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fixit
Dodge Dakota
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7/27/2007
01:24:21
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 Subject: o2 sensors
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i want to replace my o2's. i've got 80,000 on my 2002 3.9 now and did full tune up and still having hesitation problems. all sensors are still factory. I really have little to no money to do this job but want the truck to run right and be able to accelerate when pulling into traffic. NGK site has universal and OEM sensors. of course OEM is the best option but what the dif between the OEM and universal beside having to solder wires to the harness? if that's the only dif then i'm going to buy the uni's, it will help on the wallet.
also, i have 4 o2 sensors. i have 2 on the drivers side and 2 on the passenger side. they are just shortly down the exhaust after the manifold. I'm assuming the two bubbles on each side are cat converters. Is the top sensor that's closest to the hood the pre cat sensor and the bottom sensor closest to the ground the after cat sensor? Then shortly down the exhaust closer to the muffler there is another tube like device with no sensors at all, is this another cat? Even if it's not the o2 sensors it would be good to replace them and rule that out. thanks for the help.
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fixit
Dodge Dakota
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7/27/2007
01:53:02
| RE: o2 sensors
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NGK website-
precat meaning front and closest to hood and aftercat meaning rear closest to ground? is this right?
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Bob Lincoln
Dodge Dakota
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7/27/2007
09:03:16
| RE: o2 sensors
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If saving money and fixing your vehicle is your objective, don't just replace O2 sensors with no diagnostics that indicate them to be a problem. Otherwise, you'll just be pissing money away and having to fix what's really wrong.
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daddio
Dodge Dakota
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7/27/2007
09:39:43
| RE: o2 sensors
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"precat meaning front and closest to hood and aftercat meaning rear closest to ground?"
you are correct. pre= before
i'm with Bob though, why would you want to change them unless they are known to be bad? have you got a MIL with the code implicating the O2's?
first i would try a can of Seafoam in the tank before springing for the injectors. if the injectors are dirty the Seafoam will help.
have you tried reading the codes? turning the key on/off/on/off/on will display codes in the odometer.
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fixit
Dodge Dakota
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7/27/2007
22:56:22
| RE: o2 sensors
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i have not MIL light. i tried reading codes before with the key but didn't get it to work.
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daddio
Dodge Dakota
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7/27/2007
23:09:51
| RE: o2 sensors
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you don't have a MIL, what makes you think the o2's are bad? have you had a sudden drop in mileage?
when you do the key on/off by on i mean on and not start. it should work. if no codes it will say "pdone".
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fixit
Dodge Dakota
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7/27/2007
23:27:28
| RE: o2 sensors
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yup, just tried it again. last time i did it i was turning key all the way off. No codes, it says pdone. I know o2's can be off a little and not show codes. I checked all vacuum lines too and they appear to be good. I don't know what else to do. But your right, to spend the money on o2's and not need them man that would really piss me off. Maybe injectors are dirty. Havent run any cleaner through. i use to do it maybe every 10-12000 miles but read how bad it is for you sensors. i will try the seafoam stuff, heard it can foul some plugs though. I want to get new plugs again even though these only have maybe 4-5000 miles on them. i took them out to put the fr5's in. took the fr5's out cause they were burning white and put the champs back in. maybe i don't have a good seal beings the crush collars for the champs were already pressed. only other thing i can think of would be the fuel pressure or fuel filter. I guess now you can get the fuel filter from mopar now and not the whole pump. before you couldn't do this. does the filter come off the pump? i had to change out a fuel pump in my old S10 truck and had to take the bed off as it proved easier, i don't have a lift.
