4.0 OHV Top Dead Center questions.

[RonD]

I am sure the Cam sensor could cause rough idle but it shouldn't.
4.0l OHV engine was used from 1990 to 2000 in Rangers
Cam sensor was added in 1995
1990-1994 ran just fine without it
It was added for Sequential Fuel injection and to lower emissions
1990-1994 ran Batch Fire injection

The CRANK sensor is what times the spark and fuel injectors, the Cam sensor was added to refine that timing since it rotates 1deg for each 2deg of crank movement, but not to over ride it.
If Crank sensor pulse doesn't match Cam sensor pulse then Cam sensor pulse is ignored, and computer sets a Cam sensor code.
If Cam synchro was 180deg off then pulse would match crank sensor but injectors would be 180 off
This is why compression stroke TDC is so important

 

[crokarlo]

Exactly I think it's why it ran super rough before. Right now I have the engine at TDC 0 degrees compression stroke and I have the tool on the cam syncro. I'm about to stab it in and put the sensor on it and bolt everything back up and hopefully it should run fine now. I think running it at 10 degrees after TDC was causing issues last night.


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[crokarlo]

When I had it at 180 it ran like shit. No acceleration. Very rough idel. Lots of surging would correct itself here and there but on going problems. Last night at 10 degrees after top dead center it ran perfect and smooth with a little roughness. And had no power under 20 but above 20 had power.


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[Cris Lopes]

Goodnight! I need help to synchronize the camshaft sensor. Searching the web, I found that there are two types of camshaft sensors, and two ways to sync. I had to change the camshaft synchronizer and the sensor, I bought the one that comes with the alignment tool. I followed this information from the website: https://www.therangerstation.com/tech/ford-camshaft-position-sensor-cmp-3-0l-4-0l-5-0l-engines/. To test, I put the 1st cylinder at 0º TDC (compression stroke) and with multimeter I measured the voltage of the sensor, I found 11.49 V. I read in another forum that the 1st cylinder would have to be at 10º ATDC before starting the installation of the camshaft synchronizer . The engine is running, but I think it can get better. Did I install it right?

 

[RonD]

Welcome to TRS

The computer will sync the cam sensor timing with crank sensor timing if its within 2 to 3 degrees of being correct
If its off more than that you will get a Cam sensor code, one of these 3
P0341 Camshaft Position Sensor Circuit Range/Performance
P0342 Camshaft Position Sensor Circuit Low Input
P0343 Camshaft Position Sensor Circuit High Input

So..................you can't "fine tune" the cam sensor, well you can but..........computer will just readjust it after you do, lol

 

[seanagins]

Cylinder #1 has TWO Top Dead Centers
1. Compression stroke TDC
2. Exhaust stroke TDC

So you need to find Compression stroke TDC first, or the rest won't matter

Yes, you put crank pulley at 10deg After TDC, when using the install tool
If you cut a piece of tape 34mm or 1.33", and put it on the LEFT of TDC line on pulley, end of tape will be 10deg After TDC

EDIT
I had right before OOPS

I am struggling with finding TDC for each cylinder to perform a cylinder leak down test....
Any suggestion?

 

[RonD]

Look up the firing order of the engine

4cyl engine fires every 180deg of crank rotation
V6 every 120deg(1/3) of crank rotation
V8 every 90deg(1/4) of crank rotation

Find #1 TDC Compression stroke
Test it
If facing the front of the engine Turn crank 120 deg clockwise, 1/3 of a turn, and you can test next cylinder in firing order
Repeat until all 6 are tested

You can put tape in the crank pulley to make it easier, 3 pie slices with one on TDC mark

 

[seanagins]

Look up the firing order of the engine

4cyl engine fires every 180deg or crank rotation
V6 every 120deg(1/3) of crank rotation
V8 every 90deg(1/4) of crank rotation

Find #1 TDC Compression stroke
Test it
If facing the front of the engine Turn crank 120 deg clockwise, 1/3 of a turn, and you can test next cylinder in firing order
Repeat until all 6 are tested

You can put tape in the crank pulley to make it easier, 3 pie slices with one on TDC mark

I am working on a 1997 Ford Ranger XLT 4.0 liter OHV engine and trying to perform a cylinder leak down test on each cylinder. I have the firing order for my engine as, 1-4-2-5-3-6.

