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Old 11-03-2012, 06:06 PM   #16 (permalink)
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..yep looks nice for sure Zenkat.

So I re-hooked the green and black vacuum lines correctly now from #2 solenoid, back to the turbo and stock WGA. But I've left on the MPX 62 mm TB for now (since I wasted the money and bought it and the machining is so nice on the unit) -- so thought I should at least try it out in this configuration (with the stock WGA). I'm now getting about 12 psi peak boost and holds at about 10 psi (so definitely less than before) - and the boost and power is peaky as opposed to better mid-range boost with previous setup.

BUT I'm hoping that when I take it in next week for a dyno tune with the DSP, that they can get the boost and AFR working well -- even with the MPX TB. If not, then I'll have to put the stock TB back on.

Any recommendations?
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Old 11-03-2012, 06:09 PM   #17 (permalink)
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Are you on the 93 tune or stock tune?

If youre on the 93 tune you should be boosting more then that.
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Old 11-04-2012, 12:26 AM   #18 (permalink)
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So I have the vacuum lines from the #2 solenoid hooked up right now (black to the WGA and green to the turbo). But I've left on the MPX 62mm TB for now (since I wasted money and bought it and the machine-work is so nice) -- thought I might as well try it out. So went for a drive and it's only getting about 12 psi boost and holding about 10 psi. This is quite a bit less than the old set up with AGP WGA cranked up (but I hated all the fluttering with that WGA).

I haven't done the Diablo Sport tune yet -- that's next Wed. I'm hoping that when I take it into the shop next week for the dyno tune
that I'll get better results. If not, then I'll have to put the stock TB back on and try tuning again.

My main question is, SHOULD I LEAVE THE MPX TB ON when I take it in for the DSP tune??
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Old 11-04-2012, 12:44 AM   #19 (permalink)
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If your car is stock turbo, there is really no reason at all to go for a 'dyno' tune. Huge waste of money. Keep investigating the forum. You may just need a battery reset if you havent already. Do you have a wideband? You should be able to put on the 93 tune and adjust the wot fuel yourself to get it dialed in.
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Old 11-04-2012, 04:45 AM   #20 (permalink)
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This ^.

A dyno tune is not needed on a stock turbo unless you had a very custom setup or going balls to the wall for power.

Those boost numbers are about okay for a stock tune. Still a little low. Verify all lines are in the correct spot, zip tie EVERYTHING, and do a good boost leak test.

Yes you can leave the TB on. Just verify with the diablo that the TPS is going into WOT.
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Old 11-04-2012, 08:51 AM   #21 (permalink)
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not trying to thread jack, but in his case going back to pcm controlled boost and dsp would there be any benefit from a S2 wg vs the stock wg?
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Old 11-04-2012, 03:02 PM   #22 (permalink)
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Quote: Originally Posted by coolbet13 View Post
not trying to thread jack, but in his case going back to pcm controlled boost and dsp would there be any benefit from a S2 wg vs the stock wg?

Not much advantage to a S2 really. Maybe +1psi past 5500rpm.

With that said, if you have a S2 already or found one super cheap (<$30), I'd use it.
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Old 11-04-2012, 08:59 PM   #23 (permalink)
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Stage 2 will also hold a little more boost during shifting (if you dont have a wot box) and the boost curve wont drop AS fast.
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Old 11-07-2012, 10:56 PM   #24 (permalink)
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OK Zenkat and TunerLover --- here's the update as of today after I took the car into the shop and played with the DSP and simultaneously had it hooked up to the dyno.

Just to refresh, here's what the car has on it today (so still fairly stock):
CAI, mopar/borla catback exhaust, mopar stage 1 PCM, Hondata intake manifold gasket, Granatelli wires and NGK Iridium plugs, stock WGA (I took the AGP WGA off), and MPX 62mm TB. As far as I can tell, I have all the vacuum lines hooked up correctly, and I put new T-bolt clamps on the cold side pipes of the intercooler and double-check tightness on the other IC inlet hose fittings.

We installed the 93 oct. tune with the DSP, but it was horsepower and torque curves were peaky (not smooth), so we decided to do a custom tune which produced a much smoother, increasing set of curves, reaching peak torque (262 ft-lbs at wheels at 4250 rpm) and peak hp (240 hp at wheels at 5250 rpm).

These numbers seem OK but maybe a bit low?? What has me puzzled though is that the boost peaked at 16 psi at 2800 rpm, held fairly steady at around 15 psi up to 4800 rpm, and fell down to 13-14 psi towards redline.

So here are my questions (sorry for being so long winded):

1) We had programmed the max. boost within each of the 1000 rpm increments (e.g., 3000-4000 rpm, 4000-5000 rpm, 5000-6000 rpm) to peak at 25 psi. So why aren't I getting more boost?? Is it a boost leak, or will the stock WGA not allow this much boost??

2) Is the MPX TB still screwing things up?? I regret buying it now.

