Aleromod.com - View Single Post - '00 2.4L Hesitation

richthofen · 11-02-2009, 02:06 AM

New here, so thanks in advance for any help. 2000 Alero 2.4/auto, 156K miles, and I'm dealing with a rather irritating problem. Started about a month ago--the car started idling rough and would occasionally cut off at stoplights and/or going around corners. Got some advice from a local guy, former mechanic, who said that the spark system often causes a miss--I replaced the plugs, issue got worse. Took everything apart again and he tested the coils and coil housing for voltage, diagnosed it as a bad coil housing. Replaced that and the plug boots. Ran slightly better, but still not right, and developed a bad hesitation that's gotten steadily worse. Pulling away from a stop, I give it gas, and the tach doesn't move, car doesn't accelerate, unless I feather the throttle or really nail it. At speed but low RPMs, it bucks when I try to accelerate. At freeway speed it acts mostly normal. Idle is still rough and it still stalls occasionally. Intermittent SES light, code PO172 Bank 1 Too Rich.

Any ideas? I have purchased a throttle position sensor, thinking that might be it, but I'm not entirely sure where it's located. Does anyone have a pic/diagram? Or am I likely barking up the wrong tree? Could it be a vacuum leak, and if so where are the likely points? I also want to do a seafoam treatment (intake/gas, not oil just yet since it's not due for a change) just for the heck of it and the consensus from what I've read seems to be just pour it down the intake on the 2.4. Where exactly should I introduce it? Just after the airbox, or do I disconnect it farther down? Thanks for any advice, this is really killing me, it's kind of scary just to drive to and from work like this...

11-02-2009, 02:06 AM	#1
richthofen GX Member Join Date: Nov 2009 Location: Durham, NC Posts: 33	'00 2.4L Hesitation - Help Pls? New here, so thanks in advance for any help. 2000 Alero 2.4/auto, 156K miles, and I'm dealing with a rather irritating problem. Started about a month ago--the car started idling rough and would occasionally cut off at stoplights and/or going around corners. Got some advice from a local guy, former mechanic, who said that the spark system often causes a miss--I replaced the plugs, issue got worse. Took everything apart again and he tested the coils and coil housing for voltage, diagnosed it as a bad coil housing. Replaced that and the plug boots. Ran slightly better, but still not right, and developed a bad hesitation that's gotten steadily worse. Pulling away from a stop, I give it gas, and the tach doesn't move, car doesn't accelerate, unless I feather the throttle or really nail it. At speed but low RPMs, it bucks when I try to accelerate. At freeway speed it acts mostly normal. Idle is still rough and it still stalls occasionally. Intermittent SES light, code PO172 Bank 1 Too Rich. Any ideas? I have purchased a throttle position sensor, thinking that might be it, but I'm not entirely sure where it's located. Does anyone have a pic/diagram? Or am I likely barking up the wrong tree? Could it be a vacuum leak, and if so where are the likely points? I also want to do a seafoam treatment (intake/gas, not oil just yet since it's not due for a change) just for the heck of it and the consensus from what I've read seems to be just pour it down the intake on the 2.4. Where exactly should I introduce it? Just after the airbox, or do I disconnect it farther down? Thanks for any advice, this is really killing me, it's kind of scary just to drive to and from work like this...