Engine Tapping and CEL

[Cory Conner]

I'm new to this forum and the explorer world but I appreciate all the help in advanced! So recently I purchased a 94 4.0 explorer 4x4 with 330k on it, the price was right at $800 and I was looking for a fun 4x4 for the family. It had a check engine light on but I had never scanned an obd1 before so I believed the guy when he told me it was only the mass air flow sensor. After using a jumper wire and getting the codes flashes back at me it also gave me a 332 and a 558. I replaced the intake manifold gaskets, it was clear they needed replacing. The CEL went off after replacing the gaskets, interesting. I drove it like that for a couple days with no issues. Battery died on me so I bought a new one and noticed the vapor purge valve vacuum lines had cracks in them so I replaced the vacuum lines and the purge valve itself. Then I started it and the CEL was back, weird. Now a new problem surfaced. It would take between 30 seconds and 5 minutes for the CEL to illuminate after startup, during that time it ran great with no issues. As soon as the CEL comes on an engine tap begins, as far as I can tell it sounds like lifters but I’m no mechanic. It also has trouble staying running while idling, often the RPMs drop for a second then it catches itself. Does anyone have any idea where I should start to diagnose or is the answer ‘You bought a high mileage car that starting to give up.” Sorry for the long post but I’m trying to give as much information as I can.

 

[974X4BLACKSPORT]

Start with the basics, spark plugs & wires. Also after it warms up check for exhaust leaks, the can sound like lifter tapping. When its running and making noise, poke your head around the exhaust ports (watch out for long hair, sleeves and jewely), listen for leaks, if it is leaking you will (if hearing is good) hear it, and you might even see a black train left by the exiting exhaust.

 

[massacre]

I would try and see what the intermittent CEL code is.
Imho, OBD-I is not as precise when troubleshooting so reading the codes and testing stuff is really the only way to get to some problems.
Plus it will help people here to be more helpful towards you, as you are in the right place members here are super knowledable

PS
Welcome to the site

 

[92exp4x4]

Welcome! You will definitely be doing yourself a favor to get a scanner that does OBD1. As already mentioned, start with the basics. Fuel, spark and compression.

Vacuum leaks can trigger mass air and O2 sensor codes. I'm dealing with this very thing now with two of my own vehicles. That's why resealing your intake helped. Did you do both the upper and lower intake together? You can have leaks between the lower intake and the cylinder heads. Check all other points of air leakage and eliminate them. The intake tubes were bad about tearing at the throttle body. Also the rubber gaskets dissolve after years of heat and oil. Make sure the tubes at the manifold tree are good. If you have a bad transmission modulator valve, it can suck trans fluid into the intake through the vacuum line. This will change how the engine runs and it will ruin the rubber vacuum hoses and cause them to leak.

The hunting idle can be a mass air problem. I accidentally left one of mine unplugged and it did that very thing. Mine also has an issue with the idle air control. Yours could be sticking. Pull it off and clean the carbon out of it. It may help the hunting condition.

Lifter tick is very common in these engines. Eventually they will collapse completely and will need to be replaced. I'm a huge fan of Lucas oil additive. Since you just got the vehicle, drain about two quarts of oil from the engine and top off with transmission fluid. Drive it on the highway about 50-100 miles or so and change the oil and filter. Substitute 1qt for the Lucas and see if that helps your tick.

The detergents in trans fluid will help clean some of the crap from the engine and oil passages. Just keep in mind that if the only thing holding the engine together is carbon, then it may be rebuild time! The pushrod 4.0 is good for about 330,000 miles until needing overhaul. That seems to be the magic number based on things I've read on this forum for a vehicle that is serviced regularily. That is assuming you have the factory installed engine still in your truck.

I hope some of this helps. Let us know what you find.