3) I had the Iridiums gapped to .038" (this is what I read on Forum a while back). But the tuner mechanic said that's way too much and said they should be gapped to .028". Which gap is correct??

THANKS AGAIN for your help on this guys!!
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Old 11-07-2012, 11:53 PM   #25 (permalink)
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1) i have read of 25-27 psi boost spikes. Have you done the boost leak test? Spray soapy water EVERYWHERE.

3) No experience with those spark plugs here. I although have seen many people have sucess with the 4306's. They run about $2 ea. Wouldn't hurt to try them gapped @ .35, and see how she runs.

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Old 11-08-2012, 05:50 AM   #26 (permalink)
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Quote: Originally Posted by Todd@VanIsland View Post
OK Zenkat and TunerLover --- here's the update as of today after I took the car into the shop and played with the DSP and simultaneously had it hooked up to the dyno.

Just to refresh, here's what the car has on it today (so still fairly stock):
CAI, mopar/borla catback exhaust, mopar stage 1 PCM, Hondata intake manifold gasket, Granatelli wires and NGK Iridium plugs, stock WGA (I took the AGP WGA off), and MPX 62mm TB. As far as I can tell, I have all the vacuum lines hooked up correctly, and I put new T-bolt clamps on the cold side pipes of the intercooler and double-check tightness on the other IC inlet hose fittings.

We installed the 93 oct. tune with the DSP, but it was horsepower and torque curves were peaky (not smooth), so we decided to do a custom tune which produced a much smoother, increasing set of curves, reaching peak torque (262 ft-lbs at wheels at 4250 rpm) and peak hp (240 hp at wheels at 5250 rpm).

These numbers seem OK but maybe a bit low?? What has me puzzled though is that the boost peaked at 16 psi at 2800 rpm, held fairly steady at around 15 psi up to 4800 rpm, and fell down to 13-14 psi towards redline.

So here are my questions (sorry for being so long winded):

1) We had programmed the max. boost within each of the 1000 rpm increments (e.g., 3000-4000 rpm, 4000-5000 rpm, 5000-6000 rpm) to peak at 25 psi. So why aren't I getting more boost?? Is it a boost leak, or will the stock WGA not allow this much boost??

2) Is the MPX TB still screwing things up?? I regret buying it now.

3) I had the Iridiums gapped to .038" (this is what I read on Forum a while back). But the tuner mechanic said that's way too much and said they should be gapped to .028". Which gap is correct??

THANKS AGAIN for your help on this guys!!

1) You just wasted money if you went to a dyno shop that didnt have the actual CMR tuning software for Diablo. I hope you did not pay a lot to have some "tuner" just make adjustments on your handheld. The stock wastegate COULD be weak. Look into maybe a stage 2 WGA or FM. It could also be a boost leak. Did you do a good boost leak test? The stock WGA can spike plenty of boost (20+) and will hold around 13-15 at redline.

2) Its probably not. A throttle body wont change much on a stock turbo. Now I did ask you to verify to make sure the throttle body is seeing full voltage when going WOT. There was a probably with MPX throttle bodies were people were getting low boost and going lean because the TPS would not see its full voltage and never go into open loop (wot).

3) If you were not getting spark plug blow out, your gap is fine.
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Old 11-08-2012, 04:59 PM   #27 (permalink)
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Good answers Duster.

1) I haven't done a boost leak test, but will do one. One thing I forgot to mention in previous note is that the way things are currently set, when I apply 1/4 to 1/2 to 3/4 throttle, I only get about 3 psi boost. It's only when I apply WOT that I get the 13-16 psi boost I mentioned (which still is low). So something is not working right here?? -- it always used to give me part-throttle boost of at least 5-12 psi.

2) No, I haven't checked to see that TB is getting full voltage -- should that be just less than 12 volts?

3) no spark blow out at .038" -- idles and runs smoothly
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Old 11-13-2012, 07:49 PM   #28 (permalink)
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Part throttle overboost is BAD. Told you that already. You will only get a few PSI under normal part throttle driving, that's the way the PCM boost and stock WGA is designed. It's supposed to make the car feel like a normal car when driving around town.

I told you not to 'dyno tune' your car. Did you really take it to a dyno so some dude could push buttons on your handheld? That's NOT tuning. I can do that shit on the road in front of my house.

Yes, the 93 tune is going to be peaky, especially in the torque department. When you spike high boost at low RPM, it does that.

In order to see one possible reason why it wont boost, you need to log the WGDC% and see where it's at. If you really did increase the boost on the handheld and it wont raise, it is possible you've hit 95% and your WGA just won't hold anymore. This is usually due to boostleaks, but I found stock WGA's to sometimes be hit or miss. An FM WGA or S2 WGA might be a better option.

Your TB isnt the problem. Definitely DEFINITELY pick up some t-bolt clamps and boostleak test that car (leak test it to 30psi if possible).
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