Popping sound when accelerating?

[Shawnie_leaf]

Need help! I have a Ford Ranger (1999, V6 3.0L, Fuel Flex Engine) that is making a popping sound when I am accelerating the engine. Originally, I had a really rough idle and decrease in power when accelerating (no code). I brought it to a mechanic (spent $280) and he said that he thought that the problem was with the fuel injectors and suggested that I replace them (so I did).

Now, it feels like the problem is worse! Driving is rougher, still has a decrease in power, and now there is a popping sound that is coming out of the air intake?!?!? Any idea what is going wrong?

 

[Uncle Gump]

I've seen lean fuel mixtures cause that. Also firing order not right will do it too.

I've also seen a wiped out cam lobe... bent push rod... bad rocker arm... etc cause popping out the intake.

I would take valve covers off and check mechanical movement of the valve train.

 

[Paulos]

Check your timing also. Have you ever replaced the camshaft position sensor? I understand that they can cause timing problems when they go bad. And a dirty MAF sensor can cause the lean condition Uncle Gump mentioned. Make sure the intake hose between the throttle body and intake isn't damaged, and that there are no vacuum leaks (bad or disconnected hoses).

 

[Paulos]

I've never had a 3.0L Ranger, but I've read some bad things regarding the camshaft position sensor on the 3.0. You should read this https://www.therangerstation.com/tech_library/camshaft_position_sensor.shtml. The issues you're having could be symptoms of the sensor acting up, and if it is, it needs to be changed soon (along with the camshaft syncronizer it attaches to). I understand they should be inspected at 50K and replaced at 100K. If you have no idea if it's ever been replaced, it would - at the very least - be cheap insurance according to the article above, and may be the cause of the issues you're having.

 

[RonD]

You describe rough running which means misfires
When a cylinder misfires all the fuel is not burned so its dumped into the exhaust manifold

It can be ignited by the next firing cylinder on that side of the engine IF that exhaust pulse is hot enough and that causes a "pop" sound
When accelerating all the cylinders get HOTTER, so exhaust gets hotter...............and can ignite unburned fuel in the manifold
Its a backfire so not in the intake side

First thing to do is a compression test, period
Reason is, compression will be a good or bad result, no intermittent or grey area to deal with
And if it IS a compression issue you won't be wasting time and MONEY on non-fixes
So best to take it off the table as the problem, or find out it is the problem right up front

Compression test is done with all spark plugs remove first, cold engine
Then test each cylinder and write down results
3.0l runs 9.3:1 compression ratio, so expected results would be 155-165psi in each cylinder
Actual numbers are based on the gauge and battery condition, what you want is the average number on the day of the test
Cylinders with much lower numbers than average have burnt or leaking exhaust valve usually
Much higher can be bad cam lobes as mentioned above