some time ago I posted that my 93 ranger 4 litre xlt was, under load or going uphill, pinging followed by reduction in power and check engine light coming on. I began my journey by installing a kandn air filter, chipping out the catalytic converters and going to a flow through type muffler with 2.25 exhaust pipe as well as decarbing the engine. All the above increased the power pretty good but didn't solve the pinging thing. The computer wasn't storing the code as the incidents were not close enough together. I went back to regular fuel which made things worse and the events to occur more frequently and this caused the computer to store the codes. Result was a dirty mass air flow sensor which the mechanic cleaned out for free. Runs much better now but still pings occasionally but rarely and not as bad.

just thought I'd post it for anyone looking for answers....thanks to the posters for great info...

marmot

 

Thanks for the info. I have a new (to me) '94 explorer that is talking to me going up hills. There isn't any loss of power, but the knocking is bugging me. I'm going to clean the MAF sensor one night this week, and I'm also planning to clean the EGR valve. Glad it worked out for you....

 

I have had similar pinging and knocking issues with my '90 4-cylinder Ranger. I think you are on the right track but let me explain what I have been through.

Along with cleaning and finally replacing the MAF sensor, I had some of my own diagnostics. The EGR valve seemed to be working O.K. however in following up on another thread from this forum I dug deeper. The EGR control was failing. Here's how I diagnosed it: Remove the vacuum line from the EGR valve, insert a "tee" fitting and a scrap piece of vacuum hose to reattach the line to the EGR valve. Another piece of vacuum line from the "tee" to a vacuum guage - long enough that you can take the guage into the cab. Drive the truck and at some point approximately 5" of vacuum will appear on the guage as the EGR valve opens. In my case, the vacuum would slowly disappear back to 0 at which point the pinging began while maintaining a constant speed - about 45 mph as I recall. So, inserted a second "tee" fitting another section of vacuum hose inside the cab and a vacuum pump. Drove down the road again while watching the vacuum guage. As the vacuum began to drop from 5 to 0, while maintaining a steady speed, the pinging began again. I used the vacuum pump to restore the 5" and the pinging stopped.

Trip to the Ford Dealer parts department and ordered a new EGR control valve - $41. This item is attached to the passenger side inner fender on my truck - but follow the vacuum line from the EGR backwards and you should be able to locate it on your truck. The part number for my '90 is E8TZ-9J459-A. Problem solved.
When I took the old control valve apart many of the connections were rusted and some rubber parts had deteriorated.

Good luck

Russ