O2 sensor and other problems

[Houndawg]

First post here. We're having problems with my wife's 96 ES. It starts hard most of the time. Once it's finally started the idle is goofy. It'll idle smooth for a few seconds, then miss a couple times. idle smoothe again then miss. I'm not sure it truly a miss, but it'll idle at around 800, then the needle will drop. You can feel the engine buck. If you don't let the car warm up for a while it'll stall when you put it in gear and hit the gas. I can usually get it going by goosing it to get the idle steady before I put it in gear, and then feathering the gas when starting to move. I've changed the plugs, wires, cap, and rotor. I also changed the fuel filter. The problem seems to be worse when the A/C is on. The CEL came on a while back and brought up a O2 code. I haven't changed the O2 sensor yet, but it doesn't seem like it would be causing this sort of problem. The mechanic I use sometimes took off the EGR and cleaned the carbon out of it, and he also cleaned the throttle plate. This really didn't change anything. I checked that the IAC was operational by listening for the motor when the key was turned to Run. It's operational but I have no way of knowing if it's operating properly. Another thing I've noticed is when driving down the highway, when the A/C compressor kicks in, sometimes the headlights will dim for a few seconds and then brighten back up. Before I spend a thousand bucks replacing every sensor and module under the hood, can you guys give me some ideas? Codes are usually misleading, and I don't have a scanner to troubleshoot with.

[Houndawg]

14 reads and nobody has any ideas?

[ThePauser]

I'm not sure on these cars, but with my 88 Starion the TPS needs to be at a certain voltage. With the Starion the TPS needs to be at .5 volts with the ignition turned to the ACC position. The TPS can also have "dead spots" in it while you push down the gas pedal. Hook up a volt meter to the TPS and check to see if the transition is smooth all the way to WOT(wide open throttle). With my Starion, the baseline voltage is supposed to be .5volts, and it should go all the way up to 5 volts smoothly.

Again, i'm not sure on the specific voltage range for the Galant's TPS, but i'm sure someone knows. And if not, i'll find out.

Good luck.


John

[Moosh]

The Galant TPS is rising rate as well, don't know what could be causing your problem.

[GalantSpeed]

os2 sensors can mess up your idle completely, having faulty o2's can cause shrugs in the idle and in take off as well as hesitation, cause bad gas consumption, i'd replace them if i were you. whats the mileage on the g? also check ur starter if your having slow starts.

[Houndawg]

Would I need to change both O2's or just the front?

[GalantSpeed]

i'd change both, although if i'm not mistaken you can just change the front one, the back is like a back up so if the front gets a bad reading then the back one will pick it up and read to make sure it was a correct reading. i just looked at advanced auto parts and they have o2 sensors from BOSCH for like $50 and some change each...

[JiP]

i'd change both, although if i'm not mistaken you can just change the front one, the back is like a back up so if the front gets a bad reading then the back one will pick it up and read to make sure it was a correct reading. i just looked at advanced auto parts and they have o2 sensors from BOSCH for like $50 and some change each...


Bla screw the back one. Its enough of a pain in the ass to change the front one..unless your gona have a mechanic do it.

The o2 sensor going bad could cause major problems defintly at idle since its one of the main sensors used in closed loop to give feed back about whats goin on fuel wise.

As far as the iac, I drove a good 4 months with the IAC unplugged and it didnt change anything in idle or crusing. Hell I drove with the 2g turbo isc unplugged for months and that 60mm tb didnt even change my idle.

But as always with cars the anoying part is that the cause could be 20 different parts and usualy no one can tell u this particular part is defintly the cause. Those of us with dataloggers and guages all over have a much easier time identifying the problem...

[GalantSpeed]

i stand corrected, thanks for the info JiP https://www.thegalantcenter.org/style_emoticons/default/biggrin.gif

[Houndawg]

Just got done changing the O2 sensor (upstream) and it didn't fix the problem. It took me longer to change the O2 sensor than it did for me to change the front pads and rotors. I had to heat the boss up with a torch just to get it loose. You'd think they would have mounted the sensor sideways so you could get it off without going through the engine compartment with long extensions and a u-joint. That and there was no room between the crossmember and the sensor for my O2 socket to fit, so I had to bend some metal.

I guess I'll have to take it to my local, overpriced Mitsubishi dealer and have it plugged in to find out what's causing my problems. Anybody have any idea what that's going to cost me?

[seth98esT]

my iac motor is dead(pretty sure, installed a good iac and idled great) and i am fine on cold starts but on warm starts i get an idle between 2-2.5k. so it doesnt sound like you iac is bad...