Rough idling or something of the sort?

[INF3RN0666]

Hi

My 2000 impala 3.8L has 190000 miles on it and it has some issues, but some more serious than others. The car literally SHAKES when it's idling or in park, and it gets worse when it gets warm/hot. I'm thinking it's the EGR valve. The thing is, 3 months ago, the mechanic advised me to disconnect it and I did (i know it's a bad idea). The car ran fine. Now, this shaking is scaring me. He says he thinks the engine is failing but there's no noise coming from it and the car doens't overheat or create smoke. But the smell of gas is apparent when you idle it. Any ideas?

[Steel]

Smell of gas from the tailpipe means its misfiring for whatever reason. Smell of gas from under the hood means that its leaking somewhere and the injectors probably arent getting enough fuel pressure to keep it idling properly. But if its leaking gas, that's bad. You're risking an engine fire which would basically total the car if you don't get it fixed.

[INF3RN0666]

Thx for your help
Likelyhood of the misfiring being electrical is high, right? You doubt that the engine is failing or anything like that? The thing is, the mechanic only mentioned codes for the EGR and the ABS system. The mechanic says that the crank shaft is busted or the piston arms (the things attaching the piston to the crank shaft, i dunno their name). The last car ran till 500000km and the engine was fine. I doubt this engine is failing at 300000.

[UncleBob]

there are many things that can cause a misfire. Namely, fuel, spark and compression....or all of the above. Sensor failures can skew things to cause it too.

BTW, running it like that for extended time is a good way to fry the cat

[GreyGoose006]

if the rods were broken, the engine would probably turn over once, then sieze in place, never to run again (untill you rebuilt it at least)

i might be wrong, but i think that the engine is mounted transversly in the impala, because it is front wheel drive.
if you had a misfire, the vibrations would be front to back, not side to side, and would be a lot harder to detect, unless maybe two adjacent cylinders, one on each bank was not firing.

i really cant remember how this engine is mounted tho, so maybe i'm wrong.
if it is mounted normally, then it is probably just a misfire.

[INF3RN0666]

Yes, it is transverse because the pullies are parallel to the tires. but u gotta keep in mind that it only shakes when it's idling. it is a front to back vibration. However, why would it just misfire at low rpm, and not high RPM. or is it just harder to detect at high RPM?

[UncleBob]

Not all misfires are hard misfires (IE, happen at all RPM's). Like I said, can be caused by a multitude of reasons. I could give you a generic list of $1000+ things you could try replacing, but it would be a lot cheaper to just get it diagnosed at a shop IMO.

[GreyGoose006]

well it could just be that it is harder to detect at higher rpm's
although, i'm going with the "its not a hard misfire" theory.

you should take it to a shop, or buy a scan tool to read what the computer is trying to tell you.

[1mmueller]

Originally Posted by INF3RN0666

Hi

My 2000 impala 3.8L has 190000 miles on it and it has some issues, but some more serious than others. The car literally SHAKES when it's idling or in park, and it gets worse when it gets warm/hot. I'm thinking it's the EGR valve. The thing is, 3 months ago, the mechanic advised me to disconnect it and I did (i know it's a bad idea). The car ran fine. Now, this shaking is scaring me. He says he thinks the engine is failing but there's no noise coming from it and the car doens't overheat or create smoke. But the smell of gas is apparent when you idle it. Any ideas?

First of all get a new mechanic. Disconnecting an Emmisions device like the EGR valve is a not so good thing. If it is malfunctioning Replace it. An Egr Valve actually makes your vehicle more efficient at cruise speeds. I agree with the others also that say you need to find the cause of your misfire. A simple tune up may just be in order. Also check the fuel pressure regulator hose for fuel from a leaking regulator. That engine can also leak coolant from the Intake Plenum near the EGR pipe area. You could also try using a good diagnostic scanner like this one
www.OBD2scanners.com