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boomer
Dodge Dakota
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12/13/2006
09:12:25
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 Subject: LAZY o2 SENSOR?
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Whats happinin fellas? I just need a few opinions..The last couple weeks I've noticed that mas gas mileage blows. It dropped from about 300 miles to an 18 gal. tank to about 250 sometimes less! WTF? So I'm thinkin that my crappy boshe o2 sensors suck like Larry from J&J auto said, only I'm finding out first hand. I dont have any power either, I really have to floor it to get it to downshift and even then im not gettin as much as I should. I got the boshes before I knew about the NGK sensors. My check engine light comes on sometimes but will go back off after a couple trips. Its on right now so I'm going to take it to autozone or somethin so they can check the code.
Anybody got another idea what this could be? or am I right on the money? thanks
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daddio
Dodge Dakota
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12/13/2006
09:26:55
|  RE: LAZY o2 SENSOR?
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boomer, if you have an '00 or newer truck you don't have to go to autozone. you can read codes from the odometer by turning the key on/off/on/off/on. codes will display in the odo and Pdone is finished.
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boomer
Dodge Dakota
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12/13/2006
10:07:03
| RE: LAZY o2 SENSOR?
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I should have included some of that info huh?
'98 SLT 2wd automatic clubcab 3.9 V6 with one wheel peel
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boomer
Dodge Dakota
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12/13/2006
17:11:39
| RE: LAZY o2 SENSOR?
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ok, i went to autozone and they checked the code..the dude said it was multiple cylinder misfires..I'm confused because my truck runs smooth with no sign of bad timing or anything. the guy said it could just be moisture in the gas, but i've filled up a couple of times since this cycle started. i think its the o2 sensor, anyone got any ideas?
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GB2000
GenIII
12/14/2006
05:41:51
| RE: LAZY o2 SENSOR?
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Would moisture in the distributor cap cause multiple misfires like that? The symptoms do sound like it could be the O2 sensor...but that code doesn't make sense to me.
...unless the sensor is making it miss and the only thing messing up enough to throw a code is the misfiring?
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HEMIKOTA
Dodge Dakota
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12/14/2006
06:16:22
| RE: LAZY o2 SENSOR?
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If your 02 sensors are new, reguardles of the brand, I would first look into a tune up. When I had a bad 02 sensor it showed a lot of the same symptoms as it did when i had a bad distributor cap. Since the autozone guys told you it was a misfire it is most likely not the o2 sensor. The tune up will also give you a good excuse to upgrade to NGK plugs, performance wires and a brass cap and rotor. The cold weather, depending on where you live, will also make your mileage drop.
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Joe M.
Dodge Dakota
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12/14/2006
07:59:51
|  RE: LAZY o2 SENSOR?
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Change in the weather will also mess with the tire pressure
you keeping a good check on it?
you'd be amazed at how much differance 1 or 2 lbs. would make to your MPG's bro
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Bob Lincoln
Dodge Dakota
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12/14/2006
08:11:30
| RE: LAZY o2 SENSOR?
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"ok, i went to autozone and they checked the code..the dude said it was multiple cylinder misfires"
"i think its the o2 sensor"
No correlation whatsoever. A bad O2 sensor is not going to cause this code.
First of all, calculate your gas mileage correctly and accurately. Top off the tank, drive a tankful and top it again, then divide miles by gallons. Don't judge from the gauge.
Then approach the diagnosis logically. You have a misfire code. Usual suspects are the ignition system (dist cap, rotor, wires, plugs). You might not even notice the condition that tripped this code. My truck ran perfectly, yet the center tower of the dist cap was FULL of white aluminum oxide dust. I changed it out immediately with a cap with brass contacts.
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boomer
Dodge Dakota
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12/14/2006
14:44:54
| RE: LAZY o2 SENSOR?
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GB2000, I completly agree. The next time I do a tune up I'm definetly gettin better wires, NGK plugs, and brass cap and rotor. I do live in michigan so it does get pretty cold. Its been a couple weeks since I've checked my air pressure, that should help a little bit.
Bob, I understand that a bad o2 sensor will not throw a code for a misfire but I've heard the bosh sensors get "LAZY" as larry said before, meaning that it doesn't adjust the air/fuel mix like it should but its not enough to throw a code for some reason. So I'm thinkin that the mix is so out of whack I don't get much power out of it. thanks for the info about the distributor, I'll have to check that out for sure. Thanks guys, much appreciated. I'll update as soon as I find out more.
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Joe M.
Dodge Dakota
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12/15/2006
08:38:24
| RE: LAZY o2 SENSOR?
