24PSI After Downpipe Install?

nawx

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Hey can someone check my datalog? I just finished installing the downpipe earlier and flashed a tune with a target PSI of 21.5. Maybe I'm not understanding this but I see that its shooting past that on WOT pulls.

Am I supposed to be looking at Converted MAP or TC Pressure?
At around 56 seconds I see it go past @
1:23
8:40
9:04
10:03
11:24
That's just a few. There's probably more too lol

Thanks in advance :)
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PowerPerLiter

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Hey can someone check my datalog? I just finished installing the downpipe earlier and flashed a tune with a target PSI of 21.5. Maybe I'm not understanding this but I see that its shooting past that on WOT pulls.

Am I supposed to be looking at Converted MAP or TC Pressure?
At around 56 seconds I see it go past @
1:23
8:40
9:04
10:03
11:24
That's just a few. There's probably more too lol

Thanks in advance :)
MAP PRESSURE is the actual air thats pressurized the cylinders are recieving. Boost pressure is measured early on in the system so it doesnt show pressure losses.

The car should learn to open the wastegate farther the more you drive it to lower the boost closer to command.

The back pressure loss from removing the cat and old d/p makes the turbo work much more efficiently so it is spinning and building boost quicker than stock and its over shooting target boost.
 

gtman

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I checked out the datalog. Keep in mind I can give you the basic info I see but I'm not an expert in terms of diagnosing any issue.

You are overshooting pretty much all your targets every time. And often by a wide margin. I'm posting a screen from one of your pulls. A couple things look a bit different to me than other datalogs I've looked at. And maybe the experts can chime in. Your TP.CMD and TPS numbers look odd to me for WOT. Also we recently had a member that appeared to have some weird wastegate numbers and yours look similar. Maybe JR from KTuner can chime in here. Your fuel trims look great and IAT, K.Control and such are fine. Even the .59 is actually good considering all the WOT pulls you did on the datalog.

Honda Civic 10th gen 24PSI After Downpipe Install? newre.GIF


Here's another one where you overshoot the target drastically as well. If your numbers were normal before the downpipe, I'm assuming you need a custom tune.

Honda Civic 10th gen 24PSI After Downpipe Install? Capeeture.GIF
 
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PowerPerLiter

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The tps actual is not meeting command because the boost is higher than command (computer doing this trying to lower map pressure as its seeing the variance).
 

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My suggestion would be to try a lower boost target map but it may still mess with the tps if its still overshooting. Disabling vsa may help with this.

Your having a compound issue that is feeding itself....let me explain....downpipe allows for over shooting the target boost pressure....ecu reacts by trying to close the throttle plate (unbeknownst to you) this restricts air going into the engine....which then allows the boost pressure to raise even further because the tplate is trying to restrict the air output from the turbo....exaggerating the issue.

If the throttle plate was NOT trying to close; the boost in the rest of the system would be allowed to flow into the engine, which would help even out the command vs actual.

Make sense?

I would do the pedal dance to disable vsa myself and test to see if it helps any. "carefully" I might add.
 


gtman

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PPL, here's a screen with some really crooked numbers. This was right as the OP let off on the throttle after going WOT. The TC target and actual MAP difference is drastic. I know in that scenario there will be a difference but why +10 psi here?

Honda Civic 10th gen 24PSI After Downpipe Install? 2Capture.GIF
 

PowerPerLiter

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PPL, here's a screen with some really crooked numbers. This was right as the OP let off on the throttle after going WOT. The TC target and actual MAP difference is drastic. I know in that scenario there will be a difference but why +10 psi here?

2Capture.GIF
He was rolling out of the throttle it looks like.

Can you screenshot that frame exactly .5 and 1 second later in that datalog for me?
 

PowerPerLiter

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The diverter valve (which we can't log for) more than likely wasn't commanded to be opening yet due to throttle command; which was still at 58%. Transient fluke i suspect.
 
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nawx

nawx

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My suggestion would be to try a lower boost target map but it may still mess with the tps if its still overshooting. Disabling vsa may help with this.

Your having a compound issue that is feeding itself....let me explain....downpipe allows for over shooting the target boost pressure....ecu reacts by trying to close the throttle plate (unbeknownst to you) this restricts air going into the engine....which then allows the boost pressure to raise even further because the tplate is trying to restrict the air output from the turbo....exaggerating the issue.

If the throttle plate was NOT trying to close; the boost in the rest of the system would be allowed to flow into the engine, which would help even out the command vs actual.

Make sense?

I would do the pedal dance to disable vsa myself and test to see if it helps any. "carefully" I might add.
That's good to know. I think I'll run it on low boost for the time being until I'm able to get a custom tune.

These are my settings:
I actually have it set to Medium VSA and I have Early Spool enabled.
Should I bring some of these down to help with the over boost? Makes me almost want to go back to the stock dp until I can get a custom tune.

Honda Civic 10th gen 24PSI After Downpipe Install? LOSLflW


I also took a couple screen grabs from where you asked gtman.
https://imgur.com/a/V9zcFOM

Thanks again for the help. You guys are great :)
 

PowerPerLiter

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.......yes...... set all responsiveness and early spool shit to factory....
 


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nawx

nawx

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Ok I pretty much reverted everything back to the stock settings. I did leave the VSA to Medium though. I'll get another log when the rain gives me a little break lol
 

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Ok I pretty much reverted everything back to the stock settings. I did leave the VSA to Medium though. I'll get another log when the rain gives me a little break lol
Good luck. Eagerly awaiting to see your new logs. I've a '17 EX-T on OTS Stage 2 tune and never ventured into making any adjustments. Will be very interesting to see your logs for comparison.
 

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Ok I pretty much reverted everything back to the stock settings. I did leave the VSA to Medium though. I'll get another log when the rain gives me a little break lol
Is the downpipe catted or not? I am pretty sure most if not all people that have a downpipe without a custom tune have this overboost issue. They just dont bother to datalog and see what is going on. I am not sure if decatted builds more overboost that a catted one.

I was thinking to install a catted downpipe on stock ECU but wasnt sure. Maybe I ll do it, running the car on ECO mode until Ktuner release initial support for the ECU so I can run a custom tune.
 
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nawx

nawx

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Is the downpipe catted or not? I am pretty sure most if not all people that have a downpipe without a custom tune have this overboost issue. They just dont bother to datalog and see what is going on. I am not sure if decatted builds more overboost that a catted one.

I was thinking to install a catted downpipe on stock ECU but wasnt sure. Maybe I ll do it, running the car on ECO mode until Ktuner release initial support for the ECU so I can run a custom tune.
Its a catless downpipe. I'm basically gonna run it on ECO until I can get a custom tune lol. I'm alright with that. I do a ton of commuting anyways.
 

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Its a catless downpipe. I'm basically gonna run it on ECO until I can get a custom tune lol. I'm alright with that. I do a ton of commuting anyways.
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