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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! |
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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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. |
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 ? |
Re: Turbo B18B1 ‘flatlines’ after roughly 5psi
Originally Posted by AllMtrRex
(Post 51737352)
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.
Originally Posted by 2x0
(Post 51737374)
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.
Originally Posted by Balor_Gr
(Post 51737612)
When you use 1/3 and it pulls like normal it produces full 12psi target boost?
Do you hear the vtec engaging ? |
Re: Turbo B18B1 ‘flatlines’ after roughly 5psi
Originally Posted by GSR_ITR_BOIB
(Post 51737302)
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
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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? |
Re: Turbo B18B1 ‘flatlines’ after roughly 5psi
Originally Posted by GSR_ITR_BOIB
(Post 51737637)
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. Or yeah, as others have said it could be boost cut. Colder weather could cause this to happen as well. |
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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Re: Turbo B18B1 ‘flatlines’ after roughly 5psi
Originally Posted by Txdragon
(Post 51737695)
Do this and report back. I'm going with a wonky spring or diaphragm..
Originally Posted by K7-1Ktrevor
(Post 51737703)
Sounds like boost cut possibly. Can you post a video of what it's doing on YouTube and post the link in here?
Originally Posted by 2x0
(Post 51737775)
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.
Originally Posted by 2x0
(Post 51737815)
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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Re: Turbo B18B1 ‘flatlines’ after roughly 5psi
Originally Posted by K7-1Ktrevor
(Post 51737703)
Sounds like boost cut possibly. Can you post a video of what it's doing on YouTube and post the link in here?
Originally Posted by 2x0
(Post 51737775)
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.
Originally Posted by 2x0
(Post 51737815)
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.
Originally Posted by 2x0
(Post 51737815)
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 |
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. https://cimg7.ibsrv.net/gimg/honda-t...d16ec3429.jpeg https://cimg8.ibsrv.net/gimg/honda-t...69b0f634b.jpeg https://cimg9.ibsrv.net/gimg/honda-t...6db93605f.jpeg https://cimg1.ibsrv.net/gimg/honda-t...255b52316.jpeg https://cimg2.ibsrv.net/gimg/honda-t...02e5ce176.jpeg |
Re: Turbo B18B1 ‘flatlines’ after roughly 5psi
That diaphragm tho... It's toast, amigo.
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Re: Turbo B18B1 ‘flatlines’ after roughly 5psi
Plugs look like you're running pretty rich.
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Re: Turbo B18B1 ‘flatlines’ after roughly 5psi
Originally Posted by Txdragon
(Post 51738821)
That diaphragm tho... It's toast, amigo.
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Re: Turbo B18B1 ‘flatlines’ after roughly 5psi
Yeah man, that carbon buildup on the plugs :ugh:
At the very least replace those bad boys. |
Re: Turbo B18B1 ‘flatlines’ after roughly 5psi
What are you using to regulate boost, just spring pressure?
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Re: Turbo B18B1 ‘flatlines’ after roughly 5psi
Need data logs to know anything really
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Re: Turbo B18B1 ‘flatlines’ after roughly 5psi
Originally Posted by Txdragon
(Post 51738821)
That diaphragm tho... It's toast, amigo.
Originally Posted by AZ_CIVIC
(Post 51738946)
Plugs look like you're running pretty rich.
Originally Posted by NVturbo
(Post 51739240)
Likely from a poor install of the W/G spring.
Originally Posted by 2x0
(Post 51739263)
Yeah man, that carbon buildup on the plugs :ugh:
At the very least replace those bad boys.
Originally Posted by rice a roni
(Post 51739353)
What are you using to regulate boost, just spring pressure?
Originally Posted by LightningTeg
(Post 51739597)
Need data logs to know anything really
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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 shit start there |
Re: Turbo B18B1 ‘flatlines’ after roughly 5psi
Yeah, makes no sense. I second the datalog.
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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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