Mileage tune up - what to do

Lil-Pony · Sep 24, 2013

Truck info:
1998 dodge 1500 ram 5.9L magnum.
299500 miles motor has never been rebuilt, still has plenty of power.
I've noticed a miss when the trans is in reverse, but goes away in park, neutral and drive...
I've replaced the rotor, cap, wires and spark plugs at 298xxx
I've notice it runs a little rich I'm the morning but I guess that's expected to help on cold start.
I'm wondering how to check the O2 sensor with out a 1000$ diagnostic machine...

RonD · Sep 24, 2013

Live scan tool can show you the O2 sensor numbers in real time, O2 sensors become sluggish as they age.
You will see a voltage reading, .2 to .8 should be the upper and lower limits with engine running at normal warmed up temp.
.4/.5 is the sweet spot the computer tries to keep the O2 sensors at.
If you snap open the throttle and close it, you should see the high and low numbers and then back to the sweet spot, these changes should be instant, if numbers are slow in changing then time to replace that sensor.

You can rent these scanners.
I have never used the $15 bluetooth OBD II interface devices for smart phones, but they may have live numbers that can do the same thing.

Lil-Pony · Sep 25, 2013

Could I just hook a volt meter up to it some how?

RonD · Sep 25, 2013

You could try........but voltage is below 1 volt DC so not sure how much help the info from a regular volt meter would be.
If O2 sensor was bad computer would know it and set the CEL, so you are just looking for slow voltage changes, which might be caused by the voltmeter, so you end up replacing a working O2 sensor.

O2 sensors have recommended replacement period of 70,000-100,000 miles, so at 299,000 those could be replace just on spec.
And at that high a mileage there will be more burnt oil in the exhaust, which is bad for O2 sensors

The two on the exhaust manifolds are the ones that set the fuel mix, the one or two on the exhaust pipes are there to test catalytic converter operation, so those can be replaced but really up to you, they don't get the high temps the "upstream" O2 sensors do.

Lil-Pony · Sep 25, 2013

So best bet is to just pull them, I know my O2 sensor in my b2 was all rusty and when I swapped it out she ran 100 times better.

Mileage tune up - what to do

Lil-Pony

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RonD

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Lil-Pony

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RonD

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Lil-Pony

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