2003 3.0 liter limp mode

[yelim]

I have a 2003 Edge with 3.0 auto tranny. 118000 miles. I just did a brake job all 4. Replaced idler and tensioner pulleys. Truck is now in limp mode. I have replaced the crank sensor and have a cam sensor that won't plug in because the pins are different. Will get it replaced today. The crank sensor did not change anything. Had codes checked yesterday and showed no codes. Check engine light comes on with key but goes out when started. Where do I go from here? How do I trouble shoot with no codes or lights?
Any help would be appreciated.

 

[RonD]

Crank sensors rarely fail and if they do engine will not start.

Open Loop is when engine is cold or computer has detected a problem in data coming in from sensors, so computer is running pre-programmed timing and air/fuel mix.
Is this what you are calling "limp mode"?

Because there is also a "limp mode" for automatic transmissions, which is not related to engine sensors.

Yes, 3.0l Cam position sensor and it's housing/shaft have about a 100,000 mile life span, it will usually start squealing because of bushing failure, since this housing/shaft also powers the oil pump it is a good part to replace just because.....

And Yes, there are two types of cam position sensors, 2 wire and 3 wire, they are different types of signals so are not interchangeable by changing connectors.

 

[yelim]

Also changed cam sensor. It is not squealing. It is a 2 wire. Neither sensor made any difference. What I am calling limp mode is rough idle like a misfire, in park engine will cut out at around 32 or 3300 rpms and not go past that. Transmission shifts and works fine. I have also changed plugs and wires. Fuel pump is next.
What would be the symptoms of open loop?

 

[RonD]

In Park or Neutral computer engages a REV Limiter, it kicks in just above 3,000 RPMs, so your cutting out at 3,200-3,300 is normal and correct.

Rough idle can be a few things.
Dirty fuel injectors, run a can of Seafoam in the gas tank once a year.

Failing coil pack, usually you would get a p030x code, and the x would be 1 to 6, not 0
Check coil pack spark plug connections, they can get corroded from arcing so even with new wires problem still exists.

Dirty MAF sensor, clean it

Small vacuum leak, this leans out idle mixture, so rough idle but engine should be fine when above idle RPMs, computer uses O2 sensors then.
If idle is better cold, less misfires, then vacuum leak could be the issue

Worst case is recessed valve seats, this was an issue with the 3.0l in the early-mid 2000's, but I think it was '04-'06.
If possible do a compression test, that's the only way to test for that


Computer has 2 "modes"
Open Loop is when computer is using Factory data in memory to operate the engine.
It does this when engine is cold, because O2 sensors don't work until they are above 650degF.

Closed Loop is when computer can use all the sensors to operate engine at best efficiency, best MPG, so it doesn't use Factory data.

Limp home covers a few things but rough idle wouldn't be one of them.
If computer is getting data from a sensor that is out of its normal range it will switch back to Factory data, this will usually cause a loss of power, but you can "limp home".
This is in essence Open Loop, so engine will run OK just not great.

Transmission limp home doesn't effect engine operation, computer sees one of the transmission sensor that is out of range so it switches to factory preset shifting, so you can limp home

 

[yelim]

Thank you. Didn't know of rev limiter. Will do what you said.
Do you know of a vacuum diagram online? Or a repair CD?

 

[bucko]

Thank you. Didn't know of rev limiter. Will do what you said.
Do you know of a vacuum diagram online? Or a repair CD?

You may have one of these as a decal under the hood in front of the radiator (on top). Or simply enter your year Ranger, along with the engine size (3.0) in the Google search box. Plenty of results will pop up.

 

[yelim]

Changed fuel filter and cleaned MAF sensor and running much, much better. Thanks for the help and education.

 

[RonD]

Good work

Thanks for the update, it will help others to know what worked for you