Turbo B18B1 ‘flatlines’ after roughly 5psi

 
Old 09-24-2018, 09:32 PM
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Default Turbo B18B1 ‘flatlines’ after roughly 5psi

Hey guys and gals. So I have a 2000 integra. I boosted the factory B18B1. It’s tuned to 12.4 lbs of boost, making 356 hp.

I just recently rebuilt my Garrett T3/T4 hybrid turbo with a kit from G Pop Shop and had the turbo balanced. Everything has worked well for a while now - car pulled hard all the way to redline, boost held up to redline, car ran great!

As of recent, and out of nowhere, the only way I can think to describe it is that the car ‘flatlines’ somewhere around 5 psi. When I say flatlines, I mean it as if you’re looking at a dyno graph. Like the power curve would be curving upwards until around 5 psi and then it would horizontally flatline. I can hammer on it and it’ll throw me back in my seat, and when it flatlines, I actually lift up off the back of my seat because of the power loss (if that’s the right term to use). What’s weird is that the boost gauge reads full spool - it reads 12 psi.

Now, here’s something else that’s weird as well. Sometimes, I can do a partial throttle pull - probably about 1/3 of the throttle - and it’ll pull the whole way to redline as it should. This is only sometimes though. Other times, it flatlines even at partial throttle.

The car runs fine when I baby it - no problems whatsoever.

It is external wastegate, and I know that the wastegate can get stuck open or closed, so I’m going to eventually pull the wastegate off and open it up, but I have yet to do that. I plan to do a boost leak test within the next couple of days to start, but any other suggestions are well appreciated! Thanks in advance!
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Old 09-25-2018, 04:09 AM
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Default Re: Turbo B18B1 ‘flatlines’ after roughly 5psi

Sounds to me like the clutch is on it's way out if this occurs during full throttle low speeds but not rolling into it.
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Old 09-25-2018, 04:41 AM
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Default Re: Turbo B18B1 ‘flatlines’ after roughly 5psi

Could be a tuning issue, or ignition related problem. Is there any perceptible misfiring when it happens? Does it go rich or lean? What fuel do you use?

Start by replacing spark plugs, reduce the gap slightly. Make sure timing is still correct, belt didn't jump a tooth and dizzy timing is good.
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Old 09-25-2018, 08:15 AM
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Default Re: Turbo B18B1 ‘flatlines’ after roughly 5psi

When you use 1/3 and it pulls like normal it produces full 12psi target boost?
Do you hear the vtec engaging ?
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Old 09-25-2018, 08:32 AM
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Default Re: Turbo B18B1 ‘flatlines’ after roughly 5psi

Originally Posted by AllMtrRex View Post
Sounds to me like the clutch is on it's way out if this occurs during full throttle low speeds but not rolling into it.
The clutch is near brand new. It’s a comp stage 4. It’s not the clutch. I know what a bad clutch feels like, and this definitely is not clutch related.

Originally Posted by 2x0 View Post
Could be a tuning issue, or ignition related problem. Is there any perceptible misfiring when it happens? Does it go rich or lean? What fuel do you use?

Start by replacing spark plugs, reduce the gap slightly. Make sure timing is still correct, belt didn't jump a tooth and dizzy timing is good.
No noticeable misfires. The car has always ran rich. Though I don’t have an AFR gauge in the car anymore, when I did, the AFR was 10.1. I’m tuned on 93 octane and I’ve never ran anything but 93. The spark plugs are brand new and are gapped to .028”. I will definitely check the timing belt and ignition timing, though the dizzy doesn’t feel like it’s loose at all.

Originally Posted by Balor_Gr View Post
When you use 1/3 and it pulls like normal it produces full 12psi target boost?
Do you hear the vtec engaging ?
Yes, it’ll hit the 12 lb target. This is an LS - it’s non vtec.
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Old 09-25-2018, 09:18 AM
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Default Re: Turbo B18B1 ‘flatlines’ after roughly 5psi

Originally Posted by GSR_ITR_BOIB View Post
I know that the wastegate can get stuck open or closed, so I’m going to eventually pull the wastegate off and open it up
Do this and report back. I'm going with a wonky spring or diaphragm..
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Old 09-25-2018, 09:24 AM
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Default Re: Turbo B18B1 ‘flatlines’ after roughly 5psi

