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Engine Cutting out in boost

Old 06-14-2018, 07:08 PM
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Default Engine Cutting out in boost

Hi everyone! I'm new to the forums and new to tuning.
When I get into about 4700 rpm in first gear, it seems to hit a rev limiter? It is at about 5psi of boost or so there. In second gear and up, the "rev limiter" drops to about 4000 rpm.
I thought it was spark blowout and tried gapping down the spark plugs to .025. It didn't make a difference. I turned off overboost protection, and it made no difference.
Any ideas? Also, I'm running MSPNP2. I attached a datalog of two quick pulls.

Thanks!
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Old 06-14-2018, 07:51 PM
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What are your overboost settings like? It could be hitting that
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Old 06-14-2018, 11:30 PM
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I disabled overboost to test if it was that so there is no overboost protection right now.
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Old 06-15-2018, 05:16 AM
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What sort of injectors are you running? I'm seeing close to 100% duty cycle.
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Old 06-15-2018, 11:59 AM
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Originally Posted by phipplet View Post
I disabled overboost to test if it was that so there is no overboost protection right now.
Not a good approach. Overboost protection can save you engine from inadvertent changes in MS settings / popped boost control hoses / etc.

I know of at least (2) situations where a replacement engine could have been avoided if overboost had been employed.

Pretty sure it saved my rods when I re-plumbed the EBC incorrectly.
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Old 06-15-2018, 11:10 PM
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Originally Posted by Skamba View Post
What sort of injectors are you running? I'm seeing close to 100% duty cycle.
Im running RX8 injectors. I might not be getting enough fuel with those?
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Old 06-15-2018, 11:11 PM
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Originally Posted by DNMakinson View Post
Not a good approach. Overboost protection can save you engine from inadvertent changes in MS settings / popped boost control hoses / etc.

I know of at least (2) situations where a replacement engine could have been avoided if overboost had been employed.

Pretty sure it saved my rods when I re-plumbed the EBC incorrectly.
Ok, thank you for the input. I'll be sure to raise it instead of just disabling it.
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Old 06-16-2018, 04:53 AM
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Originally Posted by phipplet View Post
Im running RX8 injectors. I might not be getting enough fuel with those?
If they're the real deal, those injectors are good enough for what you're trying to do. I've heard stories of fake rx8 injectors though. If there's any time to upgrade to EV14 injectors (e.g. flowforce or id1000), this would be a good one.

It could also be that you've tuned your car based on a low fuel pressure, which could be the pump or fpr.
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Old 06-17-2018, 10:02 PM
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Originally Posted by Skamba View Post
If they're the real deal, those injectors are good enough for what you're trying to do. I've heard stories of fake rx8 injectors though. If there's any time to upgrade to EV14 injectors (e.g. flowforce or id1000), this would be a good one.

It could also be that you've tuned your car based on a low fuel pressure, which could be the pump or fpr.
So I ended up putting on a secondary fuel pump to bump up the fuel pressure, and while it helped my tune, I am still having the same issue of my engine cutting out in boost. I'm going to try new spark plugs tomorrow and see if it helps.
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Old 06-18-2018, 02:40 AM
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Originally Posted by phipplet View Post
So I ended up putting on a secondary fuel pump to bump up the fuel pressure, and while it helped my tune, I am still having the same issue of my engine cutting out in boost. I'm going to try new spark plugs tomorrow and see if it helps.
Be sure to check your logs for injector duty going near 100%. In your previous log your car was also running pretty lean during the 'cut out'. You might also get some hefty detonation in those situations.
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Old 06-18-2018, 02:55 AM
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Originally Posted by phipplet View Post
So I ended up putting on a secondary fuel pump to bump up the fuel pressure, and while it helped my tune, I am still having the same issue of my engine cutting out in boost. I'm going to try new spark plugs tomorrow and see if it helps.



If the pump is determining your fuel pressure you got problems friend.

If you're concerned about the fuel pressure put a gauge on it. You have a fuel pressure regulator that should be handling pressure controlling duties.
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Old 08-05-2018, 06:40 PM
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So I have some updates on my problem.
The car runs great now when it is cold. I can pull all the way through the rev range with 6lbs of boost, but as soon as it is hot, it will not go into boost at all.
As soon as it leaves vacuum and goes into boost it is like it is hitting a wall. The engine cuts out and acts like a rev limiter.
I am thinking it has something to do with my tune.

