MS2Extra Tuning Question - Hiccup at WOT above 4500 rpm

[jbh]

Hi,

I have been working through an install on my mildly built toyota 22RTE.

I'm at a compression of approx 8.0:1
Adjustable cam at 3* retard (SOHC)
Stock turbo peaking at approx 7 psi. non-intercooled.
430 cc injectors
Aeromotive high pressure fuel pump
Aeromotive AFPR set to 45psi at 0 vacuume (100kpa)

At WOT, as I approach the 5000 rpm range, I get a considerable hiccup (see timestamp 6758 in log file)

I can't seem to find anything within megasquirt that is triggering this. I have headphones and a mini amp connected to the knock sensor, and can't hear any major detonation (unless I'm missing it with an untrained ear)

Here is the log file and my ms tune.

Any help or suggestions would be greatly appreciated.

Thanks

JBH

2016-04-19_14.14.54.msq

2016-04-19_13.44.04.msl

[slow_hemi6]

All the boost fell out of it before you lifted the throttle. Whatever let the cat out of the bag I don't think it was the MS. Something external, BOV or WG isuues?

[jbh]

No BOV. Possibly the internal WG on the stock turbo?

It is as though I lost boost, which put MS into a leaner point on the fuel map and compounded the issue.

I'll look over the WG mechanics as well as the charge pipe rubber fittings as well as vacuum hoses that may not have been able to handle the pressure.

I kind of have the stock turbo,manifold, and smog equipment installed just to pass my smog test this week. Then will be going to a GT28R. I'm just wanted to get a good tune with the stock gear to save away in the archives for my bi-annual smog check.

Any other suggestions? I have some time set aside to trouble shoot this tomorrow.

Thanks.

JBH

[39ClevoUte]

Hi Just some observations and question I guess as I am new to MS.
In your EGO settings it shows active above 6000rpm, rest seem normal but wouldn't 6000rpm mean it would hardly ever be used?
The knock sensor settings appear to be set to ignore knock sensor > 85kpi and >3500rpm, so knock sensor shouldn't be causing change?
The only thing I could see in your log that happens just before the problem is ADC6 and or EGT6 start to spike (down), then at 6757 stays down, then MAP seems to drop first, but maybe the logging isn't that accurate when everything changes in a few milliseconds. I don't understand what ADC6 or EGT6 represent in your setup.
Only other thing is dwell changes a bit before the issue also.
Maybe someone who knows can add some meaning to these.
Regards Rob
PS problem in log seems to be closer to 5000rpm not 4500.

[jbh]

EGO control and accel enrichments are bypassed for tuning. Knock is set for the lower rpm range where it is more typical.

ADC6 is a spare analog input and is not used.

Not sure what EGT6 is doing, but I don't believe the data is valuable. See here for related discussion. http://www.msextra.com/forums/viewtopic ... 00&t=48220

This issue occurred early in tuning stages, so I am looking for the solution before I commit more time to developing my tune.

Thanks for the input.

JBH

[jbh]

Checked all vac lines as well as intake for potential leaks under pressure. Everything is tight. Waste gate operates smooth. vac lines to waste gate are ok. I do have a small exhaust leak at the cat, but this is downstream from the turbo. Will address this today.

On a test drive (no new data log) I experienced the same issue. As I reached 4700 to 4800, there was a strong lurch, and you could hear the turbo spool down and pressure drop, even before I was able to let off the throttle.

It is it possible that I am losing spark (maybe overloading the ignition coil with my MS settings) and as a result, there is no combustion to drive the turbo, and thus, a dramatic decrease in manifold pressure? However, the engine does not stall after the event. I looked through my tune again to see if there is something that would be triggering a spark cut, and couldn't find anything.

Based on the old data log I posted (problem hasn't changed) as well as my tune, does anyone have any other theories?

I just can't seem to find any inciting incident in the logs.

Thanks,

JBH

[turbo conversion]

I have never used table switching before so not sure how to set it up.

