Intermittent Fuel/Spark Issue - Need Help - New Logs
 

Car is a 96 with a 00 stock motor. Running Brain built DIYPNP, FIC 650's, 320lph fuel pump, AFPR, I/E/H, etc

Ever since a track day about 3 weeks ago, I've had this intermittent low throttle fuel/spark issue where all of a sudden the car sounds like a Subaru and AFR goes crazy. I went out for a drive today after replacing my spark plugs, and sure enough the issue is still there. See attached log - it starts almost immediately.

I'm getting to the end of the tests I can think of and I could really use some experienced help here. So far I have:

- Verified base fuel pressure @ 3bar
- Check plug wires/connections
- Test injectors with Megasquirt
- Replaced old fuel pump w/320lph
- Replaced plugs w/ BKR7E-11's @ .030

I don't want to keep fixing things that aren't broken and possibly add to the problem, but I'm concerned about my coil pack and possibly MS firmware (currently on 3.1.0).

Anyone have anything similar happen to them? Any help is greatly appreciated!

** LOG UPDATED 03/30 - STILL SHITTING THE BED **

Forgot to attach the tune. See above

Dumb question but I need to ask... FIC650s are listed as low-impedance "peak and hold" style injectors. Do you have a peak and hold board or are you using resistors?

Not a dumb question, because I don't know the answer. Braineack built this for me, so he would have to answer that. I'll PM him

When you had him build it, did he ask what injectors you would be using? Did he give you a tune file that already had the injectors specs or did you have to set it up yourself?

Unfortunately I can't remember, and I don't have a record of it through email or PM's.

Is there an another way I can tell? I have detailed pics of the board I can check easily.

I'll have to look at the log when I'm home. Sounds like youre dropping a clyinder or 2, either spark or fuel. Log will show if the MS is doing it, otherwise could be the wiring/drivers.

Thanks Scott, I look forward to your response. Let me know what you need from me.

Wait Chiburbian - My injectors are listed as high-z, not low-z:

650cc FIC Mazda Miata Fuel Injector Clinic Injector Set (High-Z)

"This injector set contains high impedance injectors matched to the saturated injector signal generated by this vehicle’s OEM ECU, OR is suitable for use with an aftermarket ECU made or set up for high impedance injectors."

This one looks like it could use some more tuning on the VE and acceleration enrichments, but I didn't see much beyond that in the log.

Matt, thank you for the response.

My VE table produces my target AFRs consistently. I will look more into the Accel Enrich settings, however those are what was provided by Braineack when I received the ECU and they never caused a problem before a month ago when this started happening. It doesn't make sense that the car ran well with those Accel settings, then all of sudden started acting like it's running on 2-3 cylinders at random every time I drive it. Wouldn't those setting produce repeatable bad results if they were the root issue? I will check your recommendations regardless and do more testing. Thanks again for the input.

Jesus. F'ing. Christ. I attached the wrong log previously. Update original post with a couple of my most current logs that show my issue. So sorry to all that have looked so far :facepalm:

The TPSdot seems to be triggering a bit too easily; you might want to raise its threshold. That's about all that jumped out at me. Maybe you could push the space bar when the problem happens to mark more clearly where things go wrong?

Thanks again Matt! I will read up more on TPSDot and see if I can solve this.

I read up on AE here: MegaSquirt Acceleration Enrichment Tuning

Updated the TPSDot threshold to 45% up from 40% and drove the car for 40 minutes without a single problem! It looks like this single setting 5% difference was my issue, which is kind of crazy. I took out the ECU yesterday for pictures, so it's also possible that a connection was lose as well, but I can't be sure at this point.

Big thanks to Matt! PM'ing to buy you beer. :beer:

Spoke too soon. FML

See attached log on first post. Issue is present during pretty much the entire log.

AFR, TPS, everything is just going crazy. No idea what's going on...

Can you hit the space bar when the issue surfaces? That will make it easier for me to look up on a data log.

