my engine cut-offs on Drive when brutally accelerating
06-11-15, 01:57 PM
#32
I once had the exact same issue but with my wrx back in the day after doing a larger turbo upgrade. When i got on it, at a certain rpm, it would cut out, come back in and cut out if i kept my foot on the ground. Turned out to be a loose wiring harness that would slide out of it's socket ever so slightly when the motor was under heavy loads like a hard acceleration but would re-establish the connection once the motor cut out cause the load was lost.. Go around the engine bay and try to make sure all the electrical plugs are tightly connected. maybe a wire can even be close to some metal and causing it to short under load? I experienced no CEL when this happened and drove fine when driven normally. Good luck. Keep us posted! hope it's simple!
06-11-15, 05:10 PM
#33
Pole Position
... To expand on what Lobux is getting at.. Sounds like the car is breaking traction. In "normal mode" there is very limited wheel spin allowed, and the ECU will cut throttle if needed. In "sport mode" more wheel slip is allowed.
Try this, hold the TRAC button 5 seconds, while stopped, to disable traction control. Now do a pull in normal mode, and see if there is any throttle cut
Try this, hold the TRAC button 5 seconds, while stopped, to disable traction control. Now do a pull in normal mode, and see if there is any throttle cut
06-12-15, 07:59 AM
#34
Lead Lap
monitor the throttle position via OBDII. I have had a similar issue with unknown throttle cut. It will drop throttle position to 49% around 3500-4500 rpm. no CEL, no log. The ISF ECU has persistence and cannot be reset even with TIS. We have 10 hrs of trouble shooting with no further information. I cannot seem to find a sensitivity to the problem. The tech would not troubleshoot it any further because there were no codes thrown.
Fig
Fig
06-12-15, 08:00 AM
#35
Lead Lap
I was just thinking...that is the same thing that happened to my is250 and then many rebuilds had to be done to to carbon build up.. I had the same damn thing happen to me with my is250..EEK..this is scary
06-12-15, 10:50 AM
#36
The IS-F should not have the carbon buildup issue, it has port injectors so fuel passes over the top of the valves and cleans off the buildup of carbon. The is250 carbon buildup is due to being only direct injected, fuel does not get to the top of the valves to help clean the carbon.
06-13-15, 10:55 AM
#37
Tech Info Resource
iTrader: (2)
Deep in the engine code there is a rate limit for rpm increase. If the ECM detects rpm increasing at a rate it does not like, it will cut fuel. Norwood discovered this quite some time ago with his turbo'd IS-F which is why despite all the work put into it, it was impossible to run more boost than the 6 psi. I suspect it is also at the core of why we don't have a Pro EFI piggyback.
Nitrous users would not likely run into this because they are running adequate rubber to prevent wheelspin. This limits rpm increase pretty handily. Which goes back to why I asked about tires.
Nitrous users would not likely run into this because they are running adequate rubber to prevent wheelspin. This limits rpm increase pretty handily. Which goes back to why I asked about tires.
Thread
Thread Starter
Forum
Replies
Last Post
supersc30
Performance & Maintenance
10
02-12-17 12:11 PM