73 replies to this topic

[neggles]

Hey guys!

 

I've been on a bit of a long journey with this car but I'm hoping that someone can help me out in one way or another.

 

It's an MY2002 (revD) 3gen AUDM Liberty B4 5MT.

 

The ECU in the car has been modified by ECULabs and is running their software, this is because I want flex-fuel support.

 

I have ID1000 injectors (as the plan is to run E85) and supporting fuel system mods (pump/lines), Pierburg 3port BCS, a GM 3 bar MAP and GM IAT (installed in the throttle-side TMIC end tank) sensors, and a nice straight through exhaust. I've done some other things but they're not relevant to this particular problem. The MAF is new, the plugs are new, the packs all work, all the sensors work, I never get a CEL.

 

When I first got the car it was stock, but had a blown motor. I swapped a new one in (finding a motor from a revD was hard but I got there) and though the tune wasn't the greatest (stock tune never was on these) it did behave as you would expect, sequencing into twin mode from 3500 to 4000 or thereabouts and making ~1bar of boost on the primary and ~0.5bar in twin turbo mode. I'm lead to believe these are accurate numbers (less boost in twin mode due to more flow) but if any of you have experience with a revD/E and can let me know what I ought to be seeing boost-wise stock, that would be great. One of the problems i'm trying to rule out here is a failed secondary turbo.

 

I handed the car over to a fairly well respected tuning shop which has turned out to be a forking disaster. They do not have any forking clue what they're doing with ECULabs and I hope the next time someone asks them to tune an ECULabs ECU they turn them away. I won't name names but they're north of the city and they're probably the dudes to talk to if you're running a single-turbo Haltech setup on a Supra or Skyline but definitely not for 3gen TTs running ECULabs.

 

They installed the MAP/IAT/injectors (with plenty of fork-ups along the way... I'm not smart) but couldn't get it to behave on the dyno. I found a software glitch in my specific ECULabs firmware and had that fixed, and then decided to take it to someone who knows a little bit more about what the fork they're doing.

 

When I got the car back I could not for the life of me get it to sequence into twin mode below 6500rpm, but when it did sequence, oh BOY did it take off like a rocket for that last 1000rpm (redline 7500). I concluded there had to be something wrong tune-wise preventing it from sequencing, or something wrong with the BBOD.

 

So I took it to Got It Rex in Sunshine West, as recommended by ECULabs and the people I should have gone to in the first place. They've got her running like a dream on the single turbo but couldn't get it to sequence into twin turbo mode, so they handed it back over.

 

I took out the BBOD and cleaned every single line and solenoid, made sure the restrictor pill is in the right place, everything is working fine there. All the vacuum lines go to the correct points and the vacuum resorvoir is hooked up and holding vacuum. Then I notice they had the secondary duty cycle set to 100%, and in the case of the revD it appears that higher duty cycle bleeds more pressure out of the EGV +ve port and thus causes the valve to open LESS, so they were effectively commanding the car into single turbo mode at all times, which explained the weird results I was getting on a datalog. This also resulted in the car never building more than like 3psi of boost, which was pretty strange.

 

I tried the factory secondary duty map and got the same result, sequencing at 6k rpm even though the DPS is reporting zero differential pressure from 4k rpm upwards, but again there was no real boost pressure happening. It's been suggested that maybe my secondary turbo has kicked the bucket, and if this is the case I do conveniently have another one (off the old engine), and I suspect tomorrow I'm going to drop the y-pipe and check it anyway but would that make sense with these symptoms? and if so, why the hell did it work at 6500rpm with a mostly-stock-but-modified-for-injectors tune?

 

So I tried the opposite, setting the secondary duty to 0% and reasoning that this would cause it to have the mother of all VODs but at least prove twin turbo mode was working. Nope. It spends 2000rpm-6000rpm attempting to change over, the differential pressure sensor reports 3psi more boost coming from the primary than the secondary from ~4500 up, and then at 6000 it suddenly slams the intake air valve open as if it's decided that it's waited long enough. It's consistent. Every time, 6000rpm.

 

Here's a dropbox link to a log file: https://www.dropbox....150950.csv?dl=0 since I can't attach it to the post for some reason. I had the secondary duty set to cut out entirely at 4k and be circa 20% below 4k for this particular example but the behavior is consistent enough that it shouldn't really matter.

