I finally bit the bullet and got an Accessport. Car is still stock with the exception of the GrimmSpeed intake filter. Flashed Stage 1 91 with normal wastegate option. While I like the smoothed out throttle response, the car feels slower. I noticed that peak boost is below what I had recorded before - car display showed max. as 21.9 psi. With the new map, I now usually see between 11 and 12. Granted, these days it's been very cold, so I would expect to see some impact, but not in that direction. Besides the tune, nothing else has changed. I did some logging as per Cobb's requests (3rd gear pull from 2500 RPM to red, attached (Excel sheet, rename back to xlsx due to restrictions)). They came back saying I should check for a boost leak but the car is almost brand new, only 14k kms on it and it seemed quicker on stock. Any ideas?
2020 WRX Stage 1 Lower Boost than Stock?
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Here is a plot of your boost pressure as a function of RPM. TD Boost Error is in Orange.
![327407]()
Yes your boost curve is a few PSI below target. This curve represents the idealized target boost your ECU is attempting to hit:
![327410]()
Ignore the "21.9 PSI" observation. As XJman has already pointed out, that's a spike and is not relevant to the discussion.
As you have mentioned, it's very cold, so the ECU is likely targeting lower peak boost. Without compensations, the ECU should target 19 PSI peak boost.
It's my recommendation that you try the HWG map to see if we can pull that TD Boost Error to zero +/- 0.5 PSI.
Yes your boost curve is a few PSI below target. This curve represents the idealized target boost your ECU is attempting to hit:
Ignore the "21.9 PSI" observation. As XJman has already pointed out, that's a spike and is not relevant to the discussion.
As you have mentioned, it's very cold, so the ECU is likely targeting lower peak boost. Without compensations, the ECU should target 19 PSI peak boost.
It's my recommendation that you try the HWG map to see if we can pull that TD Boost Error to zero +/- 0.5 PSI.
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You weren't kidding about the cold. Your IATs were -22 degrees C.
I don't have any insight into the ECU strategy for the FA-powered cars. The target boost will usually be lower because of the cold temps. The ECU compensates for IAT.
Here's an example of the compensation table on a STOCK EJ257 (this is the only comparison I can offer up).
![327412]()
So for my car at your temperature, target boost would be about 14% lower than at 20 deg C.
Anyway, everything looks normal. The HWG map should remedy the lingering TD Boost Error, but take caution when the temperature start to climb again. It's very likely that Cobb doesn't plan for temps as cold as what you are seeing. You don't want to be in a position where your engine is grossly overboosting.
I don't have any insight into the ECU strategy for the FA-powered cars. The target boost will usually be lower because of the cold temps. The ECU compensates for IAT.
Here's an example of the compensation table on a STOCK EJ257 (this is the only comparison I can offer up).
So for my car at your temperature, target boost would be about 14% lower than at 20 deg C.
Anyway, everything looks normal. The HWG map should remedy the lingering TD Boost Error, but take caution when the temperature start to climb again. It's very likely that Cobb doesn't plan for temps as cold as what you are seeing. You don't want to be in a position where your engine is grossly overboosting.
I had the same issue with the cold! My car wouldn't get above 10,11 psi when it was super cold. Then I brought my car into the shop I work in to check for boost leaks, found nothing. Then as I left the shop and my car was warmed up, and getting warmer intake temps, boost was back to normal! Untill my ecu realized it was cold again and went back down to 10/11psi
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Moderator powers. It allows us to see people who have multiple accounts used to spam the board and group ban them. It can also be used, in this case, to help one of us possibly offer up advice based off of user location
Were you running on stock tune then?
So, Cobb support asked me to try Stage 91 high wastegate, then Stage 0 and today I got a chance to test the first one. It was warmer today (about -17°C, if you want to call that "warmer") and I did get some higher boost values, sheet attached as before. I tried to re-create your fancy graph @zax, but my Excel skills are rusty...
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Still something going on. You have a 2 PSI TD Boost error that is still present. Boost on the left dependent axis, TD Boost Error on the right dependent axis. Interesting that they have nearly identical shape.
![327484]()
Looks like the boost is following the right curve, but not quite hitting target boost. If it were me, I would tighten up the Integral portion of the boost control. I'm not sure there's much you can do in your circumstance without Cobb's help. This could be a mechanical problem, but given what I see above I don't think there's any reason you can't resolve this in software.
Looks like the boost is following the right curve, but not quite hitting target boost. If it were me, I would tighten up the Integral portion of the boost control. I'm not sure there's much you can do in your circumstance without Cobb's help. This could be a mechanical problem, but given what I see above I don't think there's any reason you can't resolve this in software.
Attachments
I also have to add another observation: during the extreme cold period, I had a lot of trouble starting the car. At first, I thought it was the crappy stock battery, but even with a booster connected it would not start easily. It sounded like it died almost immediately. I managed to get it to start by giving it some gas while cranking and it finally came on. That week I had gotten gas from the local Safeway instead of my usual Petro Canada gas station and I suspect bad fuel. Got 94 octane from Petro Canada after this experience and added a can of Seafoam. The first graph was while on the Safeway fuel (which was labelled 91 Premium), the second one is on the 94 octane Petro Canada fuel.
We're also expecting warmer temperatures in the next few days (above 0°C).
We're also expecting warmer temperatures in the next few days (above 0°C).
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