Boost Issue

[Sensei]

Took two logs yesterday at WOT in 3rd gear. Car is hitting just 11psi with the WGDC going up to 100% at over 5k rpms. Previously hit 18 psi plus. Original stock turbo with original boost controller. Car was freektuned by Justin on a Dyno a few years ago maybe 5 years at this point. From searching around seems like the likely suspect is the tube connecting the TIP to the BCS being clogged. No CEL on. Plan is to take to the intake off, check turbo for shaft play and inspect/replace the hoses and boost tubes. Figured I might get some input on the logs and potential causes before I get to it. My take on the logs is everything looks ok other than the low boost and high WGDC. Log 93 is an old one where everything was okay. 94 and 95 are the new ones. Also plan to post the solution once I get it sorted out.

[180mph]

Ill let someone more educated chime in here but to me it seems something mechanical is going on.

Considering that your LTFTs were at -5 in log 93 before and in log 94 your LTFTs are at -15 I would start by checking all of vac hoses for tight connection.

I am somewhat of a novice compared to the great people on these forums so take my .02 with a big grain of salt.

Thanks

[Pu Manchu]

prolly a boost leak somewhere between your turbo outlet and throttle body.

[Sensei]

It was hot as hell out today so I only messed with the car a bit this evening. I confirmed the hose from the TIP to the BCS is not clogged so that easy fix is not the issue. All the other hoses are in place and look okay but it's impossible to tell for sure without really getting in there.

Originally Posted by 180mph Ill let someone more educated chime in here but to me it seems something mechanical is going on. Considering that your LTFTs were at -5 in log 93 before and in log 94 your LTFTs are at -15 I would start by checking all of vac hoses for tight connection. I am somewhat of a novice compared to the great people on these forums so take my .02 with a big grain of salt. Thanks

I'm not too worried about the LTFT. They're showing that I could use a MAF cal but not much I can do without paying for a retune and I don't think the LTFT are related to the low boost I'm seeing. If the BCS is the issue and I replace it I'll be getting retuned and the LTFT will get sorted out at that point. The plan for now will be to take the intake off and replace all the 4 mm and 6 mm vacuum lines with thick walled silicone ones. I'll also check that the BCS opens when it gets 12 volts.

Originally Posted by Pu Manchu prolly a boost leak somewhere between your turbo outlet and throttle body.

I'd think a boost leak causing the loss of 7 psi would throw the AFR way out of wack and the car would have drivability issues. The car feels fine other than the missing power. I'll still give all the FMIC piping couplers and the BPV a look while I'm at it.

[180mph]

I don't think that running "lower boost" will mess with your afr.

My argument here comes with how I'm self tuning my new corksport turbo. For safety I set my wgdc to 0 across the board on first startup. This forces my boost to 14-17 psi off wg spring pressure.

Even though I'm "targeting" 20 psi and actually achieving 14 psi my AFRs stay around 11.2. The ECU is much better at correction than you would think.

If nothing mechanical has changed from log 93 to 94/95 I would really be suspecting an air leak with intake/vac etc.

Sorry I can't be of more help

PS... Confirming proper operation of the BCS also seems like a good theory to the problem... I have nevy experienced a failing one so this could be useful knowledge for me in the future

[Sensei]

Originally Posted by 180mph I don't think that running "lower boost" will mess with your afr.

I was refering to Pu Manchu's suggestion that a boost leak was the cause of the problem. If the car was losing that much air after the turbo I think we'd see it in the logs. AFR would be rich since the car expects more air to be going to he engine. MAF voltage/flow + boost wouldn't match between logs 93 and 94/95 which they do match. IIRC boost is measured at the intake manifold so low boost with a realatively higher MAF value and rich AFR is what I'd expect out of a substantial boost leak.

[Fstrnyou]

Pu Manchu was likely suggesting a leak between turbo and TB because of fuel trims changing to -15

Escaping air in a pressure zone would normally make the engine run rich. It's clear the ECU is pulling fuel to correct the richness.

At WOT, the leak could be much much worse, which coukd lead to low boost readings.

[Sensei]

Originally Posted by Fstrnyou Pu Manchu was likely suggesting a leak between turbo and TB because of fuel trims changing to -15 Escaping air in a pressure zone would normally make the engine run rich. It's clear the ECU is pulling fuel to correct the richness. At WOT, the leak could be much much worse, which coukd lead to low boost readings.

The ECU is pulling fuel at cruise however the AFR at WOT is good for all the data logs. At this point I'm pretty confident the issue is with the BCS or vacuum lines to the BCS. Other possibilities would be the PCM not sending the proper signal to the BCS (hope not $$$). Maybe a bad turbo but I think that is less likely. Once the silicone lines come in and the heat lets up I'll be getting to work on it.

[Sensei]

I had some time after work today. I got the inake/TIP off and tested the BCS. It had continuity between the two pins but it didn't open when supplied with battery voltage. The BCS not opening fits with my other symptoms. I ordered the Grimspeed EBCS and plan to run it in 2 port mode until I get retuned. I'll check in to confirm the new EBCS fixed the low boost (spring pressure only) with high WGDC issue once I get it installed.

[MSMS3]

Originally Posted by Sensei I had some time after work today. I got the inake/TIP off and tested the BCS. It had continuity between the two pins but it didn't open when supplied with battery voltage. The BCS not opening fits with my other symptoms. I ordered the Grimspeed EBCS and plan to run it in 2 port mode until I get retuned. I'll check in to confirm the new EBCS fixed the low boost (spring pressure only) with high WGDC issue once I get it installed.

