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-   -   CEL, limp mode, and mileage (https://www.focusfanatics.com/forum/focus-svt/807329-cel-limp-mode-mileage.html)

adrianvr6 10-11-2018 08:17 PM

CEL, limp mode, and mileage
 
Heyo. Brand new here. Nice cars, everybody.

Question #1: will *any* CEL engage a limp mode and/or gas mileage decrease, or just certain ones?

Question #2: is my P0135 (front O2) CEL decreasing my mileage?

Byron King 10-11-2018 10:23 PM

These cars do not have a limp mode... why do you ask?

Yes and can cause some odd behaviors, experienced that first hand.

adrianvr6 10-11-2018 11:10 PM

Quote:

Originally Posted by Byron King (Post 11338607)
These cars do not have a limp mode... why do you ask?.

Somewhere along the line of my forum bingeing lately I must have come upon this misinformation and latched onto it.

Interesting to hear your experience with weird behavior and O2 sensor issues. Replacing it Monday. Is replacement usually the fix? Or could the sensor be functioning correctly and it's indicating an engine rich/lean mix?

Byron King 10-12-2018 12:20 PM

Could be either, but with the age on our cars it can't hurt to start there. If it's ever been replaced and it isn't a Ford brand O2 it's probably bad. What are your fuel trims doing while driving?

I asked why you thought these cars had limp mode, I figured your car was running bad.

adrianvr6 10-12-2018 03:48 PM

It seems to be running quite well besides a total gutlessness below 2k rpm... seems like that's more of an SVTF thing than anything else. (Maybe not?)
And definitely eating gas like a mofo... hopefully that will get better. (Maybe not?)

Unsure about the actual rich/lean mix. I'll take out the BlueDriver and see if I can find fuel trim on my drive this evening.

Byron King 10-12-2018 10:00 PM

Very normal, my car starts getting a lot of torque around 1900 rpm. Difficult to take off when ac is on, if I'm on a hill I shut it off.

Been measuring for a couple months now, averaging 28 mpg, what are you getting?

adrianvr6 10-14-2018 09:19 PM

OK so check it out. I have very little idea how to interpret this data...

Took some fuel trim data from a 6-minute drive to Canadian Tire a few days ago. (Obligatory "Eh" [wiggle] ).
City driving. There were 2 lights, some slow bits, some hard acceleration, never got going more than 50km/h. Total of ~780 data points.

https://i.imgur.com/dJHAnrY.png

The average values are:
O2 Bank 1 Sensor 1 Short Term Fuel Trim = 1.6
O2 Bank 1 Senor 2 Short Term Fuel Trim= stuck at 99.2 the whole time (maybe this is the one triggering my CEL?)
Short Term Fuel Trim Bank 1 = -1.1
Long Term Fuel Trim Bank 1 = -2.0

A quick read of this article helped me learn that a negative value is running rich / positive is lean, but I don't know whether the values I recorded are significant or not.

Any insight from the data?

felixthecat 10-14-2018 10:37 PM

I'd replace the o2 sensor......btw when was the t/b replaced?

adrianvr6 10-14-2018 10:47 PM

Yup, am replacing the front O2 sensor ASAP. I have the special tool now, just need to order the part tomorrow b/c I guarantee my local Ford place won't have it (but hey you never know)... and borrow a jack and some stands... so probably next week it'll be done.

It's an unknown on the timing belt unfortunately. I'll have to pay a mechanic for that job. Ugh. Interference engine makes it a bit of a timebomb eh? Well it's at 170km (About 105K miles?) so not too overdue...


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