Hey Guys,

I recently inherited a 2000 Ford Ranger 2.5 2WD with 122K on it. It's in decent shape and runs well (save for the detonation under load), but suffered from lack of routine maintenance. The truck has had issues with detonation (pinging) ever since I can remember, and will start detonating any time you give it half throttle or more in 4th and 5th gear. It's especially bad under load, such as climbing a hill, yet has never thrown a CEL. It was taken into a local shop about 2.5 years and 20K miles ago to diagnose the detonation. They installed new plugs, wires, fuel filter and an EGR valve and solenoid, as well as cleaned the intake and injectors. I wasn't around the truck that often after all this work, but I don't think it made much, if any difference.

Now that it's mine and I'm getting it ready to sell, I changed the oil, fuel, and air filters, Seafoamed the intake, crankcase, and fuel tank, as well as cleaned the throttle body and MAF with the appropriate cleaners. I got very little smoke out of the truck during the treatment, but the detonation issue got MUCH worse when I took it out for a drive. I pulled a plug on the passenger side; it was the correct Motorcraft plug and it looked decent, but showed signs of running lean. The most alarming thing i noticed was the gap was at .055 when the truck specs .042 - .046! I'm guessing the shop just threw the new plugs in and never bothered to properly gap them.

I bought new Motorcraft plugs and went to town on replacing all eight of them, including removing the upper intake to access the driver's side ones. All the plugs came out looking the same and gapped at around .055. The intake looked pretty clean and had very little residue. One of the plug wires did break when removing them, so a new set of Motorcraft wires are on the list. I'm just hoping all this work takes care of the detonation, especially with new, properly gapped plugs. I verified operation of the EGR, but I'm considering replacing the DPFE sensor since it's original. I'm hoping the MAF or some other sensor isn't the issue, as I don't want to throw parts or money at the truck when I just want to get it running well enough to sell it.

Since I've torn this far into it, I'm thinking I should dig a little deeper and replace the timing and accessory belts (both original!), as well as replace the water pump and flush the coolant (original as well). I'm guessing I should replace both the accessory and timing belt tensioners at the same time, too, right? Anything else I should consider? There are no leaks to speak of on the truck, other than a little weeping on the power steering pump.

Any input will be much appreciated!

 

How did you check the EGR valve? Did you just pull vacuum on it and see if the engine stalled or ran rough? Or, did you tee into the vacuum line and install a vacuum gauge and watch for vacuum being applied by the computer via the EGR solenoid as you drive it? You might need to bring along your lovely assistant so she can drive and you can watch the gauge, or vice versa. Distracted driving is not recommended.

When I hear lean and pinging, I also think vacuum leak. Have you checked for leaks at the intake, vacuum lines, fuel injectors, air sneaking past the MAF.

Throttle position would affect ignition advance. Can you check that TPS is functioning properly?

A code reader and some live data would go a long way in shedding some light on this. You could check any sensor that affects air/fuel ratio and gain other valuable information. Lots of possibilities, but the data will help narrow it down.

Someone has posted this link before and it has some really good information on how to test various sensors. Poke around here and try some of these tests before you replace any more parts: Part 1 -Ford Index of Articles

Have you searched for any TSBs for this? The OHVs had issues with pinging and Ford had TSBs for how to deal with it. Maybe there's something for this engine, too.

Those plug gaps aren't too bad, but I wouldn't recommend running more gap than specified as it can be hard on the coil. When I pulled the plugs on my Aerostar, some of the gaps were more than double the spec (over .100 inch) but you never would have know by the way it ran. So much for 100k mile plugs. They were OEM with only single platinum on either the electrode or ground, depending on the bank.