Sounds like boost cut possibly. Can you post a video of what it's doing on YouTube and post the link in here?
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Old 09-25-2018, 10:32 AM
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Default Re: Turbo B18B1 ‘flatlines’ after roughly 5psi

Originally Posted by GSR_ITR_BOIB View Post

No noticeable misfires. The car has always ran rich. Though I don’t have an AFR gauge in the car anymore, when I did, the AFR was 10.1. I’m tuned on 93 octane and I’ve never ran anything but 93. The spark plugs are brand new and are gapped to .028”. I will definitely check the timing belt and ignition timing, though the dizzy doesn’t feel like it’s loose at all.
Could be spark blowing out, especially with that big a gap and running that rich. Usually I'd start at around .025" gap and reduce from there as needed. Currently I am running .019" gap on mine. Also could be getting wayy too fat if it was reading 10:1 already. Colder air could mean it's dumping even more fuel in to compensate.

Or yeah, as others have said it could be boost cut. Colder weather could cause this to happen as well.
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Old 09-25-2018, 11:01 AM
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Default Re: Turbo B18B1 ‘flatlines’ after roughly 5psi

This is all ignoring the fact that 10:1 on pump gas is way too rich to begin with. There would be no reason not to tune it at low-mid 11's, you are just losing power and making it run like crap. Especially when variances come into play and it might be running in the 9:1 range if compensations aren't set up properly.
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Old 09-25-2018, 01:27 PM
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Default Re: Turbo B18B1 ‘flatlines’ after roughly 5psi

Originally Posted by Txdragon View Post
Do this and report back. I'm going with a wonky spring or diaphragm..
This was my original thought as well. Maybe I will start here before I move to a boost leak test.

Originally Posted by K7-1Ktrevor View Post
Sounds like boost cut possibly. Can you post a video of what it's doing on YouTube and post the link in here?
Right now I’m at work for the night, so if the rain holds off tomorrow (which I doubt it will), I’ll get a video up and posted, if not tomorrow, then I’ll shoot for Thursday.

Originally Posted by 2x0 View Post
Could be spark blowing out, especially with that big a gap and running that rich. Usually I'd start at around .025" gap and reduce from there as needed. Currently I am running .019" gap on mine. Also could be getting wayy too fat if it was reading 10:1 already. Colder air could mean it's dumping even more fuel in to compensate.

Or yeah, as others have said it could be boost cut. Colder weather could cause this to happen as well.
Wow, I thought .028” was pretty small, beings that factory B1 specs call for .044”. I’ll pull the plugs tomorrow and check the gap and report back with the gap size and color of the plugs. Also, this originally started happening in the 80+ degree weather, so I’m thinking we can rule out the cold weather being a problem.

Originally Posted by 2x0 View Post
This is all ignoring the fact that 10:1 on pump gas is way too rich to begin with. There would be no reason not to tune it at low-mid 11's, you are just losing power and making it run like crap. Especially when variances come into play and it might be running in the 9:1 range if compensations aren't set up properly.
I agree that 10:1 is too rich. This is how it’s always ran since I’ve had it tuned, unless there’s something wrong with my AFR gauge, which I’d doubt. Though again, I don’t have the AFT gauge in the car anymore.
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Old 09-26-2018, 12:24 AM
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Default Re: Turbo B18B1 ‘flatlines’ after roughly 5psi

Originally Posted by K7-1Ktrevor View Post
Sounds like boost cut possibly. Can you post a video of what it's doing on YouTube and post the link in here?
Boost cut will be incredibly distinguishable and really rough. Unless the boost is solenoid controlled, I wouldn't consider this.
Originally Posted by 2x0 View Post
Could be spark blowing out, especially with that big a gap and running that rich. Usually I'd start at around .025" gap and reduce from there as needed. Currently I am running .019" gap on mine. Also could be getting wayy too fat if it was reading 10:1 already. Colder air could mean it's dumping even more fuel in to compensate.

Or yeah, as others have said it could be boost cut. Colder weather could cause this to happen as well.
This leads to a rough-running pull just as distinguishable as boost cut. Sudden stop/jerk at the moment of occurence.
Originally Posted by 2x0 View Post
This is all ignoring the fact that 10:1 on pump gas is way too rich to begin with. There would be no reason not to tune it at low-mid 11's, you are just losing power and making it run like crap. Especially when variances come into play and it might be running in the 9:1 range if compensations aren't set up properly.
While the fat A/F is a problem, I wouldn't believe it would be THE problem.. I myself considered A/F here, but it shouldn't have anything to do with the boost level. When I first started my tuning process, I was still able to hit 12 psi in high 9, low 10s. It did cause some power loss, but not boost loss.