 

I know the smart thing to do is swap the ECU out for aftermarket management like a Haltech Elite or swap to single-turbo, so right away I'm going to reject those ideas. I don't want single turbo (the stepped power delivery of the sequential twin system is really fun, and I already have a daily driver single-turbo car) and I really don't want to spend $2500 on an Elite 2500 when I already dropped a grand on ECULabs and a wideband.

 

So beyond the bolded bits above, some questions;

 

• Has anyone here had any experience with a RevD/E using ECULabs?


• Has anyone had an experience similar to this (I could find none except one referencing a broken +ve solenoid, which is definitely not my issue here, i've tested and cleaned it myself and it clicks when the ECU is in test mode so the drivers are all OK) and if so how did you resolve it?


• Does anyone know (or know anyone who might have a better idea of) how the revD decides when to stage into twin mode? The maps I have available seem incomplete.


• Am I just being an idiot and ignoring an obviously blown secondary turbo?

 

This godforsaken machine is doing my head in, but I am determined to make it work. I would be incredibly grateful for any help anyone is able to give as subyclub seems to have almost all of the knowledge of how these work (insofar as I can't find anyone who knows their ass from their face when it comes to B4s other than here and SL-I) and it's incredibly frustrating to get this close to completing a project and then get cockblocked by software for six months.

 

E: See post #32 here for more info

[zahmad]

B4 guru in the house. He'll help you sort it out...:

[neggles]

A stuffed or incorrectly plumbed intercooler intake air control valve will blow open from the boost at around 6k rpm.

Somehow I think there may be more to your problem than that.

Are you sure the lines are plumbed correctly?

 

I should point out that I'm not looking at whether the valve is physically opening but rather the open signal in the ROMRaider log. It lines up with what I experience in the car, as well. I really don't think it's something mechanical - the 6k rpm IAC opening is too consistent, it is always commanding open on the first log entry above 6k RPM. I will gladly defer to your expertise, though.

 

Nevertheless, when I turn the ignition on in test mode, the IAC valve opens and closes (as does the ECV) until the vacuum tank runs out of vacuum, so we can probably count that out as an issue.

 

I've quadruple checked every line and cross referenced with an MY2002 service manual diagram as well as the original setup that I carefully documented before I removed the old engine from the car. It worked flawlessly (or as flawlessly as a stock tune ever does, there was almost no VOD, it was more of a plateau of mild discomfort than a valley of death) prior to the installation of the MAP/IAT/Injectors, which is clearly something I should have done myself rather than farming it out as now I'm not entirely certain how it's been done.

 

My current leading theory is the relocated IAT sensor, now being just prior to the throttle butterfly as opposed to being located inside the MAF, is throwing things off as the correction table for secondary duty cycle based off IAT is pretty significant; picture attached.

 

On the other hand, my logs only show an IAT in the mid 20s (ambient was ~11c) so I'm not sure.

 

If it wasn't such a gigantic pain to swap out the injectors I'd swap the stock ones back in and reload the stock tune just to see if it still behaves...

Attached Files

•  secduty.png   50.98KB   10 downloads

[duncanm]

diagnose the secondary turbo by forcing open the ECV and secondary pressure relief valve (SPRV?) wth the appropriate vac/pressure.

 

Now when you say you set the ECV duty cycle to 0% and 'it spends its time 2-6k trying to change over) - does this mean the secondary is spooling (ECV open) - but the IACV is shut ? (and hence no secondary pressure contributing to boost) ?

 

  The 6k opening of the IACV may just be the ECU logic: if you're revving that high, the ECU assumes you'll get secondary boost easy so doesn't need to look at the differential pressure to make its decision - and is always in twin mode regardless of pressures.

 

  Are you sure the differential pressure sensor is ok?  Do  you get the right voltages out of it if you manually vary pressure across it (presumably, you could also log its output - I'd be looking at that and the IACV control outputs).

[neggles]

Alright alright I'll force it into twin parallel mode tomorrow and see if it boosts like it ought to, to get the possibility of the 2nd turbo being blown out of my mind (or confirm it).

 

Correct, with secondary duty and secondary max duty (the labels for ECV +ve duty / max duty) set to 0 across the board, from around 2000rpm the ECV opens but the IACV stays shut right up 'till 6 grand even though the DPS shows <2psi difference from around 4 grand. On the other hand the system does need a boost source to work and I was making all of 2psi of boost on the primary turbo with that configuration, so that might not be a lot to go off, and this is also exactly what you'd expect if the ECV is slammed open while the SPRV is recirculating, all the exhaust pressure is going into pointlessly spinning the secondary.

