MY car has developed a stumble...how great. It only occurs atfer driving it for like 10-15 minutes when it is warmed up to about 190 degrees. It will slowly develope too, like the stumble won't be too bad, but then eventually it will turn really bad, then violently making the car jerk forward, then after a while it will die. I have replaced the Battery, PCV and fuel filter, but otherwise it is stock. It only has 25K miles as well. On another note, it has been sitting for 7 months, and did something like this last year, only it wasn't as bad as it is this year. I added some heat to try to take the moisture out of the gas. What are some things I should check? I have new plug wires, but I need to cut them to length and didn't want to cut them till I installed my headers.

 

bump......please.

 

Opti or vaccum leak maybe.

 

Sorry to say buddy but its your opti going. Eventually your car will get worse to the point were it will just die on you. Call Jason Cromer and get a brand GM opti.

 

With only 25K miles? I am always carfull while cleaning under the hood as well. Is there any way of testing my opti? how much does one cost? How hard is it to put in?

 

Do you hear a clacking or loud ticking noise when your about to come to a stop???

If it's a bad stumble and makes the car jerk when accelerating and slowing down it's most likely the opti, and it's not that easy to test.

Not that easy to replace, either, but I would consult a haynes or chilton manual to do it, too many little steps that would be forgotten on the net.

And if you want to know why, it's because you have bridged terminals in the cap & rotor section of your optispark distributor, for some reason gm decided to use a special conductive ink inside of them in order to change the actual output of the spark for each cylinder, to make spark plug wiring simplified. It's not really a matter of time or miles on your car, when they go they go, although cars with higher miles are more at risk. Mine went at about 80k.

 

I just fixed my horrible stumble. Replaced a bunch of stuff... but it ended up being my fairly new O2s were bad. Replaced them and everything went back to being great.

 

How do I test if my O2's are failing. There is no load clacking from the front of my car.

 

does it do it at all rpms, or just idle?

and does it make any kind of whistling noise when it's stumbling?

 

When it warms up it stumbles all the time...at least to 3000 rpm, I havn't had it any higher than that. It runs much better above idle than at idle. It use to make a very faint whistling/squeak like noise that I could never figure out. It stopped, which pleased me at first, till the car stalled at a red light.

 

hmm....because my car has a small stumble at idle. the rpms drop from like 700 rpms to 500 rpms. just every once and a while. when it drops it makes a whistling noise.

if i give it just a little bit of gas, to bring the rpms up to 1200 rpms or so it completly clears up.

i already replaced the IAC, and i'm about to do plugs/wires when i install my headers.

it's hardly noticable at all......i was just wondering if my problem was the same as yours.

 

No,I don't think mine is the same. Still, does anyone know how to test the o2's? I heard if you unplug tha MAF it sends it into a closed loop and doesn't use the o2's. Is this true? Whats are some other small things I can check before I dump my money into an opti.

 

this was happening to me. turned out to be bad 02's. unplug em and see how the car runs. if the SES light comes on and the car is running fine then you know what your problem is.

 

Just detach them from the exhaust manifolds?

 

I bet you its an intake manifold leak or a vacuum leak.

Check all your vacuum lines.

You need to get it scanned while its stumbling to see if its running lean etc.