Discussion on how bypass valves can affect LTFTs.

[Sacrilicious]

Originally Posted by Docnox Now that I finally have the aem wideband in my car, I saw that I'm running rich as fuck. Cruising: ~14.5 Half: ~12.5 WOT: 10-10.5 I'm still running the stock bpv with a SRI and stock exhaust. Will an aftermarket one help out in this situation, or make me run even more rich?

if you're on the stock tune, that's completely normal. that's just how rich our engine runs, because it's trying to protect itself from the heat generated by cramming 15+psi of boost into the cylinders.

[Phantom]

Originally Posted by Sacrilicious ya, if you're running hybrid mode on the turbosmart, you're almost guaranteed to run too rich on shifts (pops and backfires). VTA is guaranteed to run richer than BPV, because you're dumping metered air to the atmosphere...less air, same amount for fuel = rich as a pig. you can either leave it like this and make sure the spring tension is adjusted so that you at least run normally at WOT and deal with the fact that you will pop and backfire on shifts, or you can go conservative and put the valve in full recirc so that it runs as smoothly as stock (clean AFRs and no pops/backfires on shifts...not moreso than stock, anyways).

I am currently running my Turbo Smart in full recirc. The popping I was getting I think is from a spring being too tight. Seems bit better now. Still need to work on the spring tension

[Sacrilicious]

Originally Posted by Phantom I am currently running my Turbo Smart in full recirc. The popping I was getting I think is from a spring being too tight. Seems bit better now. Still need to work on the spring tension

awesome... ya, you just need the spring to be a little bit tighter than it absolutely needs to be in order to hold boost. you don't want to go much farther than that, because you will run into trouble from its being too tight.

[08_ms3_gt]

i'm running the AP v1.03 Stage1+SRI map, combined with my Forge BPV (blue spring) and HKS SRI.

LTFT's of about 7 when engine breaking, 5 when idle/cruising, -1 at part throttle, and -7 at WOT. those values seem counterintuitive, indicating that the ECU is reducing fuel as throttle increases (right?), but the AFR does stay below 12 at WOT. fuel pressure is consistently above 1600PSI as well.

the problem --> boost is low, as in staying closer to 14-16PSI than the 18 prescribed by the map. i get a decent peak of 19-20 but it quickly drops. the primary suspect is the BPV.

i'd like to keep my forge installed, but i'm not sure about the 'ideal' spring setup. blue was working well for awhile. any suggestions, Sacrilicious? FWIW my latest maps are posted in the Cobb AP forum, "103 finals are out", top of page 7. Here.

My current plan is to swap to the stock BPV and check boost.

[DaleNixon]

Try 1 shim with that blue spring?

[08_ms3_gt]

Originally Posted by DaleNixon Try 1 shim with that blue spring?

i've entertained that idea although i thought using the stock BPV should show me what the boost is supposed to look like. IMHO the Forge is a better unit with quicker response and added reliability, and i would like to get it 'tuned' appropriately for my car. but should i try the stock (and potentially leaking) BPV first or screw around with springs/shims?

i swear a few people on here use the Forge BPV with the new AP maps, but i've never verified what spring/shim combo they use to get the full boost.

[Sacrilicious]

i would try the stocker on as a baseline for like 50 miles and then take some logs (including one with WG DC). that way, you know what your baseline should be. also, check to be sure that you don't have any weird leaks in the system. your boost should be holding more than that, so let's have a look see what's wrong. keep in mind that it COULD just be the cold weather messin with your car's ECU logic.

the fact that your LTFTs turned out however they did does not necessarily mean they are wrong, since it's dependent on the variances in your intake system. you really have to get more info before you can decide if something is wrong.

[08_ms3_gt]

Originally Posted by Sacrilicious i would try the stocker on as a baseline for like 50 miles and then take some logs (including one with WG DC). that way, you know what your baseline should be. also, check to be sure that you don't have any weird leaks in the system. your boost should be holding more than that, so let's have a look see what's wrong. keep in mind that it COULD just be the cold weather messin with your car's ECU logic. the fact that your LTFTs turned out however they did does not necessarily mean they are wrong, since it's dependent on the variances in your intake system. you really have to get more info before you can decide if something is wrong.

i've got the stock BPV installed as of now but not enough miles to log. i did try running out third a bit, and it felt strong, but i can't confirm the boost levels. yes, i did go WOT without letting the map settle into the new BPV, but i figured the LTFT's can't change all that much..?

i'll try to put some mileage on the car in the next couple days and subsequently perform a log for the stock BPV. why is the WG DC so important, by the way? shouldn't it just open when the ECU tells it to? or is it possible that the ECU is opening it too much?

