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stumbles at about 3k rpm...

1608 Views 5 Replies 4 Participants Last post by  gtkane
well it started about a week ago and has gotten worse. it stumbles hard at about 3 grand then clears up. i go to school for automotive technology and i brought it in to get some help diagnosing it. well my instructor and i eliminated the ignition system. also the exhaust and map and temp sensors. oh and throttle position sensor. it had 60psi at the schrader valve so it has plenty of fuel pressure. replaced the fuel filter. basically by the end of class he suggested that there is a rubber hose in the tank that splits often i should check. he said when they split you may lose volume even though they maintain pressure. so i dropped the tank last night only to find no rubber hose! they're metal. so does anybody have any suggestions? anybody have this problem?
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Try driving it with a scan tool hooked up. When it starts stumbling, see if the torque coverter is locking and releasing. May be a bad TCC solenoid.
well we tried running it with a scan tool. it stumbles even when parked. he was manning the scan tool so i imagine everything on there looked normal or he would have caught it. i'm out of ideas. :( thanks for the advice though i really appreciate it.
I'm wondering if this has something to do with the EGR valve ? Or since it also does it at idle maybe even a vacuum leak ?
you can try spraying carb cleaner or break cleaner around the intake gasket and it its starts running rich you know you have a leak there. just a thought. egr are usaully only at idle to have the most trouble i thought.
Funny thing about checking for vacuum leaks on the intake with brake cleaner...
That's how I always did it , until yesterday.
One of the guys at the shop was doing this(on an Astro) and when he found the leak, the engine gave a lean backfire, and touched off the brake cleaner. It burnt the headliner and at least one eyebrow.
All's well though- new headliner went in today, and his wife drew him a new eyebrow.
From now on, I'll have to find a less flamable method.
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