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Discussion Starter #1
I have been searching and searching for the last two hours and can not find an answer to my questions. I have Stage 1 PCM, AGP WGA, and Hallman MBC. I want to raise my boost up, without causing the car to go on the defensive. I have read about lots of people thinking 18 is the max on stage 1 without MAP clamp or extra fuel. But no one can say yes, I have monitored timing and anything above that will cause pulled timing. So here are my questions. If you answer them please number them as I did so I know which one you are refering to. Thanks

1. What is Most you can spike on Stage 1 PCM, with no MAP clamp or other tuning?

2. What is the most you can hold to redline on same setup?

3. If you do spike higher than what the MAP can read does that instantly put it into a safe mode with retarded timing and extra fuel, or does it only happen if the MAP is maxed out for a certain amount of time.

4. What is the best amount of boost to run on same setup considering timing being pulled, extra fuel, and other variables that are affected when you go higher than what the MAP can read and go into a safe mode? e.g.(Set to 20 spike falling 16 at redline vs. 18 spike falling to 15 at redline. Which will give the best power?)
 

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spike 18 hold 15 most cars I've tuned have been at 11.5 +/- with stage one but every car is different.stock map will not see anything higher than 18.5 psi
 

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Discussion Starter #3
SRTNOOB said:
spike 18 hold 15 most cars I've tuned have been at 11.5 +/- with stage one but every car is different.stock map will not see anything higher than 18.5 psi
Ok. Thats about what I've been hearing. SO say I spike 18.7, is that going to cause the PCM to go into safe mode? If I only spike for a split second at 19 and fall to 18 instantly is that ok? I'm trying to figure out how tempermental the PCM will be if you peg the MAP sensor.
 

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Discussion Starter #4
Bump for answer about how sensitive the Stage 1 is before it goes into a safe mode.
 

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You can boost as high as you want,My car is tuned to spike at 21psi but I tune with a wideband so I can see exactly where a/f is at.It all depends if you have things running on factory lines/tip sensor still hooked up...The computer doesn't care how much boost you run as long as it doesn't see it...
 

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exactly, buy a wide band and keep it in the mid to high 11s (air fuel ratio) and you should be straight.
 

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Discussion Starter #7
Ok. I just had an idea, but I need to know exactly how a MAP clamp works. Does a MAP clamp constantly modify the voltage signal being output from the Sensor or does it keep the voltage from going past a certain point? My reasoning is this. Lets say I want to raise my boost right up to 18-19 lbs, but I don't want the computer to go crazy if it spikes a little past 18.5. So If a MAP Clamp works how I'm thinkin it works(won't let voltage go past a certain point), I could install the CLamp at stock setting, Hook up MY Genesys Data Logger that allows me to see the exact boost level the PCM sees, adjust my boost(via WGA & BC) to where it is right at 18-19 lbs. Then adjust my MAP clamp to clamp at 18 lbs(the Clamp won't let voltage equal to 18.0 or higher through to the PCM) and then I would never have to worry about it seeing more than 18.5(which it can't see anyways). Plus this would be safe because I'm only boosting about .5-1 psi more than what the computer thinks. This could be my easy way of getting 19 psi until I can get to a dyno with a wideband. Does this make sense?
 

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Boosting that high will also cause the PCM to pull timing. Map clamp with fuel return line will get you the best results. Really if you think about it. Even the more you turn up the boost the PCM counter reacts by pulling timing.
 

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Discussion Starter #12
Ok Aaron. When I deep fry my turbo I'm holding you responsible. :ben: Just kidding. I plan on doing the PTP FPR mod, and MAP/TIP clamp tuned on the dyno. I also know that the computer pulls some timing at 18 psi, but not as much as when you peg out the MAP sensor and cause the PCM to go into a safe mode. The only reason I am pressing this issue is because of how variable my MBC is when I get on it. IF I punch it at 3000 rpms in second gear it will spike all the way up to 18 lbs then fall to 15 at redline. But if I punch it at 3500 rpms it only spikes to about 16.5 and falls to 15 redline. So, can you understand now, why I want to make sure the PCM can't see past 18? If I do that then I don't have to worry about pegging the Stock MAP sensor with an unexpected spike to 19. Aaron, does this make sense to you. I know I need fuel and tuning, but this is just for now until the FPR mod comes and I can get to a Dyno. If my MBC didn't fluctuate so much I wouldn't worry about this, but it does, so.....
 

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Bflaker said:
Ok Aaron. When I deep fry my turbo I'm holding you responsible. :ben: Just kidding. I plan on doing the PTP FPR mod, and MAP/TIP clamp tuned on the dyno. I also know that the computer pulls some timing at 18 psi, but not as much as when you peg out the MAP sensor and cause the PCM to go into a safe mode. The only reason I am pressing this issue is because of how variable my MBC is when I get on it. IF I punch it at 3000 rpms in second gear it will spike all the way up to 18 lbs then fall to 15 at redline. But if I punch it at 3500 rpms it only spikes to about 16.5 and falls to 15 redline. So, can you understand now, why I want to make sure the PCM can't see past 18? If I do that then I don't have to worry about pegging the Stock MAP sensor with an unexpected spike to 19. Aaron, does this make sense to you. I know I need fuel and tuning, but this is just for now until the FPR mod comes and I can get to a Dyno. If my MBC didn't fluctuate so much I wouldn't worry about this, but it does, so.....

Real easy. ditch the MBC. Set the WGA to 18psi holding 15-16. Set the map clamp to 4.6 volts and call it a day. Then when you add the FPM, adjust as needed. I would still check everything with a wideband. The settings should be fine, but you never know if something isnt working correct.

If that doesnt work....boost 30psi :thumbsup:
 

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Discussion Starter #14
Real easy. ditch the MBC. Set the WGA to 18psi holding 15-16. Set the map clamp to 4.6 volts and call it a day. Then when you add the FPM, adjust as needed. I would still check everything with a wideband. The settings should be fine, but you never know if something isnt working correct.

If that doesnt work....boost 30psi :thumbsup:
Thats the answer I was looking for. Believe it or not I was thinking about doing exactly what you said, but I wasn't sure if I wanted that much PTB. But, I think I could live with it to make consistent boost levels. I will data log just to watch timing, and the actual MAP SIgnal just to make sure, and then as soon as I can get up to RevItUp I'll get it on a dyno. Thanks for the help, as usual, Aaron. :thumbsup:
 

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You need a wideband before really cranking it up at all. AFR is relative to outside air temp. The colder it is the leaner you are, just as hotter=richer. Your probably safe at 18psi but get a wideband and watch as temps change and you will be suprised how much of a difference it makes. Midrange rpm is where it will be the richest, redline is what you need to worry about. My car drops to 13-14 by redline and it goes around 11.9-12.5, depending on temp of course. If your going to tune your car get a wideband first, don't tune it on a dyno and leave it that way. Otherwise you might end up like my brother's broken FD!
 
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