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Boost question

Old Oct 21, 2007 | 06:24 PM
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Default Boost question

Hopefully someone will have an answer for this question, it's a little different.

I just got the car back on the road (APS twins). I am running 10 lb wastegate springs.

I took the car out the first tuning session today and noticed something strange.
When I go WOT the boost gauge (manifold referenced Autometer mechanical) shows 10-11 psi. The MAP sensor shows ~145 kPa, which is about 6 lbs of boost.

I'm thinking the Autometer is wrong, and I have a boost leak somewhere. But on the other hand, the car is using lots of fuel and making good power, 75 % DC on the 60 lb injectors, & roasting 325/50 M/T's from a 30 punch with about 9 degrees of advance.

Where would I begin to troubleshoot this?
Thanks guys, this is my first turbo car & I've got a lot to learn.

Craig
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Old Oct 21, 2007 | 06:32 PM
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Does the map sensor installed show around 100 kpa with the key on and not running? What about the autometer boost guage, does it show 0? Make sure the pids in the scanner are set-up properly or that could be the problem.
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Old Oct 21, 2007 | 06:41 PM
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boost gauge shows zero. I'll check the map with the engine off and double check the PID, but being that it is reading over 1 atmosphere, I would think I have the correct PID in the scanner. Thanks for the ideas.
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Old Oct 21, 2007 | 06:42 PM
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Also, at idle, map sensor should be circa 40-55kpa at idle.

If it isnt at, or very close to 100kpa with key on, engine off, it is scaled wrong.
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Old Oct 21, 2007 | 06:45 PM
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I believe I had 2 conflicting PID's open and it was averaging the two. I was making 18 psi through the map sensor and thought it was 9 psi.
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Old Oct 21, 2007 | 06:54 PM
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I am reading about 50 kpa @ idle, and showing 15 in Hg of vacuum on the gauge which I think matches the 50 kpa if my conversion is right.
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Old Oct 21, 2007 | 07:33 PM
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OK, I checked the MAP with the engine off and checked my PID's.

I have 2 PID's in the cfg file.

Manifold Absolute Pressure (SAE) - reads 103 kPa with the engine off
Manifold Air Pressure - 2 bar (psi) - reads 0.00 psi with the car off.

BTW I am running HP Tuner's 2 bar OS & a GM 2 bar MAP. What is the proper PID? It would be nice if this is the problem.

Craig
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Old Oct 21, 2007 | 07:36 PM
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I believe they tell you to deleate the map PID and leave the 2 bar PID, you can right click on it and change it to kpa if you like. Scan the car that way and see if thats it. This is a take out from the hptuners directions.

18. (This step for 2bar and 3bar enhancement only) Open VCM Scanner and connect to the vehicle. Open the Table display (Scan -> Table Display). Right-click the "Manifold Absolute Pressure(SAE)" PID and select "Delete". This removes the existing 1 bar PID from the table, if you don't do this the histogram will not function correctly.

19.(This step for 2bar and 3bar enhancement only) Right-click again on the table display cell and select "Insert", go to the Engine -> Airflow section and choose either the "Manifold Air Pressure - 2 bar" or "Manifold Air Pressure - 3 bar" PID, double-click to insert it into the table.

20.(This step for 2bar and 3bar enhancement only) Save the new scanner configuration using File -> Save Config.


I think this is your problem.....its much worse when it shows you 9 psi and youre making 18, I was wondering why I was leaving bikes behind, and maxxing out 96 lb injectors on 9 psi on a 347

Last edited by black98ws6ta; Oct 21, 2007 at 07:44 PM.
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Old Oct 21, 2007 | 08:31 PM
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You guys rule. Deleted the map PID and reconfigured the chart and took it out for a cruise with only the 2 bar PID in the cfg file.
Now a max reading of 178 kpa. I feel like the car is getting close. A/F ratio needs more work, but that shouldn't take too much time. Then I'll hook the meth up and start putting some timing to it.
Anyone else like pushing things to their limit? lol (stock bottom end)

Edit: I found that also after you mentioned having 2 PID's on. Bah, who needs help files, right?

