O2 sensor question

[shane74]

Can a faulty O2 sensor make a rig run crappy?? Rough idle, running too rich, that kind of thing?

 

[1979jimmy350]

yes it can. If your o2 is bad you run on a preprogramed fuel curve which is programed rich so you do not lean the engine out to much.

 

[shane74]

Well, that is about the last thing I haven't changed. It just threw a O2 sensor code this last time after I replaced some other parts. I'll pick one up and replace it. It runs like crap at idle (it wants to die) and can't hardly pull itself up a hill (knocks like crazy). It started a few weeks ago. I parked it and started driving the K5 till I could figure out whats wrong with it. It started all the sudden, like a bad vaccum leak. It only does it at idle. Once above 1500 rpm, it smooths out and runs fine w/ exception to the serious lack of power up hills. Starting to really irritate me. So far I have replaced the;

cap
rotor
plugs
wires
electronic spark control sensor
throttle position sensor (yes, I set it to the correct voltage)


Oh yeah, I should mention that it's and '87 burb with a TBI 5.7/700-R4.

Anybody have any ideas for me?

 

[1979jimmy350]

when you replace the o2 sensor you might want to think about upgrading to a heated o2 sensor because they work alot better than the one wire ones

 

[shane74]

Good idea. It's all about the upgrades anyway, right?!

 

[blazerguy 90]

Replace the fuel filter.

 

[BurbinOR]

Shane,

Does that rig have a knock sensor? My TPI motor did, and it sounds like (from your description) it isn't working. I've got a scanner you can borrow for as long as you need it to check out some stuff. You can pick it up at my work if you want - I can bring it to work. PM sent to ya.

By the way, if you need ideas on the three wire O2 sensor, let me know. Not a huge improvement in our area (doesn't get cold enough but any little bit helps, eh?).

Frank

 

[shane74]

Replace the fuel filter.

Did that when I replaced all the above parts. I knew I was forgetting something.

 

[shane74]

Shane,

Does that rig have a knock sensor? My TPI motor did, and it sounds like (from your description) it isn't working. I've got a scanner you can borrow for as long as you need it to check out some stuff. You can pick it up at my work if you want - I can bring it to work. PM sent to ya.

By the way, if you need ideas on the three wire O2 sensor, let me know. Not a huge improvement in our area (doesn't get cold enough but any little bit helps, eh?).

Frank

Is that what they refer to as a "Detonation Sensor"? If so, yes, I believe I do.

 

[ntaj*ep]

Put a vacume gauge on the intake, at idle what is the reading?
Also what is your MAP sensor reading at idle?

 

[shane74]

Put a vacume gauge on the intake, at idle what is the reading?
Also what is your MAP sensor reading at idle?

I don't have one. Also, not sure where to hook it up to??

I pulled the MAP sensor and had it tested. It tested out fine, so I didn't replace it. What do I need to look for?

I do know at idle, the vaccum is low until it hits approx 1500 RPM.

 

[ntaj*ep]

I would put the gauge on the map sensor line (tee d into it) or at the vacume booster for the brakes. I would recommend you buy a gauge. Getting a good vacume reading will tell alot about engine issues. Leaks, valve issues, timing, ect. It will aid your correct diagnosis of the issue without needlessly spending more money.....

**edit**

Not so worried about the MAP itself but what the voltage is at idle. In other words if it is reading correctly or not.

 

[dyeager535]

One of the few TBI codes I linked to is for the O2 sensor:
O2 open circuit (code 13) Sounds like you got rid of that problem though?

Scanner is going to help you out, sorry I don't have links to more of the "no code" troubleshooting stuff out of the manual.

 

[ntaj*ep]

How 'bout fuel pressure readings?

 

[shane74]

Those are good.

Frank (BurbinOR) loaned me his Auto X-ray scanner today. I hope to get it figured out before the end of the weekend.