carnut114 Posted February 18, 2007 Posted February 18, 2007 Hello, I have a 1998 Subaru legacy gt wagon 2.5 auto. When taking off from a stop it has a hesitation like the engine tries to almost die out then the rpms comes up and it's fine. It does not do this all the time just here and there. Sometimes the check engine light comes on and when it does it and reads knock sensor. I have also decarbed the engine twice with sea foam and one other fuel injector cleaner. I have put new boch platinum spark plugs, new fuel filter, pcv valve. The spark plug wire look like new. I think it might me a throttle position sensor or a map sensor. Possibly a mass flow air sensor not sure. What do I have to replace to get it to stop doing this? Thanks Eric
Aczwild Posted February 18, 2007 Posted February 18, 2007 sounds like what was happening to me when my MAF sensor went JDM'd All to hell Thanks Jimmy @ Hkc-Speed.com! RIP Coxx & Thanks
carnut114 Posted February 18, 2007 Author Posted February 18, 2007 It that the mass air flow sensor? I had one of those go bad on a pontiac along time ago but the engine always stalled out. This engine never does just tries to. Thanks for the advice.
Aczwild Posted February 18, 2007 Posted February 18, 2007 Yeah thats the Mass Air Flow sensor. Mine would hesitate a lot, when you go to drive away after starting the car I could pretty much put my foot all the way down and the car would just crawl away for 6 or 7 secs JDM'd All to hell Thanks Jimmy @ Hkc-Speed.com! RIP Coxx & Thanks
carnut114 Posted February 18, 2007 Author Posted February 18, 2007 Mine just bogs down for a split second before it takes off. I wonder if it could just be starting to go bad? Eric
carnut114 Posted February 19, 2007 Author Posted February 19, 2007 It stalled out on me today when i went to stop. It started right up though.
Aczwild Posted February 19, 2007 Posted February 19, 2007 Engine definitely isnt getting enough fuel, I'd say the Mass Air Flow sensor is definitely on its way out JDM'd All to hell Thanks Jimmy @ Hkc-Speed.com! RIP Coxx & Thanks
SiouxBe Posted February 20, 2007 Posted February 20, 2007 I'd say the MAF is dirty...clean it! In addition, get rid of the Bosch plugs and put in NGKs. Also, check the electrical output of the Alternator as it my be on it's way out.
SLegacy99 Posted February 20, 2007 Posted February 20, 2007 Bosch plugs will kill ya. A huge no no in the area of japanese cars. NGKs only.
dplacen Posted February 20, 2007 Posted February 20, 2007 Bosch plugs will kill ya. A huge no no in the area of japanese cars. NGKs only. +1
dplacen Posted February 20, 2007 Posted February 20, 2007 I had a bad front o2 sensor do crazy things as well.
carnut114 Posted February 21, 2007 Author Posted February 21, 2007 I checked the alternator output it is good. I will have to take apart the air flow sensor and clean it. The boch platinum plugs i installed when i got the car. I have 5k on them now. I bought the car at 135k and they had the original ngks worn down to nubs. I didn't buy ngks since they are 19 bucks a plug. The auto part guy at the store said they will take ant platinum plug. What do the do to the engine thats so bad? Could that be causing the hestitation problem? Eric
SLegacy99 Posted February 21, 2007 Posted February 21, 2007 Bosch plugs decrease performance and efficiency. They will also eventually cause cylinder misfires (your CEL will flash at you), at which point you will have to replace the plugs anyway. So yes, I do believe this could be part of your problem. I bought my LGT with 69K and found out the plugs were Bosch. Once I had the NGKs the car ran smoother and faster. And no more misfires either.
carnut114 Posted February 22, 2007 Author Posted February 22, 2007 I bought the ngk plugs and installed them tonight. I got them for 9.88 a plug. I changed the wires too. I actually had autolite platinum in there, i thought it was bosh. I took it for a ride and it seemed smoother idel with no hestitation so far. I'll keep you posted. I checked the maf sensor and it was very clean.
yotabeater Posted February 25, 2007 Posted February 25, 2007 $10 a plug????? i paid $9 for my whole set of ngk v-powers!
carnut114 Posted February 26, 2007 Author Posted February 26, 2007 9.88 Was the cheapest i found. Auto barn online had them for 16 a plug. The plug was ngk PFR5B11.
carnut114 Posted March 7, 2007 Author Posted March 7, 2007 The culprit was a bad fuel filter. It hasn't done it yet and i just drove iton a 900 mile trip.
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