I also bought some flowforce 640cc injectors and fab9 COPs
Both of these things didn't really make a difference.
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Old 08-05-2018, 06:55 PM
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Originally Posted by phipplet View Post
So I have some updates on my problem.
The car runs great now when it is cold. I can pull all the way through the rev range with 6lbs of boost, but as soon as it is hot, it will not go into boost at all.
As soon as it leaves vacuum and goes into boost it is like it is hitting a wall. The engine cuts out and acts like a rev limiter.
I am thinking it has something to do with my tune.

I also bought some flowforce 640cc injectors and fab9 COPs
Both of these things didn't really make a difference.
Post your tune and a log of the issue.
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Old 08-05-2018, 07:14 PM
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I am not a tuner by any means so there may definitely be something wrong in my tune.
Attached Files
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2018-08-04_19.57.07.msl (92.4 KB, 10 views)
File Type: msq
CurrentTune1.msq (119.0 KB, 8 views)
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Old 08-05-2018, 07:37 PM
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You need to change req fuel for your new injectors. Also change your deadtimes if you haven't. Your VE table is completely jack up at least in part because of that.

Are you running a wideband?
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Old 08-05-2018, 07:44 PM
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Originally Posted by SpartanSV View Post
You need to change req fuel for your new injectors. Also change your deadtimes if you haven't. Your VE table is completely jack up at least in part because of that.

Are you running a wideband?
I am running a wideband. I run good AFRs in boost (when it works). I changed the required fuel, but I don't think I changed the deadtimes. I will do that now. I'll try that and drive the car around for a bit and let you know. Thanks for the help so far.
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Old 08-05-2018, 07:59 PM
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Originally Posted by phipplet View Post
I am running a wideband. I run good AFRs in boost (when it works). I changed the required fuel, but I don't think I changed the deadtimes. I will do that now. I'll try that and drive the car around for a bit and let you know. Thanks for the help so far.
My bad. Was looking at a different tune. Req fuel looks right.

The AFR reading in your log isn't making any sense. I believe running VEAL without properly configuring TS for your wideband is creating a nonsensical VE table. Does the display on the wideband match what TS is showing?



Your main issue is that absurd table. It's likely choking on fuel. You need to figure out what setting is causing VEAL to create that monstrosity and then start fresh with a basemap VE table.
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Old 08-05-2018, 08:10 PM
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First of all: I want to be your parts dealer.
Second: I don't see, in the posted log, the effect you are talking about, but without TPS, it is hard to know your inputs.

Your VE table looks like a Topographical map. Go to Trubokity.com and download the appropriate base map to get some idea of what it should look like, Shape-wise.


No way this will work.

No wait, upon looking at log, there are a few other possible issues:

Have you calibrated your MAT Sensor?
Where is it located?
Have you calibrated your AFR Sensor?
Where is it located?
Does the reading in TS match the reading on the AFR gauge (if you have one).
Is this a 1.6 with a non-variable TPS? Otherwise, have you calibrated you TPS?

Where are you located?

Is there someone you can take the car to so the MS can be set up as a starting point?

Can you describe (pictures would be good) your set-up. What you have done, what the previous owner has done? A build thread?

Maybe go to the Meet and Greet and check in.
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Old 08-05-2018, 08:15 PM
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Originally Posted by SpartanSV View Post
My bad. Was looking at a different tune. Req fuel looks right.

The AFR reading in your log isn't making any sense. I believe running VEAL without properly configuring TS for your wideband is creating a nonsensical VE table. Does the display on the wideband match what TS is showing?
My wideband and TS both say the same thing, so I would think VEAL would be able to work?

Originally Posted by SpartanSV View Post
Your main issue is that absurd table. It's likely choking on fuel. You need to figure out what setting is causing VEAL to create that monstrosity and then start fresh with a basemap VE table.
Are there any other settings that would cause VEAL to be thrown out of wack?
I think you are right about too much fuel. I pulled my plugs today and they were pretty covered in carbon.
I might just manually tune it instead of relying on VEAL then.
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Old 08-05-2018, 08:15 PM
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Yeah MAT can't possibly be staying at 70 the entire time. You need to give TS info about your sensors.

https://trubokitty.com/#/tune

Bottom of that page has instructions.

VEAL works fine when you set everything up correctly.
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