RS2.5 REV LIMITER

On the Phase-II EJ25, fuel is cut at around 6500 rpm. You'll stop (positively) accelerating. That's it.

How do you know you had a backfire?

Thanks for the info, (Verbs Under My Gel)

It certainly made a quite loud bang type sound which sounded like it came from the intake. I would have identified a similar noise on other cars as the mixture being too lean if it was intake noise so the fuel cut off theory appears valid. I believe that on some cars power to the ignition coil/s is cut when rpm limit is exceeded rather than fuel being cut off which can cause the car to miss repeatedly as the engine speed ramps up and down with the throttle held fully open.

I couldn't say whether the EJ25 motor would maintain its speed just under the rev limit since I naturally backed off anyway. If the fuel cut off valve is either on or off then the fuel flow would stop until the engine speed was below the rev limit. Therefore the mixture would be correct air/ fuel to begin and then (lots of air) / fuel at the limit which equals lean and hence the backfire.

If the fuel cut out was a true regulator as you have suggested and not a cutoff then the airflow would have to be reduced also to maintain correct mixture at the rev limit with the throttle wide open.

I'll dig through the service manuals when I get a chance, but most likely the fuel is "cut" by the ECU ceasing to send signals to the injectors.

Thanks (Verbs Under My Gel)

Hi verbs,

It happened again when I was passing a truck and it hit the rev limit but this time it did as you suggested and positive acceleration stopped. Pity it didn't have a buzzer on it like some WRX's have to warn the driver that revs were about to be limited. Never had a car that did that before, normally one would keep going until torque ran out then change up a gear when in a hurry. So I was halfway passed a long truck with oncoming cars approaching and acceleration stopped. You don't study the tacho when your busy passing, one normally watches the traffic.

No, you don't. Pardon my butting in here, but surely your ears can tell you that you're about to run out of revs! My 2.5L AT downshifts to hold a set speed and when it gets around 5K, I pull the plug very shortly. How fast were you going to overrev yours? (sounds scary to me!)