99 Grand Caravan surging with CEL

flyhigh · 09-07-2009, 12:43 AM

I have a 99 grand caravan with the 3.3 liter V6. We have been having a consistent problem with the O2 sensor tripping the CEL and causing poor fuel economy (15-16). I have replaced the upstream sensor 3 times, first two times it was a Bosch sensor and the last time I broke down and went to the dealer. I cant believe with three different sensors they could all be bad. I then pulled the wiring harness out and checked all the connections and resoldered the entire harness. The strangest thing about this problem is that the light doesn't always stay on. It comes and goes but mostly comes. When the light is on we get better performance and better gas milage then when the light turns off. The engine will chugs all the time and the van stinks of foul exhaust when we park it. I am at my wits end with this thing. I don't know what to do but have been wondering if it could possibly be the ECM? Oh I have also tryed looking for broken vaccum lines and haven't found any.

RIP · 09-07-2009, 02:55 AM

Any unexplained coolant or oil loss? Burning coolant or oil can eat oxygen sensors. Did the mechanics happen to tell you if the sensors they removed had excess deposits on the sensor tip? A leaking fuel injector can create a rich mixure and eat the sensor. Hard starting and raw fuel smell are indications of a leaking fuel injector. Silicone in sealers or cleaners can eat sensors.

ECM (actually PCM)? Sure could. Only components in the circuit are the sensors, wiring and the PCM. Might try inspecting the PCM connections for corrosion or damaged contacts. Disconnect the battery before disconnnecting/reconnecting the PCM.

Alphabravo · 09-07-2009, 07:44 AM

Quote:

Originally Posted by flyhigh

I have a 99 grand caravan with the 3.3 liter V6. We have been having a consistent problem with the O2 sensor tripping the CEL and causing poor fuel economy (15-16). I have replaced the upstream sensor 3 times, first two times it was a Bosch sensor and the last time I broke down and went to the dealer. I cant believe with three different sensors they could all be bad. I then pulled the wiring harness out and checked all the connections and resoldered the entire harness. The strangest thing about this problem is that the light doesn't always stay on. It comes and goes but mostly comes. When the light is on we get better performance and better gas milage then when the light turns off. The engine will chugs all the time and the van stinks of foul exhaust when we park it. I am at my wits end with this thing. I don't know what to do but have been wondering if it could possibly be the ECM? Oh I have also tryed looking for broken vaccum lines and haven't found any.

Did you use silver anti-seize on the O2 sensor when you replaced it? I heard that kills them as well. Copper anti-seize should be used. I don't know of this personally but I heard this from a BMW mechanic.

plymouthsrock · 09-07-2009, 08:39 AM

The clue here is that the van runs better in "open loop". The ECM is getting a faulty signal from somewhere (sensor, wiring, or internally). Can you check the voltage at the O2 sensor wire?- I believe it should be about .5V with the sensor disconnected, engine running.

flyhigh · 09-07-2009, 11:27 AM

The oil consumtion is not any more than what you would expect on a van with 130,000 miles and I have not seen any coolant loss. I was the one that replaced the O2 sensors and non of them looked too fouled up. The first one I replaced was due to the fact I did use the wrong type of anti-seize. I removed the O2 sensor and cleaned the opening then replaced the sensor. I used carb cleaner and a tooth brush. Should I have used something stronger to remove the anti-seize? When the CEL came back on I went to the local dodge dealer and bought the OEM sensor.
The van starts just fine. How would I check to see if I have a leaking Injector? Like I said I pulled the wiring harness off the O2 sensor and inspected it and cleaned it.
How should I go about testing the O2 sensor? The manual I have here only talks about testing the heating element, or is that what I need to test? Thanks for your help!

jpb53 · 09-07-2009, 06:14 PM

A code number would help. Less guessing that way.

flyhigh · 09-08-2009, 12:18 AM

Code P0134; Upstream O2S Stays at Center, Neither rich or lean condition detected from the oxygen sensor.

jpb53 · 09-08-2009, 12:27 PM

This might help you.
http://www.obd-codes.com/p0134
Have you checked the heater circuit? At the O2 connector the black wire is the ground. You should have 5 ohms or less to ground. The dark green with orange tracer wire is the voltage supply for the heater. You should have battery voltage with key on. If you don't have DMM you can use a simple test light. Test light is better in some instances because you are putting some load on the circuit.

flyhigh · 09-08-2009, 09:38 PM

jbp53,
Thanks for your help. If I am thinking this through properly with the fault I am getting if there is no voltage at the O2 sensor than there is either still a problem with the wiring or a problem with the PCM. I appreciate all the help and will get back with either the solution or the next problem as soon as I have time to trouble shoot the wiring again. Thanks

Spit · 09-14-2009, 01:52 PM

Could you have a vacuum leak or an exhaust leak, causing the 02 sensor to correctly read an out of spec value and throw the fuel air into a manual overide (CEL light on)

Since you've changed the sensor 3 times and the same thing happens...seems likely that the sensor isn't the problem, it may be the wiring to the sensor, or other components that effect the fuel/air mix. Have you checked all of the vacuum hoses and tried cleaning the MAF Sensor, EGR valve etc.

Spit

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