[Sacrilicious]

Originally Posted by 08_ms3_gt i've got the stock BPV installed as of now but not enough miles to log. i did try running out third a bit, and it felt strong, but i can't confirm the boost levels. yes, i did go WOT without letting the map settle into the new BPV, but i figured the LTFT's can't change all that much..? i'll try to put some mileage on the car in the next couple days and subsequently perform a log for the stock BPV. why is the WG DC so important, by the way? shouldn't it just open when the ECU tells it to? or is it possible that the ECU is opening it too much?

well, it really depends whether the LTFTs will change much. IDEALLY they should be 0%, but that's not how it usually works out, since parts aren't perfect and will have slight differences that will affect how the air flows over the MAF sensor. i wouldn't worry too much about it, though. just let the LTFTs learn properly to be safe. the reason i wanted to see the WG DC was to see if your car is leaking boost. if the WG DC is sitting at 100%, and you're boost 12 psi, you're definitely leaking. if it's only 20%, then your car is proooobably detuning itself for weather.

[08_ms3_gt]

Originally Posted by Sacrilicious well, it really depends whether the LTFTs will change much. IDEALLY they should be 0%, but that's not how it usually works out, since parts aren't perfect and will have slight differences that will affect how the air flows over the MAF sensor. i wouldn't worry too much about it, though. just let the LTFTs learn properly to be safe. the reason i wanted to see the WG DC was to see if your car is leaking boost. if the WG DC is sitting at 100%, and you're boost 12 psi, you're definitely leaking. if it's only 20%, then your car is proooobably detuning itself for weather.

i've uploaded some new logs with WG DC included. the boost is still low, even with the stock BPV and proper 'learning' allowed for the ECU. fuel pressure, knock, etc. look okay. the ambient temp. was 13*F. the logs are here.

please let me know what you think.

[franchize]

I have to say using the old style HKS SSQV I have TONS OF BACKFIRING, and lots of pops on deceleration. The deceleration pops are cool actually, but the backfiring on shifting is extremely loud sometimes.

I'm changing to the new HKS BPV and see if that helps.

[iracer7]

Good info, thanks. Looking to get a Tursmart BOV.

[Silver Ecstasy]

I'm sorry for posting on an old thread but it seemed relevant to my situation.

Since having a Dashhawk, I haven't been able to really get the higher PSI's that everyone else seems to gain with doing any BPV on their MS3 (Forge, HKS, Turbosmart, etc. etc). I ran a Forge for the longest and didn't like the part-throttle driveability, so I switched to stock. The car ran pretty smooth and didn't have any heavy surges or drops in boost, however, I'd still never see a consistent 15psi during WOT.

Now, i've got the Turbosmart BPV and the spring seems pretty soft. After doing some testing today, Boost is holding the same or even maybe .50 psi less. So i'm having SU send me the stiffer spring. I'm hoping this will fix it, or the 30* cold weather here is royally messing with the car.

I noticed someone said to log WG DC? What should you be looking for during test runs? During WOT, or higher PSI scenarios, what SHOULD your WG DC be? I've checked over and over for leaks and nothing seems to be leaking. I've thought maybe a vacuum hose is plugged or something so I unplugged it (as Turbosmart suggests) and it hisses air and idled poorly (meaning, it's working properly, no kinks).

[Sacrilicious]

Originally Posted by Silver Ecstasy I'm sorry for posting on an old thread but it seemed relevant to my situation. Since having a Dashhawk, I haven't been able to really get the higher PSI's that everyone else seems to gain with doing any BPV on their MS3 (Forge, HKS, Turbosmart, etc. etc). I ran a Forge for the longest and didn't like the part-throttle driveability, so I switched to stock. The car ran pretty smooth and didn't have any heavy surges or drops in boost, however, I'd still never see a consistent 15psi during WOT. Now, i've got the Turbosmart BPV and the spring seems pretty soft. After doing some testing today, Boost is holding the same or even maybe .50 psi less. So i'm having SU send me the stiffer spring. I'm hoping this will fix it, or the 30* cold weather here is royally messing with the car. I noticed someone said to log WG DC? What should you be looking for during test runs? During WOT, or higher PSI scenarios, what SHOULD your WG DC be? I've checked over and over for leaks and nothing seems to be leaking. I've thought maybe a vacuum hose is plugged or something so I unplugged it (as Turbosmart suggests) and it hisses air and idled poorly (meaning, it's working properly, no kinks).

