Solved o2 sensor question

[xplorernewb]

Getting ready to replace my o2 sensors. Both sensors are toast by the looks of it. One appears to have a dent in the side of it. Im certain thats why my car is running like crap right now, but i didn't have these symptoms last time i had o2's replaced on other vehicles. Is this typical of bad o2 sensors on the obd1? Its not sending any codes, rough idle about normal speed but hangs for too long until i stop completely. Tps and vacuum lines are new, plugs new. Where should i begin after the sensors are replaced if that doesn't help?

 

[Number4]

The O2's won't necessarily cause the car to run bad, unless they reduce gas which will cause your car to want to die potentially. If they add gas, you'll usually just end up with crappy mileage and eventually a bad cat. Now, if the cat goes bad, the car may run bad or even die (if it's clogged.)

In most cases the O2's aren't bad. But, if you can get them cheap enough, why not replace them? Up to you.

You can Google plenty of videos on how to test them. 9 times out of 10, they won't be your issue.

 

[xplorernewb]

Well crap.. I unplugged maf, no change
Unplugged iac, idle dropped a tad and sounded much better
Unplugged tps, idle went up
No vacuum leaks
Pcv was a little oily but functioned properly
I have no ac, all lines have been replaced, tps was replaced. Plugs are new.

This is what it does - idles within spec, but as soon as i start driving, the rpms will hang until i change gears or stop. It will stay at 1800rpm until i come to a complete stop usually. Sometimes its fine, but will idle harder then usual. Also i noticed i can raise the idle if i pump the brake pedal. It doesn't get stiff unless the car is off and i pump it once or twice or sometimes it will be solid first thing in the morning. And sucks up the gas like crazy. This things driving me nuts

 

[xplorernewb]

I also unplugged both vacuums at the air box and no change, checked the hoses and all is good. Could there be a leak in the air box?? Hmm

 

[decipha]

sounds like the brake booster is leaking causing a vac leak and/or is complicated by a weak iac valve

 

[xplorernewb]

Replaced iac, no change other than higher idle so i unplugged it and it idles around 1100, replaced booster no change.

 

[2stroke]

If it idles at 1100 rpm with no IAC, 9/10 you have a vacuum leak. If you have messed with the throttle body, you may be out of adjustment. Maybe OBD I is different, but bad O2 sensors can certainly cause poor running. Any easy test is to check the exhaust. A strange pungent smell often is a sign of running lean. The same can be said for running rich, but your pipe will be coated in black if not leaking goo. Also the color of the spark plugs will tell you if you are rich or lean.

 

[FR-425]

Sticking throttle linkage/TB?

 

[Rhett]

Is this a manual transmission truck?

I also would investigate the throttle body, the adjustment screw can work wonders.

 

[xplorernewb]

Yup manual 5 speed. Ill try lowering the idle screw. ive never messed with it. I replaced the tps a while back, could i have installed it wrong? Maybe the knob thing the sensor spins is stuck in the open position? Would that throw off the computer or something to make it think the throttle is pulled open thus asking for more air, but wont give it until i plug in the iac?? Gahhh irritating

 

[2stroke]

Start by cleaning the throttle body good inside and out. The TPS is "non adjustable", but plenty of us have adjusted it anyway. Start with the IAC unplugged. Adjust the throttle body until it idles at 500-550. Then verify the TPS has 0.8-0.98 volts.

 

[xplorernewb]

Should i allow the engine to get warm before adjusting the idle screw? Voltage at tps is .841 with it disconnected from the tb and .845 with it connected. I plugged it back in and it started idling low, just enough to keep it running, low enough for the battery to stop charging at its max. Shut it off and restarted, same thing. Took it for a drive and it was idling at 1000 again within 5mins, with iac unplugged.

 

[xplorernewb]

Im used to dealing with holley carbs, just got out of that but now im wishing i hadn't. Do not like this tb

 

[xplorernewb]

Ok cleaned tb, adjusted idle screw, got it down to 500 with iac unplugged. About 800 plugged in but hangs at 2k or so when i let off the pedal. Tps reads .831. The thing is, the idle screw is now backed out so its not touching.. not sure what to do now.

 

[Maniak]

How long is the hang at 2k? I know when I had a bad throttle body that it would hang most times and it was more of a stuck.. I could snap the throttle open/closed and the idle would come back down... Sometimes it would hang for a few minutes and then eventually come back down...

In my case the throttle body was worn so the shaft had moved some and the throttle plate was dragging/sticking on the side of the TB.

~Mark

 

[xplorernewb]

Ok so its now at .844, and 5.034

 

[xplorernewb]

With the tps completely removed .835 and 5.034

 

[xplorernewb]

Idle hangs about 8 seconds when first started, about 6 between revs. Blipping the throttle doesn't change it

 

[xplorernewb]

I just removed the tps from the tb (iac plugged in) but left it plugged in and it idles great and no hanging idle. With the tps removed, i just grabbed the deal the tps goes onto and twisted it. Does that mean the tps is bad?

 

[xplorernewb]

So... with the tps plugged into the harness, but removed from the throttle body its fine. As soon as i install it even with it running, it immediately starts acting up. But if i uninstall it again and put my finger into the sensor and turn it, i can make it die, run the way its supposed to, or imitate the issue. And even if i move it slightly out of its spot, it will act up. But if i move it back slightly it'll be fine. All of this is happening with the iac plugged in. Cant find the old tps or id plug it back in. Might just go pick up a new one