am i hearing detonation, pinging, or backfiring?
 

Can't tell what this is. here is what is happening:
when cold mostly- i accelerate I hear a popping sound like pop-pop-poppop-pop. if i let up a little and steadily accelerate, it will not do it, BUT i can tell that it wants to. it does it rhrough 1st and second mostly. i have to bring the rpm's up high before shifting or it will do it more in the next gear. it does it mostly in the lower rpms- basically low rpms. my last tank of gas was regular, but i just put in super and it did it today as well. timing is set at just under 13 i believe. I THINK WHEN THE CAR WARMS UP, IT RUNS FINE, BUT HAVENT DRIVEN IT ENOUGH THIS WEEK TO BE SURE. what can i do? thanks-

PS
IF ANYONE CAN GIVE ME A NUMBER I CAN CALL FOR A SPEEDO GEAR FOR A 90LX WITH 3.55'S I WOULD APPRECIATE IT! CANT FIND THE RIGHT ONE ANYWHERE!

I guess technicaly you're hearing backfiring through the intake as opposed to the exhaust... but whatever it's called can be caused by a couple of things from way off timing to crappy gas (so I'm told) to any other factor that would effect valve timing in relation to ignition timing. When I first did my heads I had it bad and it was ignition timing.. that was cleared up and all was good.. and then some months later I had what you had, popping durring acceleration and I was told it could be BAD GAS or a lean condition... though I'm sure it could be a number of things.. that's what makes it a pain the arse to diagnose


as for the speedo... ford dealers suck. they are usless, around here at least, see if someone get hunt down the part number from an FMS catalog or something.. and then you can order the part through the dealer as long as you have the par tnumber
-as

jimmy-d - Where are you at? Some dealers stock and sell motorsports and other aftermarket parts. Tommie Vaughn Ford on houston is where I get all of my stuff, right off of the shelf for the same price or cheaper than you can order it out of a magazine.

I bought a '90 Lx about 1 year ago. When I bought it, I had the same popping noises. The guy I bought it from put bad gas in it. I use Chevron Supreme and it took a couple times of filling the tank to completely solve the problem; it runs fine now.

For the speedo gear, here's a few places:

Summit Racing Equipment - 1-800-2303030 (the best place)
Holcomb Motorsport - 1-800-475RACE
Mustangs Unlimited - 1-888-2292929
Texas Mustang - 1-800-5271588
California Mustang - 1-800-7750101
Brothers Performance - 1-800-4862681

Could be bad gas, give the new gas a couple of days to mix in and work. I'd first visually check the spark plug wires for cuts or places where it could be rubbing up against headers or exhaust manifolds. Check your plugs. Check air filter-- could be terribly clogged.

thanks for replies. i live in new york, so i will have to call the places metnioned to find the speedo gear. thanks. as far as the plugs are concerned, they are in good shape as well as the air filter. I started the car today and let it warm up and it did not do the popping but i did not accelerate fast at all to avoid it happening. maybe will have to settle in first, i hope!