old 02-16-2009, 02:01 PM   #20
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Fail Points:

1> Lack of gauges - you can't troubleshoot without useful information (boost/wideband)
2> 87 octane - You can't be serious.

Change these above mentioned points, and you'll get some useful posts.
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