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sprinkles08
sprinkles08, ASE Certified Technician
Category: Chrysler
Satisfied Customers: 22371
Experience:  ASE Master & Advanced level certified, Chrysler Master Certified, Trans and Hybrid Specialist
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I have a 2005 Chrysler Town & Country with a 3.3L

Customer Question

I have a 2005 Chrysler Town & Country with a 3.3L engine. My problem is low speed misfire.

This van had a coolant leak that was not corrected in time for it to cause the engine to overheat and the heads to become damaged. It also had a bit of a misfire before this happened.

I replaced the radiator and heads with re-manufactured ones and the engine fired right up and it seems to be fixed except for the low speed misfire, which continues.

It misses at idle and say below 25 mph but seems to be okay once you get up above that.

So far I’ve replaced the spark plugs, spark plug wires, coil pack, EGR valve and the idle air control valve all without fixing this problem. There are no OBD codes showing up. The fuel pump pressure has been tested and it’s within specs.

I can attach the sound of the engine idling with the air filter & cover removed. There is an odd, intermittent sucking noise coming from the throttle body intake that coincides with the misfire, but that may be nothing.

While I've been waiting for your reply I removed the throttle body and cleaned it out. It was full of gunk but it's clean now, and the miss remains. Still waiting for a reply. I just changed the throttle position sensor with no luck. I've been trying to find a vacuum line off somewhere but can't see one.

Can you offer any suggestions as to what may be going on here or what I can try next because I'm just about out of ideas.

Submitted: 1 year ago.
Category: Chrysler
Expert:  sprinkles08 replied 1 year ago.

Hello and welcome to JustAnswer!

I'm wondering if you're actually experiencing a lean condition due to a weak upstream oxygen sensor heater rather than an actual misfire. A weak heater will cause the engine to run abnormally lean at low engine speeds, especially in cold weather, and at stops. You may be hearing the IAC opening further at idle to keep the engine running as it starts to run poorly.

Are you able to upload the recording here?

Customer: replied 1 year ago.

Hello,

Yes I can upload the sound but not tonight. It's like a chuffing sound that is coordinated with the miss. I removed the plenum today and the injectors. I also got a cam sensor but it's not fitted. I was going to try a new set of injectors but I like your idea. Do you know where the upstream sensor is because at this point I'll try just about anything!!!

Expert:  sprinkles08 replied 1 year ago.

The upstream sensor is threaded into the rear exhaust manifold. You can try unplugging it and disconnecting the battery to clear adaptives, and then see how it runs.

Customer: replied 1 year ago.

Okay I'll give it a try tomorrow and let you know what happens.

Thank you...

Expert:  sprinkles08 replied 1 year ago.

You're welcome!

Customer: replied 1 year ago.

Can you tell me what you mean by: adaptives.

Expert:  sprinkles08 replied 1 year ago.

Adaptives are a measure of how much fuel is taken away or added, stored in memory.

Customer: replied 1 year ago.

Okay thanks...

Expert:  sprinkles08 replied 1 year ago.

You're welcome!

Customer: replied 1 year ago.

Okay I disconnected the battery then replaced the front 02 sensor then the (old) injectors, with new "O" rings, the plenum etc, and I'm sorry to say I seem to have gone from bad to worse.

Now I have a P0135 code coming up, and it's still missing as it was. Before I didn't have any codes. Do I have a bad (new) sensor?

Expert:  sprinkles08 replied 1 year ago.

Where did the sensor come from?

Customer: replied 1 year ago.

Hello again,

From Advance Auto. Since then I've replaced both 02 sensors (I replaced the front 02 again) and the cam sensor all without luck. If I didn't have so much money into this thing I'd push it into the lake... Now I'm wondering about either the cat converter or the cam shaft. Both BAD things...

I've had enough for one day !!

Expert:  sprinkles08 replied 1 year ago.

Aftermarket cam, crank and oxygen sensors are almost expected to cause repeat issues.

Did you disconnect the upstream sensor, disconnect the battery and drive it before you replaced the sensor?

Customer: replied 1 year ago.

Did you disconnect the upstream sensor, disconnect the battery and drive it before you replaced the sensor?

No I did not... Should I have ?

Expert:  sprinkles08 replied 1 year ago.

Yes, that's what I recommended doing and you said you were going to do today.

Customer: replied 1 year ago.

No Sir. The conversation went as below...

You said: The upstream sensor is threaded into the rear exhaust manifold. You can try unplugging it and disconnecting the battery to clear adaptives, and then see how it runs.

I said: Okay I'll give it a try tomorrow and let you know what happens.

I then said: Can you tell me what you mean by: adaptives.

You replied: Adaptives are a measure of how much fuel is taken away or added, stored in memory.

Frankly I didn't understand what you were talking about in that sentence. I did disconnect the battery but I didn't drive the car.

Expert:  sprinkles08 replied 1 year ago.

You needed to unplug the upstream sensor, disconnect the battery to clear adaptives, and then drive it to see if it runs better.

Customer: replied 1 year ago.

So I should clear adaptives, there you go again. I asked you yesterday what you meant by that and you said: Adaptives are a measure of how much fuel is taken away or added, stored in memory. Nothing about driving the car, and how can I drive the car with the battery disconnected. Remember you are the expert here, I am the amateur. Please can you explain more clearly what you mean...

Expert:  sprinkles08 replied 1 year ago.

Yes, you're disconnecting the battery to clear adaptives since I'm assuming you don't have a scan tool to do it manually.

Disconnect the upstream sensor.

Disconnect the battery, reconnect it.

Drive the van to see how it runs.

Customer: replied 1 year ago.

So I disconnect the upstream sensor and battety. Reconnect the battery. Then drive the car. Do you mean with the sensor disconnected?

I do have a scan tool by the way. I've got it... adaptives = OBD codes.

Expert:  sprinkles08 replied 1 year ago.

Yes.

Customer: replied 1 year ago.

My mistake...

I actually asked two questions in my last response.

1, So I disconnect the upstream sensor and battery. Reconnect the battery. Then drive the car. Do you mean with the sensor disconnected?

Yes or No

2, I've got it... adaptives = OBD codes.
Yes or No

Expert:  sprinkles08 replied 1 year ago.

Part of your last post may have been lost because there was only one question posted at the end.

Yes, unplug the upstream sensor, disconnect the battery to clear adaptives, and drive the van to see if it runs any differently.

Adaptives don't have anything to do with fault codes. Adaptives are a stored measure of how much fuel is added or taken away.