Running lower PSI than tuned for...

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Boostian

Member
Joined
Jul 8, 2013
Messages
616
So I just picked up my Turbo T from a buddy of mine and was going over all the documentation that came with it. I know the whole history of the vehicle and when driving it, am only getting to 12psi max. In reading the receipt that came from Turbo Tweak (v5.7 chip), the "Intended Max Boost with THIS chip" is listed at 18psi. All the other items listed in the tune are correct.

Assuming I have all the supporting mods already to go to 18 (and looking over the docs, I seem to), is there a downside right now to running it at 12 (i.e. too rich a mix)?
 
No harm. Just be rich & not get the full potential of the setup. Is the wastegate rod adjustable? Sounds like either the stock non adjustable rod or the previous owner has no tension on the spring if it's an adjustable.

One more question. Aftermarket boost gauge or stock disco lights? Be positive it's only getting 12 psi before you try to up it any more.

Posted from the TurboBuick.Com mobile app
 
Sign says scanmaster.. so you can turn the boost up and make sure you dont see any knock.

All the mods and keeping the boost low.. no problem. But why mod it to keep it slow?
 
And from what I learned before, if you are running less boost than the chip is programmed for, you will run rich. It's also possible to get knock when running too rich as well. Whenever you go WOT, the injectors are spraying for the boost set in the chip.
 
No harm. Just be rich & not get the full potential of the setup. Is the wastegate rod adjustable? Sounds like either the stock non adjustable rod or the previous owner has no tension on the spring if it's an adjustable.

One more question. Aftermarket boost gauge or stock disco lights? Be positive it's only getting 12 psi before you try to up it any more.

Posted from the TurboBuick.Com mobile app

The rod is adjustable (threaded), I'm just not comfortable doing it myself just yet. I'm still reading and absorbing about preload and all that. Also have the SM and am getting zero knock at wot but my buddy said it does appear to be runnin rich when you drive behind the car and I get on it. The MPG is also very sub par.....driving in boost or just cuising I'm getting like 8 or 9

I know the car was set up right when it was initially modded because I know and spoke with who did it (Jim Dunn). Guess the next step is to fig out the wastegate and slowly add boost an watch the knock

Aftermarket boost gauge. Don't have one on my stock dash



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If its threaded, its the easiest thing you could do on your own. I wasn't comfortable either. But I promise its super easy. Take the clip off thats holding the arm to the flapper, pull arm off and shorten the rod. I'd say shorten the rod about 2-3 complete turns. That should put you at approximately 15. Thats the easiest adjustment you can make IMO. No point in riding around at 12 lbs of boost. But to each is own i guess. The gas mileage isn't effected by this. There is something else going wrong if you're getting MPG that low.
 
And, the O2's at WOT will tell you if you're rich, not someone behind you when you get on it.;) Thats the point of having the scantool in there.
 
Havent paid a ton of attention to the O2 readings to be honest. was mainly focused on knock and coolant. What should the reading be around? Ive watched videos on how to set the wastegate and all that, but none of them clearly showed how the turns affect the boost after preload is set.

Im mechanically savvy, I just never jump into anything myself that im not 100% sure is correct.
 
One turn on the rod is usually around one pound of boost. The Scanmaster will save your O2's and knock in memory if you go WOT for around 3 seconds. 12lbs of boost is a very safe tune. Your car will start to come alive as the boost number increases. Heck install a alky kit and get the boost up around 28psi and report back.:p WOT O2's should be around 790 or higher if you want to stay safe.
 
One turn on the rod is usually around one pound of boost. The Scanmaster will save your O2's and knock in memory if you go WOT for around 3 seconds. 12lbs of boost is a very safe tune. Your car will start to come alive as the boost number increases. Heck install a alky kit and get the boost up around 28psi and report back.:p WOT O2's should be around 790 or higher if you want to stay safe.


Thanks for the info. Id like to up the boost to where the chip is for now. I do plan on doing akly down the road but thats not for a while yet. I need to get used to the car, learn her quirks, and def want to do a steering rack before making it too too fast.

So basic idea is one turn (shortening) the rod is about 1psi? I can work with that and monitor how the car reacts.

Also, just to verify, im pretty sure that once you have the end of the rod where you want it, you snug that nut up to it, correct?

Thanks again.
 
Yes, this is correct. Whatever's holding the arm to the flapper, put it back. I forgot to put my mine back, and low and behold the arm of the WG fell off.:mad: i had to install my non-adjustable back on there. Keep in mind, that you might see knock at 18lbs of boost on just 93 at the top of 3rd gear. Each car is different though, so you might get away with it. See how it goes and keep us posted.
 
Ok I did 5 full turns in hopes of seeing 17 psi. Did a few WOT runs of at least 3 seconds. Boost only went from 12 to 13-14. Saw 14 max. In checking the SM my o2's were at 792 and 3.0 for timing. I felt it hesitate a little as the retard number on the SM started moving. I guess it peaked at 3.0 cause I only saw .9 when I was watching it.

Any reason for this? (Thanks for the help by the way. My wife was wondering why I wanted to tinker with the car at 7:30am after I just got of work)


Posted from the TurboBuick.Com mobile app
 
I'd verify your boost gauge is reading correctly. It wouldn't be unheard of to get knock at 14 psi with 93 octane, but it is unusual. If your gauge checks out correctly, lower the boost. Don't continue detonating it.

No knock is good.
Any knock is bad.
Any knock is bad.
No knock is good.




Posted from the TurboBuick.Com mobile app
 
I'd verify your boost gauge is reading correctly. It wouldn't be unheard of to get knock at 14 psi with 93 octane, but it is unusual. If your gauge checks out correctly, lower the boost. Don't continue detonating it.

No knock is good.
Any knock is bad.
Any knock is bad.
No knock is good.




Posted from the TurboBuick.Com mobile app

Im looking around (no luck searching on this forum really, found some typical BS online) and found people saying to test it with an air compressor? But that would only be as accurate as the gauge on my compressor. Is there a way to completely accurately test it? Its a relatively new Autometer Phantom....

I should probably check the fuel pressure also.
 
Definitely check the fuel pressure. I personally don't see you getting knock at 14lbs of boost with the timing as low as it is in the TT street chip. Bring the boost back down until you can verify the fuel pressure rising with boost 1-1
 
I wouldn't be surprised to see that your fuel pump is possibly going south (possible due to the Walbros having a bad batch at some point) which will explain why the boost was turned down so low when you got the car. Keep us posted.
 
Yea I'm gonna drop it back down to what it was until I can check the fuel. It's also 100* in Philly right now. Def don't wanna screw with it running well when it's this hot.

Anyway to check the boost gauge?


Posted from the TurboBuick.Com mobile app
 
Only if you have an air compressor. I think your gauge should be fine though. Get a fuel pressure gauge that reaches the windshield, and varify your fuel pressure is rising 1 to 1 with boost as its suppose to do
 
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