Ticking at full throttle.

[Iron Weasel]

I have a 94 XLT 4x4 4-door with a bone stock 4.0, approximately 180k on it.

Yesterday while on 45 miles trip to buy some tires I found for sale on Craigslist, the blower motor completely stopped working.....since it was relatively quiet without the A/C goind full blast, I heard something I apparently hadn't noticed before.

At full throttle either on level ground or going up hill there's a rapid ticking noise coming from the engine. Can't pinpoint it from inside the cab, but it sounds like it's from the top end. I replaced the plugs along with some other parts (MAF sensor, shocks, A/C compressor) about 2 months ago as part of the "Weasel Summer Maintenance" package. I used NGK platinum plugs (http://www.autozone.com/autozone/parts/Ngk-Gp-Platinum-Spark-Plug/1994-Ford-Explorer-4WD/_/N-j56q5Z8gctd?counter=13&itemIdentifier=441310_0_0_), ran a can of Seafoam through the gas tank and also directly into the engine via the vacuum line method, changed the oil using a Motorcraft filter and 5w-30 dino oil, and put in a 198° thermostat at the same time I did the plugs.

One thing of note is the octane rating for fuel - due to the altitude here (5000+), we have 86, 88, & 91 octane with 10% ethanol. I normally run the 86 octane from the same one or two stations, though I have used fuel from other stations as well and have tried the 88 octane on occasion as well. Changing stations or octane didn't really seem to make a difference.

The thing that's driving me nuts is that it's only at 100% wide open throttle...if I back off just a bit it'll quit ticking.

 

[KobeJ05]

dont know if this will work for you but i was putting in stp octane booster and it worked on every full tank of gas i put in.

 

[MrShorty]

Do you know what "ping" or "spark knock" sounds like? Under those conditions (hard throttle on the highway going uphill), this engine has a tendency to ping. There are a few common causes, all of which have been discussed before (you might put appropriate terms into the site's search engine).

Cleaning the MAF often helps, but you note that you replaced the MAF.

Loose lower intake bolts often cause this ping, and often you can simply tighten them back up to fix.

You might check for any other vacuum leaks/air intake leaks.

 

[n2epv]

Could the ticking noise be a small exhaust leak instead of a spark ping? An exhaust leak would follow the engine speed and be very evenly spaced (if that makes any sense). Spark knock is more random, but still happening faster with a faster engine speed and higher throttle. I would think that spark knock could also be made to go away with high octane gas (unless something's really out of sorts with your engine).

 

[92exp4x4]

Could just be a combination of 180,000miles and 100% throttle. I try to never run my vehicles that hard. I understand though, that there are those moments when full steam is required!

I'd say its ok as long as it is not making noise during normal driving. Most likely you have a small exhaust leak, like n2epv stated. Look for black soot or cracks at connections, manifold etc.

 

[Iron Weasel]

Could be any number of things, I suppose. But since it only does it at WOT, and with 31's and 3.73 gears, it doesn't move very fast anyway, it's not that big of a deal.

Mainly just curious about the possibilities of what it could be. Next time I go fill it up, I might try 10 - 12 gallons of 91 octane to see if that does anything.

 

[Slowlyvverot]

ticking...hmmm are you sure it isn't just your lifters? That's what it sounds like to me.

 

[Iron Weasel]

If it were the lifters ticking, the noise would be there all the time. Doesn't make noise on start-up, doesn't make noise at anything less than wide open throttle, even going up hills it won't make noise unless I mash the pedal to the floor.

It's not a dire problem, so I'm not too overly concerned with it, more out of curiosity than anything.

 

[backfrmcolorado]

On the subject of fuel and the octane scale in the west compared to the scale in MI where in at now... we got 87, 89, and 93 i thinks with also 10% eathanol. I had the same issure with that pinging noise when i drove to Grand Junction, CO this past spring.I used the low grade fuel and went I-70 from Denver to Grand J and up hill i had a real bad pingin noise really bad around the Eisenhouer tunnel. Anyway try useing a bottle of Octanebooster and see if that helps. It did for me in the moutains i refilled on the way back with high grade and octane booster and no pings. Good luck

 

[ShadeTreMechanic]

Greetings. I have the same problem with my 94 Navajo, I found higher octane fuel to be a temporary fix, or a band aid if you prefer. I found a vacuum leak, plugged it and it helped significantly. Although I didn't have to get to WOT for my engine to start rattling very loud. You could have the windows down and the radio going at a decent level rolling at 70 mph down the interstate and hear it quite well. Now you can hear it when you get into it reasonably hard. I am still looking for the rest of the problem but I would try looking for a rotted out vacuum hose somewhere.