420a dsm wont stay at idle

[936DSMboy]

okay so ive had a check engine light for a while and since the car ran great until yesterday well I ignored it. so on the way to my local walmart the car starts to want to turn off as im sitting in traffic waiting for the lights to change but once the car accelerates then its a whole different story and it doesnt shake or seem to want to turn off on me at higher rpms far from idle. so I take it to autozone to get checked for the CEL light and it turns out that it could be one of the 3 problems

1:bad cat

2:exhaust leak near rear o2 sensor, which I would hear and I dont see.

3:bad rear o2 sensor

so the car pretty much wont idle and it sounds like a cammed race car and it kinda shakes....uhmmm by the way I have a brand new magnaflow cat which isnt even like a year old. ###z help

 

[Fotowntalon]

cat shouldn't cause idle problems unless its plugged up. Changing the 02 sensor sounds like a good place to start as well.

 

[936DSMboy]

yeah im ###### gon start with the o2 sensor, ima take it to my mechanic so that he can check it throughly tomorrow he said that the o2 sensor in the back shouldnt cause the car to want to turn off and sound like a cammed car. I'll keep yall posted

 

[92awddsm]

Clogged cat usually doesn't effect idle. It will keep it from revving. Rear o2 will only cause a cel, not compromise idle or overall performance. I would look for a vac leak first if it were my car

 

[936DSMboy]

yes sir thats what my mechanic said that it was probably a vacumm leak.....well so far he is having a hard time finding a leak. Ive had the car in the shop for a week now, I miss driving my bish

 

[936DSMboy]

So I talked to my mechanic once again and he said that it appears that my car could has a messed up valve. he said that he already checked for vacumm leaks and found none. Does anyone know how much the price would be to replace all the valves and springs ? Once again my dsm proves to me that its a gold digger

 

[96 420a-t]

Your mechanic should tell you.

 

[Fotowntalon]

Clogged cat usually doesn't effect idle. It will keep it from revving. Rear o2 will only cause a cel, not compromise idle or overall performance. I would look for a vac leak first if it were my car

I've only had experience with my clogged cat, and it idled like dog poop (and thats being nice) as well as having horrible acceleration and overall acting like it wanted to keel over.

As for Valves, thats not going to be what kills you in price, it will be the labor.

 

[4UH8ERS]

Keep in mind a low idle vacuum leak is going to be post Manifold absolute pressure sensor. A vaccum leak at the TB or one of the vacuum lines on the back of the manifold will increase idle because the MAP recognizes it.

If you car sounds like a drag car with a low loping Idle and runs fine upon acceleration and cruising then I would almost bet your EGR valve is stuck open causing the intake to be filled with exhaust gas at idle. 2 ways you can verify that are.

1. trace EGR valve gasket on coke can and make a home made block off plate.

2. Do a smoke test, take a long drag off a cigar and blow smoke in the intake from a vacuum hose on the plenum. Make sure to seal the TB intake side though with a latex glove or baloon or something. This will prove if you have an intake leak also.

 

[936DSMboy]

So it turns out that my mechanic said that my car could have low compression in the pistons....so that could explain why it has trouble at idle. I'll let yall know what happens, he is suppose to take the engine appart soon and really tell me what is wrong.

 

[21_Eclipse]

I personally had this problem mine is still going on a little bit actually. a good place to start would be minor check ups before you spend any real money, did you see if your spark plugs are gapped right and check your cam shaft sensor i know my cam shaft sensor is loose and it tends to come out when the car shakes a little bit again just a couple of things to look out for.

 

[Fotowntalon]

So it turns out that my mechanic said that my car could have low compression in the pistons....so that could explain why it has trouble at idle. I'll let yall know what happens, he is suppose to take the engine appart soon and really tell me what is wrong.

He has to take the engine apart to check the compression, maybe you are explaining it weird, but i am not liking your mechanic.