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fixit
Dodge Dakota
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7/27/2007
23:29:49
| RE: o2 sensors
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forgot to mention, i'm getting average MPG 17-20 and champ plugs burning slight brown
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daddio
Dodge Dakota
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7/27/2007
23:44:37
| RE: o2 sensors
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is this truck a 4x4, RC, CC or QC? if you have a 4x4 or QC your not doing to bad. if your plugs are tannish in color your alright. that's what you want. O2's can get lazy without tripping the MIL but usually you experience a sudden drop in mileage.
as far as the fuel filter, check the pressure at the fuel rail. there is a schrader valve there that you can put a test gage on. it should be @ 49# + or - 5# at idle with a warm engine. if it's low it could be a filter but i doubt that's your problem.
exactly what is the truck doing now?
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fixit
Dodge Dakota
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7/28/2007
00:54:59
| RE: o2 sensors
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2002 3.9 2wd regular cab 5spd
truck runs good on highway at normal cruising speed. if i downshift and get on it like to pass, it will accelerate kind of sluggishly and it feels like it's stumbling and once in while it will feel as if it bucks but nothing extreme. also sometimes when cruising i find it hard to maintain my speed without using cruise control. i'll fall a little under 65mph so then i give a little gas to catch up then i'm over 65, its weird!!
one thing i have been noticing on start ups is that it feels like it don't start smoothly. Doesn't fire up real crisp but kind of choppy. it doesn't miss though, or maybe it's a slight miss that causes what feels like slight jerks when accelerating hard to get in and out of traffic.
i put new cap and rotor on, new wires, new plugs(4000 miles on them now), cleaned my K&N drop in, new pcv valve.
i have 74,000 miles on truck all original sensors. i've done the sensor mods on here backk and forth a few times and currently all back to factory as i thought maybe this was causing the trouble. It was well over 1,000 miles ago that i put all back to OEM so i doubt the computer needs to relearn, should be fine by now. i wonder if moving them around so much would have caused any problems by i have no codes.
couple people have said about the cat converters but i have power but it's just slow power if that makes sense. i have no unusual smells from exhaust. Have noticed exhaust tips are blackened with carbon. I have flowmaster 50 series straight single out after axle. also have stant 190 thermo in because it's supposed to run the closest to optimal temps according to Larry.
i did change my pinion seal about two weeks back and questioned whether i made the pinion nut too tight but it was in torque specs and DAM close to what the torque was when turning pinion before taking apart. I will recheck the torque again as soon as i can get it to my dads garage and jack the rear up.
can you rent test guages for fuel pressure anywhere?
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fixit
Dodge Dakota
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7/28/2007
00:56:33
| RE: o2 sensors
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i've even run water remover in the gas thinking maybe water in the gas.
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daddio
Dodge Dakota
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7/28/2007
11:08:55
| RE: o2 sensors
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have you tried some Seafoam? what i usually do with it is put about 1/2 bollte in the tank and run the other 1/2 thru the TB. this stuff works. it will clean your fuel system.
are the plugs properly gapped? they should be gapped @ .040".
on your rear diff. if i remember right(it's been quite a while) there is a cruch sleeve in there to keep the pinion in alignment with the ring gear. you torque it to the required torque and leave it. if you overtorque it you can't just back off on it because you've already crushed that sleeve too far. so now it will have to be torn down, replace the crush sleeve and re-torque where it should be.
i could be off a little on this but the best thing to do there is get a manual or bring to a shop. it can be costly if the rear burns up.
when i first started DYI'ing i relied on repair manuals when i got stuck. and never attempted anything i hadn't done before without one nearby.
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fixit
Dodge Dakota
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7/28/2007
13:38:53
| RE: o2 sensors
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with the seafoam, is it ok to pour into the throttle body if you have multi port injection? i didn't think you wanted anything down inside the intake manifold.
yes plugs are gapped at .040
i marked everything at the pinion nut including the pinion gear shaft and nut. when i tightened it i tightened it back to all those markings and if anything it is not as tight. the marking on my pinion nut was off by like 1/8-1/4 inch to the looser side and also checked the torque. torque was right in range so i didn't make any tighter. i'm thinking the nut may not be as tight now because the crush washer was compressed therefore not requiring as much tightening and still get the drag on the pinion.
