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Old 12-14-2005, 02:48 AM   #1
ruski
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Exclamation Ok, Problem... Maybe... Suggestions + Help pls

Background:
I bought a used 2005 STi. It had a couple of mods on it (TBXS Downpipe, Highflow cat, midpipe, rfl exhuast, x02 racing top mount intercooler, Blow-off valve, and Injen CAI) and no engine management as I was told. The exhaust was to loud for me so I bought a helix catted downpipe and a greddy evo 2 exhaust. I replaced the Injen CAI with the stock box and a K&N Air Filter. I have left on the x02 racing top mount and blow-off valve (set to full recirculation). I have also just added ported+polished+coated stock headers, and a set of defi gauges(boost, oil pressure, and EGT). EGT probe located on nipple on 4th cylinder (really a 4th+2nd mix) maybe 3in from the end. Tuning scheduled for next week. And I also put in 1 step colder NGK Plugs because I am running on CA 91 oct.

Now that I have gauges and get the headers back on the car I go take it out for a little drive to check everything out. Well after looking at the boost gauge and egts, I get a passenger to confirm what I am seeing. Boost is hitting 20.5psi and EGTs at hitting just under 1800f. As far as I knew this was not a reflashed computer. I looked under the passenger floor pan and set to see if there was a UTEC but I didn't see one. The car isn't boost creeping as it hits 20.5psi and starts to taper down to 15 or so at redline (4th gear).

My question: What the hell is going on?!? I thought stock boost level on an STi was 14.5psi? How on earth do I get the EGTs down I thought those shouldn't pass 1600f? How do I figure out if the car has been reflashed?


QUCK SUMMARY
Mods:
K&N Filter
1 step colder NGK Plugs (yes the right plug for the STi)
x02 Racing Top Mount Intercooler
GFB Blow-Off valve (set to full recirculation)
Helix Catted Down Pipe
Greddy EVO 2 Exhaust
Defi Boost, Oil Pressure, and EGT gauges
Ported+Polished+Coated Stock Headers
NO ENGINE MANAGEMENT (I think, I was told none, used car). Tuning scheduled for next week.
Boosting to 20.5psi in 4th gear!! Will taper back down to 15psi or so at redline.
EGTs just under 1800f!!
Running on CA 91 oct.

My question: What the hell is going on?!? I thought stock boost level on an STi was 14.5psi? How on earth do I get the EGTs down I thought those shouldn't pass 1600f? How do I figure out if the car has been reflashed?


Thanks for the help,
Evan
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Last edited by ruski; 12-14-2005 at 02:55 AM.
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Old 12-14-2005, 08:05 AM   #2
2fas4u
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Did you find a manual boost controller installed? I wonder if they went that route and you missed it? Or.... There was a reflash of the ECU. IF it was a Cobb AP you would never know it as there is no hardware left behind...

As far as EGT's go. Firstly the 1600 deg number is for CAT's benefit really. The old stories about valves melting at 1600 is bunk! The 1600 number is for the stock CAT's.. With that said I dont enjoy running any higher temps then I have to, ever...

My suggestion is to get EM fast! The only way you will get your boost and EGT's under controll is via EM...
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Old 12-14-2005, 02:07 PM   #3
ruski
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I have a good idea on what a manual boost controler would look like but where would it be located?

I just ordered a Cobb AP and it should show up today. If the car has already been mated to another Cobb AP will there be a problem if I try and mate this one to it? If the car has an ECUTek reflash, the same question?


Evan
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Old 12-14-2005, 02:21 PM   #4
Underboosted
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check the tube coming off the turbo actuator, it should be going straight to a "T" that goes straight to the intake and to the MAP. if there is anything in line with that and it looks like a one way valve and has a twisty knob on it...its more than likely a MBC.
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Old 12-14-2005, 02:22 PM   #5
Underboosted
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also if you cant afford EM than go buy a MBC $50 and install it then set it to 14.5 psi for now anyway...
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Old 12-14-2005, 03:08 PM   #6
ruski
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I will have EM it comes today, Cobb AP. I'm scheduled for a protune from Gruppe-S next week. If the car has already been mated to a Cobb AP and I try to mate it to another one what will happen? If it was an ECUTek reflash and I try and mate it to a cobb AP what will happen?


What can cause hight EGTs?
To rich?
To lean?
Hight boost (that I know)


Evan
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Old 12-14-2005, 03:12 PM   #7
Underboosted
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to lean will cause high EGT, i.e... >12:1

you cant really run to rich (withing reason), because rich is safe...

idealy you want about a ~10-11:1 AF at full boost
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Old 12-14-2005, 04:18 PM   #8
supersport
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What is happening is boost spike, I have the same problem with a catless APS exhaust and AP stage 2. my peak EGT's are a little below 1600 (Approx. 1550). Your EGT's should go down a little with the EM but the temps you have don't seem that bad.