 

I was under the impression that the car didn't start spooling the secondary until a few thousand rpm, but i'm seeing EGV +ve and EGV +ve duty from the low 2000s on the logs, so in retrospect I don't know how else I expected that to go.

 

I agree about the IACV opening at 6 grand; it's too consistent to be anything other than a bit of "this should be done by now, open it" logic in the ECU.

 

The DPS is definitely working exactly as it ought to, I've tested it with a known pressure source and also been logging the data (it's in there as "pressure differential sensor"). The IACV control output is in my logs also (Intake Air Solenoid iirc) and I've been using that as an indication of whether the ECU thinks it's in single or twin mode. It also worked perfectly prior to the MAP/IAT/Injector change.

 

I'm going to do some more experimenting with the stock EGV +ve duty maps and boost target maps loaded into the car.

 

I also think I might just have found something; the speed limiter in the ECU appears to have been set to 0kph. I'm unsure how much of a difference that makes, but I've wound it back up to 250. Not driven it since that change.

[duncanm]

I was under the impression that the car didn't start spooling the secondary until a few thousand rpm, but i'm seeing EGV +ve and EGV +ve duty from the low 2000s on the logs, so in retrospect I don't know how else I expected that to go.

My understanding is the ECV is effectively used as a wastegate when on primary (primary wastegate held closed with much wastegate duty cycle), so that the primary is spooled ASAP. The primary wastegate is only used in twin mode to control boost. This should be fairly clear if you log the primary WGDC.
 

I also think I might just have found something; the speed limiter in the ECU appears to have been set to 0kph. I'm unsure how much of a difference that makes, but I've wound it back up to 250. Not driven it since that change.

I'm not sure how the speed limiter kicks in, but wouldn't be surprised if it opened up the SPRV to limit boost, you may have found your problem.

[neggles]

Primary WGDC comes up the moment there is any throttle percentage and never goes away. It actually hits 100% briefly at some points.

 

But the original map from the 2-port had it very low, not much above 20-30%.

 

This confuses me also, as I too thought that the primary wastegate was not used during single turbo mode.

 

That's an interesting point, and might explain why I've never seen SPRV solenoid #1 turned on... Jeez, if that's the problem I'm gonna be so annoyed this has been driving me mad for weeks

[duncanm]

yed - don't forget 100% WGDC means max boost - WG will only open if manifold pressure times ratio of (WG solenoid + tubing) and pill resistance is greater than WG spring (10psi?).

0% WGDC gives wastegate spring pressure.

[neggles]

WG spring is just over 8psi on this model.

 

Hmm... Maybe I just need to massively raise the single turbo WGDC?

 

Okay, I've got a few things to check out and try out. Will report back tomorrow with results - thanks very much

[neggles]

Alright guys, riddle me this:

 

Why would the differential pressure sensor report +9psi while runnning in TT mode? I managed to get the car to stage into twin mode and stay there through a gear change, and the DPS reported positive pressure. Manifold pressure held steady around 1 bar so I'm confident both turbos are working.

 

Now I'm starting to doubt whether the DPS is correctly hooked up.

 

I loaded the stock boost targets and secondary duty cycle tables into the car, then zeroed the primary wastegate duty tables.

 

Log file here: https://www.dropbox....130159.csv?dl=0

 

Gonna pull off the intercooler and re-recheck the DPS lines because something's not going the way it's meant to. Why would the DPS see 9psi more pressure at the SPRV crossover than manifold?

[neggles]

Okay, um, I take it back, maybe it's the ICV.

 

When you apply vacuum to my ICV it closes (this is the default state with the solenoid not energized);

 

 

But when you remove vacuum it only opens halfway;

 

 

If i gently blow into the control line it opens the whole way;

 

 

When the solenoid is energized the vacuum is just disconnected and the control line is open to atmosphere, which I suspect means it's not opening the whole way since the spring seems to only open it partially.

 

I take it the valve is meant to open the whole way when you remove vacuum?

[neggles]

MYSTERY SOLVED.

 

Well, hopefully. It looks like I can modify the system to apply boost pressure to the ICV instead of atmo as a temporary workaround. In the meantime... Jesus, where do I even look for a new one of these?!

[neggles]

Damn, that's just my luck! I'll chuck up a WTB post.

 

This still isn't explaining why it's waiting so long to command twin turbo mode, mind you. The IAC is being left closed by the ECU until 6k RPM for some reason.

 

Might explain why I never got the correct amount of boost in TT mode, though. Gonna have a look at the SPRV also while I'm in here.