Last edited by calongo_SS; Oct 21, 2007 at 08:39 PM.
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Old Oct 22, 2007 | 11:00 AM
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Umm are you running 10psi on the stock hypercrap pistons? Did you change out heads to lower your compression? Seen too many blown stock pistons to have much confidence in them much past 7 or so on stock heads and maybe a bit higher on bigger chamber heads.

I was going to throw my Aps on my 346 but now waiting till next spring and doing it on a 408.

Anyway should be interesting to see how yours holds up.I would think if you do keep the tune very conservative it might be doable.
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Old Oct 22, 2007 | 11:05 AM
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Tune will be ultra conservative. I'm going to put it on a dyno and limit the power with timing. I'm also running meth. I'm going to have the conservative street tune with probably 10-12 degrees of timing and a track tune with somewhere in the neighborhood of 16-17 deg. I will be tuning the meth as rich as I can get it without bogging, probably 10.8:1 or so.
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Old Oct 22, 2007 | 11:19 AM
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Ok saw in your setup that you are stock heads? So you took out the standard springs and put in the 10psi springs?
Even with meth and conservative tune I do think you are looking at broken ringlands sooner rather than later. I would for sure be sticking to the stock APS springs if I had did install this kit on my stock bottom engine with stock heads.

Well it should be interesting to see how long your stock engine holds up. Wish you the best of luck. It was very hard for me not to throw the kit on my current engine and have some fun for a few months before winter storage. Oh well spring is only 5 months or so away.
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Old Oct 22, 2007 | 11:21 AM
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Unless I screw something up in the tune it will live for quite a while. I don't drive the car more than once a week, so it's not going to be taking a daily beating. And if it blows, it'll come back stronger.
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Old Oct 22, 2007 | 11:37 AM
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Well thats the right attitude to have and pretty much same as mine. Only thing that worried me is if guy did take out engine wonder how much possibilty things would go out the manifolds and thru the turbos and wreck them? That would be annoying and was foremost on my mind. I have two souvenir pistons from buddies cars. One was sts but he screwed up with his boost controller and betting that one went way past 10. Other one was ati procharger at about 8psi. The guy with procharger was good tuner but didn't have alc.Both cars lost the ringlands in some pistons. The guy rebuilt the sts car to stock and sold the turbo so guess the turbo was fine.
I would expect close to 600rwhp at 10psi. Should be fun.
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Old Oct 22, 2007 | 11:40 AM
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Oh yeah, the car feels as fast or faster than it did on a 150 shot and it's barely got any timing at all in it. It's gonna be fun...
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Old Dec 11, 2007 | 09:19 AM
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Originally Posted by calongo_SS
Oh yeah, the car feels as fast or faster than it did on a 150 shot and it's barely got any timing at all in it. It's gonna be fun...
did you ever get your aps tt dyno'd? if so can you post a link to the results? thanks.
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Old Dec 11, 2007 | 09:49 AM
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Yeah, how is it doing? I had to put mine away for the winter. So now I gotta live vicariously through those that live in the warmer climates. I can't wait for spring to tear up the roads once again!!!!! Until then, we need more turbo details!
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Old Dec 11, 2007 | 11:33 AM
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The only dyno in town is.... broken. Should be up and running in a few weeks. I was supposed to take it to the track this past weekend, but that fell through too. It's still running strong :knocks on wood:
I finally started putting some timing in the tune the other day, hopefully it holds up long enough to go to the track & dyno it.
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Old Dec 11, 2007 | 02:34 PM
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Originally Posted by Hugger Z
Yeah, how is it doing? I had to put mine away for the winter. So now I gotta live vicariously through those that live in the warmer climates. I can't wait for spring to tear up the roads once again!!!!! Until then, we need more turbo details!


Its 80* today here in sunny FL . Yay.
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