You guys all seem to know so much about Broncos and even though they've always been my favorite, I just recently got my first one, which is a 1990 full size EB. 5.8 ltr. V8 engine, etc.

I recently let a "friend" do a tune up for me because, honestly, I couldn't afford a full tune up through a garage at this time. Ever since this though my truck has been making "popping" noises when running.. like mini-backfires. Also, when I have it in park and race the motor there is usually one loud backfire.

At first he had put the plug wires on in the wrong order and the truck would hardly move. Since then he said he fixed it, but obviously not. I was wondering if someone may have a schematic or drawing of the correct firing order of the plugs for this truck so I can just do it my self. The order is listed under the hood, but I'm not sure where to start. If I knew which spark plug was #1 and which was #8 I could check all the wiring. (Also, anyone know the right or best gapping the plugs should have so I can double-check what he did?)

As for the tune up, I had new spark plugs put in, new wires, new cap, new rotor, air filter and changed the oil as well. Is there anything else I should test/change/look at to help complete the tune up and keep the engine from popping, backfiring or missing as it seems to be doing?

I've read a lot about people being able to test their trucks electronically to get "codes" that tell them things that may be wrong as well. Could someone maybe tell me where such a device plugs into in the truck to take such a reading? Perhaps I should purchase one to take a look.

I apologize if some of these questions sound silly but I'm really not very mechanically inclined at the moment. Though I've decided to start taking steps to learn more about the truck and how to repair some of the problems myself.

Thank you for any and all help you can provide.

C.

 

The firing order for the 5.8 is 1-3-7-2-6-5-6-4-8. The distributor spins counterclockwise and the cap should have the number one post marked accordingly. From there you should be able to trace the individual plug wires back to their respective sparkplugs. Cylinders 1-4 are down the passenger side of the engine from front to back and cylinders 5-8 are the same way on the driver's side.

The symptoms are indicative of at least one set of crossed plug wires.

As for pulling the codes, check out www.fordfuelinjection.com or get yourself a Haynes service manual. The process of pulling the codes is described in detail in the Haynes manual. You don't even really need a code reading device for your truck. the codes can be "pulled" with a paperclip or short piece of wire.

 

Don't forget to change your fuel filter and maybe your pcv valve.

 

Most likely you have two cables crossed. Not really a need to get codes for that. If it isn't that then maybe for some reason he turned your distributor a bit and your timing is off; I don't see why he would have moved the distributor though but it is another possibility.

And about the codes; don't buy a code reader...use the paperclip method that greystreak spoke of. If you can count, you are good to go. I'd suggest buying the Haynes Emmisions manual which talks about the codes and shows how to do the paperclip method.

 

Double check the plug wires of course, but ALWAYS check for codes, it's fast and its better to know for sure. I check my truck for codes at least once a month whether i'm experiencing problems or not, its better to catch the problem as its still developing rather than checking for codes while your broke down on the side of the road, or trying to limp home........

 

Just noticed my screw up here and figured I'd rectify it. Firing order can't include the #6 plug TWICE so the corrected firing order is 1-3-7-2-6-5-4-8.

 

[QUOTE=greystreak92]The firing order for the 5.8 is 1-3-7-2-6-5-6-4-8. The distributor spins counterclockwise and the cap should have the number one post marked accordingly.

You got a pretty cool v-8 if you got two #6 cylinders!! Or is that a radial engine?

 

As for the plug gap; they usually come pre-gapped these days but I believe it should be .044

 

Thank you all for all of the help and advice. It really is appreciated. I finally got most of the problems taken care of. Two of the wires were crossed somehow. Turns out the popping noise was because I need a new donut-gasket to fix a small exhaust leak. I'm supposed to get it replaced on Monday, then hopefully everything will be taken care of for a while.

Thanks again.

 

Donut gasket? where? The Bronco and F-series didn't have donut gaskets between the manifolds and the Y-pipe.

 

Honestly, I'm not really sure. The guy I had look at it and tell me that mentioned something about a small leak, possibly near the catalytic convertor, I believe he said. He mentioned a gasket needed to be replaced and made a circle-type shape with his hands. I could have sworn he mentioned something about a "donut gasket", though perhaps not. Unfortunately, I was distracted with something at the moment so just kind of nodded along. Dumb, I know, but too late now. My last vehicle had a donut gasket down there so perhaps I just heard what I wanted to hear. Sorry.

If nothing else, I'll find out where the leak is on Monday when I go to get it fixed and I'll let you know. I do know that the repair is only going to run about $40, so it can't be anything too major.

C.