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Turbo 13B w/MS3Pro: Fires up for a second then dies after fixing MAP signal

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Turbo 13B w/MS3Pro: Fires up for a second then dies after fixing MAP signal

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Old 11-17-18, 03:47 PM
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Turbo 13B w/MS3Pro: Fires up for a second then dies after fixing MAP signal

Been having trouble starting my turbo FC. Engine struggles to start, and when it finally does fire up, it doesn't really catch. Even with trying to modulate the throttle to try and catch it and get it to stay on, it doesn't.

I had been able to previously get the engine to start, but my MAP sensor was incorrectly plumbed and did not read any vacuum. So today I decided to fix that issue ( changed nipple on TB for vacuum source) and now I've been running into these issues.

Engine is an s4 turbo motor with an s5 turbo. Intake and exhaust have been mildly ported. Currently using VE and afr tables from Aaroncake. I've attached my tune and datalog as well. The datalog from 2018-11-17 is with the proper MAP signal, while the one from 2018-11-16 is without the proper MAP signal (but an engine that does start and holds an idle ~1100rpm via idle stop screw).

I've tried adjusting req fuel to go from 8.0 to 9.0, but that hasn't helped either. I did pull of the UIM to ensure all the vacuum lines, fuel lines and connections are proper, and there indeed were.

A bit lost right now and hoping someone could see something in my logs/tune that I'm missing. Bit frustrating b/c it was running yesterday, albeit without proper MAP signal.
Attached Files
File Type: msl
2018-11-17_12.31.17.msl (177.9 KB, 7 views)
File Type: msq
2018-11-17_12.38.36.msq (285.0 KB, 2 views)
File Type: msl
2018-11-16_11.14.59.msl (2.72 MB, 2 views)
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Old 11-18-18, 11:30 AM
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have you set your timing?

adding MAP would have changed where the car is on the timing and fuel table.
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Old 11-18-18, 03:41 PM
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I haven't set the timing yet other than the initial stabbing of the CAS.

Do you think it would be worth it to remove the MAP sensor vac line again replicate the conditions to get it to idle, and then set timing ?

Edit: Went ahead and pulled vac line to map sensor and the car does fire up again...

I'm going to pick up a timing light and set timing.

Just to verify, the leading mark on the pulley (yellow) is 5 degree ATDC? So if I want to set timing I should set fixed timing within the MS3Pro and set the fixed timing to positive 5 timing for fixed advance?

I got a little confused because aaroncake's guide says enter -5 for fixed timing when setting timing, but wouldn't that mean 5 BTDC?

Edit2: I realize the error in my logic. Negative 5 degrees makes sense since ATDC means the ignition is retarded 5 degrees. Hence the negative 5 in the timing ADVANCE to achieve 5 deg ATDC.

Last edited by ApexHunter; 11-18-18 at 06:35 PM.
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Old 11-18-18, 06:55 PM
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Update. Got a timing light. Entered -5 degrees for fixed timing advance. Hooked up timing light to L1 wire. Adjusted CAS until pin lined up with yellow (leading) mark on pulley.

However, the engine dies when I move the CAS to achieve negative 5 degrees (5 deg ATDC). I was able to see that the engine was lined up before it totally died, but is that normal? Also the CAS seems to be almost all the way to one side now.

Regardless, even with the timing properly set, I still can't get the engine to start properly with the MAP sensor attached to proper vac line. I've attached my latest datalog and .msq
Attached Files
File Type: msl
2018-11-18_16.00.25.msl (96.7 KB, 4 views)
File Type: msq
2018-11-18_16.03.52.msq (285.5 KB, 4 views)

Last edited by ApexHunter; 11-18-18 at 09:26 PM.
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Old 11-18-18, 10:02 PM
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Did some reading about the CAS being almost to one side. Maybe the CAS drive gear under the front cover is backward? I looked through my photos I took during my engine rebuild and the only photo I have of the gear makes it seem like its the correct direction. Photo attached here.




I wish I had a better photo, but apparently this is all I have. Looking the gear, I don't see a chamfer and the grooves seem to point the correct direction. Leading me to believe the gear is correctly installed. Still stumped by why my CAS gear is all the way to one side and why my engine won't run with the MAP sensor plugged in.

I also restabbed my CAS for good measure, but haven't tried to run it since then.

Edit: Upon closer look at photo... maybe that is the bevel I'm seeing... Gonna get an inspection mirror and try to see if I can get a closer look via the CAS hole.