Matt, I am not able to mark the log after the run in TunerStudio, however it is present throughout the entire 2014-03-30_10.49.00 log.

I also uploaded the previous log, 2014-03-30_10.42.11 which shows the car running normally for a while then the issue happening 3/4 through at the 872900.0s mark.

I am logging myself while driving - sorry about forgetting to hit the space bar while managing everything else.

If you can get the issue happening consistently, would you be able to shut off the engine and use Output Test Mode to check to be sure both ignition channels are sparking?

I'll see if I can catch it. Is this the correct procedure and settings I should be using?

MS2/Extra - Output Test

Not really sure what I should expect if the test is successful or not.

The new 3.3.1 code has made output test mode a lot easier - it now works the same way as the MS3:

Megasquirt MS3 Output Testing

We'll have to see what the test turns up and take it from there.

I am still on firmware v3.1.0

I am going to upgrade to see if that helps the situation. It's been something I've been considering anyway, I was just hesitant to potentially add to the issues I have.

Updated to 3.3.1

Went out for a spin but the problem is still there. I tried to stop the car and run the spark test, but nothing happened. Not sure what to be looking for while running the test. What means it is successful?

Define nothing happened?

Dumb question, have you checked your spark plug gap?

Also, have we had you check your grounds? I have found that things get wonky sometimes if you don't have dedicated grounds running to the block itself.

There was no response when running the test so I shut it off.

New BKR7E-11 plugs were installed a couple weeks ago and gapped to .030.

I have not checked the grounds. Will look into that tomorrow

Specifically, check the grounds on the ECU to the block as well as the injectors to ground.

How are your injectors attached to your harness? Check for any places where any heat shrink tube might have chafed through and you may be shorting your injectors.

Grounds are solid. No visible issues with wiring to/from injectors. I am using plug-and-play adapters from FIC that were zip-tied to the stock harness so they can't come loose. Checked those as well and everything looks good.

Taylor ThunderVolt wires have about 8k or less on them and look to be in great condition. Could be related though, so I'll try swapping them out for my old set of NGK's in the next couple days when I get some free time.

I'm leaning toward the coil pack at this point. LSx coils may be in my very near future.

If it wasn't sparking (you might want to use one of the inline spark tester tools to make it easy), I'd suspect the coil pack is having problems that cause it to shut down when it heats up.

i'd borrow a coil pack (if that's possible) before I spend the money on LS coils. Nothing wrong with them but no point throwing money at a problem.

How long does the car need to run before it starts having this problem? Could your dwell be set too high maybe?

Unfortunately, I don't know anyone with spares near me test the coil pack. I look at the upgrade as eliminating a weak link that will fail inevitably. Car was boosted before and will likely be again so it makes sense to do it now instead of later.

The issue is intermittent so it comes and goes at random. The problem I have with tracing this back to MS settings like dwell is that I never had a single issue before this. It started out of nowhere and I'm running the same settings Braineack supplied with my DIYPNP that worked for close to a year without issue. I can try to play with it, but I'd be worried I would do more harm than good.

Swapped in my backup set of NGK wires and took it out for a test drive. Seemed to run well for 40 minutes or so until all of a sudden after a WOT onramp, the car bucked heavily and started puking heavy whitish smoke (oil). I limped the car back home, check oil level and it's completely dry. There is a misting of oil from the top of the valve cover and pools near the exhaust manifold and the drivers side of the block looks pretty covered. I couldn't see any holes in the block, but at a minimum my rings are shot.

Now shopping for long blocks. GOOD TIMES... :beer: :beer: :beer:

Fuuuuuuuuuuck

Carnage pics or it didn't happen!

Repeated dry compression numbers confirmed what I assumed:

1: 190
2: 115
3: 190
4: 190

What were your afrs at wot before you started having all these problems?

12.6:1 at torque peak raising to 13:1 at 7200 rpm cut. Tune is attached on first post for specifics. AFR targets were inline with actual AFRs.

The motor had 170k+, a short stint of boost, and a lot of track days. It served me well.