I just replaced the last two remaining spark plugs (#3 & #4) on my 5.8L 1995 Bronco. Prior to replacing these two spark plugs, the engine ran well. After I repplaced the spark plugs, the engine ran rough. I re-checked the seat and the gap and nothing was amiss. I have double checked the sequence of the firing order and all is good. I also replaced the spark plug wires. I though maybe the timing, but can someone tell me where the SPOUT is si I can disconnect it. I did find that there was a cannister on that side that the bottom had rusted out. I do not know what this cannister is, but my best guess is that it is part of the air pump-which doesn't work.

 

What parts did you use for the tune up? Are they the same as you replaced or did you change the heat rating of the plugs? Did you use different size wires? Did you replace the cap and rotor button?,if not did you clean them at all? If every thing is right and ok with your ignition system check your vacuum hoses. On my last tune up I hit a vacuum line and didn't know it. I rechecked every thing and put all the old parts back onto the engine to see if that was the problem, then I saw the hose broken. It was fine and working but it was dry rotted and it broke off the tip when I hit it. Replaced that hose and every thing went back to normal.good luck.

 

"What parts did you use for the tune up? Are they the same as you replaced or did you change the heat rating of the plugs"-I replaced the spark plugs with the same ones I had replaced the other 6 with previoulsy. Yes, these are different ah the heat ranges than the ones replaced, but this was not an issue with the other 6 plugs.

Did you use different size wires?-I had to replace the wires since the original ones were tore up. I used OEM replacement wires.

Did you replace the cap and rotor button?-No, I did not replace cap and rotor, but that will be on my next things to do.

If every thing is right and ok with your ignition system check your vacuum hoses.-The only thing I can see was that cannister that appears to be part of the air pump for the emissions, but that was plugged up, so as far as I can tell, that should not affect the system.

On my last tune up I hit a vacuum line and didn't know it. I rechecked every thing and put all the old parts back onto the engine to see if that was the problem, then I saw the hose broken. It was fine and working but it was dry rotted and it broke off the tip when I hit it. Replaced that hose and every thing went back to normal.good luck.-When I was replacing one of the spark plug wires, I accidently pulle the entire electrode connector off of the cap and had to re-insert back in. It appears to have gone back in the way it came out, but I am not sure. Maybe it it now totally disconnected because the engine runs like it is missing a hit off of the spark plugs. Thanks.

 

"When I was replacing one of the spark plug wires, I accidently pulle the entire electrode connector off of the cap and had to re-insert back in."

My bet is that this is your problem. Did you feel the wire click onto the plug when you hooked that wire back up? Try pulling that plug wire with the engine running. If you don't notice a difference in the way the motor runs then thats your problem.

Your spout connector is on the drivers side inner fender. It's on the main wiring harness about a foot off the firewall. If it's never been pulled it could still be tucked into the wiring harness and hard to see.

 

I have replaced the distributor cap and have triple checked the spark plug wires. Nada. I also have checked the timing. Nada, still. I also found the spout conector. Thanks.

I have found that the cannister on the passenger side of the engine has a vacuum and I am guessing that that is the problem, but I do not know what the cannister is. I am going to try to remove it and take it in. It looks like it is part of the EGR or Air pump. It has three big hoses connected to it-2 on one side and one on the other with a vauum hose coming up through the base of the cannister.

 

Is this cannister black and shaped like a coffee can? If so the cannister is used to trap fuel fumes that are not burned and at time of fill up. Look in a chiltons manual for cannister purge system. I know what it is but I've never had to work on the system or replace any parts of it before.It should have a black colored dessicant material in it somewhere. That is the actuall part that traps gas fumes. I can see how this could cause a vacuum leak, because the system is supposed to allow the fumes to be reinserted into the engine to be burned, but this is supposed to happen at highway cruise so I would think the system would be closed at idle not allowing a vacuum leak at low rpm. Read up on the system that might be your problem. good luck

 

Mine has three cannisters. One moulded on the side of the A/C evaporator housing by the tranny dip stick for A/C heater controls vac. Second looks like a big grocery store can for engine controls vac. If you live in the rust belt check it. The charcoal cannister is under the battery area but it is purged at certain times by the computer. Buying a vacuum tester for about $30 is worth the money for checking the ageing, cracking vacuum system.