Hard cut at random intervals
 

Background:
The battery in the car had a melt down (literally) on a drive, lead and terminal connections melted, was my fault re. connections.
The car was breaking down/ cutting off on the drive back home and I assumed it was due to the connections wiggling/not tight.

Now with a new battery, it will still constantly break up/cut (hard cut) with no backfire, in any gear at any rev range and at any speed.
The cuts normally last for around 1-2 seconds, sometimes <1 second and at most ~2.5 seconds. Also, it can cut 2-3 times within 5 seconds of accelerating (while changing gears).

Not sure if solenoids are at fault here, but want to rule out anything easy first.

Notes:

• Spark plugs are relatively good
• New Battery and is charged
• Checked and cleaned the ground terminal on the battery terminal. (Cant find any other terminals to check)
• Noticed a blown-out fuse, cabin (not sure if relevant, did have issue with cigar input)
• Starts and revs completely fine in Neutral
• Apexi Power FC, I can tell by driving that the tune is lost.

Thanks.

Does the dashboard turn off during those cuts?

On the commander, open the sensor check screen.

Go for a drive and when it does cut out look and see if your VTA values highlight black

Hey, what do I know, but I had to put a lead shim on the negative terminal to get full contact on a replacement battery.
Link

Good point, I did change out the terminal, I'll try this.


I forgot to note, that I don't have a hand controller, datalogit, fc-hako or pro commander.
I am trying to source a hand controller and will try the above. Curious, is there any check for a specific solenoid of the 8 in rack?
https://cimg8.ibsrv.net/gimg/www.rx7...438e6406e2.jpg



Thats a tricky one, my rev meter is already not working... but when it cuts; sometimes the overheat exhaust light might flash once/come on and speedo drops (like turning off the car but also due to the engine cut). No other lights come on, so unsure if the dash is turning off.

Sounds like detonation to me. I'd stop driving it.

well he's gotta find the problem somehow lol you are right though. it would be advised to stop driving until you get a commander. not knowing what it is or could be could make things worse. for the time being, limit your driving to troubleshooting purposes. the sensor check screen works the same for all FDs regardless of series

nothing yet - hard time finding fc controller locally.

Can you reinstall the stock ECU?

Yes - can do. What can be done with the stock ecu?

the stock ECU supports old school diagnostics via counting the blinks of the check engine light. Should give you a means to try and see what faults the ECU is showing. Theoretically, anyway. Can't hurt to try.

How old are your injectors? My car was sitting a while and I can see my car dumping fuel because the injectors got hosed from sitting too long with the ethanol fuel we have in my area.

if you have no CEL, there is a method to use a pair of LED's in the diagnostic port, with the stock ECU

Update:

1) Finally sourced a controller, the table below is from the sensor check screen during the different states. Checks out that the fuel cuts - is there anything else to see?
https://cimg1.ibsrv.net/gimg/www.rx7...70deab1f7a.png
2) Correct no CEL for me, I will attempt to do the LED on the diagnostic port soon

Poke at and shake the engine harness while the car is idling and see if the idle dips or it does something weird. The data there is somewhat inconclusive but that by itself is something of a clue.

if you could get a video of the commander check screen while this is happening it would help as well

I had a somewhat similar issue. Intermittent power cut, or loss. In short, I was overloading the stock FP power circuit with my oversized fuel pumps.

https://www.rx7club.com/3rd-generati...relay-1149692/