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sprinkles08, Chrysler/Dodge/Jeep master tech
Category: Dodge
Satisfied Customers: 23004
Experience:  ASE Master and Advanced Certified, Chrysler/Dodge/Jeep Master Certified, Trans and Hybrid Specialist
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2002 dodge van 3500 5.9 at 45mph coughs and backfires

Customer Question

2002 dodge van 3500 5.9 at 45mph coughs and backfires sometimes i can floor it and it goes on past i have replaced 3sensors on the transmission 2 sensors on throttle body fuel pump in gas tank intermidiate oil pump drive gear and bushing had the control module repaired still have the problem
Submitted: 11 months ago.
Category: Dodge
Expert:  Juan Crespo replied 11 months ago.

Hi there.

It's not uncommon for these engines to exhibit this kind of symptom whenever there's a problem with crank sensor signal - this can have several root causes, such as bad sensor, connection/wiring, PCM and/or cracked/loose flex plate (flywheel). The proper way to diagnose this issue is with a DRB-III or equivalent scan tool capable of reading engine data. Do you have access to such tool?

Customer: replied 11 months ago.
no I do not have the scan tool--the scanner I am using is at the NAPA parts house. At one point I traded relays (the AC and Trans) and for a little while the van ran good and I thought it was fixed but then It started acting up all over again.
Expert:  Juan Crespo replied 11 months ago.

I'm afraid I won't be able to help you. I'll opt out so others may try. Please do not rate or reply until another expert responds or the site will cycle this back to me.

Expert:  sprinkles08 replied 11 months ago.

Hello and welcome to JustAnswer!

It sounds like you're describing the engine running lean due to a weak upstream oxygen sensor heater. Can you unplug the upstream sensor, disconnect the battery to clear the adaptives, and then see how it runs with the sensor unplugged?

Customer: replied 11 months ago.
Could you please tell me where this upstream oxygen sensor heater is located? thanks!
Expert:  sprinkles08 replied 11 months ago.

The heater is inside the sensor.

Customer: replied 11 months ago.
i unplugged the sensor and disconnected the battery then connected it back took the van out on the road no change.
Expert:  sprinkles08 replied 11 months ago.

Are no codes setting?

Customer: replied 11 months ago.
po 748 i have changed that trans sensor twice
Customer: replied 11 months ago.
We cannot continue to wait 24 hour--24hour and so on. Would you please just end this conversation? Thank you