Need help.

[gerG]

My 2002 3.7 died the other day. I had just got back from the store, I started it up to pull out of the garage and it just died. It wouldn't restart. I was just under 1/4 tank of fuel, thought it might have ran out so I added 2 gallons or so and still no start.

Only code is for an o2 sensor that has been needing replaced for months. I tried giving a little throttle and it started but ran terrible, sputtering pretty bad. I can hear the fuel pump prime when I turn the key.

I was told it was the pcm, foolishly before diagnosing I ordered one programmed for my Jeep and just changed it out with no change.

Where should I start to figure this out?

 

[HoosierJeeper]

Kind of sounds to me like a bad crank position sensor. Maybe do some reading on that.

 

[Conundrum2006]

The crank sensors are a possibility, you should get a code but that doesn't always happen in these newer cars.

It will run (badly) with the throttle opened a little ?
What will a bad TPS do to the 3.7?



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[Royy]

Have you checked all vacuum hoses? The fact that it only starts with some throttle and then sputters a lot, that sounds exactly like what happens when you have a really bad vacuum leak.

 

[Conundrum2006]

Which o2 sensor is the code for?
If it's upstream (before catalytic converters) they control the fuel mixture and maybe a few other things I'm not thinking about, down stream is for monitoring the how well the catalytic converters are doing their job.

On the old XJ (Cherokee) a bad o2 could cause a no start.
But I'm not 100% sure it's your issue. Being able to run at all is a clue just not sure for what.



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[gerG]

Bank 1 sensor 1. Thanks for the input getting ready to start tinkering!

 

[gerG]

Fuel pressure 45 with key on 50+ cranking. vacuum lines check out.

 

[gerG]

Replaced crank sensor no change.

 

[HoosierJeeper]

What brand sensor did you use? These like Mopar only!

 

[gerG]

What brand sensor did you use? These like Mopar only!

That *****. Got BWD I believe.

 

[Conundrum2006]

What happens if the oxygen sensor that failed is disconnected and it is tried to start?
Not suggesting doing it asking if this could be a way to test .

BTW if you do have to replace the O2 sensor jeeps are very particular about the brand, NGK / NTK I think is the oem manufacturer.

This may have end up going back to basics with stuff like testing compression to make sure the engine is healthy enough to run. Seems like it could still be a bad sensor but I'd hate to have you keep throwing money at it.

With the BDW sensor is it doing the same thing including running roughly?


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[gerG]

Yes with the BWD sensor it still will only start with throttle and run rough and won't idle.
I got a new O2 sensor NTK to install. Of course its the hardest one to get at!
Will be a couple of days before I can mess with it though.

 

[Sephiroth]

Mine had a similar problem, it would sputter and stall if i let off the gas turned out to be the iac

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