Hesitation?

RoadTrippin · 11-03-2009, 10:02 PM

From a stop I have a problem with slight hesitation during acceleration. Sometimes I feel like it is going to stall out on me but it has yet to do so. NO CEL, no backfiring yet, just the hesitation. It just started within the last two days.

I usually run 87 octane gas as that is mid grade up here in Denver and for the past two weeks have been running 85 octane gas just as an experiment. Im starting to think that may have been a bad idea but am curious as to why it would start now vs the 1st tank of 85. I bought some BG 44k today and plan on putting it in on the next fill up but was seeing if anyone else had an idea as to why all of a sudden this could start.

The car is an 02 RS, Auto

yarrgh · 11-03-2009, 10:09 PM

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05Impreza2.5RS · 11-04-2009, 07:41 PM

I have been having the same hesitation in my 05 Impreza. I changed out the spark plugs and wires over the weekend, but that seemed to do nothing. I used my Accessport to check and see if there were any ECU trouble codes. To my surprise there were about 30 codes! Most of the important codes seem to involve the Secondary Air Injection System. Has anyone else had these codes, and if so what they did to fix the problem?

01LGT · 11-05-2009, 02:55 AM

check upstream o2 sensor, i've had problems w/out a CEL where it does something similar. plugs may cause this as well

RoadTrippin · 11-05-2009, 11:53 AM

I changed the fuel filter today and I still am having the problem. It isnt as bad as before but is still there. Im going to give it a few days before I try something else. After I changed the fuel filter the CEL came on and it was cylinder 2 misfire. There was a tiny bit of water in the spark plug boot from when I cleaned off the battery terminals, I blew it out and it hasnt thrown a CEL since.

Im thinking next steps would be fuel injector cleaning then spark plugs. Though I did change the plugs maybe 20k miles ago.

RoadTrippin · 11-07-2009, 11:56 AM

Ok so did some checking and it turns out the valve cover gaskets were toast causing oil to leak on the plugs. New valve cover gasket, spark plugs, and wires runs like new.

11-03-2009, 10:02 PM	#1
RoadTrippin Scooby Newbie Member#: 161175 Join Date: Oct 2007 Chapter/Region: RMIC Location: Mountains....	Hesitation? From a stop I have a problem with slight hesitation during acceleration. Sometimes I feel like it is going to stall out on me but it has yet to do so. NO CEL, no backfiring yet, just the hesitation. It just started within the last two days. I usually run 87 octane gas as that is mid grade up here in Denver and for the past two weeks have been running 85 octane gas just as an experiment. Im starting to think that may have been a bad idea but am curious as to why it would start now vs the 1st tank of 85. I bought some BG 44k today and plan on putting it in on the next fill up but was seeing if anyone else had an idea as to why all of a sudden this could start. The car is an 02 RS, Auto

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11-03-2009, 10:09 PM	#2
yarrgh Scooby Specialist Member#: 80465 Join Date: Jan 2005 Location: Aurora, CO Vehicle: 2001 2.5 RS Black Diamond Pearl	search...

11-04-2009, 07:41 PM	#3
05Impreza2.5RS Scooby Newbie Member#: 156674 Join Date: Aug 2007 Location: Colorado Vehicle: 2005 Impreza 2.5RS Aspen White	I have been having the same hesitation in my 05 Impreza. I changed out the spark plugs and wires over the weekend, but that seemed to do nothing. I used my Accessport to check and see if there were any ECU trouble codes. To my surprise there were about 30 codes! Most of the important codes seem to involve the Secondary Air Injection System. Has anyone else had these codes, and if so what they did to fix the problem?

11-05-2009, 02:55 AM	#4
01LGT Scooby Newbie Member#: 224816 Join Date: Sep 2009 Location: Rapid City, SD Vehicle: 2001 Legacy GT	check upstream o2 sensor, i've had problems w/out a CEL where it does something similar. plugs may cause this as well

11-05-2009, 11:53 AM	#5
RoadTrippin Scooby Newbie Member#: 161175 Join Date: Oct 2007 Chapter/Region: RMIC Location: Mountains....	I changed the fuel filter today and I still am having the problem. It isnt as bad as before but is still there. Im going to give it a few days before I try something else. After I changed the fuel filter the CEL came on and it was cylinder 2 misfire. There was a tiny bit of water in the spark plug boot from when I cleaned off the battery terminals, I blew it out and it hasnt thrown a CEL since. Im thinking next steps would be fuel injector cleaning then spark plugs. Though I did change the plugs maybe 20k miles ago.

11-07-2009, 11:56 AM	#6
RoadTrippin Scooby Newbie Member#: 161175 Join Date: Oct 2007 Chapter/Region: RMIC Location: Mountains....	Ok so did some checking and it turns out the valve cover gaskets were toast causing oil to leak on the plugs. New valve cover gasket, spark plugs, and wires runs like new.