The AP has a low wastegate map that may help with the problem but spiking/creep from what I have understood from all my research is a mechanical problem that can only really be solved by getting the wastegate ported. So even the tuning and EM may not solve this problem.

I only notice minor boost creep on really cold nights, but the spiking happens regularly, up to about 20 lbs.

some other options are:
Manual boost controller
high flow cat

I am still in the process of experimenting with some different options for curing the boost creep/spike issue.

I don't know how the AP will react if there is previous EM. Call COBB and ask them they are very helpful.

Keep us posted on what happens with the tuning, etc., as many people are having similar issues and would like to know what solutions work best.

Happy motoring
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Old 12-14-2005, 05:19 PM   #9
ruski
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I already have a high flow cat and the evo2 is adding a bit of restriction as well. I don't think it is creeping because I can get up to 20psi in 3rd gear as well as 4th. From what I understand I thought it would only creep in 5th or 6th on a cold night.

I know where the wastegate actuator is but where is the turbo actuator, or are the same piece? I just want to make sure I'm looking in the right place to see if I can find the MBC.

Next on the list.... Calling Cobb

Thanks,
Evan
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Old 12-14-2005, 05:23 PM   #10
Underboosted
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yeah thats what i meant, i was just trying to make it easy to understand..

anyway that is where the MBC will be if it has one..
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Old 12-14-2005, 06:15 PM   #11
supersport
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There is the actual mechanism that moves the wastegate (don't know the technical term) that is clearly attached to the turbo. The other part of the turbo pressure regulating system is mounted in the engine bay on the front side of the passenger wheel well, it has a cover/heatshield looking metal plate over the top of it. There are a few vacuum hoses attached to it.

If there is a MBC it would be installed on one of those vacuum lines.

Sorry I don't know the names off the top of my head.

PS 20lbs is pretty high. The target boost for AP stage 2 is 17.5 + or - .5. I would try to keep it below 18 lbs if at all possible.

creep I have only seen once in 4th gear.
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Old 12-14-2005, 07:30 PM   #12
ruski
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I just got off of the phone with Cobb. If an old accessport was mated to the ECU i'm screwed. I could either get a new ECU or send in this one and have them rewrite everything costing me around $400. If there is just an ECUtek flash on the ecu the accessport should just overwrite it.


Another question: If I install the new accessport, and it works, and there is a manual boost controler installed will the accessport be able to override the mbc? (I don't think it will, but I might as well ask)

Evan
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Old 12-14-2005, 07:59 PM   #13
ruski
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How does a manual boost controler work? Also I installed the defi boost sensor on the passenger side of the intake manifold next to the throttle body. There was a little looped hose there and I put the T on it. I doubt it but if the T was too small could that cause an overboost problem?

Thanks,
Evan
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Old 12-15-2005, 01:09 AM   #14
ruski
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UPDATE:
I looked for a MBC but I couldn't find it anywhere, but that does mean I could have just missed it.
I also installed a Cobb AP and everthing went well (set to base 91 oct map) so at least it didn't have an accessport connected to it before. I took it out for a drive and while it is good news it isn't great.

Old peak EGTs: a hair under 1800 (4th gear)
New peak EGTs: about 1700 (4th gear)
That is a good difference but this was still a short little test.

Old peak Boost: about 20.5psi
New peak Boost: about 19.5psi
Less in this case is better but still way to much over the 17.5psi the base map is suppose to be.

Anybody know how much the Defi Guage can be off? I didn't get a chance to use the AP digital boost reader, but I'll try that tomorrow. My mods are a bit out of cobbs stage 2 map but they arn't THAT much off.

Evan
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Old 12-15-2005, 11:48 AM   #15
BigJ04STi
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Where did you tap for the Boost gauge??

I'd definitely check the AP's boost readings to compare...

Also, Does the DP you put on have a splitter on it? Just wondering...if so and it was too close to the wastegate flapper and was holding it shut...you'd easily reach way too much boost, especially in higher gears.

Just an idea...
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Old 12-15-2005, 12:52 PM   #16
ruski
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The downpipe I have does not have a splitter it is just a bellmouth. The boost isn't going to 19psi+ and staying there, but it is hitting there at its peak then will start to lower the closer I get to redline.
I installed the defi boost sensor on the passenger side of the intake manifold next to the throttle body. There was a little looped hose there and I put the T connector that came with the defi guage on it.

On a side note I plugged in the accessport into the car after I came back in and while the car was off it was reading -1.7 for boost pressure while the defi guage was reading 0. I am beginning to wonder if the computer is getting a wrong boost reading? Also how accurate is the defi boost guage?

Evan
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