unless your stock BPV was broken and leaked a lot at WOT, you should not really see a "gain" in boost. the main mods that really give you more boost are any that mess with boost control like the AP, SB, MBC, etc. i ran with the stock BPV under a number of mod levels, and it performed about the same as any forge BPV that i've tried for the purpose of holding boost. the partial throttle response difference and release sound was the main difference to be had with an aftermarket valve.

so, to answer your other two questions:

1. your TS BPV sounds like it's working as intended.
2. the "correct" WGDC depends entirely on what your mods, boost control, and weather conditions. in general, people log to see if it's being maxed out at the top of the rev range to see if they're overworking their turbo. they also use it to diagnose boost spikes as boost kicks in...if your WGDC pins itself to wide open when you floor it and then you see a gigantic boost spike before the boost settles back to like 16psi, then you know that you should try retuning your WGDC tables so that your car isn't overly-aggressive with the WGDC as it applies boost.

EDIT: fyi: mods that mess with how load is calculated have been known to cause boost spikes beyond what a stock ms3 should see, but the boost that is held still remains pretty close to stock unless you get a tuning solution like the AP, SB, or a MBC (this is the most basic "tuning" solution, imo...not the best by far, but it does screw around with boost).

[Silver Ecstasy]

Well, i've done zero tuning, only MSCAI, MSCBE are mods. I was spiking in the high 20's and it would settle down to 13psi which just seems so odd to me when everyone else will see 15psi or higher. I know of a few local MS3's who run with Forge BPV's that consistently sit around 15 or 16 psi. And i've tried understanding why my car just simply won't have it.

Also, when I was watching WG, I think I remember it would go to 0 when i'd floor it, then slowly creep up to 25?

[Sacrilicious]

do you have the airflow straighteners on your MSCAI? one of the main issues with the MSCAI is that its MAF housing doesn't have stock airflow characteristics, so it screws up how the ECU calculates load and how much air it thinks is coming in.

[Silver Ecstasy]

Yep, and I have it installed properly per MSCAI's instructions. It just seems like the car is so quick to bring the boost back down. Or if I'll do a 3rd gear pull, i'll never see anything north of 12psi. It's typically 12 or lower.

[Sacrilicious]

does this happen only in the cold, or even when it's warm out? our cars detune themselves in the winter.

[Silver Ecstasy]

Well, it has happened more recently in the cold. But in the summer, it's not like it was very willing to hit those pressures either. I know nothing can be determined without a log really, but it's hard to log, trying to figure out where I can run the car hard and safely to log anything.

[Sacrilicious]

ya, it would be really useful if you could give us logs with the AFR, boost, WGDC, etc. the MSCAI works better with the straightener, but i have heard of people having issues even with the straightener.

[Silver Ecstasy]

So, AFR, Boost, WG DC, i'd assume Throttle Position too right?

[Addikted To Boost]

I wouldnt worry about not holding boost especially in the colder months. The air is more dense and the car hits its load targets with less boost because of the increased density of the air charge. Even when its warm out my car on stock tune and mods in my sig will hit like 15.5 lbs of boost and then taper to about 12 by redline. Its just the stock tune nothing to worry about. I just finished checking out my ltfts and at idle it is 0, during decel in gear it is about +3%, light load it is around 5%, and 13% at wot and heavy throttle. Thanks for this post it was very informative. How do those numbers seem?

[Silver Ecstasy]

Thanks for the info on the stock boost though! Just seems odd when others are holding better than me, and they're in the same area as where i'm at.

My LTFT's with stock BPV were opposite. +9.4 cold idle, +2.3 cruise and +0.0 WOT.

[Sacrilicious]

addikted: what spring/shim combo are you using on your forge BPV? your WOT ltft is pretty high.

silver: your LTFTs look good...addikted is right that your car may be running 100% as intended because it thinks it has achieved its commanded load value. intakes can affect how load is calculated, and i bet that it's probably fooled around with what your car is doing to lower your boost. remember: our cars are load tuned, which means that cars that have skewed load calculations can boost more/less accordingly.

[Silver Ecstasy]

I see! Thanks so much!! I am going to attempt a few logs if I get the space to do so..

I have AFR, Vac/Boost, WG DC, Abs Thrttle Pos.

I noticed while cruising, WG stays at 0, when I go WOT, it'll shoot up real high near 100 for a flash of a second, then reel it down almost to 0. What does that mean?

