Issues related to turbo and boost

[507.si]

Hello Everyone,

I’ve been running into this issue for quite some time and I just can’t seem to figure it out. On factory setting, with my downpipe i’m hitting about 16 psi of boost which so far for my Si has been normal, but in certain gears it’ll hit peak boost but can’t keep it such as 4th. With the tune, I’m supposed to be hitting about 22-25 on map 2 and 3 respectively, however, the car won’t even break the 19 psi threshold. I’ve taken it to Honda and they said they can’t figure it out. I’ve tried almost everything and at this point I don’t know what to do. Any recommendations?

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[arpypat]

First off, I'm going to say that it's a BAD IDEA to go to a Honda dealer with perceived issues related to an aftermarket tune... BIG NO-NO

Some questions for you:

• What tuning device are you using?
• Do you have a custom tune or an off-the-shelf ("OTS") tune (TSP, Phearable, etc.)?
• Are you sure that you don't have boost-by-gear enabled?

 

[507.si]

Im

First off, I'm going to say that it's a BAD IDEA to go to a Honda dealer with perceived issues related to an aftermarket tune... BIG NO-NO

Some questions for you:

• What tuning device are you using?
• Do you have a custom tune or an off-the-shelf ("OTS") tune (TSP, Phearable, etc.)?
• Are you sure that you don't have boost-by-gear enabled?

I’m using the Ktuner V2 with the phearable 1.5 tune. Boost by gear is disabled. Also the person at Honda who looked at it is my long time friend who hasn’t told them about my modifications.

 

[arpypat]

Im
I’m using the Ktuner V2 with the phearable 1.5 tune. Boost by gear is disabled. Also the person at Honda who looked at it is my long time friend who hasn’t told them about my modifications.

If you could post a datalog, some people here might be able to help you out. Maybe send it to John Vega @phearable too if you think there is a problem with your tune or car.

Could well be a boost leak.

Or, more likely, you might just be driving in Map 1. Since you're using Ktuner, you have 3 different Maps to choose from. Map 1 has factory boost levels (~19-20 PSI max). If you leave your Ktuner disconnected, your car will revert to Map 1 every time you stop/start the car.

 

[507.si]

If you could post a datalog, some people here might be able to help you out. Maybe send it to John Vega @phearable too if you think there is a problem with your tune or car.

Could well be a boost leak.

Or, more likely, you might just be driving in Map 1. Since you're using Ktuner, you have 3 different Maps to choose from. Map 1 has factory boost levels (~19-20 PSI max). If you leave your Ktuner disconnected, your car will revert to Map 1 every time you stop/start the car.

That’s the thing because I’ve tried it in Map 2 and 3 and the car wouldn’t go past 19 psi sometimes it’ll hit lower levels of boost. As of the moment, I have no boost leaks. I feel it could be an overall turbo issue. I had just gotten a new clutch and flywheel as well since the stock one burnt out.

 

[Chaucer]

Where do you live? I’ve noticed that once ambient temps are 100+ these cars dial the boost back hard. Even running E35 my car won’t go past 25psi.

 

[507.si]

Where do you live? I’ve noticed that once ambient temps are 100+ these cars dial the boost back hard. Even running E35 my car won’t go past 25psi.

I live in Florida and I’ve been having this issue for a long time. The car in general is just having issues with boost.

 

[NukeKS14]

.. As of the moment, I have no boost leaks...

How do you know that? Did you perform a boost leak test yourself or are accepting the testimony of your friend? Unless you've actually performed a boost leak check yourself, I wouldn't be so confidant. It's pretty darned easy to do and I would really recommend anyone with a boosted car have the basic tools around to do one yourself as a periodic check on things.

If you have in fact done one, then disregard. Just used to trying to help people that are 100% confidant that 'that isn't it' and the solution gets overlooked because 'I can feel it in my bones, it's something else'. I'll advocate for easy checks of equipment over shotgunning or part replacement 100% of the time. Not trying to be aggressive or rude, just want to clarify for us to help we need to know exactly what's been done to troubleshoot so far on your end. I totally get that your friend works at the dealership. Not telling you to not trust him, just, some of this stuff requires testimony/performance on your end.

What fuel are you using also?

Temperature will play a part too. With your IC saturated, it's probable the ECU would be limiting boost threshold to protect the engine. As said, if you can include datalogs, it's possible we might be able to catch something that's contributing to this, either in settings/tune. Some things that will keep the turbo from building full boost include but aren't limited to;

- boost leak
- possible wastegate issue (unlikely)
- AFRs (if you're running pig rich and EGTs are way down, the turbo won't spool nearly as well. Lower energy in the exhaust stream.)
- aggressive timing (again EGT will be influenced with timing. Overly advanced will throw heat into the cylinder instead of exhaust stream and reduced energy in exhaust = less spool.)
- User error on map selection
- Poor quality fuel causing ECU to limit\reduce power from knock
- Boost Dampening relative to how long you're actually WOT not allowing it to achieve target
etc....

basically it's a crapshoot unless we can see what the ECU is actually doing when you're not achieving your desired boost; we're just spitballing.

