unwanted acceleration & surging
#1
07-31-2011, 12:25 PM
unwanted acceleration & surging
New member first major problem, need help and or suggestions.2005 Elantra, 4 door, auto trans, 209000 miles.
Returning home last night on toll road running 70 mph, everything fine. Touched the brake to release cruise and started slowing down for toll booth. Car didn’t feel right when it started slowing down. About 40 mph it didn’t want to slow down. Rpm would drop for a little bit (slowing) then back up to 2 grand (surge). Rpm would stay up more than it would stay down like it should. Had to use brakes as I went throught the pikepass lane to get the speed down. Rpm about 2 grand and speed with brakes applied was about 30mph. Run it back up to 70, resume cruise and everything is good. Take my exit and same thing when I try to slow down. Stop at stop sign and Rpm about 2grand with foot on brake holding car at rest, it would come down to idle then go right back up. (NOTE; Foot is not on brake and accelerator at the same time. Getting kind of worried about getting home now) Going through small town car does not want to go 25mph without really riding the brakes. Also it would down shift to keep the rpm up at that speed. Then it would idle normal and I would have to let off the brakes momentarily until it revved up again, back on the brakes. Motor would not settle down at speeds less than 35 or 40 mph. Seems the motor wants to run about 2 grand under load. Had to pull a hill with curves on it, motor worked fine at 25mph and 1800 to 2000 rpm while climing the hill. Get to top of hill here we go again. Using cruise at 40 mph it surges a little. Using cruse at 25mph motor surges bad and hunts for the right gear for the rpm. Got in driveway at home, shut motor off. Restarted in neutral motor surging at idle then went to 4 grand and stayed there. Killed it. Tried again this morning and it idled for a moment then went to 3 grand, killed it again. Note; I don’t think the brake switch has anything to do with this problem as it doesn’t matter if the cruse is on or off if trying to drive at speeds less than 40mph. I plan on getting a scanner Monday to check the codes. Any help or clues are appreciated.
Returning home last night on toll road running 70 mph, everything fine. Touched the brake to release cruise and started slowing down for toll booth. Car didn’t feel right when it started slowing down. About 40 mph it didn’t want to slow down. Rpm would drop for a little bit (slowing) then back up to 2 grand (surge). Rpm would stay up more than it would stay down like it should. Had to use brakes as I went throught the pikepass lane to get the speed down. Rpm about 2 grand and speed with brakes applied was about 30mph. Run it back up to 70, resume cruise and everything is good. Take my exit and same thing when I try to slow down. Stop at stop sign and Rpm about 2grand with foot on brake holding car at rest, it would come down to idle then go right back up. (NOTE; Foot is not on brake and accelerator at the same time. Getting kind of worried about getting home now) Going through small town car does not want to go 25mph without really riding the brakes. Also it would down shift to keep the rpm up at that speed. Then it would idle normal and I would have to let off the brakes momentarily until it revved up again, back on the brakes. Motor would not settle down at speeds less than 35 or 40 mph. Seems the motor wants to run about 2 grand under load. Had to pull a hill with curves on it, motor worked fine at 25mph and 1800 to 2000 rpm while climing the hill. Get to top of hill here we go again. Using cruise at 40 mph it surges a little. Using cruse at 25mph motor surges bad and hunts for the right gear for the rpm. Got in driveway at home, shut motor off. Restarted in neutral motor surging at idle then went to 4 grand and stayed there. Killed it. Tried again this morning and it idled for a moment then went to 3 grand, killed it again. Note; I don’t think the brake switch has anything to do with this problem as it doesn’t matter if the cruse is on or off if trying to drive at speeds less than 40mph. I plan on getting a scanner Monday to check the codes. Any help or clues are appreciated.
#2
08-24-2011, 10:57 PM
Update
Pulled the codes, got one about the TPS and one about it running lean on bank 1 (I think.) Changed the TPS and now have an extra. (Didn't help) Took it to shop and they said I had a leak on the intake manifold gasket. Ordered gasket from parts store, got it installed this evening. Idles better than it has in a long time. NOTE to everyone, when we removed the manifold from the car, buddy actually removed one of the intake nuts without a wrench, it was that loose. Gasket was still intact, but changed it any way since we had it apart. None of the 5 nuts was what I would call any more than just snug. So if your car is not idling smooth check the intake bolts. This could save you some money and a headache.
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