Car won't start with standard ecu

[SonicSW20]

Think a lot of you are missing the point. Right or wrong injectors it should still turn over.
From the description the op is saying it just dies so i guess everything goes blank and lights go out when turning to ignition start?
If so this is an electrical problem.

My point is, he's made things worse by swapping the ECU. I'd swap back to the PFC, check the thing behaves as it did before (it clearly started and drove) and then work the issue through with the PFC. Swapping from aftermarket to stock ECU without a full knowledge of why the aftermarket ECU is there is highly unlikely to help the situation, as the OP has found out.

Exactly, if the original issue is just a misfire it's rather overzealous to jump straight to ECU being the problem or even just to read codes. Start with the ignition components, codes aren't really going to help you there anyway if it turns out to be a worn rotor arm, worn plug etc.

[Caleb-mr2]

As my first post... battery... immobiliser?... trace the power to the ignition switch then to the relay then starter..
Getting it cranking is the first job.
You can even take a power feed to the starer exciter wire to see if starter will even crank... could be that simple.. duff starter.

I'm wondering if it's an immobiliser but would that not be a problem with the apexi ecu as well or does using an aftermarket ecu disable the immobiliser??

[Caleb-mr2]

Think a lot of you are missing the point. Right or wrong injectors it should still turn over.
From the description the op is saying it just dies so i guess everything goes blank and lights go out when turning to ignition start?
If so this is an electrical problem.

My point is, he's made things worse by swapping the ECU. I'd swap back to the PFC, check the thing behaves as it did before (it clearly started and drove) and then work the issue through with the PFC. Swapping from aftermarket to stock ECU without a full knowledge of why the aftermarket ECU is there is highly unlikely to help the situation, as the OP has found out.

Exactly, if the original issue is just a misfire it's rather overzealous to jump straight to ECU being the problem or even just to read codes. Start with the ignition components, codes aren't really going to help you there anyway if it turns out to be a worn rotor arm, worn plug etc.

I've changed the spark plugs, distributor and rotor arm along with the ignition coil. It's not the ignition. What is happening is that the fuel pump relay is clicking and every time it does the car stumbles and misfires. Does anyone know why this might happen??

[qwakers]

bad earth bad relay damaged wire feeding the switching side of relay.

[SonicSW20]

My point is, he's made things worse by swapping the ECU. I'd swap back to the PFC, check the thing behaves as it did before (it clearly started and drove) and then work the issue through with the PFC. Swapping from aftermarket to stock ECU without a full knowledge of why the aftermarket ECU is there is highly unlikely to help the situation, as the OP has found out.

Exactly, if the original issue is just a misfire it's rather overzealous to jump straight to ECU being the problem or even just to read codes. Start with the ignition components, codes aren't really going to help you there anyway if it turns out to be a worn rotor arm, worn plug etc.

I've changed the spark plugs, distributor and rotor arm along with the ignition coil. It's not the ignition. What is happening is that the fuel pump relay is clicking and every time it does the car stumbles and misfires. Does anyone know why this might happen??

Probably best to list everything you've done so far to try and solve it!

[shinny]

"What is happening is that the fuel pump relay is clicking"

Sooooo... why haven't you changed the relay yet?

OK, it's not that simple. There are two relays involved.. the circuit opening relay and the fuel pump resistor relay. I doubt either would be heard within the cabin while at WOT. But anyway...

If I were seriously thinking there was the question mark over the fuel pump then I'd start by shorting FP and B+ on the diags port and trying to recreate the issue. That will cause the pump to run fullspeed regardless of what the relays are doing. If you still experience an issue then it's not the relays.

[C35Rob]

The car I bought was misfiring and as I got an apexi power fc I couldn't read codes. I've just bought the standard ecu and fitted it.

The car had an aftermarket ECU fitted... generally people fit one because their mods go beyond what the stock ECU can handle. The obvious mismatch would be bigger injectors (which would cause the stock ECU to flood fuel into the engine), but all kinds of other mods and wiring changes could easily mean a standard ECU won't plug-and-play with the car again.

Unless you are absolutely sure the engine is so lightly modified that the APEX'i PFC is just there to provide mapping, I would return to the PFC and figure out how to get codes out of it. (Does that mean you need to buy a hand commander?)

there are no 'error codes' with a power FC, commander or not.

[shinny]

there are no 'error codes' with a power FC, commander or not.

Every day is a school day

[SonicSW20]

But with the commander you can get readouts of voltages etc I think? So if you know where they should be it can help narrow things down.

[Race Idiot]

Yeah doesn't the commander have a sensor error page, or something similar. I vaguely remember that when I tested my old one out.

[C35Rob]

But with the commander you can get readouts of voltages etc I think? So if you know where they should be it can help narrow things down.

Yeah you can; main menu, ETC, sensor/sw check

It'll give you output voltages of sensors and a black or white dot depending on whether something is active or not but no OBD style error codes, so unless you know what you're looking for and the engine is running it's fairly useless

[Caleb-mr2]

Ever have one of those you're laughing but inside you're crying moments lol.

Sooooo went back to the apexi power fc unit and tried to start it and........ nothing. Thought that was strange as everything was fine and ready to go. Only 4 months ago the battery was changed for a new one so I never thought to even check there. I recently got it back from my mechanic with a flat battery so I charged it no problem and it had 12.7v with a multimeter so a new battery with 12.7v good stuff.

Turns out in the two weeks he had it, the door was accidentally left ajar twice so it spent days draining both times. On the off chance as now it wasn't working with the apexi or standard ecu I got it load tested which of course said it was finished.

Long story short a 4 month old battery has been killed by silly mistakes and that's why it won't turn over

Hopefully a new battery and I can check codes with the standard ecu.

[androo007]

Glad it was an easy solution! You sure it was the door open, and not alternator failure etc?

[shinny]

Glad it was an easy solution! You sure it was the door open, and not alternator failure etc?

You'd have got warning lights for an alt failure

[Caleb-mr2]

Yeh just a stuffed battery as far as I know.

I swapped my mx5s battery over to it and it fired up no problem. The apexi ecu was still causing a misfire. Swapped in the standard ecu and again fired straight up

Was running rough on idle but the misfire had stopped. Ran codes and got 21 so o2 sensor

Never in my life have I been so happy to find out something is wrong with my car!

Hopefully a a new sensor and she'll be sweet.
If anyone knows a good place to get one cheap let me know or the part number!