This is topic Question on 02 sensors. in forum Tech Talk at Northern California Ford Owners  .


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Posted by CobramanPhil (Member # 2170) on :
 
Question....what would the symptoms be of decaying 02 sensors? I just datalogged my car (with a tweecer...thanks Andrew!) and I am getting very lean readings for low speed or part throttle (anything below 2500rpm or so). The car bucks and burps at low speed throttle. It actually seems to "load" and then finally when it reaches close to 2500rpm it seems to just take off.

To be honest I think I noticed a similiar situation (seems to load up) a while back, but it would only do it when the car was cold and not warmed up fully...again..it only did it on occasion and it was very slight.

Could the 02 sensor be at fault...sort of a gradual thing and then finally starting crapping out????

What do you guys think???
 
Posted by Black94 5.0 (Member # 655) on :
 
Do you have access to a voltmeter?

See how much the O2's are actually "switching"...Find the signal wire and you should watch your voltage change every couple of seconds or LESS...I forget the exact allowed time for a properly fuctional O2 to "switch", but I'm sure you can find out that info on the web...The longer it takes for the O2 to switch the worse the O2 is performing...

Obviously make sure there is no carbon build up on the O2 itself...

How many miles are on your currant O2's?
 
Posted by 9lbpony (Member # 3510) on :
 
*cough*120,000 miles*cough*

It was actually odd to see - the car would read next to no voltage on the O2s and the car would stay in open loop. Once the RPM/load increased a little, the car would go closed loop, hit a decent A/F (based on the commanded) and the O2s would look fine. Under this condition, the car was quite peppy.

I'm still bothered by the 10" of vacuum at idle. On startup the car is in open loop and thus the O2 sensors are ignored. I guess the smog pump could make it that lean but the low vacuum is excessive for that cam I think.
 
Posted by The Nick (Member # 2244) on :
 
quote:
Originally posted by CobramanPhil:
The car bucks and burps at low speed throttle. It actually seems to "load" and then finally when it reaches close to 2500rpm it seems to just take off.
That is similar to the problems my car is having. Especially the bucking under 2500 at part throttle. I wonder if my 02 sensor is bad...
 
Posted by CobramanPhil (Member # 2170) on :
 
quote:
*cough*120,000 miles*cough*
Hahah...lol. Andrew hit that on the spot. I still have the original sensors on my car:eek:. Well they look kind of clean (must of been when the extra coolant came out a while back when I blew a headgasket and it cleaned them off pretty well [Big Grin]

Regardless...I am changing them (just ordered new ones). I actually also just received the steeda #19 camshaft today. After looking at 9lbpony's tweecer rt and how powerful the software is I assuming that I will not have any problems running the tfs cam with my car. Anyone want to buy a brand spanking new steeda #19 cam??? They go for $200 and I will sell for $175 (and I will deliver it to you if your local [Big Grin]

Here is a thought..perhaps I simply have a dirty mass air meter (it is the stock one and I never cleaned it).

[ May 21, 2004, 11:41 AM: Message edited by: CobramanPhil ]
 
Posted by CobramanPhil (Member # 2170) on :
 
ttt
 
Posted by street_illegal_stang (Member # 1554) on :
 
I'm still bothered by the 10" of vacuum at idle. On startup the car is in open loop and thus the O2 sensors are ignored. I guess the smog pump could make it that lean but the low vacuum is excessive for that cam I think. [/QB][/QUOTE]

that low of vacuum could be making you map sensor
act up...i had that prob w/the hesitation under load.in my case it was the map.
also this is a long shot but the sump in your gas
tank could have broke off its tack weld so your not getting proper fuel pick up..long shot.
 
Posted by 9lbpony (Member # 3510) on :
 
very interesting that you point this out - I had been a little surprised by the low timing advance at idle and that could be a result of it thinking the load was "off" based on bad info from the MAP. Good call.
 
Posted by badazz (Member # 1773) on :
 
go purchase some bosch 02 sensors, way better imo
 
Posted by CobramanPhil (Member # 2170) on :
 
Okay...I should be getting those new 02's by today or tomorrow (hopefully usps doesn't screw up the delivery and tries to deliver them to my old house.

Explain this MAP thing to me (or is it a BAP for a 94-95 car?). If the new O2s don't make a difference after I swap them out I need to go in a different direction in fixing this thing... [Big Grin]

[ May 24, 2004, 11:32 AM: Message edited by: CobramanPhil ]
 
Posted by CobramanPhil (Member # 2170) on :
 
Well I replaced my 02 sensors and guess what...the same dang behavior (bucking at anything lower than 2500rpm). I am going to disoconnect my battery when I get home today and leave it off for good 30 minutes (tapping brakes too). I actually had one of the 02 sensors disconnected (I was under a time restraint so I had little time so I disconnected the battery for 5 minutes and tapped the brakes after I installed the o2s but I forgot to connect both!..the car seemed to run better though? [Smile] As soon as I had both 02 sensor connected..drove it through the neighborhood and uggggly..same problem (low rpm cruddy behavior..bucking so bad I almost flew out of my seat!).

Any other ideas guys? Tweecer should be here at the beginning of next week, but I am not even sure if that will allow me to solve my problems with my car [Frown]
 
Posted by 9lbpony (Member # 3510) on :
 
which fuel pumps do you have and it might be interesting to bump up your base fuel pressure a little. It still feels like it's running lean at low load for some mechanical reason. I could see a tired fuel pump not pushing full pressure at low voltage.

Worse come to worst we can test "parts" (like MAP and such) by pulling them off my car and testing them out on yours.

My new headers are on and my noises appear to be gone. Also I need to pull your temp tune off my notebook and send it to you before your TwEECer arrives.
 
Posted by CobramanPhil (Member # 2170) on :
 
Thanks Andrew. I have a newly installed high pressure 255lph walbro (intank), a vortech t-rex, a fmu, a kenne bell regulator (also new), and the stock 24lb injectors...cool. When you have some free time (I should have my tweecer by the end of next week..if not earlier) we can swap parts to see what happens...let me know your availability...I sort of have to go through "approval" first if you know what I mean [Roll Eyes]
 




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