99 xj, dealer DRB3 won't communicate..

[Sidewinder CC]

Will I have any problems not running the downstream o2 till I get them replaced. And do u see any prob getting the ntk sensors from rock auto vs the dealer, there like 32$ apiece on rock auto?

It would be a good idea to get them from Rockauto, they seem to be the cheapest.

I cannot, or will not, recommend operating without an oxygen sensor if it is violation of Federal Emissions Standards. Your call.

 

[theviper90210]

Rockauto it is then. And Sorry about the not running a o2 question, didnt even think about it when i asked it. Ill let you know when i get it updated.

 

[Ecomike]

If you run with out a working O2 sensor, the computer runs the engine rich. This in turn causes too much fuel to reach the CAT converters, and overheats the CAT which eventually damages the CAT. Overheating the CAT causes the honeycomb break up clogging the exhaust system. Also it fouls the combustion chamber, valves and spark plugs with carbon, that can lead to hot spots and pre-ignition, pinging that damage the engine. Also running the engine too rich may dilute the oil with fuel. So no, it is not an good option.

 

[theviper90210]

Ok guys o2 Sensors fixed. all is running good, no CEL (was able to use my bluetooth OBD2 adapter and Torque app on android to clear the code), so what else if anything should I take a look at before going back to the dealer for the keyfob. and seeing if there drb will now work.

 

[Sidewinder CC]

Ok guys o2 Sensors fixed. all is running good, no CEL (was able to use my bluetooth OBD2 adapter and Torque app on android to clear the code), so what else if anything should I take a look at before going back to the dealer for the keyfob. and seeing if there drb will now work.

Look in your wallet. Make sure you have enough cash or a credit card. :spin1:

 

[theviper90210]

hahah yea i know, but since I know the dealer they will do it for $40 if it works and no charge if it doesnt.

 

[DualSportDad]

Check the air bag module... If it was wheeling rig the orc gets wet pretty easily and once that happens its done.

 

[theviper90210]

Ahh that makes since wit was a wheeling rig before I bought it, so carpet or anything, and isnt that the module under the driver seat I bet it was wet at some point, would unplugging it make the drb3 communicate? Any way to test the module to see if it has a electrical problem?

 

[Sidewinder CC]

Ahh that makes since wit was a wheeling rig before I bought it, so carpet or anything, and isnt that the module under the driver seat I bet it was wet at some point, would unplugging it make the drb3 communicate? Any way to test the module to see if it has a electrical problem?

The airbag module was moved to under the center console per a TSB for earlier XJ's and at production on later XJ's for the moisture reasons.

The Airbg module doesn't have SCI transmit capbilities but can screw up the CCD Bus if it goes bad. Unplugging it to get DRB III communication may be a drill in futility.

 

[DualSportDad]

Re: Re: 99 xj, dealer DRB3 won't communicate..

The airbag module was moved to under the center console per a TSB for earlier XJ's and at production on later XJ's for the moisture reasons.

The Airbg module doesn't have SCI transmit capbilities but can screw up the CCD Bus if it goes bad. Unplugging it to get DRB III communication may be a drill in futility.

Even if it gets moved up any water that sits in the vehicle when it evaporates will bet into the module. I've been through this.

As far as going further with diagnosing the problem you will need a ossiliscope (sp?) And some wiring diagrams.

 

[kastein]

If you run with out a working O2 sensor, the computer runs the engine rich. This in turn causes too much fuel to reach the CAT converters, and overheats the CAT which eventually damages the CAT. Overheating the CAT causes the honeycomb break up clogging the exhaust system. Also it fouls the combustion chamber, valves and spark plugs with carbon, that can lead to hot spots and pre-ignition, pinging that damage the engine. Also running the engine too rich may dilute the oil with fuel. So no, it is not an good option.

That's the upstream - I am not sure the downstream affects the fuel mix on a 99, iirc it's just to tattle on the catcon being toast on those years?

 

[DualSportDad]

Re: Re: 99 xj, dealer DRB3 won't communicate..

That's the upstream - I am not sure the downstream affects the fuel mix on a 99, iirc it's just to tattle on the catcon being toast on those years?

Downstream sets the goal voltage for the upstream o2.

 

[kastein]

Good to know. Thanks for the correction!

 

[Sidewinder CC]

Good to know. Thanks for the correction!

From a Dodge RAM website. Some insight into the O2S goal voltages. Note the fuel economy statements. You probably see statements in the forums concerning fuel economy that the downstream O2S does nothing but monitor the CAT. Myth busted.

[SIZE=+1]Upstream Oxygen Sensor Goal Voltage[/SIZE]
From Star Center News #5, February 2000 - tests for those who have access to OBD II or OBD III code readers.

Since the introduction of OBDII with both upstream and downstream O2 sensors, the downstream O2 sensor has been used to evaluate catalytic converter operation and to control converter efficiency.

When looking at the upstream goal voltage, it should fluctuate above and below the normal center (.4 to .6 volts) based upon what the downstream O2 sensor is reading. The vehicle should be driven through all speed ranges when checking goal voltage. If the goal stays high or low all the time, a thorough check of the downstream oxygen sensor should be made. Be sure you check the sensor, wiring harness, connectors, catalytic converter, and inspect for exhaust leaks.

Although a MIL lamp may not be illuminated, there are instances when the downstream O2 sensor goal voltage is out of range, causing driveability problems or low fuel economy.

If the downstream O2 sensor tends to stay below center all the time, the PCM will adjust the goal voltage higher in an efforet to correct the low O2 readings of the downstream sensor. This can result in low fuel mileage.
If the downstream O2 sensor has a tendancy to stay above center, the PCM will set a low goal voltage which results in a lean fuel mix which can cause the engine to run hotter and aggravate a spark knock condition.

Sometimes a service technician will reset the PCM and take it for a test drive. The PCM does a recalibration after the reset, and the problem may go away until the PCM has completed a relearn of the system and then begins to attempt to correct for the downstream sensor error. If the symptoms reappear after several days of driving after a service is performed, check the downstream O2 sensor, the exhaust system, the wiring, and the catalytic converter. Note: a worn out catalytic converter can produce symptoms similar to a bad downstream O2 sensor.

 

[theviper90210]

Glad my thread could start some in site to something lol! Now we know

 

[Sidewinder CC]

Glad my thread could start some in site to something lol! Now we know

Cool, but did you have the DRB III put on it yet?

 

[theviper90210]

Not yet, going to check out that airbag module this week