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Vacuum lines and gauge install Help to Newbs

Old 09-05-2008, 01:04 PM
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Originally Posted by ddnspider View Post
so correct me if im wrong,but now youre arguing its not the "correct" way to tune?even if it works?if you do it the "right way" and you have a good a/f curve and no issues with tip in/out then its ok.but if you do it the "wrong way" and have a good a/f curve and no issues with tip in/out then its not ok?sounds like semantics,but then again im no tuner.
Then why are you arguing this point???

The end result might be getting what you want, but your LYING to the PCM to get it. In most GOOD tuners eyes, thats is NOT the correct way to do it...
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Old 09-05-2008, 01:07 PM
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Originally Posted by thunder550 View Post
I didn't say the tune was wrong, I said that the tune had to be fudged to cover an improper hardware setup. Your tuner was working with what he was given, and sounds like he did a decent job. It will probably work very well most of the time too, but the key word there is "most". There is no way to tune around the fuel pressure spikes that you'll get from the pressure increase inside the charge tubes the the throttle snaps shut and before the blowoff valve has a chance to open to relieve that pressure. Normally it wouldn't matter, because if the FPR was plumbed into the intake manifold behind the throttle body it would not "see" this pressure spike. Maybe it's not a big enough issue for you to even worry about. If you're content with the way it runs, then by all means, leave it alone. I'm just trying to help out others who may read this thread.
fair enough.so would swapping the reference point either way then cause the tune to be off?
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Old 09-05-2008, 01:08 PM
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Originally Posted by kbracing96 View Post
Then why are you arguing this point???

The end result might be getting what you want, but your LYING to the PCM to get it. In most GOOD tuners eyes, thats is NOT the correct way to do it...
youre lying to the pcm?thats funny.so what do u call it when u max out a maf and only have to go on VE?
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Old 09-05-2008, 01:10 PM
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Yes, because you have incorrect values in the VE and MAF tables to cover for the incorrect FPR reference.
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Old 09-05-2008, 01:12 PM
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Originally Posted by ddnspider View Post
youre lying to the pcm?thats funny.so what do u call it when u max out a maf and only have to go on VE?
It reverts from using a correct MAF table to a correct VE table. If you go full SD, then your running off a correct VE table only.
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Old 09-05-2008, 01:14 PM
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Originally Posted by ddnspider View Post
fair enough.so would swapping the reference point either way then cause the tune to be off?
If you are already tuned to compensate for the higher fuel pressure when in vacuum, then yes, your tune would be off.

Originally Posted by ddnspider View Post
youre lying to the pcm?thats funny.so what do u call it when u max out a maf and only have to go on VE?
This would be called working around the limitations of the stock PCM. When you put a vehicle into speed density mode, you tell the PCM that the MAF has failed, so that it reverts to the VE tables for fueling. It's not the best way to do it, but it really is the only good way to have a stock PCM control a high HP forced induction build. As kbracing said, if your VE table is set up correctly, you're not "lying" to the PCM.
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Old 09-05-2008, 02:07 PM
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Originally Posted by thunder550 View Post
How many screenshots do I need to post to prove my point? The PCM can't predict what you are going to do. All it can do is react to the inputs that it's given, and while that doesn't take a lot of time, it does take some time. There will always be a delay in a system that is reactive. Notice in the screenshots below that the magnitude of the error is relative to the change in throttle position. The smaller the change, the smaller the error. The larger the change, the larger the error.

Lean spike on throttle tip-in
http://i217.photobucket.com/albums/c...der550/ss1.jpg

Rich spike on throttle release
http://i217.photobucket.com/albums/c...der550/ss4.jpg

Lean spike on throttle tip-in
http://i217.photobucket.com/albums/c...der550/ss2.jpg

