2.3 Barely made it home tonight

[JTB530]

Hello All,
I have a 90 Ranger 2.3 5-speed it is a high mileage truck around 230,000. Other than burning and leaking oil it has been super dependable. Tonight on the way home about 35 minutes into my drive, I was running around 75 in 5th I slowed down to around 60 and started to accelerate again. I noticed a loud popping under the hood and let off the gas, it went away. As soon as I pushed the throttle down it popped again. This time I realized I was hearing a backfire through the breather under load. I backed off the throttle and nursed it home. It has a rough idle/miss as well. The plugs and wires were replaced around 2 years ago as well as the fuel pump. I have limited tools to diagnose the problem at this time but would love some suggestions on where to start.
Thanks in Advance

 

[DevinViss]

does it back fire at idle

 

[PirateB]

2 years on plugs and wires? I'd start there.

Sent from my DROID RAZR HD

 

[JTB530]

The backfire only occurs under load.

 

[DevinViss]

disconnect the coil pack on the intake side and see how it runs if it gets worse pull the plugs in the exhaust side and inspect them.

 

[JTB530]

There was no change after disconnecting the intake side coil

 

[DevinViss]

does not sound like a spark issue the is the MIL on

 

[JTB530]

the mil didn't come on until i unplugged the coil.

 

[DevinViss]

pull the plugs

 

[DevinViss]

when did you replace the timing belt last

 

[RonD]

I think you may have a valve issue, so not good or easy to fix, if tools are limited and time is a factor.

Have a look at these threads:
http://www.therangerstation.com/forums/showthread.php?t=140474

http://www.therangerstation.com/forums/showthread.php?t=139579&highlight=tulip
Page 2

The 2.0/2.3 can also "tulip" the intake valve, the valve gets hot usually from being under load, i.e. 75mph down the highway, maybe it pings a bit(lean mixture so even more heat) and the edges of the intake valve cup a little, so valve is no longer closing all the way, so popping and missing.

 

[JTB530]

The timing belt was done within the last few years. I plan on bringing home some tools tomorrow night to dig a little deeper. I'm leaning towards a valve issue as well. If I have a valve issue I might as well go through the whole engine. Is there a place that you guys would suggest for a complete/master rebuild kit. The truck has too many new parts on it to scrap it. Thanks again for all your help.

 

[RonD]

If you get the valve cover off you will be able to see if a rocker has failed.

You can check for a "tuliped" intake valve by removing a spark plug from a cylinder then rotating the engine, with valve cover off, until both valves are closed.
Put a rubber hose on the spark plug hole and blow in it, if you hear air coming out the intake then the valve isn't sealing/closed.

 

[Andy D]

Slick trick Ron, I'm hoping for an easy worn out rocker for the OP. At 230, k miles, You either do as little as possible, or go big. Have you completely eliminated a faulty spark under load ?

 

[Bachelor-house]

I suspect a bad coil pack, bad wires or plugs.
If you have a buddy with a 2.3, you could install a known working coil pak (exhaust side) to test it. (check your plugs and wires too)