That said your 2 VE tables look odd to me, shouldn't table 1 be say 25 kpa to 100 kpa and table 3 be 101 kpa to 230 kpa?

David

[jbh]

David.

Thanks for catching that. I did not intentionally have fuel table switching enabled. However, I don't have any input to the PE1 pin on the MS harness board. Maybe some noise was generated within the MS board that triggered this at 4700 rpm?

Either way. I disabled table switching and will go for a test drive when i get home.

Will report back.

JBH

[jbh]

So I cleaned up a few of the issues in the configuration of my tune. Disabled table switching.

I attached my updated tune as well as new log file. The hiccup is still there. At exactly 4800 rpm this time. You can clearly see the boost fall out, and the MS respond accordingly. I'm leaning towards a hardware issue, but everything appears to be functioning properly. Intake and vac lines are tight. waste gate operates smoothly. Maybe it is time to stuff the gopro in the engine compartment to monitor the waste gate to totally eliminate that as a potential problem.

Any other ideas as to why this is occurring? Is this detonation? IAT is only at 140* when this event occurred.

Only known issue is an exhaust leak at the cat, downstream of the turbo.

Bad turbo journals that give up at that rpm?

Anyone see any issue with my MS tune at 4800rpm that could be the culprit?

Thanks to everyone for their help thus far. This forum has been an invaluable resource to this point.

JBH

2016-04-21_14.02.19.msq

2016-04-21_13.48.34.msl

[turbo conversion]

If it is something in your tune I am not seeing it, wish I could be more helpful.

I would think it is something mechanical but not sure what.

David

[turbo conversion]

I do have a question about your settings under Programmable On/Off Outputs.

Not sure what it is for but under ALED Power On Value and Active Value are both set to off.

The reason I ask is in the data log On/Off Outputs Status Bits is jumping from 68 to 4 and 68 to 0 when problem happens.

No idea what this is but it is the only thing I see change in the log when it is getting into boost.

David

[jbh]

ALED is running a factory 'turbo' light in the gauge cluster. Essentially, in boost, the light illuminates (fancy huh?). It looks like the status bits variable changes when I drop below 100 Kpa.

I'm working through my smog test in CA now. Just need to dial in the tune below 100Kpa and swap in the stock narrow band O2 sensor for the test.

Once this is done, I'll get my full time running gear on (GT28R) and will revisit this problem.

Thank you everyone for your help. It has helped me at least correct some bonehead mistakes in my tune that would have tripped me up further down the road.

Cheers,

JBH

[jbh]

Thought I would post an update to this.

Current setup is now Garrett GT28R (GT2560R)
Mishimoto intercooler
Turbosmart BOV
Aeromotive FPR
AEM Water Meth

In MS, I moved to a high and low kPa spark map for more detail. Adjusted my AFR targets to between 13.5 and 12.5 at 100kPa and 12.5 to 11.7 at 220kPa.

The hiccup / hesitation issue is now resolved. I'm running only 10 psi of boost now with no issues. Smooth power through the full RPM range.

I'm still not entirely sure what was causing the original hesitation, although I have my suspicions:
- Cracked stock turbo manifold that was fairly significant. Maybe the leak increased exponentially with exhaust pressure, resulting in loss of boost/stalling the exhaust turbine?
- Cleaned up the fuel map in and around 160 to 220 kPa and 4500 rpm to 6000 rpm. I had some pretty rich numbers there for safety, and maybe over-enriched the mix as I approached that RPM threshold.

Either way, it was extremely helpful to have the input I did from this board. Thanks all. I'm sure I'll come across another couple questions once I start messing with the boost control tuning.

Cheers,

JBH

[turbo conversion]

I would think you are correct about the manifold, a leak could cause manifold pressure to drop thus no boost.

Glad to hear you have it sorted out

David

[xmas077]

Have you notices your voltage seems to vary from 12.5 to 14 volts on your log