[Sacrilicious]

EDITTED TO REMOVE BAD WGDC INFO

[Addikted To Boost]

Originally Posted by Silver Ecstasy I see! Thanks so much!! I am going to attempt a few logs if I get the space to do so.. I have AFR, Vac/Boost, WG DC, Abs Thrttle Pos. I noticed while cruising, WG stays at 0, when I go WOT, it'll shoot up real high near 100 for a flash of a second, then reel it down almost to 0. What does that mean?

I am running the forge with blue spring and 0 shims. I had the cpe xcel cai for about a year and i recently took it off and switched to the cobb sri, and my ltft's were pretty much what i posted in my previous post. During the year or so i had the cpe xcel on my wot ltft was 0 or maybe .8, and at idle it was like -8% now i have switched back from the cobb to the cpe and im still getting those screwy ltft's that i posted above. Maybe its because of the colder weather and they will settle back down.

when you are cruising you are building no boost, when the car goes under load at wot the wastegate is what determines how much boost is bled off to meet boost and load targets. Fore example, if youre cruising in 6th gear and nail the gas at like 60mph, the boost isnt needed because the calculated load is not high enough and it will bleed all the boost at first and then gradually introduce the boost as load gets higher and higher, until it gets to the point where it has reached its boost/load equilibrium that it wants then it will bleed boost again. At least that is how i understand it someone please correct me if i am wrong. It cuts boost after like 5000 rpm on stock tune and tapers down to 11-12 psi by 6000 rpm.

[Sacrilicious]

hrrm...not sure what to tell you about your LTFTs, addikted...it's hard to tell whether you have a slight leak somewhere in your intake or not. have you tried cleaning your MAF sensor (not the teardrop thing, but the 2x resistors way up the tube)? a dirty MAF sensor can cause your LTFTs to go up.

[Silver Ecstasy]

See, with some Forge MS3's, they'll hold 16psi. Shouldn't the WGDC stay in a higher range then to bleed it off?

I guess what would help is, spoon-feeding just what the WGDC # means during different scenarios.

[Sacrilicious]

EDITTED TO REMOVE BAD WGDC INFO

[Silver Ecstasy]

Ok makes sense. But shouldn't it keep it spinning while you're making boost? Obviously, it never shuts down completely while the car is running but 0 should mean it's making zero power? Or am I understanding this wrong.

[Sacrilicious]

EDITTED TO REMOVE BAD WGDC INFO

[Silver Ecstasy]

Ok I do understood correct. But i'll be in Boost showing whatever measly #'s i'm getting and my WGDC is at 0 during WOT after the initial big spool up. That's what I don't get...

[Sacrilicious]

EDITTED TO REMOVE BAD WGDC INFO

[Silver Ecstasy]

Exactly!! I wonder if my wastegate is fubared, or the hose is not properly connected. I'll try to log tonight but I don't have a way to download the log damnit... (Apple, no copy of win xp around)..

[Addikted To Boost]

Originally Posted by Sacrilicious hrrm...not sure what to tell you about your LTFTs, addikted...it's hard to tell whether you have a slight leak somewhere in your intake or not. have you tried cleaning your MAF sensor (not the teardrop thing, but the 2x resistors way up the tube)? a dirty MAF sensor can cause your LTFTs to go up.

yea i clean the maf sensor about every other oil change...i just reset the ecu last night so the thing has only about 40 miles on it now and the numbers have began to fell, -6% at idle, 2% at light throttle, 4% at decel, and 12.5 for heavy throttle/wot... i sort of romped on it alot this morning because i forgot that it was just reset so maybe i should reset it again and drive a little easier... but i think it will lower over time anyways.

[Sacrilicious]

you're using a DH to log, right?

[Silver Ecstasy]

Yep!

[Sacrilicious]

Originally Posted by Addikted To Boost yea i clean the maf sensor about every other oil change...i just reset the ecu last night so the thing has only about 40 miles on it now and the numbers have began to fell, -6% at idle, 2% at light throttle, 4% at decel, and 12.5 for heavy throttle/wot... i sort of romped on it alot this morning because i forgot that it was just reset so maybe i should reset it again and drive a little easier... but i think it will lower over time anyways.

hrrm...sounds like that's just where your WOT ltfts want to be. i remember dread saying that his cobb sri was giving him high WOT ltfts, but i don't remember what he ended up doing...

Originally Posted by Silver Ecstasy Yep!

ya, just drop the log here whenever you get it and we'll all have a look at it and tell you what we think.

[Silver Ecstasy]

Thanks man, I appreciate all the help so far!!