Lean spike on throttle tip-in
http://i217.photobucket.com/albums/c...der550/ss3.jpg
Your tip in needs work. the logs are delayed and dont read near as fast as the ecu is working. the o2 is also delayed. here is a screen shot of one of my logs showing the exact opposite of yours. rich spike on tip in. this was before i had my tune right. unfortunately all my later, better logs and tunes were lost when my hdd drive died in my laptop.
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Old 09-05-2008, 02:17 PM
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Originally Posted by TrendSetter View Post
Your tip in needs work. the logs are delayed and dont read near as fast as the ecu is working. the o2 is also delayed. here is a screen shot of one of my logs showing the exact opposite of yours. rich spike on tip in. this was before i had my tune right. unfortunately all my later, better logs and tunes were lost when my hdd drive died in my laptop.
Unfortunately, there is no transition fueling tables that we have access to in the factory PCM, like I'm assuming you have in FAST Lean tip ins are almost a way of life with the factory PCM's.
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Old 09-05-2008, 02:26 PM
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Originally Posted by kbracing96 View Post
Unfortunately, there is no transition fueling tables that we have access to in the factory PCM, like I'm assuming you have in FAST Lean tip ins are almost a way of life with the factory PCM's.
maybe so, but my point is the ecu runs plenty fast enough to adjust its ipws no matter how fast you can open or close that throttle, with plenty of time to spare. just because the tuneup isnt right, doesnt mean its a hardware limitation.
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Old 09-05-2008, 02:49 PM
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i found an old HPTuners log from a car i was tuning in 05.

1 frame on the log is 1/10th of a second
it took ashley that long to go from 0% to 47% throttle
same time frame the ecu went from 3.5 to 12.5 ipws
log data is transmitted from the ecu at a fraction of the speed the data is collected, processed, and used.
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Old 09-05-2008, 02:53 PM
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i dont know who to believe,im so confused!!!!Trendsetter just proved that the ECU is quick enough to react.....and the other guy thought there was vacuum in the charge pipe
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Old 09-05-2008, 03:02 PM
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Originally Posted by TrendSetter View Post
i found an old HPTuners log from a car i was tuning in 05.
Well it looks like you're right about the PCM speed, but regardless, a spike in fuel pressure will cause the injectors to flow more than intended because unless you're in DFCO the injectors never shut off completely.
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Old 10-24-2008, 09:52 AM
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quick question, putting a line coming from where the old PCV port (on the side of the intake after the TB) to the side of the WG, is that still ok? i mean in theory it would be seeing boost when the TB is open. but once it snaps shut would anything happen to it?
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Old 10-24-2008, 01:52 PM
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Originally Posted by reject View Post
quick question, putting a line coming from where the old PCV port (on the side of the intake after the TB) to the side of the WG, is that still ok? i mean in theory it would be seeing boost when the TB is open. but once it snaps shut would anything happen to it?
that line would see vacuum when the throttle blade is closed.
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Old 10-24-2008, 01:52 PM
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would anything wrong happen?
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Old 10-24-2008, 02:40 PM
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nope,you should be good to go.
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Old 10-24-2008, 03:22 PM
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*mr burns voice from simpsons* ...."exxxxcellent"
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Old 09-10-2009, 01:39 AM
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why doesnt someone just call aeromotive and see where to reference it and end this discussion lol. Behind the throttle body sounds more logical to me though fwiw lol.
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Old 10-29-2009, 11:52 PM
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Default WHERE to hook small vacuum line in 98 ls1 camaro?

Hi,

I am installing a vacuum gauge in a pillar pod in my 98 Camaro z28. I have NO problem with mounting or any of the electrical connections BUT I can find NO small vacuum lines in the engine compartment to hook the small T and small vacuum line that came with the gauge. Every vacuum line I see is the 1/2" size, way too big for this little T. I'm an older guy and all the cars I've worked on always had the small vacuum lines in abundance. Can somebody PLEASE tell me where to hook the clear plastic tubing and T? Every thing I research simply says "fine a vacuum line and splice in the T. Easier said then done. Please help. Thanks Wayne
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Old 10-30-2009, 08:02 AM
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Wayne,
If you go to a place like Ace Hardware or something of that nature you can get a T fitting that has 1/2" line on 2 sides and a smaller fitting on the 3rd side. This will allow you to splice into the vacuum line and have all fittings tight.
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