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i'm following this one
will be watching for the update
and yea i agree with you
the lazy O2 that larry was telling us all about
if it leaned or starting leaning the mix out
you'd start noticing it more when the cold weather set in
he mentioned some way of testing them to see if it was screwing up (cant remember how)can anyone else?
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Bob Lincoln
Dodge Dakota
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12/15/2006
09:14:20
| RE: LAZY o2 SENSOR?
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The complaints about the Bosch sensor are mainly with modified engines, not stock. I have had a Bosch sensor in my car now for 81K miles and 4 1/2 years, and it gets exactly the same gas mileage as when the car was new, and same low emissions as when new. I think you're wasting time and money to go after the O2 sensor.
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Dan M
Dodge Dakota
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12/15/2006
09:16:22
| RE: LAZY o2 SENSOR?
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how many miles are on the truck? when was the last time you did a tuneup?
what was the code? P0300? That is Random/multiple cylinder misfire detected. or was it muliple codes indicating misfires on differnet cylinders? There is a difference there.
if it's P0300 then it could very well be bad o2 sensors. How long have you had the bosche sensors on there?
if it's more than 1 code indicating misfires on differnet cylinders, i'd say it's time for a tuneup. Start there first.
back to P0300 ..
could be plugs/wire/distributor cap/coil
could be bad injectors
could be bad o2 sensor
could be bad cat
could be camshaft postion sensor
does the exhaust smell like rotten eggs? that's a good sign it's bad cat. Also if you check exhaust temp with vehicle fully warm should be about 100 deg difference between exhaust pipe in front of cat and exhaust pipe behind cat.
if your cat is bad, you have other problems still to fix as they don't just go bad. You're probably running rich which takes us back to sensors and tuneup.
Pretty much most of the sensors on the truck send data to the pcm which is used to calculate air/fuel mixture and when to fire the ignition system. Them going bad is a possibility, you need more information to detemnine the correct action to take.
- Dan M
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boomer
Dodge Dakota
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12/15/2006
10:54:54
| RE: LAZY o2 SENSOR?
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well, for one, its not completly stock. i put jba headers on a while ago due to the exhaust manifold bolts breaking off in the head, and of course i replaced all the bolts with new grade 8. plus, as of right now, there is no cat. (i know i'm gonna hear it for this one)
I got about 125k on the truck. I replaced the cap and rotor a while ago. the o2 sensors were replaced about the same time. I have all this info wrote down in my log book. The plugs and wires were just changed about a month ago or so. I got 7mm wires but it sounds like I bought the wrong kind from what everyone else says to use. The plugs are what the manual says to use, champion copper. I WILL be replacing them with the one unit colder NGK plugs.
And as far as the actual code read, I dont know, the dude there just told me what it was. I'm pretty sure it was just a single code tho, i think he would have told me if it was pulling more than one. he "seemed" like he knew what he was talkin about.
I definetly would like to get some new injectors and replace some of the sensors. like I said I'll update when I know more.
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boomer
Dodge Dakota
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12/15/2006
11:25:30
| RE: LAZY o2 SENSOR?
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ok, just got my log book out my truck. I replaced the cap and rotor over a year ago. maybe its time huh? ok heres my list in my log book of some of the stuff I've done.
10/5/05 - distributor cap and rotor, bosh platnium plugs, wires, bosh universal front o2 sensor.
12/29/05 - bosh rear o2 sensor
4/14/06 - bosh regular front o2 sensor replaced because universal sucks.
7/14/06 - installed headers, cat removed
11/14/06 - replaced bosh platnium plugs with champion copper plus 436 RC12LC4.
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Dan M
Dodge Dakota
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12/15/2006
13:26:22
| RE: LAZY o2 SENSOR?
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You should not need to do a tuneup yearly. The interval for a tuneup is what 30k miles? I doubt you've driven 30k miles since you tuned it up. But it could be bad wires. How many times you have removed the plug wires? It's fairly easy to damage the boots. You can test with multi meter but that involved removing the wires.
What about the distributer sensor? ever replaced that?
as far as cylinder misfire goes, engines misfire all the time because the ignition sequence happens so rapidly, mostly it's un noticed since it's so quick. But if you get a DTC on misfire you've got a problem with the ignition system or the air/fuel mixture making it to the combustion chamber is wrong.
only have a year on the o2 sensors should be ok, they may not work 100% but should not be degraded anough to cause problems with cylinder misfires..that is of course based on what the air/fuel mixture and ignition system look like. and the fuel/air mixture coudl have degraded the o2 sensors.
I'd start with the ignition system first, check that out.
- Dan M
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GB2000
GenIII
12/15/2006
18:20:27
| RE: LAZY o2 SENSOR?