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GB2000
GenIII
7/28/2007
19:28:36
| RE: o2 sensors
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"with the seafoam, is it ok to pour into the throttle body if you have multi port injection? i didn't think you wanted anything down inside the intake manifold."
Yep...it's fine. Pour it slowly and keep the engine running. Then I believe the directions say to shut the engine off and let sit for 5 minutes. That'll allow it to start cleaning everything out. When you start it back up, it'll smoke like hell. After you've burned a lot of it out, give it a few good revs as there's still some in there and it'll start to smoke like hell a lil more. Or just take off and drive it on some back roads.
When my friend did it on his Civic, it sounded like it was gonna hydro-lock...was clattering and everything. Then when he started it up, he could only feather the gas without it trying to stall. It ran much better once he burned it all out...even though the lil bastard told me his car wouldn't start the next morning...haha. When I used it on my truck, it didn't clatter or sound like it was gonna hydro-lock or anything. I had to keep feathering the gas while pouring it down the throttle body but that was it.
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pete
Dodge Dakota
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7/28/2007
21:43:03
|  RE: o2 sensors
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hey fix it ! check TPS sensor out check it with voltmeter look for the voltage change as you move the throttle if volts moves steady with you moving throttle and within range specs look for skip in voltage would indicate bad TPS this can adversely performance and throttle response.You readings should between 0.35-0.90 volts with key on not running. also can check Crankshaft position sensor down by damper look at wiring be sure not loose,frayed or dirty if so clean or repair it. If you choose to test out have socket that fits on it and test lead on lead with voltage 0.0 and 5.0 volts as you turn engine by hand and helps of you have all your plugs out to make engine turn easier or good relible garage be able to do this with good test equipment onhand and check rest of your sensors as well if you do this yourself voltage shouldn't be out of range if so replace sensor, many other things ignition wire leaking cracked sparkplug,dirty injectors ...... Good Luck..
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fixit
Dodge Dakota
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7/29/2007
02:51:13
| RE: o2 sensors
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got some seafoam today but did not check back here before i put it in. i just put it in the gas tank. i'll catch hell if i smoke the joint up in this apartment complex. sounds like it works a little like top engine cleaner. I used GM top engine cleaner once on my old pontiac and HOLY CRAP i didn't think a car could smoke that bad!
Anyways i had to plug a tire tonight and while i was at my dads garage i though i'd mess around and see if i couldn't find something wrong. I didn't physically see anything wrong that would be causing poor performance. i put the FR5's back in again to give them another try. I took the distributor cap off which only has maybe 4 or 5,000 miles on it if that. the tip of the rotor was all coroded and white powder stuff. Also, the contact inside the cap looked white as well as worn. I thought this was odd since i just got this cap and rotor not too long ago. Both the cap and rotor are Borg Werner and brass contacts. whats wearing the contacts out like this? I cleaned them both up with some scuff pads and put back together. I also re-torqued all my throttle body bolts to 25 ft lbs. then i put a regular paper air filter back in and also disconnected the TPS, IAC, MAP sensors and then disconnected the battery. I cleaned the IAT and the PCV. I hooked the battery back up and went to start and it stalled out but i forgot to hook all the sensors back up. So i hook them all back up and try to start again but truck won't start without resetting computer again. Finally truck fires up and clears up. Started and shut off 3 times. The truck runs awesome!!!! It will run like this for awhile and the last time it ran this good was right after i did my tune up about 2 months back but then it gradually turns back to mush!!! then it seems after i unhook the sensors and reset computer it runs great.
