New here, Hope you can help.

[Dennis Thompson]

I hope this is the right place to ask this question if not please let me know.
My boy has an 85 Ranger 4x4 with a 2.8 V6. We just bought this truck for his first vehicle and the add said it just need clutch work. Well after we got it home I ran it to the original owner who just sold the truck a few week earlier and the guy that bought either decided not to work on it or maby to just make a quick buck. Well the problem, The original owner told me the reason he sold it was because it had a interminted ignition problem that had him stumped. The truck runs good for a while then after a while it starts missing and backfiring. It has stalled a few time and wouldn't start intill coolled down. The distrubuter, coil, ignition modual, O2 senser, plug wires and plugs, and the sencer on the carb are all new. The engine and about 20,000 miles on it. Is there something else I could check?
Thanks. Dennis

 

[prozachappy]

not sure about the 2.8...but I'd check the IAC valve for an internal short. Since the problems start once the trucks at normal op temp. you really need to check the voltage signals in the whole ignition system once the truck warms up. Probably a short somewhere in the wires that kicks in once the engines hot! We had a BII with the 2.9 that did exactly the same thing. Hesitation, stumbling, backfires, sometimes it would die. Once the BII cooled down it would be fine. Problem was somewhere in the ignition wires...but like the previous owner of that ranger we could never track it down. Sorry to say we finally traded it in for another explorer.

 

[cjpwalker]

I knew a guy had a similar problem w/ his old p.o.s. F350. Turned out to be a hairline crack in the distributor cap... once it would heat up the crack would expand, and the coil would short to the block.. ran fine cold for the first few miles, but once warm it would miss, backfire, and have a hell of a time. I would look for a crack or pinched/kinked wire somewhere.

Did you actually do the tune up yourself, or did the seller tell you all that stuff was new?

 

[Runnin'OnEmpty]

Dennis, I would change the pick-up coil/stator inside the distributor. Most techs will change this out along with the ignition control module. Since everything else has been changed, I'll bet a new pick-up coil will fix it.....

The pick-up coil is not to be confused with the ignition coil.

 

[Dennis Thompson]

I would think a new distrubuter came with the pick-up coil. I will check this out and see what I come up with. Do you think if TuneX had it on there machine when it screwed up they could find it. I hate to take it there but after about three weeks of messing with it he realy wants to start driving it.
thanks. Dennis

 

[Runnin'OnEmpty]

Oops, sorry Dennis, I missed the new distributor. It certainly should have a new pick-up coil.

The symptoms you describe are classic for a bad ICM and/or pick-up coil, but since you've replaced both, then that can be ruled out. One other possibility is a faulty ignition switch. Ford had a lot of trouble with switches in the late 80's. Usually there will be something else that won't work if the switch is bad, such as the radio, A/C, interior lights,etc. If any of these don't work at the same time the missing/backfiring starts, that would confirm a bad switch.

Don't know if TuneX could find it or not. Their machine would show a miss, but probably couldn't tell specifically where it was coming from.....

 

[MrShorty]

Have you run the EEC-IV self-tests, yet. On an '85, you don't have a functional check engine light for the computer to tell you when it sees a problem, so you have to ask the computer if it can see a problem. Self-tests are real easy to run, see www.dalidesign.com/hbook/eectest.html It's quite possible the comptuer won't see a problem, but, if it does, then you know where to look next.

 

[Dennis Thompson]

Thanks for the self test info. I did forget to mention that he also replaced the EEC-IV but I'm not sure if he got a new one or a used one. I have heard on some GM cars that you have to change the ignition modual and the coil at the same time or after you replace one the other goes out. Could this be true for this? He said he never changer them at the same time but when he changed one or the other the problem went away for a while. My nest step is to change them both together.
Dennis