Last edited by ApexHunter; 11-19-18 at 10:45 AM.
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Old 11-30-18, 07:03 PM
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So it turned out that the gear must be flipped. I ended up getting a file so I could grind out the slot on the CAS so I could turn it far enough to set timing properly. The timing is currently properly set.

Engine still won't start properly with the MAP sensor plugged in. I reset the VE table back to Aaroncake's table just to remove any extraneous variables. Engine starts, revs to ~1500rpm (I am giving throttle input in order to start it), then dies immediately.

Unfortunately I can't get any real AFR readings, since the AFR gauge seems to reset during cranking.

I've attached my current msq and msl from most recent attempts to start the motor.

Really stumped at what I should be adjusting or looking at.
Attached Files
File Type: msq
2018-11-30_15.59.50.msq (285.6 KB, 3 views)
File Type: msl
2018-11-30_15.51.59.msl (593.2 KB, 1 views)
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Old 12-01-18, 01:27 PM
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Someone on the msextra forums pointed out that my injector dead time was set to 4ms instead of 1ms. Fixed that. Still running into same issue sadly.
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Old 12-03-18, 11:06 PM
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Got curious. I knew I had success with the engine starting when the MAP sensor was not reading any vacuum signal. I wanted to see what would happen if I unplugged the map sensor again.

So this is with the timing set correctly. To clarify again how I set timing. I set cranking advance to -5 degrees (5 BDTC). Then I disabled injectors. I had my timing light set onto L1 (Leading spark plug, front rotor). I then had a helper crank the engine over while I adjusted the CAS via a timing light.

So I am fairly certain the engine has the CAS stabbed properly. I've only ever used the same pulley and hub on this engine, same pulley and hub that was on the engine when I purchased the car way back when.

That all being said. I pulled and capped off the vacuum signal line that was going to my MAP sensor and attempted to start the car.

What do you know? It started! Just like it did before. Granted it needed a bit of constant throttle input to stay on, but it starts and stays on.

This lends me to believe that once the engine fires up with a proper MAP signal that the vacuum reading is causing the engine to either set the wrong timing/fuel mix. Both base timing table from Aaroncake shouldn't need much if any adjusting from my understanding and the VE table is safely rich...

So I'm not sure what's going on. Could it be that I need some sort of check valve to prevent rapid fluctuations from the vacuum signal at start up?

I know my throttle input at start up isn't helping, but I haven't been able to start the engine otherwise at the moment. I'm assuming it'll be like that until the engine breaks in.

I've attached an .msl from today's test fire.
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Old 12-06-18, 04:28 PM
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You should connect the map sensor, try start the engine and capture a data log. If the MAP sensors goes from ~100kpa to something lower (assuming you aren't at 100% TPS), the your map sensor should be working. Whether you have the correct MAP selected for calibration, you'll need to confirm.

If the MAP sensor is functioning, that likely means that your fuel values are off enough that the engine won’t stay running once it fires. The MAP is lower than 100kpa once running and it’s likely at a lower VE than if your MAP line was unplugged (and reading 100kpa). Because the engine isn’t warmed up yet, it could just be that your Warm Up Enrichment is off, but you’ll figure that out once the engine is warmed up and VE is properly set.

Cold engines don’t mind running rich, so don’t be surprised if you need much higher VE values to keep it running.
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Old 12-07-18, 12:02 PM
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Yup. Map sensor goes from 100kpa to ~50-60kpa at 1200-1500rpm (b/c of throttle input during starting). The VE table was increased to about 12% (from Aaroncake's base map) at one point as well as similar increases to the warmup enrichment and afterstart enrichment process.

Still wasn't able to get it to idle with the MAP sensor reading. I'm fairly sure the map sensor is reading correctly and calibrated appropriately (its just the GM 3-bar from DIYautotune).

I've since been returned to Aaroncake's base VE table (but retaining the richer warmup enrichment and afterstart enrichment). With the "regular" Aaroncake VE table, I can get it to start with the MAP sensor having no vacuum line, but not with the vacuum line attached.

I'm gonna try and bring the afterstart enrichment and warmup enrichment back to what Aaroncake prescribed.

Perhaps the engine is running too rich? That could explain why the motor has been needing throttle input to start. Also comparing logs from when the engine ran (no vac signal) to when it wouldn't stay on, it seems that the VE's the engine is encountering are somewhat similar, but the large difference is in the timing advance.

When the engine does idle, its at 28 degrees advance. Which is obviously a lot. I'm not too certain, but wouldn't an overly rich engine need more timing advance in order to run, since the fuel needs to be ignited earlier in order to have enough time to burn?

