10secdream

My car has been running for about 800 miles now with the new setup problem free but recently the engine starts to misfire after the engine gets warm (10 minutes of driving). The misfire is consistent and it sounds like the car is running on 3 cylinders and it doesnt matter if it is at idle, cruising or WOT. Once you let the car cool off the car will start and run normal again until it is up to temperature again and then it starts to misfire again.

Current Setup:
2003 Mazda Miata
-Koyo 36mm rad
-TDR intercooler
-BRP MP62 supercharger (10psi at redline)
-MS Labs MS3 basic
-TDR heat shield
-Innovate MTX-L
-DW 200 fuel pump
-Flying Miata 550cc injectors

I thought I was chasing an ignition issue so I put in brand new plugs gapped to 0.030", new plug wires and new ignition coils. I have also replaced the camshaft position sensor as well. I have also pulled the plugs directly after the car was misfiring and none of the plugs appeared wet and they all seemed to look pretty normal. I am looking for advice on other areas to check or perhaps something easy I am overlooking.

sixshooter

iTrader: (12)

Are these the "RX8" 550cc injectors?

10secdream

They are Flying Miata 550cc injectors.

10secdream

I attached a datalog with the car misfiring on the highway once it was warm while cruising.

10secdream

I isolated the problem to cylinder 3 and it is fuel related. Drove the car home from work and everthing was normal for about 10 miuntes and then it dropped a cylinder. I used the testing parameters in megasquirt (for injectors and ignition) and determined that cylinder 3 was not getting fuel. Next step is to pull the injector and swap it to a different location to pinpoint if it is a wiring or injector issue.

I know this is probably not a common issue but I know it is possible that injectors get stuck when warm. Can this also happen to the wiring or in the MS3 itself? I just find the issue odd that it only happens once everything gets warm.

sonofthehill

iTrader: (1)

Sounds like a loose connection to your #3 injector rather than a bad injector. Some of the early injector pig tails don't have the greatest connection.

10secdream

I agree. I will inspect the connection. It is one of those adapter connections so it does not even have a complete pig tail.

sixshooter

iTrader: (12)

Injectors are opened by an electromagnet just like a relay. Coils can stop working when they heat up and expand enough to cause the wires to no longer make contact. Then they can work again when cooler.

10secdream

Last night I moved cylinder #3 injector to cylinder #1 and I am hoping to take it on a drive tonight so I can see if the issue follows the injector or not.

10secdream

Drove the car around for an hour last night and everything ran perfect. Must have been a loose injector clip or something.