i need major help. i have a 91 mustang and it surges, hesitates, and backfires like crazy. i have replaced the mass air with a c@l 76mm calibrated for my 19 lb injectors, adjusted the tps sensor for 1 volt, replaced the bad ignition wires, checked the plugs for fouling, turned the mass air meter every which way to see if that helped, it didn't. i even had a diagnostic test done to see what it was, that came up as no data, and i am all out of ideas. the distributer cap is kind of loose, but i just replaced it. what do you guys think is wrong? PLEASE, ANY IDEAS WOULD HELP

 

If it's backfiring, I'd say it's anignition/timing problem. Check to see that the dist is locked down tight and not moving around, replace that loose dist cap or at least make doubly sure it is not cracked. Other places to look...gear on the distributer is not worn or loose, and how about the timing chain. Could it be stretched out?

 

check the battery and the terminals and lead wire to the battery.......

it might not be getting enought juice.... one of te cells in the batt might have gone bad... giving it enough to start but not run properly.. that happned to me once..... the car ran ok but the bass and + terminla were shot... it started and drove but backfired and hesitaated if you got on it .......

 

i took of the cap, and put it back on, the clasps clicked on but it still wiggles a little bit. the batt terminals are ok, i just checked those, and if someone could tell me how to check the timing it would be greatly appreciated. i have access to a timing light just dont know wher to go after hooking it up to the batt and on the first plug wire. thanks for all your input guys

 

Shine it down on the crank pully and look for the timing marks and pointer.

 

sounds like the timing chain to me.....computer has no code to throw for the chain and i assume you keep up with the maintanence

 

i couldnt find the timing table anywhere on the pulley or behind it

 

It's not on the pulley, it's stamped on the harmonic balancer which is right behind the pulley. If you look at about 11:00 behind the crank pulley, you'll se e a little triangular shaped metal pointer that spans across the harmonic balancer. You will want to line the straight side of this pointer up with the timing marks on the balancer. The numbers you are looking for are stamped into the balancer and are most likely down around 4:00 or 6:00 if the engine is stopped. You need to slide under the car and mark the 14 degrees BTDC mark on the balancer with a white grease pencil or some whiteout. That way, you will be able to see it when you trigger your timing light. Be sure to pull the spout out before you try to set the timing. That's a little gray plug that splits off just before the bigger plug that goes into the distributor. Make sure the distributor lock bolt is loose, start the car and with the light triggered and pointing at the aforementioned pointer, turn the distributer one way or the other until it lines up with your white line. Carefully tighten the lock bolt to secure the distributer in place. Do it a little at a time and keep checking that the pointer and your white mark are still lined up. Once the lock bolt is tightened all the way, check one last tine that the mark and pointer are lined up. If they are, push the spout back into its plugin and you're ready to test hop the car. If it pings when you stand on the gas from a stop, you will have to repeat the process and set the timing on 13 degrees BTDC rather than the 14. Keep doing this until the engine doesn't ping under hard acceleration. Once that happens, your timing is set to it's maximum advance. You are now ready to sniff out the next weak link.

Oops, sounds like you have the fancy timing light with the dial on the back. If so, what I have just described is what you will do if you set the dial at Zero. If you set the dial at 14, then you will want to line the pointer up with Zero on the balancer.

One last thing all of the above is assuming your engine is essentially stock. If you're spraying or have boost, you want to take it to someone who knows what they are doing or you will end up with a piston like mine that has a bay window in it. Bad thing, bad thing.

 

i think bay windows are stylish! they are also a great way to lower the compression ratio!