The Grimmspeed EBCS is very high quality. I think the solenoid may actually be a little faster than OEM. Most importantly, it has the correct plug (no splicing) and it solves the failure prone "broken plastic nipples" issues that plague the stock part. It has nice brass connections.

A good place to mount it is on the front of your battery box and just leave the old EBCS disconnected but in place, but you can mount it just about anywhere. It comes with a generous amount of new vacuum line that makes mounting easy, too. Don't even think about reusing the old lines, they are hard, brittle and probably already leaking. I always ran mine in 2 port mode.

[Sensei]

Originally Posted by MSMS3 The Grimmspeed EBCS is very high quality. I think the solenoid may actually be a little faster than OEM. Most importantly, it has the correct plug (no splicing) and it solves the failure prone "broken plastic nipples" issues that plague the stock part. It has nice brass connections. A good place to mount it is on the front of your battery box and just leave the old EBCS disconnected but in place, but you can mount it just about anywhere. It comes with a generous amount of new vacuum line that makes mounting easy, too. Don't even think about reusing the old lines, they are hard, brittle and probably already leaking. I always ran mine in 2 port mode.

Glad to here you had a good experience with the Grimspeed. I plan to run it in 2 port (bleed mode) same as the stock controller and mount it to the battery box. I also started changing out the vacuum/boost lines last night. The 6mm line from the compressor housing to the bottom of the wastegate actuator was looking pretty rough though not leaking. The others are in good shape but I'll replace them while I'm in there. I made sure the get some band hose clamps that fit so everything stays in place.

My only real concern with the GS EBCS is if the faster response and extra flow will cause a boost spike or other issue with my current tune. I've read mixed reports and it seems like it's okay with the stock tune (in bleed mode only) but maybe not with others. I'd prefer to run the current tune as it was done by a pro on a Dyno but the map is locked. I'm capable of doing some tweaks to OTS maps and self tuning but I'm sure I'd be more conservative/ lower power than the current tune. Guess I'll just need to chose between monitoring/risk using the current tune, getting a touch up tune or doing some self tuning.

[180mph]

Nice catch on that... BCS that wouldn't open definitely seems like it would limit you to waste gate spring pressure which fits your initial complaint.

Can't wait to hear about the GS EBCS. I have one that I have yet to install while I have been dialing in a baseline for my CS Turbo I installed recently. Self tuning the WGDC has been a pain in the ass so far with boost oscillations.

[MSMS3]

There is no "extra flow" It's a simple electronic controlled on-off switch - a solenoid.

If the solenoid acts faster, that just means that on the front end the turbo spool time might be a tiny fraction, maybe a millisecond, reduced. Same on the back end - it would respond quicker to an ECU call to reduce boost. If anything, a quicker solenoid could theoretically help prevent a rapid transient spike. This is theoretical and may have no real world consequences as we are talking about milliseconds or fractions of milliseconds, if at all.

But flow or peak boost will remain unchanged and determined by the characteristics of the turbo and the mapping of the ECU tune.

You will not see more boost with this EBCS than your tune calls for. It merely replicates the action of the stock EBCS in two port mode, but perhaps a little tiny bit quicker.

It worked fine in two port mode with my tune which had a boost target of almost 19 psi under max load with taper to 15 approaching redline. This was with a catless downpipe/racepipe and as much as 17-18 degrees of timing at the top of the power band, and richened AFR's for cylinder cooling to permit the timing advance. No spikes. Run it two port mode, it behaves like the stock unit.

In three port mode, you must tune specifically for its action, or you will likely get spikes or overboost on a tune developed for two port operation. That's where the issue arises. You can't run an EBCS operating in three port mode on a tune developed for two port operation.

[Sensei]

Originally Posted by MSMS3 There is no "extra flow" It's a simple electronic controlled on-off switch - a solenoid. If the solenoid acts faster, that just means that on the front end the turbo spool time might be a tiny fraction, maybe a millisecond, reduced. Same on the back end - it would respond quicker to an ECU call to reduce boost. If anything, a quicker solenoid could theoretically stop a spike. This is theoretical and may have no real world consequences as we are talking about milliseconds or fractions of milliseconds, if at all. But flow or peak boost will remain unchanged and determined by the characteristics of the turbo and the mapping of the ECU tune. You will not see more boost with this EBCS than your tune calls for. It merely replicates the action of the stock EBCS in two port mode, but perhaps a little tiny bit quicker. It worked fine with my tune which had a boost target of almost 19 psi under max load taper approaching redline. This was with a catless downpipe/racepipe and as much as 17-18 degrees of timing at the top of the power band. No spikes. Run it two port mode, it behaves like the stock unit. In three port mode, you must tune specifically for its action, or you will likely get spikes or overboost on a tune developed for two port operation.

That's reassuring and makes sense. Maybe I was reading about people who were using it in 3 port (interrupt mode).

[Sensei]

A mostly happy ending. I got the GS EBCS installed today and the original issue with the car is fixed. The car is able to achieve boost levels higher than spring pressure.

I do need a touch up tune though. To go along with the LTFTs being further out of spec than recommended I'm also getting some KR up to 1.75 around 3800-4500 and boost seems to be peaking higher at 20.5 psi than some older data logs. I don't do a good job of taking data logs every month or so to check up on the car so I've got no way of knowing whether or not the new EBCS contributed to the higher boost and KR. I took one log which is attached and replicated the KR 2 more times without logging. Either way a touch up tune should sort that out.

I appreciate everyone's help getting this figured out.