97 Ford Explorer 5.0 AWD ( Hard Starting Issue)

[Dre Ramdhani]

I recently did an engine rebuild on my 97 5.0 put everything back to stock no super modifications just a normal rebuild, i didn't have this issue before i had did the rebuild, side note it took about a month so the car sat for a month, fuel tank was full. fast forward to now, im still having issues with a hard starting problem, the engine will crank over for a long while before starting once it does start it seems to run fine no idle problems or anything, During the rebuild i did a tune up so new spark plugs , wires, and packs were added,
things i have already changed out and no results.
-Fuel Filter
-Fuel Pressure Regulator
-Fuel Pump and Assembly
-Crankshaft Position Sensor
-Camshaft Position Sensor
-Idle Air Control Valve
-Temp Control Sensor
-Purge Valve

The MAF doesnt appear to be malfuctioning as disconnecting it makes the vacuum jump but then plugging it back in it returns to normal.
these are things i can think of off the top of my head right
I have an OBD bluetooth device with the Torque Pro App for android, any other info that anyone needs please ask this problem is just mind boggling, help would be greatly appreciated.

 

[koda2000]

You've replaced a lot of stuff that I would think would contribute to hard starting. Have you ever replaced your pre-cat O2 sensors? How are your fuel trims?

 

[Centaurus5.0]

Are you certain the cam position sensor is installed correctly? Did you reuse your old harmonic balancer? How many miles on it? Showing any codes?

 

[Dre Ramdhani]

Are you certain the cam position sensor is installed correctly? Did you reuse your old harmonic balancer? How many miles on it? Showing any codes?

I have over 190,000 miles on it, i did reuse the old harmonic balance, and the issue was happening when the old cam position was in after the rebuild and continued after i put a new one in anyway.

 

[Dre Ramdhani]

You've replaced a lot of stuff that I would think would contribute to hard starting. Have you ever replaced your pre-cat O2 sensors? How are your fuel trims?

i did not actually replace any o2 sensors, as for the fuel trims no i did not measure, what should i look out for if i were to measure it?

 

[CDW6212R]

Testing things with proper tools and diagnostics is the best for any problem. We spend way more time suggesting things without testing first, so take it all, and mine, as guesses and opinions. Ideally we'd all love to have the diagnostics tools to find an answer before changing anything.

I agree with Koda, your list of things changed since the problem started, is most of what we'd all guess.

The balancer and O2 sensors should be replaced when old normally. At the 190k mark, I'd replace those items even if they aren't the cause of the hard starting. If the balancer is spun just a little(few degrees), then the new cam synchronizer is installed that amount away from where it needs to be. Thus, the bad balancer might not have been a problem yet, before, but now the timing is off if the balancer is spun a bit.

I just bought a new one last week, since reading another thread of a timing chain being replaced, and it reminded me of how old my balancer is now(195k miles). When I do the timing chain, that's the time for everything around it.

 

[fastpakr]

Curiosity question - I just had the rotating assembly in the new 5.0 balanced. Clearly there was some machining done on the old balancer. If I were to install a new one, what if anything should I do to match it up with the rest of the balanced assembly?

 

[Centaurus5.0]

Exactly Don!

When someone that needs help asks a forum whats wrong with their rig, and describes a few symptoms and no codes or measurements, they are essential walking into a room full of blindfolded mechanics and non-mechanics alike to tell them what their cars problem is by noises they make. People also have no clue as to what a new members mechanical experience is and many end up feeling either patronized or bewildered from the answers. Just when I think I know exactly what a problem is because I've seen and heard of the same problem 100 times, it often seems to be something I didn't even think about.

But if the car was right in front of me...


Did you establish #1 TDC using the balancer's markers when setting the CPS? There are many ways to mess up the timing and valvetrain when building a new engine. That was just my first assumption after reading your first post but may very well have nothing to do with the problem.

 

[CDW6212R]

Curiosity question - I just had the rotating assembly in the new 5.0 balanced. Clearly there was some machining done on the old balancer. If I were to install a new one, what if anything should I do to match it up with the rest of the balanced assembly?

No, you should be fine. The balancing process only alters the crankshaft, and rods/pistons if those were also balanced individually. The balancer and flexplate/flywheel are always left untouched. That's why those need to be very high quality, matched properly in balance, to the original components.

