hey guys, I daily drive a 2001 chevy cavalier z24 with a 5 speed transmission out of no where today my cavalier started lunging while driving. randomly it will start lunging and bucking while driving down the road with just my foot on the gas. It feels exactly like someone learning stick for the first time and bucking the car on take offs but this is doing it just rolling down the road. the car has a new fuel pump with 10,000 miles on it, brand new spark plugs, air filter, fuel filter, idle air control, and spark corks/wireset. It is stalling at stop signs and lights as well and the exhaust is crackling when I start to slow down or take my foot off the gas. the fuel pressure while idling is at 53psi, when i rev it in neutral the exhaust doesn't look rich. It idles smooth but occassionally if I rev it in neutral it will stall. currently watching the fuel pressure with the motor off to see if the injectors are leaking. Im thinking its an o2 sensor since the only time the check engine light came on was for the o2 sensor months ago but it turned off and hasn't came on since. any ideas?

I posted this in a cavalier forum but not many people go on so it can be a while before anyone sees it.

 

Sorry for not understanding what you mean in lunging/bucking. Do you mean that when you press the accelerator pedal the car starts jumping? I had the same issue with my 2005 Mustang and my friend (mechanic) said it had to do something with the injection of fuel into the cylinder. Now i cant give you any heads-up on it, because i never fixed my issue with my Stang (i sold it). If your car is jumping while pressing on the pedal it has to be something with the injection system. Either check the air intake or fuel injection modules. Take the car to a diagnostics and maintenance check-up and ask them. It should cost you around 30-50 bucks to do it. It's worth your time and nerves.

I am not a specialized mechanic, but those are my 2 cents.

 

Hey thanks for the reply. To clarify, when I'm just driving down the road the car will bog and have a very very hard time accelerating. I believe it's misfiring but I'm not getting any codes. I don't believe it's fuel related since I tested the bleed down rate of my injectors and they held 50psi for a long long time after I shut the engine off. I also here them pulsing and my fuel pressure regulator isn't leaking gas through the vacuum line. I'm bringing my ignition control module and coil packs to Autozone to get tested today. These cars have a shoddy ignition system design, I'm hoping it's the cause of this. Thanks again

 

It definitely sounds like it is something ignition related. I also have a Cavi as a daily driver, but mine is the 2200 which is a pretty rock solid little motor. It sounds like you may have a crank sensor going bad; that is what controls the timing. Or something in that circuit. But as Dr34m said, if you are not comfortable digging around under the hood, or it's just too darn cold, get it to a mechanic.

I went to that "other" forum you posted on and added a reply. Check it out, it may just be the fix to your problem.

 

Thanks for the help but I got it fixed, pulled the ignition coils out and the housing they sit in was cracked causing the coils to short and not go to the plugs. I don't have a problem with the work but the New England winters are cold. Thanks again

 

LOL Before I read your last post I was gonna tell you to check the coil pack. My 98 Camaro did exactly the same thing after a tranny rebuild. I ran it back and forth between the tranny shop, a dealership, and my own garage trying to figure it out. What happened was, when the tranny was rebuilt, the new converter started locking up like its supposed to. Unknown to me, my old one was so screwed up, it would not go into lockup mode. Anyway, when the motor was confronted with a TC that was working right, a flaw in the ignition system was exposed, causing a horrible, bucking misfire that did not throw a code. It felt like the entire car was coming to pieces, it was awful. One of the coils in the coil pack was weak, and when the TC put a full load on it going up a hill or on heavy accel, it would misfire and kick like a mule if it was at operating temp--would not do it when cold. Seemed horribly serious,but was actually a very easy and cheap fix. Only took a few minutes to replace that coil. LOL

 

Wow nice job on figuring that one out lol, I would of been in tears wondering why my rebuilt trans was causing such a problem.

 

The ECM said cylinder number 4 had misfired something like 6000 times, almost all the misfires were from cylinder 4. When I saw that, I started putting it together. Before that the tranny shop had it back in, couldn't find anything wrong with it and said it was the engine. I took it to a dealership (idiots) for a test, and they said they couldn't find anything wrong with the engine. Then I took it back to the tranny shop again, and they went through it AGAIN and found nothing. I had just put in new plugs and wires, so the next logical thing was the coil pack. LOL It was just my own ignorance at the time. I didn't know a car could misfire that dramatically and yet still not throw a code when I had had many misfire codes before when the cowl leaked water into the coil pack and I never felt a thing! Plus the fact that it only did it when hot told me it was something electrical. Only three electrical things in that ignition, and two of them were new. LOL