Odd low throttle issue

300zxturboftw · 12-27-2012, 10:54 PM

I have a rotated 35r EJ257 and I'm having this intermittent problem...

Cruising with about 10 % throttle the AFR's lean out to where its like there is fuel cut when engine breaking (AEM AFR Gauge Reads ---) but vacuum is still pulling about -10 hhg as well as a loss in power like its missing in 1 or 2 cylinders. If I increase throttle or when rpm's reach around 3k rpm + the AFR gauge comes back to 14.7 and power returns to normal.

This is completely random. Sometimes I will have the issue 1 day and not have it reappear for a week. Sometimes it happens multiple times a day. This is why I'm so stumped on the issue.

Anyone have a similar issue? Battery & alt are pulling correct voltages.

No CEL's, and I've gotten them on spark misfire under heavy boost so I know it exists, but would it go off on light load misses?

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stretchedk7 · 12-28-2012, 02:11 AM

Does the car have an aem ecu in it? Either way sounds like possibly a tuning issue.

Uncle Scotty · 12-28-2012, 02:26 AM

that or maybe a vac leak in the evap system maybe.....valve opens and ya lean out and *p00f*

300zxturboftw · 12-28-2012, 10:03 AM

I have opensource. I don't think it's a tuning issue because of the spontaneity of the issue. I'll try a smoke test or boost leak down test with the compressor. Just seems too odd for a vac leak too, but who knows.

stretchedk7 · 12-28-2012, 10:11 AM

Which makes sense. Next option would be the vacuum leak idea ^.

12-27-2012, 10:54 PM	#1
300zxturboftw Scooby Newbie Member#: 325461 Join Date: Jul 2012 Vehicle: 2003 WRX WRB	Odd low throttle issue I have a rotated 35r EJ257 and I'm having this intermittent problem... Cruising with about 10 % throttle the AFR's lean out to where its like there is fuel cut when engine breaking (AEM AFR Gauge Reads ---) but vacuum is still pulling about -10 hhg as well as a loss in power like its missing in 1 or 2 cylinders. If I increase throttle or when rpm's reach around 3k rpm + the AFR gauge comes back to 14.7 and power returns to normal. This is completely random. Sometimes I will have the issue 1 day and not have it reappear for a week. Sometimes it happens multiple times a day. This is why I'm so stumped on the issue. Anyone have a similar issue? Battery & alt are pulling correct voltages. No CEL's, and I've gotten them on spark misfire under heavy boost so I know it exists, but would it go off on light load misses? * Registered users of the site do not see these ads.

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12-28-2012, 02:11 AM	#2
stretchedk7 Scooby Guru Member#: 170602 Join Date: Jan 2008 Location: j-ville fl Vehicle: 06 Wrx 6Spd TSBorg Warner S400-Aem-2200s	Does the car have an aem ecu in it? Either way sounds like possibly a tuning issue.

12-28-2012, 02:26 AM	#3
Uncle Scotty NASIOC Supporter Member#: 16200 Join Date: Mar 2002 Vehicle: OK Houston we have an Uncle	that or maybe a vac leak in the evap system maybe.....valve opens and ya lean out and p00f

12-28-2012, 10:03 AM	#4
300zxturboftw Scooby Newbie Member#: 325461 Join Date: Jul 2012 Vehicle: 2003 WRX WRB	I have opensource. I don't think it's a tuning issue because of the spontaneity of the issue. I'll try a smoke test or boost leak down test with the compressor. Just seems too odd for a vac leak too, but who knows.

12-28-2012, 10:11 AM	#5
stretchedk7 Scooby Guru Member#: 170602 Join Date: Jan 2008 Location: j-ville fl Vehicle: 06 Wrx 6Spd TSBorg Warner S400-Aem-2200s	Which makes sense. Next option would be the vacuum leak idea ^.