 

[fastpakr]

Interesting I would have sworn some material had been removed as if it were modified to adjust weight.

Edit - the five marks at the bottom are what I was referring to.

 

[gatzdon]

What does the computer report for fuel pressure when you turn it off.

Long time to start, But then runs fine generally means check the fuel pump check valve. If bad, fuel pressure will start to drop after turning the engine off.

Not unheard of to get bad parts from the auto store.

 

[CDW6212R]

View attachment 157582 Interesting I would have sworn some material had been removed as if it were modified to adjust weight.

Edit - the five marks at the bottom are what I was referring to.

I didn't see a picture before when you posted this, that looks very odd if they drilled into the balancer. Balancing is about the reciprocating assembly and the crank balance weights, not the two components outside of the engine. The balancer and flexplate must be replaceable without affecting the balance. Who did that engine crank work, I wonder what they did?

 

[Centaurus5.0]

@fastpakr

::edited::

I think you should make a new thread so we can talk about this before we take over the OP's.

 

[Dre Ramdhani]

You've replaced a lot of stuff that I would think would contribute to hard starting. Have you ever replaced your pre-cat O2 sensors? How are your fuel trims?

I just recently got around to checking my fuel trims

Exactly Don!

When someone that needs help asks a forum whats wrong with their rig, and describes a few symptoms and no codes or measurements, they are essential walking into a room full of blindfolded mechanics and non-mechanics alike to tell them what their cars problem is by noises they make. People also have no clue as to what a new members mechanical experience is and many end up feeling either patronized or bewildered from the answers. Just when I think I know exactly what a problem is because I've seen and heard of the same problem 100 times, it often seems to be something I didn't even think about.

But if the car was right in front of me...


Did you establish #1 TDC using the balancer's markers when setting the CPS? There are many ways to mess up the timing and valvetrain when building a new engine. That was just my first assumption after reading your first post but may very well have nothing to do with the problem.

i dont know if it will help but i did line up timing marks and so when i was doing my rebuild, i am going to try to get my hands on a timing gun this weekend to make sure nothing was moved. I should also state to anyone that during the rebuild i did not touch the camshaft at all it was left in place.

 

[Dre Ramdhani]

You've replaced a lot of stuff that I would think would contribute to hard starting. Have you ever replaced your pre-cat O2 sensors? How are your fuel trims?

i just recently got around to checking my fuel trim through my torque app, both long term bank 1 and 2 read about 6.2% stable

 

[Dre Ramdhani]

thorugh my torque app
i have readings
MAF: 5.0g/s
Timing Adv: 17.5%
dont know if those would help or not

 

[Dre Ramdhani]

What does the computer report for fuel pressure when you turn it off.

Long time to start, But then runs fine generally means check the fuel pump check valve. If bad, fuel pressure will start to drop after turning the engine off.

Not unheard of to get bad parts from the auto store.

Fuel check valve? i have a fuel pressure regulator located next to the egr behind the intake manifold more towards the firewall.

 

[CDW6212R]

Fuel check valve? i have a fuel pressure regulator located next to the egr behind the intake manifold more towards the firewall.

That was asking what the fuel pressure is. It needs to be at least 32psi, preferably 35psi, and near 42psi with no vacuum reaching the FPR.

 

[CDW6212R]

The balancer cannot be checked with a timing light, or other diagnostic equipment. Every measurable is determined by the balancer itself, the timing, the crank sensor etc. They all assume the balancer is properly located in relationship with the crank. The problem is that the balancer is made of two steel components, separated by a thin elastic substance. With old age the elastic material begins to let go, and the outer steel ring moves. That movement is a growing error of timing in the ignition/fuel system. If it gets bad, then the balance of the assembly is off, creates vibration first, then destroys the engine. What we are guessing is that that old balancer is off enough that it's affecting the ignition or fuel timing, thus the symptoms.

Check the fuel pressure, either engine off just see what it comes up to, or running and check both at idle and with the FPR vacuum line removed. If everything seems to check out okay, then it's a good time to replace the O2's and balancer.

 

[Dre Ramdhani]

Okay so update: this problem really becomes a problem during hot starts, when the engine has been running for a while im driving about it gets up to temp it really becomes hard to start back after turning it off, cold starts crank long too and sometimes it fires right up no problem.