Do you have any other power mods to the car? I'm still digging into the features this ECU has before I dive into a tune myself. If there are in fact torque or power tables, it's possible that the ECU is limiting boost because you're achieving your power goal at a lower value. Don't quote me on that but it's entirely possible.

I notice on my 2020 FC3 that I at night on Sport Mode I can briefly touch 18psi but it tends to stick around 16ish. I'm on stock tune with PRL stage 1 intake, TIP insulated with DEI reflect-a-gold, and I've got an HKS exhaust on it. I run 93 octane exclusively. It feels strong, I have no doubt it's making rated power.

Here's a link to the KTuner manual explaining all of the adjustable parameters and what they do.
Table of Contents (ktuner.com)

At present, I'm planning to go the K-tuner phearable 1.5 route myself once the engine is broken in and closer to being out of warranty. I've got a couple of years experience tuning the Megasquirt on my S14 and I do instrumentation and controls at a nuclear plant for a living so I've got a good grasp on heat transfer/fluid flow dynamics and IC processes. 9/10 times the ECU is doing exactly what it's being told to do; either from a bad sensory input, tune issue (not likely here) or the output is faulted and not obeying. Datalogs won't lie and will likely give all the clarification you need to narrow down your issue.

 

[507.si]

How do you know that? Did you perform a boost leak test yourself or are accepting the testimony of your friend? Unless you've actually performed a boost leak check yourself, I wouldn't be so confidant. It's pretty darned easy to do and I would really recommend anyone with a boosted car have the basic tools around to do one yourself as a periodic check on things.

If you have in fact done one, then disregard. Just used to trying to help people that are 100% confidant that 'that isn't it' and the solution gets overlooked because 'I can feel it in my bones, it's something else'. I'll advocate for easy checks of equipment over shotgunning or part replacement 100% of the time. Not trying to be aggressive or rude, just want to clarify for us to help we need to know exactly what's been done to troubleshoot so far on your end. I totally get that your friend works at the dealership. Not telling you to not trust him, just, some of this stuff requires testimony/performance on your end.

What fuel are you using also?

Temperature will play a part too. With your IC saturated, it's probable the ECU would be limiting boost threshold to protect the engine. As said, if you can include datalogs, it's possible we might be able to catch something that's contributing to this, either in settings/tune. Some things that will keep the turbo from building full boost include but aren't limited to;

- boost leak
- possible wastegate issue (unlikely)
- AFRs (if you're running pig rich and EGTs are way down, the turbo won't spool nearly as well. Lower energy in the exhaust stream.)
- aggressive timing (again EGT will be influenced with timing. Overly advanced will throw heat into the cylinder instead of exhaust stream and reduced energy in exhaust = less spool.)
- User error on map selection
- Poor quality fuel causing ECU to limit\reduce power from knock
- Boost Dampening relative to how long you're actually WOT not allowing it to achieve target
etc....

basically it's a crapshoot unless we can see what the ECU is actually doing when you're not achieving your desired boost; we're just spitballing.

Do you have any other power mods to the car? I'm still digging into the features this ECU has before I dive into a tune myself. If there are in fact torque or power tables, it's possible that the ECU is limiting boost because you're achieving your power goal at a lower value. Don't quote me on that but it's entirely possible.

I notice on my 2020 FC3 that I at night on Sport Mode I can briefly touch 18psi but it tends to stick around 16ish. I'm on stock tune with PRL stage 1 intake, TIP insulated with DEI reflect-a-gold, and I've got an HKS exhaust on it. I run 93 octane exclusively. It feels strong, I have no doubt it's making rated power.

Here's a link to the KTuner manual explaining all of the adjustable parameters and what they do.
Table of Contents (ktuner.com)

At present, I'm planning to go the K-tuner phearable 1.5 route myself once the engine is broken in and closer to being out of warranty. I've got a couple of years experience tuning the Megasquirt on my S14 and I do instrumentation and controls at a nuclear plant for a living so I've got a good grasp on heat transfer/fluid flow dynamics and IC processes. 9/10 times the ECU is doing exactly what it's being told to do; either from a bad sensory input, tune issue (not likely here) or the output is faulted and not obeying. Datalogs won't lie and will likely give all the clarification you need to narrow down your issue.

I’ve done all the boost leak tests such as backwards pressure and the soap bubble test. No boost leaks because in factory mode the car hits peak boost. I’m thinking of going the datalog way in order to figure it out

 

[kshawn]

Let's get the data log added to this

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