Need some help here!

[davidb]

I need some advise from you all about my 95 MTX. Please let me know what you think before I throw hard earned money away. Last month I had my timming belt replaced. My car has lacking power and ran rough because the belt was missing about 8 inches of teeth. The car ran strong after I got it back. If fact, it never ran so good! Anyway, over the next few weeks my car slowly went back to running just as bad as it did before the new belt. My mechanic told me the Y-pipe broke up close to the back of the motor and thats was the cause of the new rattel and buzzing I was hearing. I agree. However, The car stumbles when I press on the gas. Seems to run OK at a constant speed without pressing much on the gas peddel. My tack moves up and down sometimes when at a red light and sometimes it idols at 1000 rpms and sometimes at 1500 rpms. Gas mileage has gotten really bad. The car just runs like crap. My mechanic says that all this is caused by the broken y-pipe. He told me that the Oxygen sensor can not read and send the correct signals to the computer and that is what is causing my problems.

Could this be the case? I dont have a check engine light (yet). The car is just runnnig real crazy. I would appreciate any feedback you all can give me.

thanks

Dave

 

[Redskull]

All signs point to YES; the O2 sensors only do there thing at closed loop, when you're cruising, or stopped (i think). If all the problems go away when you jump on the gas, it's certainly something that needs to be fixed anyway. As for throwing your money away, you can probably fix the y pipe yourself for under $5 in one afternoon. Maybe.

ac

PS - I'd probably fix it quicker than later, or just unplug that 02 sensor; all that extra air in your exhaust is making the car run extra rich, which can lead to other problems, like messed up cats and such

 

[dpsutphin]

A bad (or misreading) O2 sensor can cause exactly what you are describing. And obviously, if you have that kind of exhaust leak, the car cannot run properly. And if you live anywhere there is emmisions testing, you will have to fix the exhaust anyway to pass emmisions testing.

I would fix the exhaust first, then go from there, especially since you eventually have to fix it anyway. Usually a bad O2 sensor will set a code. I just don't know if it does when it is just sending the wrong information to the computer.

 

[thecrew2999]

also its possible the mechanic didnt use the tentioner right and it came loose.

 

[davidb]

also its possible the mechanic didnt use the tentioner right and it came loose.

What do you mean by that? He told me that if the belt walked or lost time I would get a CE light, but I have not. Today the car was idoling at 2000rpm and when I changed gears it did not seem to make a differance in the way the car ran. I guess its got to be the 02 sensor because the car runs like it's drunk.

Dave

 

[sdpatt]

I don't think you understand the meaning of the failed Y-pipe. A rattle in the Y-pipe indicates that at least one of the catalysts has been damaged - either from an impact or overheating. That damaged ceramic matrix doesn't just ratttle around in the converter; it moves to plug the cat exit or down the exhausst system until it gets stuck in a corner or bend. When it plugs the exhaust pipe, the engine cannot exhale and it will not be able to make any power at higher rpms. You need a new cat or cats (most likely just one has failed).

The O2 sensors are upstream of the cats and is not part of this problem. Replace the cat first, then see what problems still exist. You can check the timing belt by removing only the upper timing belt cover. Check the tension between the camshaft sprockets. It should be tight enough to almost make a note as it vibrates when you flick it with your finger. Then rotate the crankshaft by the crank bolt or jack one front tire off the ground, put the shifter in 4th or 5th gear, then rotate the lifted front tire. Check the full length of the belt for teeth or damage.