When the engine tries to stay on with the vac signal properly plumbed, the engine advance is properly much less, but it will not stay on past that initial start up rev.

Gonna test out my theories later this weekend.
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Old 12-07-18, 01:05 PM
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What injectors are you actually using?
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Old 12-07-18, 01:47 PM
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Have you verified that your base timing is correct? You can do this without the engine running buy using a timing light while turning the engine over with the starter and having the fuel pump off. You'll have to lock the timing in Tuner Studios to the degrees marked on your crank pulley.
It's worth asking - is this a fresh rebuild? Sometimes freshly rebuilt motors can have low compression and be difficult to start before the seals bed in. Although it sounds like yours starts and doesn't stay running.

I have a feeling your tune is too lean. On top of warm up enrichment, there is After Start Enrichment which temporarily adds fuel immediately after starting. Once this adder is gone, the engine would run leaner. I would try scaling your VE by a substantial increase (+50% to start) and give it a shot. It also might be worth the trouble to find a always-hot 12V wire for your wideband to see what your AFRs are actually doing.
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Old 12-07-18, 05:07 PM
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I'm using 550cc RC engineering Primaries and Stock 550cc secondaries.

I have verified the timing. I locked the timing to -5 deg cranking advance in Tuner studio. I then have a helper crank the motor while I used the timing light on the L1 (front rotor leading) sparkplug. Adjusted CAS until it lined up with Yellow (5 ATDC) mark.

This is indeed a fresh rebuild. I have put some 2 stroke oil in the spark plug holes to get it to start, but that was only really necessary first few fire ups. It fired up easy enough (with throttle input) without adding any oil into combustion chamber.

That was all of course without MAP sensor receiving any vacuum signal. Now with the MAP sensor receiving proper signal, it won't stay on. Starts, then immediately dies.

I'll try hot wiring the AFR gauge and doing a vast VE increase to see what happens too. Gonna just go down the list of scenario this weekend.
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Old 12-07-18, 06:12 PM
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You're sure the injectors are high impedance and aware the lower spark plug is the leading? All plug wires ran to correct coil? injector wire connectors on the correct injectors? trying to make sure we're all on the same page is all.
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Old 12-09-18, 09:13 PM
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So I directly connected the Innovate LC-1 wideband to the battery. I still get E9 (low voltage) while cranking, but it doesn't have to reheat after cranking so I can more immediately get AFRs.

I was able to get the engine fired up, but it took multiplying the VE table by 3x! Which seems like an insane amount. Especially when you consider that the engine fired up without Vacuum signal and idled on the normal VE table.

Now here's the kicker. Although the engine will fire up... it kinda needs constant jabbing of the throttle to stay on. Won't idle nicely and when you try to hold an idle at ~1/4 throttle (the TPS in the log reads 100% b/c tps is a narrowband s4 rx7 tps), it reads super lean.

Like 22.4 lean. That just doesn't make sense b/c I'm dumping fuel into the engine based on the VE table being so much richer than I ever had to need for the engine to fire up. I understand I'm now operating in a different region of the map since I'm receiving proper vacuum signal, but something just doesn't add up.

I was able to idle before with no vacuum signal ( I believe I posted a MegaLog somewhere previously on this thread), but now it requires ~ 3 times the amount of fuel and the afr reads lean and the engine doesn't want to idle.

I've attached a recent MegaLog from the engine firing up and "running" at 3x (300%) the base VE table.
[attachment=1]2018-12-09_17.48.32_3xVEtable.msl[/attachment]

I also attached for reference, here is my "BASE" tune that is taken from Aaroncake's guide. When I mention that the VE table is 3x, that is taking the table shown in this base tune and multiplying the VE table values by 3. Aka a 300% increase.



So yeah. I got it to fire up... but it requires an insane increase in fuel and the afr's read lean.

Normally I'd think there is an issue with the fuel filter or fuel injectors, but it previously ran fairly normally an idled well when I had no vacuum signal to the MAP sensor. The fact that it ran so well previously leads me to believe that the injectors and fuel filter and fuel system in general is operating correctly. The injectors are the same injectors that were always on the engine since I purchased the RX-7 years ago. I believe they are all high impedence and since there was no issue previously when there was no vac signal, I'm inclined to believe that is not the case.

I might go ahead and get my multimeter to measure resistance of the injectors, but right now I'm kinda confused at the moment at what's going on.
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