random engine cut off while on track
 

having fixed my fuel starvation issues and ran a few race last weekend, i can confirm that fuel starve is no longer an issue. but i'm still getting random engine cut off, and usually at the same spot on the track. most of the time it happens after a right hand turn. the car still get CEL blink from random misfire here and there, but that's been going on since i started tracking the car, even when i still had the old engine. i wonder if it has something to do with the stability control, even though it's turned off/disabled. or could it be bad grounding cable?

in the vid below, at the 10:10 mark, you can see and hear the engine cuts off, and usually it happens multiple times consecutively. you can hear it happens 3 times in a row there. it sounds like i'm lifting off the throttle but i'm not, the engine just totally cuts off for a split second and comes back.

Is that an electrical cut-out (bad ground)? The reason I say that is the rev and throttle signals are lost.
With fuel cut-out I still have rev and throttle traces.
I also get mis-fires on track. Have done all the normal stuff and not solved it in ~2years. Recently got much worse and it's now apparent my engine takes occasional gulps of oil either through the intake oil breather or the internal oil seal.

Maybe communication between the throttle pedal and the ECU?

I assume it's not throwing a code at you.

You're losing the RPM signal which generally means the ECU has lost sync. That either means it's losing power for some reason or the crank trigger is bad.

Can your data logger monitor power to the ECU? Completely different engine and ECU, but I had this problem on my car and it was a bad crank position sensor.

It’s likely an intermittent wiring/connector issue, but relative to that; what ignition system do you have?

this has only happen on track and i dont have a way to secure a laptop in the car to log while on track. it started happening with the old engine, then when i got the new build engine, i tried to remove the crank sensor from the old engine and it broke. so i got a new one from autozone (non oem) for the new motor and been using that one since.

also did the 20 brake stomp to reset the crank sensor a few times

i had oem coils and wire when it stared happening. then i built a d585 (ac delco) coil setup and it was still happening. then two of those d585 coild died so i switched back to the old oem coils and new NGK wire and it's still happening. just odd that it's happening on straight usually after exiting a turn, and usually on same part of the track. if it was lose wire, it would happen when i hit curbings or during high Gs corners, but that's not the case.

you can see in the video it happened again on the next lap at 12:08 mark, same part of the track. some times the rpm signal drops, some times it doesnt, from the video

i have a new odyssey pc680 that's mounted on the passenger floor. one ground wire going to the seat mount bolt, and one ground wire going to engine bay and connect to the stock battery ground cable.

trying to remember back, i think it was happening when i had the stock back in stock location also

That’s why it’s likely an intermittent wiring or connector issue. You could have an exposed wire that only touches something and grounds out or a connection that loses contact in that particular situation. It’s not unusual for it to be the wiring at the coil connector though I’ve seen that more with the BHR D585 coil system than others; the coil harness wiring can rub against the front engine pick up hook and exposes the wire and then might touch the hook and ground it out. You could start there, but honestly it could be anywhere and that’s going to be the difficult part.

if battery ground or positive wire is lose, that shouldn't matter because the alternator is still providing power, correct? that's why my kill switch disrupt the alternator to kill engine completely, not just disconnect the battery.

You said it's an autozone sensor? Replace it with a factory Mazda sensor. Again I know, different applications and all, but the issues I had with my car was caused by a bad Chinesium crank sensor. The Mazda stuff is much better quality. I agree with Mark though that it's likely an intermittent wiring short.

what's the difference between the two part number for crank sensor

Part # : N3A1-18-221A
Part # : N3A1-18-221A-PT

The -PT sensor is NLA, superseded by the other one

ah thanks,

You mention your kill switch, what kind is it? Is it a physical contact to contact kill switch? I assume if it is a spring contact switch it could have seen enough current and heat cycles to fatigue and have intermittent connection. Also something to consider.

typical 6 pole kill switch used by many racers.

https://www.ogracing.com/battery-6-pole-killswitch

i got a new oem mazda crank sensor and just did a race this past weekend. still same issues with CEL light blinking for misfire here and there, and the engine power randomly cuts off. i cleaned all the grounding points. checked all the wiring plugs. im wondering if it could be the ecu, and if the aim solo DL plugging into the obd2 port has anything to do with it. the solo DL would randomly lose connection to the ecu sometime also.

if i try a different ECU, are there different ecu serial code to match different chassis with stability control? my car is 2006 with stability control.

i lost a race this weekend because the engine cut off at a bad place on track and my competitor got around me and i wasn't able to regain the lead after that. it's so frustrating.

Try unplugging the AiM Solo device, had something similar happen with a Cobb tuning device before.

yeah i didn't really thought about that until last night when i was watching the race vids and notice the one time the engine cut off and aim lost connect at the same time, wasn't sure if that was a coincident or not, because most of the time when the engine cuts off, aim didnt lose connection.

Mr. Pockets had a problem with his OBD/CAN data acquisition system causing the engine to stutter and struggle above 7k or 8k.

I forget which system he had.

If you try a different ECU, you'll have to get it re-coded to work with the various modules in the car.

what's involved with recoding the ecu? i also have Versatuner which i had to send them my ecu serial code for them to send me the file to access my ecu. so i guess i would have to contact them if i want to use versatuner on a different ecu.

Versatuner just lets you play with the various tables.

You'd need to learn to use ForScan or take it to the dealer.

I'd pursue other avenues of investigation (i.e. disconnecting the AiM) before going through that trouble.

The 2004 PCM reflashed by Racing Beat will have the security removed and can be swapped into any USDM S1 Rx8

He’s not around anymore, but member Ebb had it done and used it on his 2005 without a matching key or module reprogramming. There was a group in Italy that was reflashing way before anyone else for an RX8 spec class racing series over there, but they could only do it on a 2004 pcm because of the security thing.

It was the Autosports Labs Racecapture Pro MK3 that MrPockets and I think maybe another member were using. One issue is the car wouldn’t rev above 8000 rpm or would break up.

Does the AIM Solo have a CAN termination resistor inside it that can be switched off? You are probably loading down the CAN bus impedance.

don't know, i'm not very good with electronic stuff :|
i can select different protocol to use for the solo DL to pull data. currently im using obd2 protocol so it pull engine coolant temp. there's two different CAN protocol i can select also. Mr. Pocket said he was using obd2 when he was having issues with engine cut off. he's using CAN to pull all his data now. so maybe next event, i'll just unplug the solo DL all together to see if engine cut off is gone. then i'll change the solo DL to use CAN, and see if that will make the engine cut off again.