Compstall

iTrader: (5)

I'm working this lady's Dakota right now. Here's her symptoms and what I've found w/ my scanner:

Two codes, one for an O2 sensor 'slow to respond', and the other for 'system too lean'.

She said an O2 sensor has been changed out twice on this vehicle. I've taken a look underneath and found that indeed the right side sensor has been swapped out. Now, every O2 sensor I've ever changed always had a nice harness w/ a connector on it, but this one's been cut and crimped on. I do suspect the crimps being a potential problem here, but here's some more details:

Tons of black soot coming out of the exhaust, inside of exhaust pipe is coated heavily w/ a nice black powdery patch on the bumper around the exhaust tip.

Here's my theory of what's happening: the O2 sensor or wiring is causing the 'slow to respond' problem, which in turn is sending an incorrect signal to the PCM. With that incorrect signal to the PCM, it thinks the car is too lean (hence the 'system too lean' code) therefore dumping huge amounts of fuel into the motor. All excess fuel is being thrown out the door through the exhaust.

Anyone run into this problem before? Anyone changed out the O2 sensors on these vehicles before, and should there be a connector with a new O2 sensor? I'm guessing that the connector might be too tough to get to, so the shop she took the vehicle too cut corners and just diked the wiring off and spliced it. I haven't taken a close look yet but that's what I'm suspecting.

Input??

CHarris

iTrader: (5)

Sometimes you can buy a cheap-*** sensor that will have to be spliced in. I guess they save money on the connector.

Buy the more expensive ones and you'll be off to a good start.

Mikey 97Z M6

iTrader: (37)

I've heard that O2 sensor wires are very, VERY sensitive to being spliced. If it must be done, I think I remember reading that it should be soldered using a special type of solder (high silver content?). Crimping them is a big no-no. Also, they'll become very susceptible to corrosion after a splicing, which can also affect the sensors performance later on.

Good luck, but it does sound like you're on the right track with it.

Mike

AndreS

iTrader: (6)

^ agreed with the above about the connections on O2 sensors.

-bad fuel pressure regulator as well? check pressure at the rail, both stopped and running. had it happen on my bronco... it caused carbon buildup in the motor, hot spots burnt valves, and one broken valve eventually.... had a bad weekend on the way to a off road GP race... the bronco got 'traded'.

after you figure out the rich condition, run a combustion chamber cleaner through it... it may save the engine.

Compstall

iTrader: (5)

Yes, I can only imagine what the inside of the head/valves look like after seeing the tailpipe. I plan on running some Sea Foam through it and cleaning the plugs and other things once I get this figured out.

I looked over the connections again where they spliced; it does in fact look like the harness is in a tight spot along with the connector being located somewhere up toward the top of the trans. bell housing and they probably did cut corners there. Another thing that could have happened is that the wires could have easily been crossed when they connected them since the wires are different colors.

Additionally, I measured the fuel mileage on the way back from her work. It gets ~9.5 on the highway and ~6.5 mpg in the city. Still way low. You only have to give it about 1/2 throttle in order to see a train of black smoke out the tail pipe.

Poik

Gross. Sounds like they bought one of the "universal" o2 sensors to replace it with and fudged something in the process.

Compstall

iTrader: (5)

I'm working on the truck now. Started it up, whacked the throttle open one time and here's what spit on the ground:





I checked the spade connectors the shop used to splice the O2 sensor in with and they are very sloppy loose. I've followed the O2 harness all the way up the back side of the engine and there is no connector; the harness runs into a larger harness so it does need to be spliced in unfortunately.

Mikey 97Z M6

iTrader: (37)

Damn, that's some nasty **** right there. Let us know what you find out...

Mike

crazylane

iTrader: (19)

The cats will probibly be clogged up too, after all this is said and done with.

Compstall

iTrader: (5)

Well, I've tested every sensor in the truck that could have anything to do with fuel control and it all tests good. I did jack up the MAP sensor playing with it and will just chalk that up to a learning experience as I'm picking up a new one tomorrow.

I had an idea that maybe I could swap the injectors over from one side to the other, but one guy pointed out that since the truck only has two O2 sensors and not 4, when they get a lean code they always default over to Bank 1 since the vehicle can't differentiate between sides. Bummer. I did remove all the injectors and cleaned them up as best I could; they were pretty nasty.

Other than that I can't find any leaks anywhere and am thoroughly frustrated with this truck since this is the first time I've ever been skunked with any vehicle and am now no longer undefeated w/ Dodge vehicles.

Rawr256

Possibly the fuel pressure regulator? What is the whole fueling system look like? If it isn't electrical than it has to be mechanical for it to be off as far as it is. Our 91 Grand Prix beater with the 2.8 does this similar thing, give it to much gas and you leave a black cloud behind you, after we got it the cat went out from this and we just put in a straight pipe. When you get high in the RPM it struggles to keep going and plugs when I pulled them were fouled bad.

It's obviously getting to much fuel. Was thinking changing the fuel lines, but that wouldn't change anything, it is already getting the fuel, it isn't starved. The pump maybe running on high mode all the time? Look into the mechanical components of the system other than the Computer side of it would be my suggestion.

Compstall

iTrader: (5)

Fuel pressure is fine. After resetting the codes or disconnecting the battery to completely erase memory, after a short drive the long term fuel trim sticks itself at 32.5%.

This truck blows black smoke at idle; no need to stomp on the gas.

Rawr256

Would totally think it is a sensor if the trims are going right to 32.5, any KR present in it? I know my dad's van has the same problem and it will max out the + LTFT and throw the lean code, he gives it the slightest amount of gas and it knocks out the ***.

Notice you say that you tested the sensors and they all check good, but do you know if the reading of the sensor is getting back to the PCM? Possibly a break further down the line? Maybe even a bad PCM?

Looked through a Haynes or anything of that sort? Generally they have steps to take when the car throws codes and places to look before advising to take it to a higher power.

Other than that stuff, I am fresh out of ideas or any other advice. Sounds like you have done everything I would have.

Compstall

iTrader: (5)

No knock retard; outside of a slight hesitation which I'm sure is fuel-dump related the truck drives fine, it's just burning a shitload of gas.

WS SIKZ

iTrader: (3)

thermostat, maybe its staying in open loop, maybe the timing is really out of place, first i suggest putin a O.E o2 sensor and do the cats. they both sound dead to me. the ecu might also have something wrong because of injectors staying open. put some noid lights and see is the injector pulls are correct and they are not staying on, the fuel pressure regulater only limits the pressure from the rail to return sholdnt be doing that much gas from that.

AndreS

iTrader: (6)

did you check fuel pressure w/ engine both running, and stopped? when this happened to my bronco, the fuel pressure would be fine w/ engine stopped (32psi), but went to 65 psi the second the engine was started. the vacuum reference part of the FPR was busted somehow.

Compstall

iTrader: (5)

Coolant temps are fine.

Truck goes into closed loop just fine.

Truck wouldn't run this good if the timing was "really out of place".

Why continuously change O2 sensors if that's not fixing the problem?

Compstall

iTrader: (5)

Yes - fuel pressure stays at 48 psi static or dynamic.

Rawr256

I would opt for burning it and getting money from insurance!

warpwr

I know Mythbusters proved nothing happens when you put sugar in the gas, but this looks like what we all thought should happen with sugar in the tank.