I'm with Pete about the TPS sensor possibly. I've done that mod a few times but always ended up returning it to OEM. I can't help but wonder how sensitive are these things and did drilling out those rivets do any damage for the worse! i will check with volt meter tomorrow. I'm assuming you gradually open the throttle and not quickly. Numbers should climb steadily and not miss or jump, correct?
it just seems to me that this may be a sensor issue here with the reason being that everytime i disconnect them and reset the computer and then hook them back up the truck runs terrific! I really doubt that cleaning the IAT and PCV would make such a night and day difference. Okay well maybe the PCV with these trucks. I put the paper filter back in because i've read a lot of bad things as well as good things about my K&N drop in but i'm really not revolving around WOT and would much rather have better filtration. I'm not sure about the MPG, I'll have to conduct an experiment with K&N versus paper air filter once i know i'm running good for awhile and the seafoam has run through. so i'm really not sure what it was tonight that i did that made the difference but obviously something hit the spot but not sure what!!!
thanks for everyone's help so far. I have solved and fixed MANY problems with my truck thanks to the help of this site! Cheers!!!!
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daddio
Dodge Dakota
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7/29/2007
10:42:57
| RE: o2 sensors
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"i will check with volt meter tomorrow. I'm assuming you gradually open the throttle and not quickly. Numbers should climb steadily and not miss or jump, correct?"
correct but, one more thing. make sure that the idle readings comes back to the same reading when returned. if it doesn't it's probably time for a new TPS.
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fixit
Dodge Dakota
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7/30/2007
00:26:31
| RE: o2 sensors
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checked TPS today. the numbers on my voltmeter did slowly increase as i gradually opened my throttle body and did return to the starting point, BUT i did notice that when i wasn't touching it at all it kept fluctuating by .001-.002 volts and it would not settle onto one number. is this normal? when i checked with voltmeter i opened the throttle as slowly as i could but it still seemed like the voltmeter could not keep up with displaying a reading even for as slowly as i was opening the throttle.
another thing is that i think it may be real easy now for the TPS to stick because the rivets were drilled out for the mod. i put them back in and they do stay there but i need washers on the torque screws to "hold" the sensors in place otherwise i think it will slip right off the rivets. I loosened as much as i thought i could today before i thought it would slip off. this sensor is not cheap either. Dealer quoted me $100 plus!!
also noticed i'm sucking gas like crazy with this seafoam in. is it because of the seafoam? If i get more of this and run some through the throttle body would that be ok. Not sure how many time you can put this stuff through the system. I know it will get to the top half of the engine much faster through the throttle body but i already put a full can in the tank.
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Shoe
GenIII
7/30/2007
03:00:14
| RE: o2 sensors
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The O2 sensors will not effect WOT runs. I know if my V6 that if I got on it real hard then tried to cruise then it would surge and stumble. A lot of sensors do not function under WOT.
Finally... a V8. '01 Dodge Dakota RC, 4.7, 5-speed, 3.92 LSD. = R/T Killer.
well at least a stock one
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pete
Dodge Dakota
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7/30/2007
10:27:15
|  RE: o2 sensors
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replace your TPS sensor to stock and no Seafoam isn't going to make it suck more gas hopefully while stuff whatever its doing might of loosen some carbon? or? causing more gas along with your TPS after you fix the TPS I would have your injectors professionally cleaned by a good shop that knows our trucks and good mechanic understands whats going on don't relie on a can Seafoam to cure problems that you are having I see alot of in this website doing all these mods. which is great but they seroiusly need to be done properly and carefully so don't ruin your truck yet alone more money out of your pocket than needed Good Luck...
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J and J Auto
GenII
8/01/2007
02:10:51
| RE: o2 sensors
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If your plugs are running brownish tan your air
fuel ratio is ok
That says the o2's are still working good
do the tps mod set to .7 .75
upgrade your ignition
Napa MO26 and MO28 cap and rotor
brass incerts around $15
MSD 8.5mm wires the stock wires have 300 ohm per
foot resistance the MSD only 50 ohm per foot
thats like squesing your garden hose off but
expecting it to flow well
NGK Vpower plugs
FR4 stock range
FR5 1 colder
gap
92 to 95 .035
96 up .040
Now you have a very strong system with a lot
more power getting to the plugs and it will help
a lot its even noticeable
Larry
J&J Auto
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