The jeep idles very erratically at times, and just today i witnessed it act like someone was inside with the throttle wide open, just flooring it. so i ran over and turned it off. It is NOT overheating in the slightest i dont think. i mean it doesnt even get to 210, i usually see it around 150, maybe 175 at the highest. just going out now and turning it over and watching the idle rpms it floated around 500, then waggled between 500 and 600 then shot up to about 800 for a little while, then crept back down to 500 etc. i noticed at one point the engine seemed to idle high in drive and sort of drive itself until i tweaked the pedal and then in settled down. Im thinking TPS, or IAC or something, id like to give a look myself but it apears to be hex or torq on and i cant find my torq keys. also on about three occasions spread out over a few months the vehicle will start sputtering after i put $20 dollars worth of gas in it. usually if im just doodling around town that day i will throw in only 10 or so, but today it happened again, i go to go on a longer haul, so i throw twice as much gas in as normal and it acts like theres water in the tank or something. sputter, power loss, a few minutes of normal running then power loss stumbling and then it cuts in and goes like its starved for fuel or something. its very bizarre it always happens after a big fill up at the gas station. my father said since its an '87 it may have some sediment in the tank and it gets stirred up and messes with the fuel flow or something, does this make sense?

 

my jeep has similar problem to the first one so it would be interesting to hear what you find out. For the second one I would check the fuel pressure and fuel filter. my jeep got to the point of stalling and i replaced plugs wires dist cap/rotor, and it turned out to be a fuel filter only allowing 20-30% of the necessary fuel through. but I would just check to see what sort of pressure you are getting in your line

 

for the high idle and the sputting if it has O2 sensors in it im not sure if 87 dose but it might try unplugging one. youll throw a code. this will cause it to go into open loop. my 99 did the sputting and erratic idle and it was o2 sensor once i upluged it. the problem went away.

 

i just had the fuel filter replace like 500 miles ago or less

 

i believe i have one o2 sensor in the exhaust system towards the engine, jsut one, not a second post cat one. so your saying i should pull that o2 sensor completely out of the exhaust, or just disconnect the wiring harness? and then start it up and if it runs fine its the o2 sensor?

 

You have a Renix system, your o2 sensor is only for closed-loop operation, basically useless, since the ECU has preloaded values and will work the same.
Try to unplug your IAC when the idle is fine, if it stays ok its bad and needs to be replaced.
If it continues to idle randomly (what i think) it is probably running lean due to low fuel pressure. It could be fuel filter, (note that there is another fuel filter also attached to the FP, in the tank, what usually happens is that this filter gets a hole from rubbing on the bottom of the tank and sucks the sediments in the pump that consequently fails) but i think it is probably the pump.
Check fuel pressure.

 

i started it and it was idleing between 5 and 6 hundred, shot up to 1000 a few times, i unplugged the IAC and it did the same thing, hung out around 5 or 6, shot up to 1000 a few times switched it off, turned it on again (still unplugged IAC) it shot up to 2000 and stuck around so i switched it right off and cranked it back over, back to the inconsistant idling, 6 or 7 hundred, then up to 9 or 1000, then back down for a little while. id love to check fuel pressure but i dont haev a fuel pressure guage, i guess ill have to take it to my mechanic and have him check it

 

If the pump is on its way out then why would it sometimes floor itself and rev so ridiculously high?????

 

Lean mix= more air, therefore acceleration.

 

I'm having that same prob, so thanks for the info, I guess I'll have to check that too.

 

also when i unplugged the IAC it did not make the engine light come on? you said it would throw a code, should the check engine light be coming on when it runs with the IAC unplugged???

 

Renix no codes or check engine lights. Never said that.

 

well i installed the new air inlet to air intake set of vacuum lines, that thexjfiles sold me (big thanks)and it arrived today. seems to be running good so far today. question. i had to splice a little vac line, because oddly enough the vac line that went to everything sank up exact on my 87 except the line to crap some sort of vac sensor or something its disc shaped but upright on its side, it was to short, so i had to steal a connector from the old line and splice in a little more line. Is there a special product i can use to coast all the splices or joints and stuff with to make sure its sealed??? id like to go through and make sure everything is sealed up tight.

 

Nice to hear it's working. You don't need any special sealer for vacuum lines, the vacuum it self applies a negative pressure to the connections and keeps the stuff together.