Compression readings from the compression test were the following:

Cylinder 1 175psi
Cylinder 2 170 psi
Cylinder 3 165 psi
Cylinder 4 150 psi
Cylinder 5 175 psi
Cylinder 6 165 psi

I am just trying to run a cylinder leak down test on each cylinder. I believe I can find cylinder one TDC, easily, but I get lost from there... Should I just simply count four notches on the harmonic balancer to get to cylinder 4 TDC from TDC of cylinder 1?

 

[RonD]

The Tone ring/reluctor wheel has 36 teeth - 1, one tooth is missing, pretend its there, lol
120 deg is 1/3 of a circle(360deg)

36/3 = 12

So you would rotate the crank clockwise 12 teeth from #1 TDC Compression stroke to get to #4 TDC compression stroke, then 12 more teeth to #2 TDC
Then 12 more teeth and you should be back to TDC mark on crank pulley to test #5 TDC

Then 12 more for #3 and 12 more for #6

Its a 4 stroke engine so crank spins 2 full turns to complete one full firing order sequence

 

[seanagins]

The Tone ring/reluctor wheel has 36 teeth - 1, one tooth is missing, pretend its there, lol
120 deg is 1/3 of a circle(360deg)

36/3 = 12

So you would rotate the crank clockwise 12 teeth from #1 TDC Compression stroke to get to #4 TDC compression stroke, then 12 more teeth to #2 TDC
Then 12 more teeth and you should be back to TDC mark on crank pulley to test #5 TDC

Thank you.

 

[RonD]

Listen at the tail pipe for escaping air on the higher number cylinders like #1 and #2 so you know what it sounds like on a "good" cylinder

When you get to #4 if you hear more air escaping then its a burnt exhaust valve which is a common issue on ALL engines that use valves, that's why most people have heard of the term "Valve Job", lol, just happens, and there are several reasons for it but nothing you can do to prevent it outside of general engine maintenance

 

[seanagins]

Listen at the tail pipe for escaping air on the higher number cylinders like #1 and #2 so you know what it sounds like on a "good" cylinder

When you get to #4 if you hear more air escaping then its a burnt exhaust valve which is a common issue on ALL engines that use valves, that's why most people have heard of the term "Valve Job", lol, just happens, and there are several reasons for it but nothing you can do to prevent it outside of general engine maintenance

SOUND advice, lol. Thanks, again.

 

[seanagins]

Listen at the tail pipe for escaping air on the higher number cylinders like #1 and #2 so you know what it sounds like on a "good" cylinder

When you get to #4 if you hear more air escaping then its a burnt exhaust valve which is a common issue on ALL engines that use valves, that's why most people have heard of the term "Valve Job", lol, just happens, and there are several reasons for it but nothing you can do to prevent it outside of general engine maintenance

cylinder 1 had a 16% leakage coming from crankcase.
cylinder 4 had a 32% leakage and I am struggling finding where the leakage is? It's not coming from the exhaust tailpipe... or crankcase...
Still have to test the other 4 cylinders.

 

[RonD]

Was radiator cap off?
Cracked head or blown head gasket will show at rad cap, coolant will start to come out once pressure is applied to leaking cylinder

4.0l OHV's were prone to cracked heads if overheated even one time

Ring leakage of 16% would not be a big deal on a leak down
Metal on metal NEVER has a good seal for air
And the rings have the most surface area to seal

Compression test is better test for air seal on the rings, since piston/rings are moving fast so only need to hold the compressing air for a split second, and in your test its above 150psi so had to hold a higher pressure than leak down pressure

Leak down is generally to see if its valves(and which one) that is leaking, or cracked head or blown gasket

 

[seanagins]

Was radiator cap off?
Cracked head or blown head gasket will show at rad cap, coolant will start to come out once pressure is applied to leaking cylinder

4.0l OHV's were prone to cracked heads if overheated even one time

Ring leakage of 16% would not be a big deal on a leak down
Metal on metal NEVER has a good seal for air
And the rings have the most surface area to seal

Compression test is better test for air seal on the rings, since piston/rings are moving fast so only need to hold the compressing air for a split second, and in your test its above 150psi so had to hold a higher pressure than leak down pressure

Leak down is generally to see if its valves(and which one) that is leaking, or cracked head or blown gasket

I looked in the radiator for bubbling coolant, but saw nothing. A tad low on coolant, but still visible from looking down the spout neck of the radiator cap fill neck.