Recently replaced Camshaft position sensor, need advice

[Ehtuttle00]

I have a 2WD 2000 ford explorer XLS with the 4.0L OHV. I just replaced the camshaft position sensor due to engine code p0340. Since it’s been replaced (about a day now), no engine light has shown up. Car accelerates fine, but when coming to a stop and once stopped and idling, the idle drops from about 1000-1100 rpm’s to about 500 rpm’s and gets slightly shakey. Any idea on what could be causing this? The plenum was properly sealed and had its gaskets replaced, all hoses have been reconnected, all sensors have been reconnected and the harnesses/wires look good, spark plug wires have been put back on the coil pack in the right firing order, and I have no visible leaks and no noises (ticking, knocking, etc). The only other thing mechanically wrong is a power steering pump that is whining (replacing that soon).

 

[410Fortune]

Nice work!

Let’s try a reset
Your computer has learned to run your engine with the old bad sensor
And it set a code
Now you have fixed the sensor and cleared the code, the pcm is ready to re learn
Just as if it was a brand new truck off the showroom floor
During this learning process the idle may fluctuate,
If it drops down to 550 or so and then catches itself… comes back up… I would keep driving and see if it continues or if it fixes itself
A good hot idle with ac off is 650-750 rpm
With ac on it should bump up to 850-1000
Rpm or so
If it continues to drop to 550 and stumble then you need to continue to check for trouble codes
If none appear try a simple reset first
Disconnect the negative battery cable for a few minutes
Try again and report back

Two more questions
1 How does she start when cold? Does the engine fire right up with bump of the key or does it “long crank”?

2 Are you sure you don’t have a slight miss? When it idles around 650-750 is the engine baby butt smooth?
A slight miss very common on ohv can be several things

 

[Ehtuttle00]

Nice work!

Let’s try a reset
Your computer has learned to run your engine with the old bad sensor
And it set a code
Now you have fixed the sensor and cleared the code, the pcm is ready to re learn
Just as if it was a brand new truck off the showroom floor
During this learning process the idle may fluctuate,
If it drops down to 550 or so and then catches itself… comes back up… I would keep driving and see if it continues or if it fixes itself
A good hot idle with ac off is 650-750 rpm
With ac on it should bump up to 850-1000
Rpm or so
If it continues to drop to 550 and stumble then you need to continue to check for trouble codes
If none appear try a simple reset first
Disconnect the negative battery cable for a few minutes
Try again and report back

How does she start when cold? Does the engine fire right up with bump of the key or does it “long crank”?

Yes I’ve done a reset/relearn process, sorry I should included that in my post. It got much better after that but still drops that idle down and stumble a little bit. When I start it up it doesn’t crank and turnover immediately like it did before, but it’s by no means a long or super rough start either. I’ll let it sit out there a while longer idling and check back in a bit.

 

[410Fortune]

There is a base idle screw on the throttle body, we don’t usually have to touch them… but it can be used to increase your base idle as a last resort

Did it do this before the cam sensor fix?
Do you have a fuel Pressure tester?

 

[C420sailor]

I believe the accepted setting for that screw is for the truck to just barely stay running with the AC on. It’ll be a low, nasty, crappy idle…but it’ll keep you from stalling out if your IAC dies

I actually battle with this periodically in my SOHC. Now and then I roll to a stop and the idle drops way low. Also, with cruise control on at 65-70 and on a long downhill, the torque converter will lock/unlock/lock/unlock.

I take the IAC off, clean it out real well, reinstall…and it’s good for another 30,000mi, no issues. So check and clean your IAC.

 

[Ehtuttle00]

There is a base idle screw on the throttle body, we don’t usually have to touch them… but it can be used to increase your base idle as a last resort

Did it do this before the cam sensor fix?
Do you have a fuel Pressure tester?

Sorry I just saw this. No it didn’t do it before the cam sensor fix. And I don’t have a fuel pressure tester. I was letting idle today while I replaced the exterior door handles and the light came on for a p0174 cylinder bank 2 too lean. Currently trying to find what is the cause.MAF voltage and readings are what they should be, o2 sensors voltage are both where they should be. I’m thinking it running lean is my issue.

 

[410Fortune]

Me too which is why I asked about fuel pressure tester
You need to check fuel pressure at the rail

Most common cause of 141 and 174 is leaking intake gaskets
174 by itself is usually followed by 171

Since you just had the intake off I would seriously consider checking your work, the gaskets should be seated properly
The big green egr o ring is also known to leak after an intake plenum job…

Check fuel pressure first to confirm it is or is not the cause

2000
Ohv operates at 64 psi fuel pressure +/- 8 psi

 

[Ehtuttle00]

Me too which is why I asked about fuel pressure tester
You need to check fuel pressure at the rail

Most common cause of 141 and 174 is leaking intake gaskets
174 by itself is usually followed by 171

Since you just had the intake off I would seriously consider checking your work, the gaskets should be seated properly
The big green egr o ring is also known to leak after an intake plenum job…

Check fuel pressure first to confirm it is or is not the cause

2000
Ohv operates at 64 psi fuel pressure +/- 8 psi

Alright I’ll be looking at all of that today

 

[410Fortune]

You can “rent” a fuel pressure tester from parts stores for testing

You should be able to visibly see if the intake gasket remained in position

If the big green egr o ring was disturbed disturbed the intake r and r then it could have torn and cause an air leak

I use a new o ring and Vaseline to ensure is slides into position

 

[Ehtuttle00]

You can “rent” a fuel pressure tester from parts stores for testing

You should be able to visibly see if the intake gasket remained in position

If the big green egr o ring was disturbed disturbed the intake r and r then it could have torn and cause an air leak

I use a new o ring and Vaseline to ensure is slides into position

Yeah I took my intake off to check my work around the manifold again, the gaskets are all in place with no tears and it’s definitely sealed. I did notice the hose connecting my air intake and the oil had a little bit of it sticking out, fought to push it all the way in and cleared the code, drove around for about 15-20 minutes and it hasn’t popped up. Starts up good again. Still has that kinda choppy idle when coming to a stop before putting it in park and is a little shakey still. I am still gonna check that green o ring your talking about just to be safe.

 

[410Fortune]

And fuel pressure

 

[Turdle]

You might also clean the iac valve internals, free up the internal moving rod

 

[410Fortune]

Good advice!! The iac is what controls the idle on these rigs
If I get a stumble at idle I have also been known to clean my mas air flow sensor along with the iac valve