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Zero WGDC. No CEL. Limp mode?


Spaceman Spiff
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2008 LGT - 18g, invidia catted DP, 1000cc DWs, TGV deletes, SPT intake, Greddy cbe

 

I stopped making boost from one day to the next. Like 0% WGDC. So far I have rebuilt the turbo and replaced the wastegate actuator, turbo inlet, TMIC, EBCS, and MAF. But then my tuner told me that it is likely the ECU isn't happy about something and it's not allowing boost. Well, why doesn't the shmarty-pants ECU tell me what the issue is? :confused:

 

IAM is 1 and there is no CEL. LVs look good, almost too good. After the above work, the car runs exactly the same. It runs decently, just not much acceleration and has trouble boosting to WG pressure, which is 14.7 psi. Maxes about 4-8 psi. The only change made to the car, that day in question, was I drove it with a bad MAF sensor. Last night, I found the EBCS to WG/comp hose had come off at the size-step adapter. Plugged back in and the same.

 

Before I take it to COBB surgeline, where should i look? Thanks.

 

Stephen

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Any logs? Are you sure WGDC is at 0%?

 

I haven't logged anything, but the btssm says it's almost always 0. An occasional 2 or 3%. According to the numbers i'm monitoring, it looks more dialed in than my freshly tuned OBXT. No knock, and fuel trims are very tight.

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Here is a log from last night, and it ain't pretty. Is rear o2 V ok? It feels like the intake or exhaust is plugged. I pulled the SPT intake off it and put on the stock airbox last night, but I didn't get a chance to test it afterwards. I'm wondering if my cat in my Invidia DP is plugged with all the oil that went thru it. Fortunately, I can borrow the one off of my OBXT to test it, if need be.

 

Does the WGDC indicate what the ECU wants or what it sees?

BtSsm_20180301_205713.csv

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The WGDC indicates what it commands, there's no feedback so the ECU can't see the "actual" WGDC. In that log, you didn't build any boost at all (maxed out around 1psi, which), which is why it's running so rich (the ECU is fueling as if it should be taking in much more air than it actually is).

 

I wouldn't worry about the rear O2, that has very little effect on the operation of the car. Can't tell from that log whether the readings look okay or not, but either way it should have negligible effect on your car.

 

I'm quite stumped... even if the wastegate were stuck open, I would still expect a little boost (not sure about the 18g, but stock wastegate pressure is around 7psi, so even with a completely open wastegate, boost should peak around there). Almost sounds like your turbo isn't spinning at all, which I just couldn't believe. If it is building boost (and for some reason that log doesn't show it), then you should hear the turbo spooling and you might just have a stuck wastegate. Also, where do you get that your wastegate pressure is 14.7psi? Are you confusing that with typical atmospheric pressure at sea level?

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I just bought a new Kinugawa wastegate actuator with a 1.0 bar spring. This evening I'm going to swap my DP out from my OBXT and see what I get. At least I can make sure my turbo spins. Although it did spin to 23 psi after the rebuild so IDK either. Nothing I've done so far has made any difference.

 

I appreciate the help Solidxsnake!

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I just bought a new Kinugawa wastegate actuator with a 1.0 bar spring. This evening I'm going to swap my DP out from my OBXT and see what I get. At least I can make sure my turbo spins. Although it did spin to 23 psi after the rebuild so IDK either. Nothing I've done so far has made any difference.

 

I appreciate the help Solidxsnake!

 

Well that would explain my confusion at your wastegate pressure number :lol:

 

It may just be a stuck wastegate. Even if the actuator seems to work, perhaps it's not sealing properly? I'd inspect that first.

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Ok, so it looks like I got it. Must have been the cat clogged. It's also possible that it's just the wastegate though. I had a hard time keeping the linkage connected during those last few times out. But the last pull seemed real good. I'll know for sure after I switch DPs again.

 

The target boost was only 14.3, so that's less than spring pressure. So would that mean that it needs no(or little) WGDC to maintain boost? It's actually running up to 15% WGDC now. And keep in mind now, it was tuned for a stock TMIC and SPT Intake. And now it has a Perrin TMIC and stock airbox with K & N Panel. So it's not doing to bad now.

BtSsm_20180303_122427.csv

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You will definitely need a retune from switching intakes, but those won't affect boost. I doubt a plugged cat would cause boost loss as well, as that would just mean you don't have any exhaust coming out, but I'm sure I could be proven wrong.

 

And yes, you should only need minimal WGDC under wastegate pressure.

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Definitely getting a tune soon. Jarrad just finished my Outback tune so I now I can send him another patient. I just want to make sure I can make consistent boost for a little while first. I also kinda doubt it's the cat. I hope not too, as I'd rather not have to spend another $500 for a new DP.
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I forgot to mention, are the DPs between your LGT and your OBXT identical (both Invidia catted)? I'm wondering if one of them is blocking your wastegate open?

 

Also, in case you're interested, the Target Boost value doesn't necessarily mean too much. The way the ECU works, it has a table for WGDC, and uses that to control the wastegate first-and-foremost. If after controlling the WGDC, the measured boost doesn't match the target boost, it'll start compensating, up to a minimum/maximum WGDC that's defined in a separate table. In that sense, even if your wastegate spring is 1bar, you might still see WGDC below wastegate pressure because of your tune.

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  • 2 weeks later...
  • 2 weeks later...
Going to Cobb Surgeline for a pre-tune inspection this week ,and then to Jarrad at PDXtuning for the dynotune next week. Yee-haw! my current tune is limitied to 15 psi on my 18g because of the stock TMIC. Now we'll see how high we can go with the Perrin TMIC on there.
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So it checked out good at Cobb on Friday. Got it to Jarrad on Monday and he pulled 291 whp/293 wtq at 20 psi out of it with the 5eat. But that was more torque than the trans wanted. Settled it back down at 290 whp/273 wtq at 17 psi. PSI's Dynojet is set up like a Mustang: reads 190/190 stock.

 

The crazy thing is....I miss the SPT intake sound. I pulled it in favor of the stock airbox, but I hate the mechanical sound that it was covering up. I'll probably put it back on and rescale it. I have my Outback for stealthiness.

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