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Not gonna rip into you bout the cat being removed...I mean after all, you only use your truck for off-road use right? :P
But I think it could all be related to it...are you running an O2 sim or anything so the post-cat sensor will give off the correct readings? It could be throwing off the readings causing the a/f ratio to go nuts?
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boomer
Dodge Dakota
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12/15/2006
20:36:31
| RE: LAZY o2 SENSOR?
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I know I dont need a tune up yearly, most of the reason why I have replaced things is because they stop working right. a couple times i've taken the boots off the plug wires and it messed them up and they would arc on the heat sheilds that surround the plug. thats when i would replace the wires, pain in the *ss let me tell you. I've never heard of a distributor sensor. makes sense now that ive heard it, maybe that could be a problem. I still want to take my cap off and see if there's anything wrong inside such as moisture or something.
The only reason I want to replace the o2 sensor is cause (as the title says) it could be that bosh o2 sensors are LAZY. I wish larry were around to help with this post. dont get me wrong, you guys are givin me a ton of help, some of this stuff I've never thought of and some never heard of. always good to learn new things.
as far as my cat goes...i just have a normal bosh o2 sensor behind where that cat would normally be. I thought about getting a simulator just so I wouldnt get an engine light, but from what I've heard the rear sensor just tells the computer if the cat is workin. it doesnt adjust anything, except the check engine light :P anyone think I should get a simulator? I've seen google ads for them for 15 bucks on here. they finally come in handy instead of gettin in the way! I know what I should do...just get a high flow cat and call it at that. i told the dude that did my exhaust about the cat giving me more back pressure but he was like back-pressure smap-pressure, that doesnt effect back pressure! maybe hes wrong but whos ever heard of that? ok im done for now, when i have time i'll check everything out. thanks again guys!
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J and J Auto
GenII
12/16/2006
23:13:02
| RE: LAZY o2 SENSOR?
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Message:
The o2 will not cause the code unless its shorted
and have never seen that happen
They will either give to much or not enough gas
What you need to do is pull your plugs and see
what they look like
should all be tan light sandy color if the o2 is
rich they will all be blackish lean all white
but they must be consistant meaning all the same
cyl misfire
coil
wires, shorting cross fireing
plug
cap
rotor very unlikly
injector, this I have seen trip the code many times
dist pickup
crank sensor
these are the pupies to check
map,tps,engine temp will not trip this code
also a bad conection will do this
if your mileage has droped I would replace the
o2 o2's go right to ngk.com there half the
price and the best o2 you can get for the mags
I will say it again I have never seen an o2 trip
cyl misfire
if you have a good performance shop around they
will have an ociliscope every sensor has a wave
pattern that can be seen great for crank and
dist pickup checking a scanner will not see an
intermitant failure or trip a code but it will
still be bad
most times when either of these do this it will
always happen at aprox the same rpm and continue
to do it maybe forever most of the time over time
they will get worse afecting more of the rpm
range and eventualy fail completly and the weird
thing here is when they do what happens is you
shut it off and it will not start
Larry
J&J Auto
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J and J Auto
GenII
12/16/2006
23:23:48
| RE: LAZY o2 SENSOR?
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forgot about the fuel pump
an intermitant pump will not trip the cyl code
but it can cause bucking and backfireing
who ever said this was right also presure has a
big effect on gas mileage
min presure 40 to 45psi on the mags they will run
lower but get crap mileage it effects the
atomization of the fuel
In all the performance aplications we use the
holly replacement that runs at 50psi we get them
from carquest, pump only
on a stock or nearky stock the master replacement
will work fine at what most are 45psi the range
on these ar 42 to 47psi which is good
the master comes with pump,filter regulator and
guage sender all in 1 unit
if your 40 or below you should thing about getting
a new pump
Larry
J&J Auto
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Bob Lincoln
Dodge Dakota
JOIN HERE
12/18/2006
08:52:48
| RE: LAZY o2 SENSOR?
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If you have no catcon and no O2 simulator, the computer sees no difference between the pre-cat sensor and the downstream sensor. This is because the catcon makes the exhaust leaner, and the downstream one should see leaner air. That will trip the O2 sensor code.
You could put an O2 simulator in, or not violate federal law and put the catcon back in so it will run correctly. A high-flow cat will not hurt your performance and will not trip codes.
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J and J Auto
GenII
12/19/2006
22:31:08
| RE: LAZY o2 SENSOR?
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Definitly on the obd2's get a cat on there it
will also alter your air'fuel ratio and it will
never run like it should
I don't know where that ever came from that a cat
will restrict flow and decrease hp its not true
I have 2 customers with motors pulling over 500hp
at the wheels with super chargers and both are
running cats it will not hurt performance unless
its pluged
Larry
J&J Auto
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