Originally Posted by 2x0 View Post
Wow, I thought .028” was pretty small, beings that factory B1 specs call for .044”. I’ll pull the plugs tomorrow and check the gap.

The factory gap specs don't account for forced induction. I don't have a B-series, but I had problems with spark blowout at any gap above .030. I settled finally at .028. Lol
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Old 09-26-2018, 10:57 AM
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Default Re: Turbo B18B1 ‘flatlines’ after roughly 5psi

So I just took off and opened up my wastegate. Spring looks fine and also seemed to work like it should (pushing it in by hand), but I noticed that the rubber o-ring/gasket that seals the wastegate is flattened out/rolled over in a spot. It won’t unroll - it seems to be stuck in place. Could this cause my problems, or is it supposed to be like that? I also checked the plug gap, which was still at .028”, but I closed it up a little bit to .025”. Also, the ignition timing is still good.







Last edited by GSR_ITR_BOIB; 09-26-2018 at 11:53 AM.
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Old 09-26-2018, 11:55 AM
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Default Re: Turbo B18B1 ‘flatlines’ after roughly 5psi

That diaphragm tho... It's toast, amigo.
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Old 09-26-2018, 01:15 PM
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Default Re: Turbo B18B1 ‘flatlines’ after roughly 5psi

Plugs look like you're running pretty rich.
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Old 09-27-2018, 03:26 AM
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Default Re: Turbo B18B1 ‘flatlines’ after roughly 5psi

Originally Posted by Txdragon View Post
That diaphragm tho... It's toast, amigo.
Likely from a poor install of the W/G spring.
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Old 09-27-2018, 04:27 AM
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Default Re: Turbo B18B1 ‘flatlines’ after roughly 5psi

Yeah man, that carbon buildup on the plugs

At the very least replace those bad boys.
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Old 09-27-2018, 06:04 AM
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Default Re: Turbo B18B1 ‘flatlines’ after roughly 5psi

What are you using to regulate boost, just spring pressure?
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Old 09-27-2018, 09:09 AM
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Default Re: Turbo B18B1 ‘flatlines’ after roughly 5psi

Need data logs to know anything really
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Old 09-27-2018, 10:45 AM
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Default Re: Turbo B18B1 ‘flatlines’ after roughly 5psi

Originally Posted by Txdragon View Post
That diaphragm tho... It's toast, amigo.
I unflattened it the best I could and put some Hondabond in there. Thinking that should be alright. Thoughts?

Originally Posted by AZ_CIVIC View Post
Plugs look like you're running pretty rich.
Yeah, I’ve been running rich.

Originally Posted by NVturbo View Post
Likely from a poor install of the W/G spring.
Could be, but I bought the wastegate the way it sat before I even opened it, so it’s hard to say.

Originally Posted by 2x0 View Post
Yeah man, that carbon buildup on the plugs

At the very least replace those bad boys.
These plugs are actually basically brand new. Probably less than 300 miles on them.

Originally Posted by rice a roni View Post
What are you using to regulate boost, just spring pressure?
MBC

Originally Posted by LightningTeg View Post
Need data logs to know anything really
Laptop is broke right now, or I would. I’ll see what I can do.
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Old 09-27-2018, 11:57 AM
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Default Re: Turbo B18B1 ‘flatlines’ after roughly 5psi

I put homda bond on a wastegate before

bad idea... you shouldve checked the wastegate for leaks before taling it apart instead of guessing


start with taking out fuel from your tune. I dont care if thats how its been those plugs look like ****

start there
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Old 09-27-2018, 12:32 PM
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Default Re: Turbo B18B1 ‘flatlines’ after roughly 5psi

Yeah, makes no sense. I second the datalog.
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Old 09-27-2018, 09:12 PM
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Default Re: Turbo B18B1 ‘flatlines’ after roughly 5psi

You cannot effectively fix the diaphragm in that wastegate... so contact Tial and buy a replacement part. They can provide a source.
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